CN112935464A

CN112935464A - Microprocessor controlled AC/DC contravariant multifunctional argon arc welding machine

Info

Publication number: CN112935464A
Application number: CN202110194240.XA
Authority: CN
Inventors: 蔡献; 陈权; 魏继昆; 黄彪; 朱宣辉; 陈法庆
Original assignee: Zhejiang Kende Mechanical & Electrical Co ltd
Current assignee: Zhejiang Kende Mechanical & Electrical Co ltd
Priority date: 2021-02-20
Filing date: 2021-02-20
Publication date: 2021-06-11

Abstract

The invention relates to a microprocessor-controlled AC/DC inversion multifunctional argon arc welding machine, which has five methods of AC/DC and pulse argon arc welding and manual arc welding; the circuit board is designed into four blocks, namely a primary inversion control board, a secondary inversion control board, an operation and display control board and a main control board; the invention adopts the microprocessor control technology to realize the conversion control of the primary and secondary inverter circuits; the time sequence of output parameters, three welding gun switch operation modes, various protections, welding parameter selection, regulation and display control are realized; dead time detection during alternating current output and a control technology of applying high-voltage arc stabilizing pulses during the transfer of positive half waves to negative half waves are adopted, so that the stability of alternating current arcs is guaranteed; by adopting a switching power supply technology, the cost is reduced, and the network voltage fluctuation resistance is improved; and various hardware and software anti-interference measures are adopted, so that the reliability of the welding machine is improved.

Description

Microprocessor controlled AC/DC contravariant multifunctional argon arc welding machine

Technical Field

The invention relates to a microprocessor-controlled AC/DC inversion multifunctional argon arc welding machine, which has five welding methods of AC argon arc welding, AC pulse argon arc welding, DC pulse argon arc welding and DC manual electric arc welding, three operation modes of 2T, 4T and spot welding and optional VRD function; belongs to the technical field of inverter welding machines.

Background

At present, the market competition of inverter type AC/DC argon arc welding machines is very strong, not only reflects the advancement and advantages of the technology, but also depends on the functions and design of the welding machine, the reliability of the welding machine and other aspects to a great extent.

In the market at home and abroad, the rated current of a small inverter type alternating current-direct current argon arc welding machine with a 220V-240V power supply is usually 160-200A (the load duration rate is 15-40% and the like). Different products have different circuit board structures, different control circuit principles and different overall structure designs, have larger difference in performance, and have larger differences in the technical measures of anti-interference and reliability guarantee of the products. The method has the advantages of few products, few welding methods, poor welding performance, complex and unobtrusive operation and parameter adjustment, poor product reliability and high repair rate. For the problem, the user has strong response and many complaints, which are not acceptable. Through market research, the main reasons for the above problems of such products are: the control circuit and control scheme are not properly designed. For example, because of the analog control circuit, the operation and display control panel has many potentiometers and function switches or setting switches for adjusting different welding methods, so that the operation and parameter adjustment is difficult to perform, and the indicator lamp only has a power supply and an overheating protection indicator lamp; the welding method is only limited to a few methods, such as alternating current argon arc welding, direct current manual welding, no alternating current pulse and direct current pulse argon arc welding method, and no spot welding operation mode. The pulsed argon arc welding is an excellent welding process method with wide application, and is mainly used for welding thin plates, joints at positions difficult to weld, and occasions with strict control requirements on heat input, workpiece deformation and the like. If the welding machine has no pulsed argon arc welding method, the application of the welding machine is necessarily limited, and the welding machine is unacceptable for many users. Furthermore, for welders with multiple welding methods and modes of operation, the more demanding the welding methods and modes of operation, it is clear that solutions with analog control are more difficult to implement. Even if this is possible, the operation and display control panels of the welder are very complex, making it more difficult for the user to operate and use the welder. This is not only true for the operating and display control boards, but similarly for other control circuits, the more demanding the soldering process and operating mode, the more complex the control circuit, and the larger the size and weight of the circuit board and the soldering machine. Due to the fact that a plurality of separating devices are adopted, the device is more easily damaged by ambient temperature and electromagnetic interference, and the product failure rate is high. Therefore, how to solve the problems and develop a welding machine with better performance is a problem which is concerned by or needs to be solved by a plurality of people in the industry of electric welding machines.

The power supply of the welding machine is single-phase 220-240V, and has five welding methods of alternating current argon arc welding, alternating current pulse argon arc welding, direct current pulse argon arc welding and direct current manual arc welding, three operation modes of 2T, 4T and spot welding and optional VRD function.

The invention adopts the microprocessor digital control technology to realize the conversion control of the AC-DC-AC-DC of the primary circuit and the DC-AC, DC pulse and AC pulse of the secondary circuit; the timing sequence and parameter control of 'air supply time in advance', 'arc striking current', 'current rise time', 'peak value or welding current', 'basic value current', 'pulse frequency', 'pulse width', 'alternating frequency', 'cleaning width', 'current attenuation time', 'arc closing current', 'gas closing time lag', 'thrust current' and 'spot welding time' is realized; realizing the switch operation mode control of the SPOT welding torches of '2T', '4T' and 'SPOT'; of course, the content of the parameters varies from welding method to welding method and mode of operation; the control of overheat, overcurrent, overvoltage and undervoltage protection, the parameter selection and adjustment of different welding methods, the state control and the parameter display are realized, and the control requirements of different welding methods are met; dead time detection when alternating current is output and a control technology of applying high-voltage arc stabilizing pulses when positive-polarity half waves are transferred to negative-polarity half waves are adopted to ensure the stability of alternating current arcs; the control of the output of direct current and alternating current, and the control of alternating current frequency and cleaning width during alternating current are realized by controlling the working state of an MOS (metal oxide semiconductor) tube group of a secondary inverter circuit; by adopting a switching power supply technology, a large and heavy low-frequency power supply transformer is omitted, the cost is reduced, and the capability of resisting the voltage fluctuation of a power grid of the welding machine is improved; and various anti-interference hardware circuits and software anti-interference measures are adopted, so that the working reliability of the welding machine is improved.

Disclosure of Invention

The welding machine has good control performance, safety and reliability, so the welding machine has better market adaptability. The good circuit and the structural design thereof are also the advantages of the invention and are the important guarantee of high efficiency, low cost production, high reliability and advanced manufacturing technology. The circuit principle, the circuit board and the whole machine structure of the welding machine are designed with own unique features. The invention is protected by the protection of the circuit and the structural design of the welding machine.

The invention relates to a microprocessor-controlled AC/DC inversion multifunctional argon arc welding machine, wherein the power supply of the welding machine is single-phase 220-240V, and the welding machine has five welding methods of AC argon arc welding, AC pulse argon arc welding, DC pulse argon arc welding and DC manual arc welding, three operation modes of 2T, 4T and spot welding and optional VRD function.

The main components of the welding machine of the invention comprise:

the shell part of the welding machine comprises a handle or a handle, a shell cover plate, a shell bottom plate, a rear panel, a front panel and a shell screw.

The invention relates to a front panel part of a welding machine, which mainly comprises the following parts arranged on the outer side of the front panel of the welding machine: the argon arc welding machine comprises a negative polarity output quick connector assembly, a positive polarity output quick connector assembly, an argon arc welding gun switch, a remote control socket, an air outlet nozzle connected with an argon arc welding gun and an operation and display control panel; the parts installed at the inner side of the front panel mainly comprise: the connecting piece is connected with the output end; the Hall current sensor is penetrated on the connecting piece; the gas pipe is connected with a gas-electricity integrated interface of the welding gun; the two groups of output quick joint components with negative polarity and positive polarity are respectively connected with a workpiece clamp cable and an electric welding clamp cable during manual electric arc welding; during argon arc welding, the two groups of positive output quick connector assemblies are connected with a workpiece clamp cable, the gas outlet nozzle is connected with an argon arc welding gun, and a welding gun switch plug is connected with a gun switch socket.

The welding machine of the invention, the spare part installed on the back panel mainly has: a power switch, an electromagnetic valve, an argon gas inlet nozzle thereof, a power supply line, a plug, a power line pull-off (also called a wire fixing device) thereof, a cooling fan or a (protection) mesh enclosure of a fan. The power line and the plug are connected to a power supply grid. The power switch controls the on or off of the power supply of the welding machine. The cooling fan is positioned at the rear part of the welding machine, and cold air enters from an air inlet hole at the rear part of the welding machine. Some heating devices or parts of the circuit part, such as IGBT and radiator, fast recovery diode and radiator, can be cooled well. The design of the air duct and the cooling mode is beneficial to ensuring the working reliability of the welding machine circuit and is one of the important reasons for realizing larger current and load persistence rate of the welding machine.

The internal parts of the welding machine mainly comprise: the welding gun comprises a primary inversion control panel, a secondary inversion control panel, a main control panel, an insulating plate, two bottom-supported circuit board supports, two auxiliary-supported plastic supports, a connecting piece connected with an output end, a Hall current sensor penetrating through the connecting piece, an air pipe connected with a gas-electricity integrated interface of a welding gun and the like; a plurality of electronic components and parts on the primary inversion control board form a corresponding control circuit, for example, a large electrolytic capacitor for filtering after input rectification, a fast recovery diode for output rectification and an aluminum radiator thereof, an IGBT single tube and an aluminum radiator thereof, an inversion main transformer, a high-voltage pack or a high-frequency transformer and the like; when the inverter control board is installed once, the devices and parts face the center of the welding machine; the primary inversion control board is connected with the circuit board bracket through a connecting screw, and then the circuit board bracket is fixed on the bottom plate of the machine shell through the connecting screw, so that the primary inversion control board is fixed on the bottom plate of the machine shell; a plurality of electronic components and parts on the secondary inversion control board form a corresponding control circuit, for example, an output filter reactor, an arc striking inductance coil, a secondary inversion power transformer, a power resistor and an aluminum radiator thereof, a secondary inversion MOS tube and an aluminum radiator thereof, a rectifier bridge, a thermistor, a copper tube, a secondary inversion MOS tube and an aluminum radiator thereof, and the like; when the secondary inversion control board is installed, the devices and parts face the center of the welding machine; the secondary inversion control board is connected with the circuit board bracket through a connecting screw, and then the circuit board bracket is fixed on the bottom plate of the machine shell through the connecting screw, so that the secondary inversion control board is fixed on the bottom plate of the machine shell; the plastic supports of the two auxiliary supports are respectively fixed with the secondary inversion control plate and the primary inversion control plate through screws, and then the plastic supports and the bottom plate of the machine shell are fixed through screws, so that the auxiliary support function of reinforcing the fixation of the two circuit boards is achieved; the insulating plate is connected with the two circuit boards below by screws above the two circuit boards of the secondary inversion control board and the primary inversion control board, and the insulating plate plays roles of insulation, connection and fixation; the main control board is fixedly arranged above the insulating board; after the installation is completed, because the devices and parts needing heat dissipation on the primary inversion control board and the secondary inversion control board face the center of the welding machine, and the insulating board is fixed on the two circuit boards below, thus, a cooling air channel is formed between the primary inversion control board and the secondary inversion control board, and under the action of the cooling fan installed on the rear panel of the bottom board of the welding machine shell, when cold air passes through the cooling air channel, the devices and the parts on the primary inversion control board and the secondary inversion control board and in the cooling air channel can be effectively cooled, so that the working reliability of the devices and the parts can be guaranteed, and meanwhile, the welding machine is also guaranteed to have higher load duration rate.

The input power of the welding machine is connected to the power input end of the welding machine, and the protective grounding PE end of the power supply system is connected to the protective grounding end of the welding machine and is also the metal frame connecting end of the welding machine. One end of a power switch on the rear panel of the welding machine is connected to a power supply, and the other end of the power switch is connected to the input end of the primary inversion control panel; the socket P1 of the primary inversion control board is connected to the P2 socket of the main control board through a plug and a control line thereof; the IN + and IN-ends of the primary inversion control board are respectively connected to the IN + and IN-ends of the secondary inversion control board; the socket P5 of the primary inversion control board is connected to the socket P1 of the secondary inversion control board through a plug and a control line thereof; the socket P3 of the primary inversion control board is connected to the cooling Fan on the back panel of the welding machine through a plug and a control line thereof; the socket P4 of the primary inversion control board is connected to a Hall sensor HECGQ of the welding machine output loop detection current through a plug and a control line thereof; the socket P7 of the primary inversion control board is connected to the electromagnetic air valve of the welding machine through a plug and a control line thereof; the socket P6 of the primary inversion control board is connected to the welding gun switch on the front panel of the welding machine and the control line of the remote control socket through a plug and the control line thereof. The primary inversion control board is mainly used for obtaining direct current IN the post-stage circuits at the IN + end and the IN-end under the action of the control circuit, and IN addition, the primary inversion control board also comprises the following components: power-on buffer control; the switching power supply circuit generates +15V, -15V and-24V; and detecting current signals of the primary inverter direct current bus, direct current voltage signals output by the primary inverter circuit, current signals output by the secondary inverter circuit, welding gun switches, remote control signals, cooling fans, high-frequency arc striking, electromagnetic gas valve control and the like. The input end of the secondary inverter circuit is connected with the output IN + and IN-ends of the primary inverter circuit; the OUTPUT1 and OUTPUT2 ends of the secondary inversion control board are connected to a positive polarity OUTPUT end and a negative polarity OUTPUT end of the front panel part of the welding machine and an electric OUTPUT interface end of the argon arc welding gun. The secondary inversion control board mainly has the function of realizing control of direct current, (square wave) alternating current, alternating frequency and cleaning width in a post-stage circuit at the ends of OUTPUT1 and OUTPUT2 under the action of a control circuit. The P5 socket of the main control board is connected to the P1 socket of the operation and display control board through a plug and a control line thereof; the P4 socket of the main control board is connected to the P2 socket of the secondary inversion control board through a plug and a control line thereof; the operation and display control panel is mainly used for realizing selection and regulation control of corresponding welding parameters under different welding methods, different operation modes and different welding methods and displaying various states and parameters under the action of the control circuit of the operation and display control panel and the main control panel circuit. The main control board control circuit is mainly used for controlling the work of the primary inverter circuit and the secondary inverter circuit according to the operation information obtained from the operation and display control board, so that the primary inverter circuit and the secondary inverter circuit output corresponding current and voltage according to the control requirement, control various parameters and output states of different welding methods according to the requirement of time sequence control, and display the parameters and indicate various states of the corresponding information through the operation and display control board.

The control circuit of the primary inversion control panel part of the welding machine mainly comprises an input filter circuit, an upper electricity buffer circuit and a control circuit thereof, an IGBT full-bridge inversion main circuit, an output rectification and overvoltage protection circuit, a primary inversion direct current bus current detection and rectification transformation and a current feedback circuit thereof, an IGBT drive circuit (comprising a low-voltage side drive circuit and a high-voltage side drive circuit), a switch power supply circuit with output voltages of VCC-Uf and VCC-Gun, a cooling Fan Fan control circuit, an electromagnetic valve DCF control circuit, an HF high-frequency arc striking control circuit, a primary inversion output voltage detection and feedback circuit, a secondary inversion Hall sensor output current detection and transformation and current feedback circuit thereof, a primary inversion output current setting and signal transformation circuit thereof, a primary inversion output characteristic control circuit, a switch power supply circuit with output voltages of +15V, -15V and-24V, The device comprises a detection control circuit for the input power supply voltage signal, a detection and output signal control circuit for a welding gun switch signal, and a detection and output signal control circuit for a remote control signal. Different control circuits accomplish different functions.

The invention relates to a secondary inverter control board part of a welding machine, wherein the input ends IN + and IN-of a secondary inverter circuit are connected to the output ends IN + and IN-of a primary inverter circuit part; the OUTPUT1 and OUTPUT2 ends of the secondary inversion control board are connected to a positive polarity OUTPUT end and a negative polarity OUTPUT end of the front panel part of the welding machine and an electric OUTPUT interface end of the argon arc welding gun. The secondary inversion control board mainly has the function of realizing control of direct current, (square wave) alternating current, alternating frequency and cleaning width in a post-stage circuit at the ends of OUTPUT1 and OUTPUT2 under the action of a control circuit. The circuit of secondary contravariant control panel part mainly includes: the device comprises a full-bridge inverter circuit consisting of four groups of MOS field effect tube groups, a switching power supply and a driving circuit for controlling MOS tubes, a Hall sensor detection circuit for outputting current, an output current filtering and high-frequency arc striking booster circuit, an alternating current arc stabilizing pulse control circuit and an output loop filter circuit. Different control circuits accomplish different functions. The output control of direct current and alternating current, and the control of alternating current frequency and cleaning width during alternating current are realized by controlling a secondary inverter circuit; during the alternating current argon arc welding, whether pulse control is provided or not, arc stabilizing pulse or arc stabilizing circuit control is also needed.

The anti-interference measure of the hardware circuit of the welding machine mainly comprises the following aspects:

1) and the input filter consists of a T1 common-mode inductor, and C77, C4, C1 and C8 capacitors. The input filter circuit is mainly used for inhibiting electromagnetic noise and clutter signals of an input power supply, preventing interference on a welding power supply control circuit and simultaneously preventing interference of high-frequency clutter generated by the welding power supply on a power grid.

2) The IGBT switch tube and the output rectifier tube have anti-interference measures, and peak interference signals can be generated in the on-off control process of the IGBT switch tube and the output rectifier fast recovery diode in the working process of the primary inverter main circuit. The interference signals are reduced or controlled by resistance-capacitance absorption (such as R73 and R75, C36; R74 and R76, C37; R81 and R85, C39; R82 and R86, C40) connected in parallel at two ends of the IGBT device and an anti-interference circuit of a capacitor C01 connected in parallel at two ends of a direct current bus. And the anti-interference circuit (such as R78, R137 and C78; R79, R136 and C35; R83, R138 and C79; R84, R139 and C38) connected in parallel at two ends of the fast recovery diode devices DX1 and DX2 can reduce spike interference signals in the rectification process of the fast recovery diode.

3) Optical couplers are adopted between the high-voltage loop and the low-voltage loop and between the microprocessor circuit system and the control circuit for electrical isolation, so that the working reliability of the control circuit is guaranteed. U11, U3 linear optocouplers, U17, U10, U12, U13 as in FIG. 3; u3, U8 linear optical coupler and U19 optical coupler in the application of FIG. 4.

4) A decoupling capacitor is arranged between the power supply end close to some main control chips and the ground so as to ensure the working reliability of the chips. For example, in fig. 3, C29, C73 capacitances; a C5 capacitor is arranged between +15V of the U6 chip and the ground; c7 and C59 capacitors are respectively arranged between +15V and-15V of the U15 operational amplifier chip and the ground; in fig. 4, 5 capacitors are arranged between VCC-Gun of the U1 chip and the ground; c60 and C3 capacitors are respectively arranged between the +15V of the U5 operational amplifier chip and the ground; a C23 capacitor is arranged between +15V of the U7 chip and the ground; in fig. 5, a C15 capacitor is provided between VCC of the U6 chip and ground; c3, C4, C6, C5 and C8 capacitors are arranged between the + V power supply of the U1-U5 chips and the ground respectively; a C1 capacitor and the like are arranged between the +15V of the U7 chip and the ground. There are many such decoupling filter capacitors, which are not listed.

5) And (4) output filtering. Referring to fig. 5, the output filter circuit is composed of an output current filter inductor L2, a filter capacitor C19, C17, and C28. The output current filter inductor L2 can inhibit current fluctuation and reduce a burr sudden change signal in a current waveform; the capacitors C19, C17 and C28 are used to prevent high-frequency interference signals entering from the output from adversely affecting the circuitry of the welding machine.

6) In the welding gun switch and the remote control circuit, because the welding gun switch and the remote control circuit are far away from the control circuit of the welding machine, and the control connecting wires are long and easily cause interference, C49 capacitors and C75 capacitors are respectively connected in parallel between the control wires of the welding gun switch and the ground; the filter capacitors of C73, C33, C34 and C4 prevent interference signals from influencing the control performance of the welder.

7) And anti-interference circuits or capacitors are arranged at other main parts, so that the working reliability of the control circuit is further guaranteed. For example, in fig. 3, R47 and C57 are connected in parallel between a given signal input end of U15B and ground to prevent interference on the given signal; r19 and C27 are connected in parallel between the output of the U3 linear optocoupler and the ground, so that interference on the U1f primary inversion output voltage sampling signal is prevented; the C62 capacitor prevents interference on the I2f secondary inversion output current sampling signal; a C18 capacitor for preventing interference of detection signals on the ARC testing secondary inversion output current; in fig. 4, a C64 is connected in parallel between the output signal input end of U5A and the ground, so as to prevent interference on the input voltage detection signal of U1 in; r8 and C2 are connected in parallel between the output signal input end of the U3 and the ground, so that the interference to a given current signal of remote control is prevented; in FIG. 6, a C5 capacitor is connected between the ground and the protective ground of the power supply system, and a C1-C4 filter capacitor is used for preventing interference signals from influencing the operation of the circuit of the operation and display part; in fig. 7, a plurality of capacitors, such as C5, C33, C17, C28, C24 and the like, connected between the control line and the ground prevent the interference signal from influencing the operation of the control part circuit of the microprocessor. There are many such anti-interference measures, which are not listed.

The above measures are an important prerequisite for ensuring the working reliability of the welding machine product made of the circuit of the invention.

The welding machine of the invention with different current grades and load duration requirements can form products with different output rated currents and load duration by adjusting the quantity and specification parameters of a small number of parts on the circuit board, so that the products are serialized. For example, the capacity of a large electrolytic capacitor of a filter after input rectification is changed; changing the current grade parameter of the input rectifier bridge; changing the current grade and the size of a radiator of the IGBT device; changing the model and parameters of the output fast recovery diode and the using number of the output fast recovery diode; the specifications, parameters and the like of the inverter main transformer and the output filter reactor are changed, and series products with different specifications can be easily formed. Such as 200A/28V, 180A/27.2V, 160A/26.4V and 140A/25.6V. These variations, of course, aim to match the production costs of the product with the specifications and performance specifications of the respective machine. In this way, each specification type of welder can achieve optimal cost control. This enhances the market competitiveness of the developed product.

The welding machine has five welding methods, three operation modes, and good control characteristic and reliability of the circuit composition of the microprocessor control and the like, so the welding machine has better market adaptability. The control circuit and the structural design thereof are also the advantages of the invention and are important guarantees of high efficiency, low cost production, high reliability and advanced manufacturing technology. The circuit principle, the circuit board and the whole machine structure of the welding machine are designed with own unique features. The invention is protected by the protection of the circuit and the structural design of the welding machine.

Drawings

FIG. 1 is a schematic structural view of an exemplary welder made using the present invention;

FIG. 2 is a schematic block circuit diagram of the welder of the present invention;

FIG. 3 is a schematic circuit diagram of a primary inverter control board of the welding machine of the present invention;

FIG. 4 is a circuit schematic diagram of a primary inverter control board of the welding machine of the invention;

FIG. 5 is a schematic circuit diagram of a secondary inverter control board of the welding machine of the present invention;

FIG. 6 is a schematic circuit diagram of the operating and display control panel of the welder of the present invention;

FIG. 7 is a schematic circuit diagram of the main control board of the welder of the present invention;

the names of the components in figure 1 are as follows: 1. a handle or handle; 2. a case cover plate; 3. an insulating plate; 4. a main control panel; 5. a secondary inversion control board; 6. a circuit board holder; 7. a plastic support; 8. a primary inversion control board; 9. an input power line; 10. a power switch; 11. an electromagnetic gas valve; 12. a rear panel; 13. a cooling fan mesh enclosure; 14. a cooling fan; 15. a chassis base plate; 16. a Hall current sensor; 17. a front panel; 18. a positive output quick connector assembly; 19. a welding gun switch and a remote control socket; 20. a negative output quick connector assembly; 21. connecting an air outlet nozzle of the argon arc welding gun; 22. an operation and display control panel; 23. an output filter reactor; 24. an arc striking inductive coil; 25. a secondary inverter power transformer; 26. a power resistor; 27. a secondary inversion MOS tube; 28. a rectifier bridge; 29. a thermistor; 30. a copper pipe; 31. a large electrolytic capacitance; 32. a fast recovery diode; 33. an IGBT single tube; 34. an inverting main transformer; 35. a high-voltage pack; 36. and a secondary inversion MOS tube.

Detailed Description

As shown in the attached figure 1, the microprocessor-controlled AC/DC inversion multifunctional argon arc welding machine mainly comprises the following structural components:

1) the shell part comprises a handle or handle 1, a machine shell cover plate 2, a machine shell bottom plate 15, a back plate 12, a front plate 17 and machine shell screws.

2) The parts installed on the back panel mainly include: a power switch 10, an electromagnetic valve 11 and an argon gas inlet nozzle thereof, a power supply line, a plug and a power line pull-off (also called a wire fixing device) 9 thereof, a cooling fan 14 and a mesh enclosure 13 of the cooling fan or the fan. The power line and the plug are connected to a power supply grid. The power switch 10 controls the on/off of the welder power supply. The cooling fan 14 is located at the rear of the welder and cold air is taken from the air inlet at the rear of the welder. Some heating devices or parts of the circuit part, such as IGBT and radiator, fast recovery diode and radiator, can be cooled well. The design of the air duct and the cooling mode is beneficial to ensuring the working reliability of the welding machine circuit and is one of the important reasons for realizing larger current and load persistence rate of the welding machine.

3) The front panel part, the spare part of welding machine front panel outside installation mainly has: a negative polarity output quick connector component 20, a positive polarity output quick connector component 18, an argon arc welding gun switch, a remote control socket 19, an air outlet nozzle 21 connected with an argon arc welding gun, and an operation and display control panel 22; the parts installed at the inner side of the front panel mainly comprise: a connecting piece connected with the output end, a Hall current sensor 16 penetrating into one connecting piece, and an air pipe connected with the gas-electricity integrated interface of the welding gun. The two groups of output quick joint components with negative polarity and positive polarity are respectively connected with a workpiece clamp cable and an electric welding clamp cable during manual electric arc welding; during argon arc welding, the two groups of positive output quick connector assemblies 18 are connected with a workpiece clamp cable, the gas outlet nozzle 21 is connected with an argon arc welding gun, and a welding gun switch plug is connected with the gun switch socket 19.

For the operating and display control panel 22 part, on the left above the panel, a nixie tube is provided for displaying parameters and error codes. On the right side of the nixie tube, four unit symbol indicating lamps of "A", "S", "percent" and "Hz" are arranged from top to bottom at positions close to the nixie tube. On the right side of the four unit symbol indicating lamps, welding parameter indicating lamps which are different from left to right in height and position and correspond to current waveform time sequences in different stages are arranged, and the welding parameters comprise air supply advance time, arc striking (or hot start) current, arc thrust (or thrust current) or spot welding time, (current) rise time, welding current or pulse peak current, alternating current frequency, base current, (alternating current) cleaning width, (current) attenuation time, arc receiving (or fire hole filling) current, pulse frequency or pulse width (or pulse time) and lagging air closing time. And a VRD ON indicator lamp and a VRD OFF indicator lamp are arranged below the nixie tube, the VRD function is a function which can be selected during manual welding, and the VRD function represents a no-load low-voltage output function of manual welding. Five indicator lamps of alternating current argon arc welding (AC TIG), alternating current PULSE argon arc welding (AC PULSE TIG), direct current argon arc welding (DC TIG), direct current PULSE argon arc welding (DC PULSE TIG) and manual welding (MMA) are arranged on the left part of the lower part of the nixie tube from top to bottom, and a selection key of a welding method is arranged on the right side of the five indicator lamps. Three torch switch operation mode indicating lamps of 2T, 4T and SPOT welding are arranged from top to bottom on the right side of the welding method selection key, and a torch switch operation mode selection key is provided on the right side of the three indicating lamps. An encoder with a key is arranged at the right side of the operation mode selection key of the welding gun switch and below the plurality of welding parameter indicating lamps. On the right side of the encoder, three indicator lights are arranged from top to bottom for remote control, tungsten electrode or welding rod diameter, and other information prompts.

For the operation and display control panel 22, when the welding machine is working, when the welding method selection button is pressed, the indicator lamp corresponding to the selected welding method is lighted, which indicates that the welding method corresponding to the lighted indicator lamp is selected, and when the welding method button is pressed in sequence, the indicator lamps of different welding methods are lighted in sequence and changed in a cycle.

When the welding operation mode selection key is pressed, the indicator lamp corresponding to the selected corresponding operation mode is lightened, the operation mode corresponding to the lightened indicator lamp is indicated to be selected, and when the welding operation mode selection key is pressed in sequence, the indicator lamps of different operation modes are lightened in sequence and change in a circulating mode.

The welding parameters and functions that can be selected and set for different welding methods are different for the operating and display control panel 22 portion. For example, when selecting the manual MMA method, welding parameters that may be selected are welding current, thrust current, and electrode diameter. Under the condition of selecting the manual welding method, the indicator lamps corresponding to the parameters of the welding current, the thrust current and the diameter of the welding rod can be selected in sequence by pressing down the keys of the encoder. When one indicator light is selected to be lightened, the corresponding parameter can be adjusted through the encoder. For example, when the corresponding welding current or peak current indicator lamp is turned on, it indicates that the welding current parameter is selected, and at this time, the welding current can be adjusted by the encoder; when the corresponding arc thrust (or thrust current) or spot welding time indicator lamp is lightened, the thrust current parameter is selected, and the thrust current can be adjusted through the encoder; when the corresponding tungsten electrode or welding rod diameter indicating lamp is lighted, the diameter of the welding rod is selected, and at the moment, the diameter of the welding rod corresponding to actual use can be selected through adjustment of the encoder.

For the operation and display control panel 22 portion, in the case of selecting the direct current argon arc welding method, there are three torch switch operation mode options of 2T/4T and SPOT welding. By pressing a key of the encoder, the 2T or 4T welding gun switch operation mode can be selected, and the 2T or 4T indicator lamp is turned on correspondingly; a SPOT welding SPOT mode can be selected, and a corresponding SPOT indicating lamp is lightened. The welding parameters that may be selected may be different for different modes. Under the direct current argon arc welding, the indicator lamps corresponding to different parameters can be selected in sequence by pressing a key of the encoder. When a certain indicator light is selected, the corresponding parameter can be adjusted by the encoder. When a certain indicator light is selected to be lightened by pressing a key of the encoder, the corresponding parameter can be adjusted through the encoder. In addition, when a certain parameter (not including the electrode diameter) is selected, the corresponding unit indicating lamp is lighted. When the key of the encoder is operated, if the 'certain' indicator lamp cannot be lightened, the parameter corresponding to the indicator lamp is not the welding parameter under the selected welding method, so that the indicator lamp cannot be lightened or selected for operation.

For the operation and display control panel 22, the modes and welding parameters for the dc pulsed argon arc welding, the selection of the ac argon arc welding and the ac pulsed argon arc welding are different from the parameters that can be selected and adjusted in the different welding gun switch operation modes, and the parameter selection and setting or adjusting method is similar to the manual welding and the dc argon arc welding described above. And are not described one by one here.

4) The parts in the welding machine mainly comprise: the welding gun comprises a primary inversion control plate 8, a secondary inversion control plate 5, a main control plate 4, an insulating plate 3, two circuit board supports 6 supported at the bottom, two plastic supports 7 supported at the auxiliary part, a connecting piece connected with the output end, a Hall current sensor 16 penetrating through the connecting piece, an air pipe connected with a gas-electricity integrated interface of a welding gun and the like; a plurality of electronic components and parts on the primary inverter control board 8 form a corresponding control circuit, for example, a large electrolytic capacitor 31 for filtering after input rectification, a fast recovery diode 32 for output rectification and an aluminum radiator thereof, an IGBT single tube 33 and an aluminum radiator thereof, an inverter main transformer 34, a high-voltage pack or a high-frequency transformer 35, and the like; when the inverter control board 8 is installed once, the devices and parts face the center of the welding machine; the primary inversion control board 8 is connected with the circuit board support 6 through a connecting screw, and then the circuit board support 6 is fixed on the chassis bottom plate 15 through the connecting screw, so that the primary inversion control board 8 is fixed on the chassis bottom plate 15; the secondary inverter control board 5 has a plurality of electronic components and parts to form a corresponding control circuit, for example, an output filter reactor 23, an arc striking inductance coil 24, a secondary inverter power transformer 25, a power resistor 26 and an aluminum radiator thereof, a secondary inverter MOS tube 27 and an aluminum radiator thereof, a rectifier bridge 28, a thermistor 29, a copper tube 30, a secondary inverter MOS tube 36 and an aluminum radiator thereof, and the like; when the secondary inverter control board 5 is installed, the devices and parts face the center of the welding machine; the secondary inversion control board 5 is connected with the circuit board support 6 through a connecting screw, and then the circuit board support 6 is fixed on the chassis bottom plate 15 through the connecting screw, so that the secondary inversion control board 5 is fixed on the chassis bottom plate 15; the two plastic supports 7 of the auxiliary support are respectively fixed with the secondary inversion control plate 5 and the primary inversion control plate 8 through screws, and the plastic supports 7 and the chassis bottom plate 15 are fixed through screws, so that the auxiliary support function of reinforcing the fixation of the two circuit boards is achieved; the insulating plate 3 is connected with the two circuit boards below by screws above the two circuit boards of the secondary inversion control board 5 and the primary inversion control board 8, and the insulating plate 3 plays roles of insulation, connection and fixation; the main control board 4 is fixedly arranged above the insulating board 3; after the installation is completed, because the devices and parts needing heat dissipation on the primary inversion control board 8 and the secondary inversion control board 5 face the center of the welding machine, and the insulation board 3 is fixed on the two circuit boards below, thus, a cooling air duct is formed between the primary inversion control board 8, the secondary inversion control board 5 and the casing bottom board 15, under the action of the cooling fan 14 installed on the rear panel of the casing bottom board 15 of the welding machine, when cold air passes through the cooling air duct, the devices and parts on the primary inversion control board 8 and the secondary inversion control board 5 and in the cooling air duct can be effectively cooled, thereby the working reliability of the devices and parts can be ensured, and meanwhile, the welding machine is also ensured to have higher load duration rate.

FIG. 2 is a schematic block circuit diagram of the welder of the present invention; FIG. 3 is a schematic circuit diagram of a primary inverter control board of the welding machine of the present invention; FIG. 4 is a circuit schematic diagram of a primary inverter control board of the welding machine of the invention; FIG. 5 is a schematic circuit diagram of a secondary inverter control board of the welding machine of the present invention; FIG. 6 is a schematic circuit diagram of the operating and display control panel of the welder of the present invention; FIG. 7 is a schematic circuit diagram of the main control board of the welder of the present invention.

Fig. 2 is a schematic circuit diagram of the welding machine of the present invention, which is designed with four circuit boards, namely, a primary Inverter Control board (One-Inverter-PCB), a secondary Inverter Control board (Two-Inverter-PCB), a Main Control board (Main Control-PCB), and an Operation and Display Control board (Operation + Display-PCB). The input power supply is connected to the ends L1 and N1, and the protective grounding PE end of the power supply system is connected to the protective grounding end of the welding machine and is also the metal frame connecting end of the welding machine. One end of a power switch KG on the rear panel of the welding machine is connected to a power supply, and the other end of the power switch KG is connected to the L, N end of the primary inverter control panel; the socket P1 of the primary inversion control board is connected to the P2 socket of the main control board through a plug and a control line thereof; the IN + and IN-ends of the primary inversion control board are respectively connected to the IN + and IN-ends of the secondary inversion control board; the socket P5 of the primary inversion control board is connected to the socket P1 of the secondary inversion control board through a plug and a control line thereof; the socket P3 of the primary inversion control board is connected to the cooling Fan on the back panel of the welding machine through a plug and a control line thereof; the socket P4 of the primary inversion control board is connected to a Hall sensor HECGQ of the welding machine output loop detection current through a plug and a control line thereof; the socket P7 of the primary inversion control board is connected to the electromagnetic air valve of the welding machine through a plug and a control line thereof; the socket P6 of the primary inversion control board is connected to the welding gun switch on the front panel of the welding machine and the control line of the remote control socket through a plug and the control line thereof. The primary inversion control board is mainly used for obtaining direct current IN the post-stage circuits at the IN + end and the IN-end under the action of the control circuit, and IN addition, the primary inversion control board also comprises the following components: power-on buffer control; the switching power supply circuit generates +15V, -15V and-24V; and detecting current signals of the primary inverter direct current bus, direct current voltage signals output by the primary inverter circuit, current signals output by the secondary inverter circuit, welding gun switches, remote control signals, cooling fans, high-frequency arc striking, electromagnetic gas valve control and the like. The input end of the secondary inverter circuit is connected with the output IN + and IN-ends of the primary inverter circuit; the OUTPUT1 and OUTPUT2 ends of the secondary inversion control board are connected to a positive polarity OUTPUT end and a negative polarity OUTPUT end of the front panel part of the welding machine and an electric OUTPUT interface end of the argon arc welding gun. The secondary inversion control board mainly has the function of realizing control of direct current, (square wave) alternating current, alternating frequency and cleaning width in a post-stage circuit at the ends of OUTPUT1 and OUTPUT2 under the action of a control circuit. The P5 socket of the main control board is connected to the P1 socket of the operation and display control board through a plug and a control line thereof; the P4 socket of the main control board is connected to the P2 socket of the secondary inversion control board through a plug and a control line thereof; the operation and display control panel is mainly used for realizing selection and regulation control of corresponding welding parameters under different welding methods, different operation modes and different welding methods and displaying various states and parameters under the action of the control circuit of the operation and display control panel and the main control panel circuit. The main control board control circuit is mainly used for controlling the work of the primary inverter circuit and the secondary inverter circuit according to the operation information obtained from the operation and display control board, so that the primary inverter circuit and the secondary inverter circuit output corresponding current and voltage according to the control requirement, control various parameters and output states of different welding methods according to the requirement of time sequence control, and display the parameters and indicate various states of the corresponding information through the operation and display control board.

FIG. 3 is a schematic circuit diagram of a primary inverter control board of the welding machine of the present invention, the control circuit of the part mainly comprises an input filter circuit, an electrifying buffer circuit and a control circuit thereof, an IGBT full-bridge inverter main circuit, an output rectification and overvoltage protection circuit, a primary inverter direct-current bus current detection and rectification conversion and current feedback circuit thereof, an IGBT drive circuit (comprising a low-voltage side drive circuit and a high-voltage side drive circuit), a switch power supply circuit with output voltages of VCC-Uf and VCC-Gun, a cooling Fan control circuit, an electromagnetic valve DCF control circuit, an HF high-frequency arc striking control circuit, a primary inverter output voltage detection and feedback circuit, a secondary inverter Hall sensor output current detection and conversion and current feedback circuit thereof, a primary inverter output current setting and signal conversion circuit thereof and a primary inverter output characteristic control circuit.

FIG. 4 shows a schematic circuit diagram of a primary inverter control board of the welding machine of the present invention, wherein the control circuit of the primary inverter control board is mainly composed of a switching power supply circuit with output voltages of +15V, -15V and-24V, a detection control circuit for the input power supply voltage signal level, a welding gun switching signal detection and output signal control circuit, and a remote control signal detection and output signal control circuit.

The circuits shown in fig. 3 and 4 are all designed on a primary inversion control board, and the primary inversion control board is connected with other circuit boards and external parts through a plug and a control line thereof according to the description of the previous fig. 2, so as to realize various control requirements of the primary inversion control circuit.

The function and operation of the circuit of the primary Inverter board (One Inverter-PCB) shown in fig. 3 and 4 will be described as follows:

referring to fig. 2 and fig. 3, a single-phase 220-24V power supply of the welding machine is connected to the input ends of L1 and N1, and a protective grounding PE end of the power supply system is connected to a protective grounding end of a metal casing of the welding machine; one end of a power switch KG on the rear panel of the welding machine is connected with the L1 end and the N1 end, and the other end of the power switch KG is connected with the L, N input end of the primary inverter board; the end L, N is connected with the input filter circuit.

1) The input filter circuit consists of a T1 common-mode inductor, a C77 capacitor, a C4 capacitor, a C1 capacitor and a C8 capacitor; the capacitor C77 is connected in parallel with two ends of the input stage of the common mode inductor T1, the rear stage of the common mode inductor T1 is connected, the rear stage of the inductor is connected in parallel with a capacitor C4, one end of the common mode inductor T1 is connected with a capacitor C8, the other end of the common mode inductor T1 is connected with a capacitor C1, and the other ends of the capacitor C8 and the capacitor C1 are connected with a protective grounding end of a PE end (welding machine frame). The input filter circuit is mainly used for inhibiting electromagnetic noise and clutter signals of an input power supply, preventing interference on a welding power supply control circuit and simultaneously preventing interference of high-frequency clutter generated by the welding power supply on a power grid; c1 and C8 are safety capacitors; the input filter circuit is arranged to ensure that the welding machine has certain EMC electromagnetic compatibility, and is one of important measures for resisting interference of a hardware circuit and improving the reliability of the welding machine.

2) The power-on buffer circuit is shown in figure 3, input alternating current also passes through the power-on buffer circuit which is composed of RT1 and RT2 thermistors which are connected in parallel and a contact K2-1 of a relay K2, then is rectified by a rectifier B1 to be changed into pulsating direct current, large electrolytic capacitors E1-E4 are charged, the voltage gradually rises, and finally the alternating current is changed into stable high-voltage direct current. The control circuit of the relay K2 is composed of a field effect transistor VT5, a U11 optocoupler, a light emitting diode D13, a voltage regulator tube Z4, resistors R54-R56 and R59, a capacitor C55 and a 24V power supply; the U11 optical coupler is used for isolating a high-voltage circuit and a low-voltage circuit, so that the reliability of a control circuit of the welding machine is guaranteed; the cathode of the light emitting diode in the U11 optical coupler is grounded, the anode of the light emitting diode is connected to R55, the other end of R55 is connected to the 18-pin K2 Control signal end of the P1 socket, the signal end is connected to the 18 pin of the P2 socket 18 pin of the main Control board in fig. 7 through a P1 plug and a Control line thereof, and finally connected to the 24 pin of the U4 microprocessor in fig. 7, that is, the K2 Control signal end is controlled by the U4 microprocessor. The collector of the U11 optocoupler triode is grounded, the emitter of the U11 optocoupler triode is connected with R54, the other end of R54 is connected with the anode of D13, and the cathode of D13 is connected with the cathodes of C55 and Z4, and the other ends of the cathodes of R56, C55 and Z4 are connected with minus 24V. The other end of R56 is connected with the G end control electrode of R59 and VT5, and the other end of R59 is connected with-24V. The S terminal of VT5 is connected to-24V, the D terminal of VT5 is connected to the anode of D10, one end of K2 coil, the other end of K2 coil and the cathode of D10 are grounded. the-24V power supply comes from the switching power supply circuit in fig. 4. The contact K2-1 of K2 is connected in parallel with the parallel RT1 and RT2 thermistors, and is connected in series between the welder power supply and the input end of a rectifier bridge B1; the action time of the K2 relay lags behind the closing time of the power switch KG, namely the K2 relay is in delayed action. When the charging voltage on the electrolytic capacitors E1-E4 is stable, the K2 relay operates, the contact K2-1 closes the parallel RT1 and RT2 thermistors, so that when the welding machine works in an inversion mode, large current flows through the K2-1 of the K2 relay. Such a circuit is called a power-on buffer circuit. The power switch is mainly prevented from being switched on instantly, and due to the fact that no voltage exists on the electrolytic capacitors E1-E4, the short circuit is equivalent to the phenomenon that large surge current is formed, and a power switch KG is burnt out. The function of the power-on buffer circuit is to limit surge current by connecting the RT1 and RT2 thermistors in parallel at the moment of switching-on. The resistance of the parallel RT1 and RT2 thermistors increases with the temperature. Therefore, the power-on buffer circuit can play a better protection role.

3) An IGBT full-bridge inverter circuit is shown in figure 3 and comprises electrolytic capacitors E1-E4, resistors R9-R10 and R14-R15 for releasing energy stored on E1-E4 after a welder power supply is turned off, a filter capacitor C01, four IGBT tubes IGBT1 and IGBT3 (which are a group of switches), an IGBT2 and IGBT4 (which are another group of switches), an inverter main transformer T5, a main transformer primary current detection transformer T8, four double fast recovery diodes DX1 and DX2 and the like. The input power supply is rectified by a rectifier B1, and filtered by an electrolytic capacitor E1-E4 to obtain + VCC high-voltage direct-current bus voltage which is supplied to an IGBT full-bridge inverter circuit. Under the action of the driving control signals of the four IGBT tubes, one group of switches of the IGBT1 and the IGBT3 and the other group of switches of the IGBT2 and the IGBT4 can be switched on and off alternately, so that the primary winding N1 of the inverter main transformer T5 obtains alternating current, and the inverter conversion from direct current to alternating current is realized. The IGBT full-bridge inverter circuit has the function of converting high-voltage direct-current bus voltage into medium-frequency (dozens of KHz) alternating current. The inversion main transformer T5 realizes voltage reduction and conversion of large current output. The inverter main transformer T5 has three secondary windings, N2, N3 and N4, with the N4 winding located in the upper left hand portion of fig. 3, i.e., the high frequency control circuit.

4) The output rectifying and overvoltage protection circuit, see secondary N2, N3 of fig. 3, T5, is connected IN between, and is the ground, also the IN-output. Two diodes are respectively arranged IN DX1 and DX2, the other ends of N2 and N3 are respectively connected with anodes of fast recovery diodes IN DX1 and DX2, and cathodes of the diodes are connected together to be an output IN + end. The intermediate frequency ac output from the inverter transformer T5 is rectified and converted into dc by the fast recovery diodes DX1 and DX 2. An absorption protection circuit of a fast recovery diode DX1 is shown in figure 3 and comprises resistors R78 and R137, resistors R79 and R136 and capacitors C78 and C35 which are connected in parallel, wherein the resistors and the capacitors which are connected in parallel are connected in series and then connected in parallel at two ends of DX 1; similarly, the absorption protection circuit of the fast recovery diode DX2, as shown in fig. 3, is composed of resistors R83 and R138, resistors R84 and R139, and capacitors C79 and C38, which are connected in series and then connected in parallel to two ends of DX 2. The resistor-capacitor series protection circuit is also an absorption circuit of the diode, and can prevent the diode from being damaged by peak overvoltage.

5) The primary inversion direct current bus current detection and rectification transformation and the current feedback circuit thereof are shown in figure 3, the primary inversion bus current is detected through the primary side of a transformer T8, and the primary side of T8 is connected in series in the primary loop of T5. The T8 can electrically isolate the high-voltage circuit from the low-voltage circuit, which is beneficial to the reliability of the work of the control circuit of the welding machine. The secondary output of T8 is detected signal, the signal passes through full wave rectification circuit composed of four diodes in D34 and D35 double diode module, and is transformed into DC signal, the output of full wave rectification circuit is connected with R97 and R116 resistance in parallel to the ground, finally the primary current detection signal I of primary inversion is obtained_1f. This signal is used to participate in the output current control of the welder of the present invention.

6) The primary inversion output voltage detection and feedback circuit is shown in figure 3 and comprises a U3 (HCNR 200) linear optical coupler, operational amplifiers U15C and U20, diodes D8 and D40, resistors R19, R20, R27-R30, R57, R102 and R110. R134, capacitors C19, C27 and C54; the working power supply is VCC-Uf, +15V (from the switching power supply circuit); the U3 (HCNR 200) linear optical coupler is not only an isolation optical coupler, but also a data transmission linear optical coupler for sampling voltage signals; the circuit of U15C is a synchronous follower; the circuit of U20 is an integrating circuit; the 6 pin of U3 is connected with +15V, the 5 pin of U3 is connected with the 10 pin non-inverting input end of U15C, R19 and C27, and the other ends of R19 and C27 are grounded; the output of U15C is connected with R29, and the other end of R29 is connected with R30 and U_1fThe other end of R30 is grounded; u shape_1fThe output voltage detection signal is output for primary inversion, is connected to a pin 7 of a P1 socket, and is finally transmitted to a U4 microprocessor control system in the attached figure 7 to participate in welding machine control; the pin 1 of the U3 is grounded, and the pin 2 of the U3 is connected with the pin 4 output end of the U20 through R20; the pin 3 of U3 is connected with VCC-Uf, the pin 4 of U3 is connected with R110 and the pin 3 inverting input end of U20, and the other end of R110 is grounded; the non-inverting input end of a pin 1 of U20 is connected with R57, the other end of R57 is connected with the anode of D40, C19, R134 and R27, the cathode of D40 is connected with VCC-Uf, the other ends of C19 and R134 are grounded, the other end of R27 is connected with R28, the other end of R28 is connected with the output IN + end after primary inversion rectification, the end is also connected with the cathode of D8, the anode of D8 is connected with R102, the other end of R102 is connected with VCC-Uf, and the circuit of the part is also part of a control circuit of VRD function.

7) The IGBT driving circuit is composed of a T7 driving transformer, VT6 and VT 2P channel field effect transistors (FR 9024N), VT7 and VT 8N channel field effect transistors (FR 024N), D30-D33 fast recovery diodes, and resistors, capacitors and the like on the periphery of the quick recovery diodes; the inverter circuit part has 4 IGBTs, so 4-way IGBT driving is provided, and the driving circuit form of each part is consistent. The input control signals of the partial circuit are U2-11 and U2-14, and the output ends of Aout (U2-11) and Bout (U2-14) of a U2 PWM pulse width modulation chip (UC 3846N) in the output characteristic control circuit. Because the signal driving power output by the U2 chip is small, the signal needs to be amplified by a driving power circuit, and then the working states of the 4 IGBTs are controlled by a T7 driving transformer and a peripheral driving circuit thereof. The control signals output by the U2 pulse width modulation PWM chip are two groups of square wave pulse signals. Two groups of square wave pulse signals have a fixed time difference in time, which is also called dead time in the profession and is one of important parameters for ensuring the alternate work of two groups of switches of the IGBT. The time is determined by the parameter settings of the peripheral devices (R26 at RT end; C16, C17 at CT end) of the U2 chip. Here, it should be noted that: the PWM signal is a signal for determining the output voltage and current of the primary inverter main circuit. The PWM signal is determined by control signals such as a current regulation given signal and a current negative feedback signal.

The IGBT driving circuit is divided into a low-voltage side driving circuit and a high-voltage side driving circuit, and 4 paths of high-voltage side IGBT driving circuits are arranged because 4 IGBTs are arranged on the primary inverter circuit part, and the form of each high-voltage side driving circuit is consistent; the T7 driving transformer has 4 independent secondary windings, and the IGBT driving circuit is divided into a low-voltage side driving circuit and a high-voltage side driving circuit through a T7. Taking one of the high-voltage side driving circuits as an example for explanation, the cathode of the D30 fast recovery diode is connected with the R93 resistor, the T7 drives the end (end with "●") with the same name of the secondary winding of the transformer N2, and the anode of the D30 is connected with the R89 resistor; the other end of the R89 is connected with the other end of the R93 resistor and connected with the G1 grid of the IGBT 1; the synonym terminal (one terminal without '●') of the secondary winding of the T7 driving transformer N2 is connected with the E1 drain of the IGBT 1; a C42 capacitor and an R77 resistor are connected in parallel between the G1 and the E1 poles of the IGBT 1; similarly, the cathode of the D31 fast recovery diode is connected to the R96 resistor, the T7 drives the dotted terminal (the terminal with "●") of the secondary winding of transformer N3, and the anode of D31 is connected to the R92 resistor; the other end of the R92 is connected with the other end of the R96 resistor and connected with the G3 grid of the IGBT 3; the synonym terminal (one terminal without '●') of the secondary winding of the T7 driving transformer N3 is connected with the E3 drain of the IGBT 3; a C43 capacitor and an R87 resistor are connected in parallel between the G3 and the E3 poles of the IGBT 1; the cathode of the D32 fast recovery diode is connected with an R94 resistor, the synonym terminal (one end without '●') of the other N4 secondary winding of the T7 driving transformer, and the anode of the D32 is connected with an R90 resistor; the other end of the R90 is connected with the other end of the R94 resistor, the G2 grid of the IGBT2, the same-name end (one end with the '●') of the secondary winding of the T7 driving transformer is connected with the E2 drain of the IGBT2, and a C44 capacitor and an R80 resistor are connected between the G2 pole and the E2 pole of the IGBT2 in parallel; the cathode of the D33 fast recovery diode is connected with an R95 resistor, the T7 drives the different-name end (one end without '●') of the other N5 secondary winding of the transformer, the anode of the D33 is connected with an R91 resistor, the other end of the R91 is connected with the other end of the R95 resistor and is connected with the G4 grid of the IGBT4, the T7 drives the transformer, the same-name end (one end with '●') of the secondary winding of the transformer is connected with the E4 drain of the IGBT4, and a C41 capacitor and an R88 resistor are connected between the G4 pole and the E4 pole of the IGBT4 in parallel.

The IGBT low-voltage side driving circuit is composed of VT6 and VT 2P channel field effect transistors (FR 9024N), VT7 and VT 8N channel field effect transistors (FR 024N), R3, R22, R98-R101 resistors, C50 and C48 capacitors, CE18 electrolytic capacitors, a primary winding N1 of a T7 driving transformer and a +15V power supply; the +15V power supply is connected with a filter inductor L3, the other end of L3 is connected with the anode of a CE18 electrolytic capacitor, R99, the cathode of the CE18 electrolytic capacitor is grounded, the other end of R99 is connected with C50, the D ends of VT6 and VT2 field effect transistors, and the other end of C50 is grounded; the S end of VT2 and the D end of VT8 are connected with the C48 and the R98 which are connected in parallel, the other end of the parallel circuit of C48 and R98 is connected with one end of the primary winding of a T7 driving transformer N1, and the other end of the primary winding of the T7 driving transformer is connected with the S end of VT6 and the D end of VT 7; the S terminal of VT7 is grounded; the G end of VT6 is connected with R101, the G end of VT7 is connected with R22, the other ends of R101 and R22 are connected with the 11 pin of the U2 chip or the Aout output end, the G end of VT2 is connected with R100, the G end of VT8 is connected with R3, the S end of VT8 is grounded, and the other ends of R100 and R3 are connected with the 14 pin of the U2 chip or the Bout output end.

Pins

11 and 14 of the U2 PWM chip are the output terminals for the PWM pulse width control signal. The control signals output by the U2 PWM chip are two sets of square wave pulse signals. When a PWM pulse signal is output, PWM square wave pulses can be formed in a primary winding of the T7, and square wave pulse signals required for driving the IGBT can be generated in 4 driving circuits on the high-voltage side of the IGBT after coupling and isolation of the T7. The PWM signal is a signal for determining the output voltage and current of the primary inverter main circuit, and is determined by control signals such as a current regulation given signal and a current negative feedback signal.

8) The output voltage is VCC-Uf and VCC-Gun switch power supply circuit, see figure 3, this part of the circuit is the switch power supply on the primary inversion circuit board. The circuit consists of a switching power supply transformer T3, a switching power supply control chip U6 (UC 2845B), an N-channel field effect transistor VT9, diodes D16, D17 and D38, PNP type triodes Q10 and Q11, a +15V power supply, and resistors and capacitors around the devices, and has the function of generating VCC-Uf and VCC-Gun power supply voltages to supply corresponding control circuits for live working. For example, the VCC-Uf power supply supplies power to a primary inversion output voltage detection and feedback circuit which is arranged in the middle of the figure 3 and consists of a U20 operational amplifier, a U15C operational amplifier, a U3 linear optical coupler and the like to work; the VCC-Gun power supply supplies power to the welding Gun switch signal detection and output signal control circuit and the remote control signal detection and output signal control circuit on the upper part of the attached figure 4. It can be known from the circuit principle of the switching power supply circuit part with the output voltages of VCC-Uf and VCC-GUN, for the primary inverter circuit board part of the invention, the VCC-Uf, VCC-GUN DC power supply voltage is generated without adopting a general control transformer and a related rectifying voltage conversion circuit. The circuit takes +15V voltage from the primary inverter circuit board portion. The size, the dimension and the weight of the switch transformer are far smaller than those of a common control transformer, so that the cost of the welding machine is reduced, and the technical additional value of the welding machine is improved. Meanwhile, the adoption of the switching power supply circuit is also beneficial to the operation of the welding machine in a larger power grid voltage fluctuation range, and the welding machine has better power grid voltage fluctuation resistance.

9) A cooling Fan Control circuit, as shown in fig. 3, the circuit is composed of a socket P3, a direct-current high-speed cooling Fan connected to a P3 socket, a field effect transistor VT3 (FR 024N), an optocoupler U12, a voltage regulator tube Z6, a light emitting diode D18, resistors R61-R62, R64 and R66, a capacitor C56, a power supply-24V and Fan Control signals; one end of the R62 is connected to the 16 pin of the P1 socket, and is connected to the 22 pin, i.e., Fan Control signal end, of the U4 microprocessor in fig. 7 through a plug of P1 and a Control line thereof, the other end of the R62 is connected to the anode of the light emitting diode in the optocoupler U12, and the cathode of the light emitting diode in the optocoupler U12 is grounded; the collector of an output triode in the optocoupler U12 is grounded, the emitter of the output triode in the optocoupler U10 is connected with R61, the other end of R61 is connected with the anode of a light emitting diode D18, the cathode of D18 is connected with the cathodes of C56 and Z6, R64, the anode of Z6 and the other end of C56 are connected with-24V, the other end of R64 is connected with the G end or the control electrode of R66 and VT3, the other end of R66 and the S end of VT3 are connected with-24V, the D end of VT3 is connected with the 1 pin of P3, and the 2 pin of P3 is grounded; pin 2 of P3 is connected to the positive pole of Fan, and pin 1 of P3 is connected to the negative pole of Fan. When the pin 22 of the microprocessor U4 in fig. 7 outputs high level, the light emitting diode in the optocoupler U12 emits light, the output stage triode in U12 is conducted, the emitter level of the output stage triode in U12 is pulled to the ground level, the field effect transistor VT3 is conducted, Fan operates to work, and cold air is conveyed to the inside of the welding.

10) An electromagnetic air valve DCF Control circuit is shown in figure 3 and comprises a socket P7, an electromagnetic air valve DCF connected to a P7 socket, a field effect tube VT1 (FR 024N), an optical coupler U10, a voltage regulator tube Z2, a diode D14, a light emitting diode D9, resistors R48-R49, R51 and R45, a capacitor C26, a power supply-24V and a Gas Control signal; one end of the R48 is connected to the 17 pin of the P1 socket, and is connected to the 23 pin, i.e., the Gas Control signal end, of the U4 microprocessor in fig. 7 through a plug of P1 and a Control line thereof, the other end of the R48 is connected to the anode of the light emitting diode in the optocoupler U10, and the cathode of the light emitting diode in the optocoupler U10 is grounded; the collector of an output triode in the optocoupler U10 is grounded, the emitter of the output triode in the optocoupler U10 is connected with R45, the other end of R45 is connected with the anode of a light emitting diode D9, the cathode of D9 is connected with the cathodes of C26 and Z2, R49, the anode of Z2 and the other end of C26 are connected with-24V, the other end of R49 is connected with the G ends or control electrodes of R51 and VT1, the other end of R51 and the S end of VT1 are connected with-24V, the D end of VT1 is connected with the anode of D14, the 1 pin of P7, and the cathode of D14 and the 2 pin of P7 are grounded; the 2 feet of the P7 are connected with the anode of the electromagnetic air valve DCF, and the 1 foot of the P7 is connected with the cathode of the electromagnetic air valve DCF. During argon arc welding, when a pin 23 of a U4 microprocessor in the attached drawing 7 outputs a high level, a light emitting diode in an optocoupler U10 emits light, an output stage triode in U10 is conducted, the level of an emitting electrode of the output stage triode in U10 is pulled to the ground level, a field effect tube VT1 is conducted, and an electromagnetic gas valve DCF acts to convey protective gas to a welding area.

11) An HF high-frequency arc striking Control circuit, as shown in figure 3, which is composed of a high-frequency arc striking generating circuit, a field effect transistor VT4 (FR 024N), an optocoupler U13, a voltage regulator tube Z5, a light emitting diode D21, resistors R68-R71, a capacitor C58, a power supply-24V and an HF Control signal; the high-frequency arc striking generating circuit consists of a secondary winding N4 of a main transformer T5 in the inverter main circuit, a relay K1, a high-voltage bag or high-frequency transformer T6, a spark amplifier FD1, an output filter reactor L2 in the figure 5, a winding N1 wound on the output filter reactor L2, high-voltage ceramic chip capacitors C45 and C47, a capacitor C46, a resistor R132 and a diode D20; for a high-frequency arc striking generating circuit, a secondary winding N4 of T5 provides power, and when a primary inversion process is carried out, a certain high-frequency high-voltage power supply is output from two ends of N4; one end of the N4 is connected with one end of a contact K1-2 of a K1 relay or a pin 3 of the relay, the other end of the N4 is connected with the C46, the other end of the C46 is connected with an 8 pin of a primary side of a T6 high-frequency transformer or one end of a contact K1-1 of the K1 relay or a pin 2 of the relay, and a 5 pin of a primary side of a T6 high-frequency transformer is connected with a common node of the contact K1-1 and the contact K1-2 or the pin 1 of the relay; the contact K1-1 is normally closed, and the contact K1-2 is normally open; one end or a pin 9 of the secondary side of the T6 high-frequency transformer is connected with an FD1, a C47 and a C45 high-voltage ceramic chip capacitor which are connected in parallel, the other end of the set of ceramic chip capacitors is connected with one end of an N1 winding on an output filter reactor L2 in the figure 5, the other end of an N1 winding is connected with the other end of the FD1 and R132, and the other end of the R132 is connected with the other end of the secondary side of the T6 high-frequency transformer; the L2 inductor is connected in series in the secondary inverter output loop of the welding machine; 4 pins of a K1 relay (coil) are connected with the cathode and the ground terminal of the D20, 5 pins of a K1 relay (coil) are connected with the anode of the D20 and the D terminal of a field effect switching tube VT4 in the high-frequency arc striking control circuit; the S end of VT4 is connected with-24V; when VT4 is conducted, the K1 relay acts, K1-2 is closed, and K1-1 is opened; when the switch of the welding gun of the argon arc welding is closed and the welding machine outputs no-load voltage, the N1 of the primary inversion T5 transformer has higher voltage, and at the moment, the VT4 is conducted, so that the output voltage of the N4 is applied to the primary side of the T6 high-frequency transformer. The secondary output voltage of the T6 is increased through the boosting effect of the T6, when the voltage of the two ends of the FD1 spark amplifier is increased to a higher value, the two ends of the FD1 are discharged, at the moment, L, C oscillation is formed by the capacitance of the C47 and the C45 high-voltage ceramic chips which are connected in parallel and the N1 (relative to an inductor L) on the L2, and a high-frequency high-voltage oscillation voltage signal is led into an output loop of a welding machine which is connected in series with the L2 through the coupling effect of the L2, so that an air gap between a tungsten electrode of a welding gun and a workpiece is broken through by the high-frequency high-voltage oscillation voltage during argon arc welding, and the arc. For the high-frequency arc striking Control circuit, one end of the R69 is connected to the 5 pin of the P1 socket, the plug and the Control line thereof through the P1 are connected to the 9 pin of the U4 microprocessor in fig. 7, namely, the HF Control signal end, the other end of the R69 is connected to the anode of the light emitting diode in the optocoupler U13, and the cathode of the light emitting diode in the optocoupler U13 is grounded; the collector of an output triode in the optical coupler U13 is grounded, the emitter of the output triode in the optical coupler U13 is connected with R68, the other end of R68 is connected with the anode of a light-emitting diode D21, the cathode of D21 is connected with the cathodes of C58 and Z5, R70, the anode of Z5 and the other end of C58 are connected with-24V, the other end of R70 is connected with the G end or the control electrode of R71 and VT4, the other end of R71 is connected with-24V with the S end of VT4, and the D end of VT4 is connected with the 5 pin of a K1 relay (coil) and the anode of D20 in the high-frequency arc striking generating circuit. When the 9-pin output high level of the microprocessor of U4 in the attached figure 7, the light emitting diode in the optocoupler U13 emits light, the output stage triode in U13 is conducted, the emitter level of the output stage triode in U13 is pulled to the ground level, the field effect transistor VT4 is conducted, the high-frequency high-voltage arc striking generating circuit works, and a high-frequency high-voltage arc striking signal is output to the secondary inversion welding loop to strike an arc. The U4 microprocessor Control system can Control the output level of the HF Control signal end according to the Control requirement to realize the Control requirement of HF high-frequency arc striking.

12) The output current detection and conversion and current feedback circuit of the secondary inversion Hall sensor are shown in the lower left part of the attached figure 3, and the circuit consists of a Hall sensor HECGQ, a socket P4, U5D, U5C, U15D and U14B operational amplifiers, diodes D1 and D37, and peripheral resistors and capacitors of the Hall sensor HECGQ, the socket P4, the U5D, the U5C, the U15D and the U14B operational amplifiers; as mentioned above, the Hall sensor HECGQ is connected to the output loop of the secondary inverter, i.e. the welding loop of the welding machine, after penetrating into the connecting piece, and is used for detecting the output current of the welding machine. The connecting wire and the plug of the Hall sensor HECGQ are connected to a P4 socket, a detected current signal is output by a pin 3 of P4, and the signal is divided into three paths of signals to be output after passing through a circuit consisting of U5D, U5C and peripheral devices. One path is output by R120 and filtered by C62 capacitorThen, I of output current of the welding machine is obtained_2fA signal, which is connected to pin 9 of the P1 jack, through the plug and its control lines, and finally to pin 15 of the U4 microprocessor of fig. 7; the other path of current detection signal is connected to the inverting input end of the U15A operational amplifier in the figure 3 through an input resistor R8 and participates in the output current negative feedback control of the primary inverter circuit, and the input current signal of R8 is a current negative feedback control signal; the current detection signal is input to the non-inverting input end of the U15D operational amplifier through R106, a circuit formed by U15D and a peripheral resistor and a capacitor (C14) is a proportional-integral circuit, the output of the circuit is connected to a post-stage circuit, the post-stage circuit is a voltage comparator circuit formed by U14B and a peripheral device, the reference voltage for comparison is determined by a voltage division circuit of R109 and R108 to +5Vref voltage, when the welding machine has current output, the current is detected by a Hall sensor HECGQ, then the current detection signal is amplified through a circuit formed by U5D, U5C and the peripheral device and then input to a post-stage voltage comparator, and the ARC testing signal output by U14B is high level due to the fact that the amplified current signal is higher than the reference voltage for comparison; the ARC testing signal is connected to pin 14 of the P1 socket, through the P1 pin and its control lines to pin 19 of the U4 microprocessor of FIG. 7.

13) A primary inversion output current setting and signal conversion circuit thereof is shown in figure 3, the circuit consists of a current setting Ig signal, a U15B operational amplifier and a peripheral resistor and a capacitor thereof, a U15B, a C76, a R107, a R113 and the like form a proportional integral circuit, the output of the circuit is used as a signal of an R111 input resistor, namely a current setting signal, and participates in the output current negative feedback control of a primary inversion circuit, the input current signal of R8 is a current negative feedback control signal, a circuit of a rear stage U15A part is a primary inversion output characteristic control circuit, and the essence is PI (proportional plus integral) operation control. The current-giving Ig signal comes from the 12 pins of the P1 socket, through the plug and its control line, to the 20 pins of the U4 microprocessor in fig. 7. Of course, the current-given Ig signal is ultimately determined by the welding parameters given by the operator panel portion of the welder of the present invention. The current given Ig signal is a current given signal of different phases.

14) A primary inversion output characteristic control circuit is shown in figure 3 and comprises a U15A operational amplifier, a U2 PWM (UC 3846N) and a resistor, a capacitor and a voltage regulator tube arranged at the periphery of the U15 PWM operational amplifier, a feedback network of the U15A is a feedback network of R16, C10 and a voltage regulator tube Z1 which are connected in series, the Z1 has the function of limiting the output voltage of the U15A, and a circuit formed by the U15A and the feedback network of the U15A is a primary inversion output characteristic control circuit which is also a PI (proportion + integration) operation control circuit. The circuit has two input resistors, R111 and R8 respectively, signals introduced by the two resistors, one is a current given signal, the other is a current negative feedback signal output by a secondary inverter circuit, the two signals are superposed on the input end of the circuit formed by the U15A and a feedback network thereof, and the polarities of the two signals are opposite to that of the U15A circuit part, namely, the current negative feedback PI (proportional plus integral) operation control is formed. The U2 PWM (UC 3846N) and the peripheral resistor and capacitor form a PWM control circuit, and the output control signals of the partial circuit are U2-11 and U2-14, namely the signals of the Aout and Bout output ends of the U2 PWM pulse width modulation chip (UC 3846N). The signal output by the U2 chip controls the working state of 4 IGBTs in the primary inverter circuit after passing through the driving circuit. The control signals output by the U2 pulse width modulation PWM chips Aout and Bout are two sets of square wave pulse signals. Two groups of square wave pulse signals have a fixed time difference in time, which is also called dead time in the profession and is one of important parameters for ensuring the alternate work of two groups of switches of the IGBT. The time is determined by the parameter settings of the peripheral devices (R26 at RT end; C16, C17 at CT end) of the U2 chip.

In fig. 3, the U17 optocoupler, R117, R50, C13 and NPN transistor Q1 form a PWM turn-off control circuit, and the input control signal of the PWM turn-off control circuit is a PWM turn-off control signal Shutdown PWM from pin 15 of the P1 socket, which is connected to pin 21 of the U4 microprocessor in fig. 7 through a plug and its control line. When the Shutdown control signal Shutdown PWM is in a low level, a light emitting diode in the U17 optocoupler cannot emit light, a triode in the U17 optocoupler is cut off, a triode Q1 is switched on, and an input signal of the R21 is pulled to a ground level, so that the PWM signal output by the U2 chip is closed, and the welding machine stops outputting current; on the contrary, when the Shutdown control signal Shutdown PWM is at a high level, the light emitting diode in the U17 optocoupler emits light, the triode in the U17 optocoupler is turned on, and the triode Q1 is turned off, so that the input signal of the R21 is not affected, and the U2 chip outputs a corresponding PWM signal according to the control requirement, so that the welding machine outputs a corresponding current and voltage. Therefore, whether to shut down the PWM signal output of the U2 chip is determined by the output level of the pin 21 of the U4 microprocessor, and finally by whether the welder has abnormal conditions such as overheating, overvoltage, undervoltage, overcurrent, etc.

15) A switching power supply circuit with output voltages of +15V, -15V and-24V is shown in a lower part of a figure 4, and comprises a switching power supply transformer T2, an optocoupler U8, a switching power supply control chip U9 (TOP 266 KG), -15V output integrated voltage stabilizer U7 (LM 79L15 ACMX), filter inductors L1 and L2, a rectifier bridge BD1, fast recovery diodes D2-D4, D6-D8, a program control tube VZ1 (TL 431), and devices around the devices, such as a resistor, a capacitor, an electrolytic capacitor and the like, wherein the circuit has the functions of generating the power supply voltages of +15V, -24V and-15V and supplying the power supply voltages to other control circuits as working power supply voltages. In this part of the switching power supply circuit, the input power of the switching power supply is connected from the upper L, N power supply terminal in fig. 3, and is rectified by BD1 and filtered by E4 capacitor to obtain +310V (i.e. the voltage across E4) high-voltage rectified current. Because the primary winding sides of the switching power supply control chip U9 and the T2 switching power supply transformer, and circuits formed by diodes, resistors, electrolytic capacitors and capacitors around the primary winding sides belong to a +310V high-voltage loop, and the secondary winding side of the T2 switching power supply transformer is an output rectifying and converting circuit of the switching power supply circuit and a filter circuit of a direct-current power supply belong to a low-voltage side circuit, in order to ensure the reliable operation of the welding machine control circuit, an optical coupler U8 photocoupler is adopted for isolation in the attached figure 4. The circuit of this part also belongs to a relatively typical switching power supply circuit, and it is understood that the working principle of this part relates to much knowledge in the aspects of the switching power supply, the switching power supply control chip U9 (TOP 266 KG) and the like. The reader may look up the relevant book or material for further understanding.

As can be seen from the circuit principle of the switching power supply circuit part with the output voltages of +15V, -15V and-24V, the primary inverter circuit board part of the invention does not adopt a general control transformer and a related rectifying voltage conversion circuit thereof to generate the direct-current power supply voltages of +15V, -15V and-24V. The circuit takes the ac supply voltage from both ends L, N of the primary inverter circuit board section. The size, the dimension and the weight of the switch transformer are far smaller than those of a common control transformer, so that the cost of the welding machine is reduced, and the technical additional value of the welding machine is improved. Meanwhile, the adoption of the switching power supply circuit is also beneficial to the operation of the welding machine in a larger power grid voltage fluctuation range, and the welding machine has better power grid voltage fluctuation resistance.

16) The detection control circuit for the input power supply voltage signal is shown in figure 4, and comprises a U5A operational amplifier, a diode D36, resistors R44, R46, R60, R72 and R112, capacitors C3, C53, C60 and C64, wherein the power supply of the U5A is + 15V-15V, and comes from the switching power supply circuit in figure 4; c60 and C3 decoupling or anti-interference capacitors are respectively connected between +15V and-15V ground; r44 is connected in parallel between the output and the inverting input of U5A, the non-inverting input of U5A is grounded, and the circuit of U5A is a proportioner; the cathode of the D36 is connected with the anodes of D3 and D2 in the switching power supply circuit, the cathode of the D36 is connected with the R72, the R60 and the C53 which are connected in parallel, the other ends of the R60 and the C53 which are connected in parallel are grounded, the other end of the R72 is connected with the R46, and the other end of the R46 is connected with the inverting input end of the U5A. The input voltage signal of R72 is the voltage across the parallel connection of R60 and C53. The output of U5A is connected with R112, and after being filtered by C64 capacitor connected between the rear stage and the ground, U is obtained_1inThe signal, which is connected to the 11 pin of the P1 socket of fig. 3, is connected to the 16 pin of the U4 microprocessor of fig. 7 through the plug of the P1 socket and its control lines. When the alternating current supply voltage at the two ends L, N of the primary inverter circuit board part changes, the voltage at the two ends of the R60 and the C53 which are connected in parallel also changes, and the output U of the U5A part circuit is U_1inThe signal will change accordingly, and the control system of the U4 microprocessor in fig. 7 can know whether the power supply of the welding machine is in a reasonable range and whether the phenomena of undervoltage and overvoltage occur by detecting the signal change of the 16 pins. If the power supply voltage is within a reasonable range, the U4 microprocessor control system does notCarrying out protection control; if the phenomena of undervoltage and overvoltage occur, the U4 microprocessor control system can carry out undervoltage and overvoltage protection control, close the output of the welding machine and stop welding operation. The undervoltage and overvoltage protection control of the welding machine is realized.

17) A detection and signal output control circuit of a welding gun switch signal is shown in the upper part of a drawing 4, and the circuit consists of a U19 optocoupler, a welding gun switch, an argon arc welding gun switch, a remote control socket, a light emitting diode D11, an NPN type triode Q9, capacitors C28 and C49, resistors R119 and R127, a +15V power supply and a socket P6. The 1 pin of the P6 is grounded, and a C49 anti-interference capacitor is connected between the protective grounding or the machine frame of the 1 pin butt welding machine; the 2 pin of P6 is connected to the anodes of the LEDs in R127, C28 and U19, the other end of C28 is grounded to the cathode of the LED in U19, and the other end of R127 is connected to VCC-Gun power supply from the switch power supply circuit in FIG. 3. The emitter of the triode in U19 is grounded, the collector of the triode is connected with the anode of D11, R119, the other end of R119 is connected with +15V, the cathode of D11 is connected with the base of Q9, the emitter of Q9 is grounded, the collector of Q9 is a Gun Switch Control signal of Gun Switch Control, the signal is connected to pin 1 of the P1 socket in FIG. 3, and the emitter of the triode is finally connected to pin 4 of the U4 microprocessor in FIG. 7 through the plug of P1 and the Control line thereof. The

pins

1 and 2 of the P6 are connected to the corresponding welding gun switch control lines in the connecting lines of the argon arc welding gun switch and the remote control socket below the front panel of the welding machine through the plug and the control line thereof of the P6, and the welding gun switch line of the argon arc welding is connected with the argon arc welding gun switch and the remote control socket through the plug, namely the welding gun switch line is connected with the

pins

1 and 2 of the P6. During argon arc welding, when a welding Gun Switch is closed, a light emitting diode in U19 cannot emit light, a triode in U19 is cut off, D11 emits light, Q9 is conducted, and a Gun Switch Control signal is at a low level; on the contrary, when the welding Gun Switch is not closed, the light emitting diode in the U19 emits light, the triode in the U19 is conducted, the D11 does not emit light, the Q9 is cut off, and the Control signal of the Gun Switch Control welding Gun Switch is at a high level. During argon arc welding, the U4 microprocessor can know whether the welding gun switch is closed or open by detecting the level state of the 4 pins of the U4 microprocessor.

18) A detection and signal output control circuit of a remote control signal is shown above a figure 4, and the circuit consists of a U3 linear optical coupler, U1 and U2 operational amplifiers, a VZ2 program control tube (TL 431), a diode D1, a P6 socket, an argon arc welding Gun switch, a remote control socket, resistors R1, R2, R4-R11, capacitors C1, C2, C4, C5, C33, C34, C74, electrolytic capacitors CX3, VCC-Uf and a VCC-Gun power supply. The VCC-Uf and VCC-Gun power supplies come from the switching power supply circuit in fig. 3. 3-5 pins of the P6 are connected to corresponding remote control lines in connecting lines of an argon arc welding gun switch and a remote control socket below the front panel of the welding machine through a plug and a control line of the P6, and a remote control device during argon arc welding is connected with the argon arc welding gun switch and the remote control socket through the plug. The VZ2, the R1, the R2, the R10 and the CX3 are parts which obtain a +5V or V-REM power supply by utilizing a VCC-Gun power supply, are connected to a pin 5 of the P6 and finally can be connected with a +5V input end of a remote control device, and a C33 filtering anti-interference capacitor is connected to +5V ground. R9 and C74 filter capacitors are connected between the 3 pins of the P6 and the ground; a C44 filter capacitor is connected between the 4 pins of the P6 and the ground; the pin 5 of the P6, which is also a given signal end of a remote control device, is connected to the anodes of input resistors R5 and D1, the cathode of the D1 is connected with a VCC-Gun power supply, the D1 plays a role in amplitude limiting, the rear stage of the R5 is an integration circuit consisting of U1, R11 and C1, and the output of the circuit is input to the U3 linear optocoupler through R7. The circuit composed of U2, R8, C2 and C6 is a synchronous follower, the output of the circuit is divided by R4 and R6, and a Remote Control signal of Remote Control is output from both ends of R6, the signal is connected to 4 pins of a P1 socket in FIG. 3, and is finally connected to 8 pins of a U4 microprocessor in FIG. 7 through a plug of P1 and a Control line thereof. The U4 microprocessor system can obtain the data given by the remote control device by sampling the signal of the 8 feet. The remote control function and the device thereof are convenient to operate when a welding operator remotely adjusts current parameters. Because the remote control line is longer and is easy to be interfered by electromagnetic waves, more anti-interference capacitors are arranged in the circuit of the remote control line, and two operational amplifier circuits are adopted, so that the characteristic of high input impedance of the operational amplifier is utilized, and the working reliability of the circuit is facilitated; the linear optocoupler is adopted, so that the effects of electrical isolation and interference prevention are achieved, the effect of data transmission is also achieved, and the stability and reliability of the work of the circuit of the welding machine are favorably guaranteed.

Referring to fig. 5, a schematic circuit diagram of the secondary Inverter control board (Two-Inverter-PCB) portion of the welder of the present invention is shown. IN FIG. 5, the IN + and IN-inputs of the secondary inverter circuit are connected to the IN + and IN-outputs of the primary inverter circuit portion; the OUTPUT1 and OUTPUT2 ends of the secondary inversion control board are connected to a positive polarity OUTPUT end and a negative polarity OUTPUT end of the front panel part of the welding machine and an electric OUTPUT interface end of the argon arc welding gun. The secondary inversion control board mainly has the function of realizing control of direct current, (square wave) alternating current, alternating frequency and cleaning width in a post-stage circuit at the ends of OUTPUT1 and OUTPUT2 under the action of a control circuit. The circuit of secondary contravariant control panel part mainly includes: the device comprises a full-bridge inverter circuit consisting of four groups of MOS field effect tube groups, a switching power supply and a driving circuit for controlling MOS tubes, a Hall sensor detection circuit for outputting current, an output current filtering and high-frequency arc striking booster circuit, an alternating current arc stabilizing pulse control circuit and an output loop filter circuit. The operating principle and the function of these circuits are explained below as follows:

1) the full-bridge inverter circuit composed of four groups of MOS field effect transistor groups is shown in figure 5, and the four groups of MOS field effect transistor groups are respectively as follows: VT1-1 to VT1-4 are in one group, VT2-1 to VT2-4 are in one group, VT3-1 to VT3-4 are in one group, and VT4-1 to VT4-4 are in one group. Each MOS tube is an N-channel field effect tube, the model is AOT2500L, and the MOS tube belongs to MOS tube devices with low voltage and large current. The four MOS transistors in each group are connected in parallel, i.e. the D terminals and the S terminals of the MOS transistors are respectively connected together, and a driving signal is used to control the G terminals or the gates thereof, for example, the driving signal between 2G1 and 2E1 controls the on/off of VT1-1 to VT1-4 tube groups, when a driving pulse signal is provided, the tube groups are turned on, otherwise, the tube groups are turned off, and the control of other groups is similar. The purpose of parallel connection of the tube groups is to enlarge the current which can be borne by each group of electronic switches, after all, the current flowing through the tube groups is a part of welding current, and the welding current is larger, so that parallel connection of the tube groups for enlarging the current is necessary, and the method is economical. In four groups of MOS tube groups, when VT 1-1-VT 1-4 tube groups, VT 3-1-VT 3-4 tube groups, VT 2-1-VT 2-4 tube groups and VT 4-1-VT 4-4 tube groups are alternately conducted under the action of a driving signal, two ends of OUTPUT1 and OUTPUT2, namely two OUTPUT ends of a welding machine can obtain alternating current, and the alternating current frequency depends on the alternating control frequency of a driving signal of the MOS tube, namely the control of alternating current argon arc welding (TIG); if the MOS tube driving signal is also controlled by the cleaning width in the alternating process, the control of asymmetric alternating current argon arc welding can be formed; if the VT1-1 to VT1-4 tube groups and the VT3-1 to VT3-4 tube groups are always conducted, and the VT2-1 to VT2-4 tube groups and the VT4-1 to VT4-4 tube groups are not conducted, the OUTPUT1 end is positive polarity OUTPUT, the OUTPUT2 end is negative polarity OUTPUT, and the OUTPUT1 end and the OUTPUT2 end are respectively connected with the positive polarity OUTPUT end and the negative polarity OUTPUT end of the front panel of the welding machine, which is the control of direct current manual welding and direct current argon arc welding; the secondary inversion control board mainly has the function of realizing control of direct current, (square wave) alternating current, alternating frequency and cleaning width in a post-stage circuit at the ends of OUTPUT1 and OUTPUT2 under the action of a control circuit.

Referring to fig. 5, a peak absorption and protection circuit is arranged in a full-bridge inverter circuit of the MOS tube group and is divided into two parts, namely an upper bridge arm and a lower bridge arm. For the peak absorption and protection circuit of the upper bridge arm, the circuit is composed of resistors R10-R13, R18, R19 and R69, capacitors C2, C12, C13 and C20, electrolytic capacitors CE10 and CE11, diodes D5 and D16, voltage-stabilizing tubes D2 and ZD2 and an N-channel field effect tube Q1. The series C12 and R11, C13 and R12 are respectively connected IN parallel with the D (also connected with IN +) end and the S end of two groups of MOS tubes of the upper bridge arm IN the full-bridge inverter circuit; cathodes of D5 and D16 are respectively connected with the S end of the MOS tube group, and anodes of D5 and D16 are connected with the S end of Q1; the parallel C2, EC10, C13 and EC11 are respectively connected in parallel at the S end of the Q1 and the D ends of the two groups of MOS tubes, and meanwhile, the series R13 and R18 are also connected in parallel between the S end and the D ends; the middle connection point of R13 and R18 is connected with the cathode of a D2 voltage-stabilizing tube, the anode of the voltage-stabilizing tube is connected with the cathode of a ZD2 voltage-stabilizing tube, the G poles of R19 and Q1, the anode of ZD2 and the other ends of R19 are connected with the S end of Q1, the D end of Q1 is connected with one ends of R10 and R69 which are connected in parallel, and the other ends of R10 and R69 which are connected in parallel are connected with the D ends of two groups of MOS tubes. C12, R11, C13 and R12 which are connected in series form a resistance-capacitance absorption circuit which absorbs the peak voltage of the MOS tube. The series-connected R13 and R18 form a voltage division circuit, if the voltage at the two ends of the voltage division circuit is higher, D2 and ZD2 voltage-stabilizing tubes can be broken down and stabilized, and Q1 field effect tubes are conducted, so that current can flow through the parallel-connected R10 and R69, and a resistor R (namely, the parallel-connected R10 and R69), a capacitor C (namely, C2, C20 and the like) and a diode D (namely, D5 and D16) absorption network are formed between the D end and the S end of the MOS tube group, and the reliable work of the MOS tube is further protected by the network, and the MOS tube is prevented from being damaged. Similarly, for the spike absorption and protection circuit of the lower bridge arm, the circuit consists of R35-R36, R38, R46, R56, R57 and R70 resistors, C23, C25-C27 capacitors, CE12 and CE13 electrolytic capacitors, diodes D10 and D11, voltage-stabilizing tubes D12 and ZD3 and an N-channel field effect tube Q15. The serially connected C25 and R35, C23 and R36 are respectively connected IN parallel at the D ends and S (also connected with IN-) ends of two groups of MOS tubes of a lower bridge arm IN the full-bridge inverter circuit; anodes of D10 and D11 are respectively connected with the D ends of the MOS tube groups, cathodes of D5 and D16 are connected with one ends of C27, EC12 and C26 which are connected in parallel, one ends of EC13, one ends of R38 and R70 which are connected in parallel, and R46, the other ends of C27, EC12 and C26 which are connected in parallel, and EC13 are connected with the S end of Q15 which is also the S end of two groups of MOS tubes; the other ends of the R38 and the R70 which are connected in parallel are connected with the D end of the Q15; the other end of R46 is connected with the cathode of D12 voltage-stabilizing tube, the anode of the voltage-stabilizing tube is connected with the cathode of ZD3 voltage-stabilizing tube, the G poles of R57 and Q15, the anode of ZD3 and the other ends of R57 are connected with the S end of Q15, and the D end of Q15 is connected with the other ends of R38 and R70 which are connected in parallel. The function of the part of the circuit is the same as that of the upper bridge arm part.

2) A switching POWER supply and a driving circuit for controlling an MOS tube are shown in the lower part of a figure 5, and the switching POWER supply circuit of the MOS tube consists of a U6 PWM chip (UC 2845B), an N-channel field effect tube Q10, a T2 switching POWER supply transformer, PNP triodes Q20 and Q21, a light emitting diode POWER-3, a voltage stabilizing tube ZD10, fast recovery diodes D1, D3, D9 and D18, and a resistor, a capacitor, an electrolytic capacitor and a +15V POWER supply on the periphery of the devices. The +15V power supply supplies power to the switching power supply, the field effect transistor Q10 works under the control of the U6 PWM chip, and conversion signals are obtained at the primary side and the secondary side of the T2 switching power supply transformer. T2 has four secondary windings, fast recovery diode, capacitor and electrolytic capacitor connected to the four windings, and has identical circuit structure. Through the output of four secondary windings, the rectification action of four fast recovery diodes and the filtering of a rear-stage capacitor and an electrolytic capacitor, five groups of direct-current power supply outputs can be respectively obtained, which are respectively as follows: a dc power supply between + V1 and 2E 1; a dc power supply between + V2 and 2E 2; a dc power supply between + V3 and 2E 3; a dc power supply between + V4 and 2E 4; a dc power supply between + V5 and 2E 5; the DC power supplies between + V3 and 2E3, between + V4 and 2E4 are the same, and the rest groups of power supplies are independent DC power supplies only with different power supply labels. These dc power supplies are connected to the driving circuits of the MOS transistor groups corresponding to the middle portion of fig. 5, respectively, according to the difference in power supply numbers and the correspondence relationship thereof.

The middle part shown in the figure 5 is a driving circuit part of an MOS tube group, and the circuit consists of a U7 (UCC 27324 DR) double-non-inverting high-speed MOS tube driving chip, U1-U4 optical couplers (HCPL-341H or A341H or FOD 3150), voltage-stabilizing tubes ZD6 and ZD7, resistors R3 and R6-R9, capacitors C1, C3-C6 and C8; 2 pins of the U1-U4 optocouplers are anodes of light emitting diodes in chips, 3 pins of the U1-U4 optocouplers are cathodes of the light emitting diodes, 8 pins of the U1-U4 optocouplers are working power supply ends, and 6 pins and 5 pins of the U1-U4 optocouplers are output signal ends and are respectively connected with a G pole or a grid and an S end of an MOS (metal oxide semiconductor) tube; therefore, 8 pins of the U1-U4 optical couplers are respectively connected with + V1, + V2, + V3, + V4 power supplies, 6 pins of the U1-U4 optical couplers are respectively connected with the ends of 2G1, 2G2, 2G3 and 2G4 of the MOS tube group, and 5 pins of the U1-U4 optical couplers are respectively connected with the ends of 2E1, 2E2, 2E3 and 2E4 of the MOS tube group; c3, C4, C6 and C5 capacitors are connected to 8 pins and 5 pins of the U1-U4 optocouplers respectively; one end of R8 is connected with the 2 feet of U1 and U3 and the 3 feet of U2 and U4, and the other end of R8 is connected with the 5 feet of U7; similarly, one end of R6 is connected with the 2 feet of U2 and U4, the 3 feet of U1 and U3, and the other end of R6 is connected with the 7 feet of U7; the 6 pins of U7 are connected with power terminals, and a C1 capacitor is connected between the power terminals and the ground; pin 3 of U7 is grounded; a pin 2 of U7 is a control signal input end output by a pin 7 of U7, is connected with a cathode of ZD6, an R9 and an anode of ZD6 to be grounded, and the other end of R9 is connected with a pin 8 of a P2 socket; similarly, pin 4 of U7 is a control signal input end of pin 5 output of U7, and is connected with the cathode of ZD7, the anode of R3, ZD7 is grounded, and the other end of R3 is connected with pin 7 of P2 socket; the 7-pin and 8-pin of the P2 socket are connected to the 7-pin and 8-pin of the P4 socket of the main control board in fig. 7 through the plug and its control line. The output of the main control board U8 chip, i.e. the output signals of

pins

7 and 8 of the P4 socket, controls the U7 chip in fig. 5, so that

pins

5 and 7 of the U7 output two columns of opposite control signals. When the input end signal of the R8 is at a high level, the MOS tube group controlled by the U1 and U3 chips is conducted, and meanwhile, the input end signal of the R6 is at a low level; on the contrary, when the input signal of R6 is high, the MOS transistor group controlled by the U2 and U4 chips is turned on, and at the same time, the input signal of R8 is low. For four groups of MOS tube groups in the secondary inverter circuit, VT 1-1-VT 1-4 tube groups and VT 3-1-VT 3-4 tube groups are controlled by a circuit of U1 and U3 optical couplers; the VT2-1 to VT2-4 tube groups and the VT4-1 to VT4-4 tube groups are controlled by a circuit of a U2 and U4 optical coupler. If the VT 1-1-VT 1-4 tube group and the VT 3-1-VT 3-4 tube group are alternatively conducted with the VT 2-1-VT 2-4 tube group and the VT 4-1-VT 4-4 tube group under the action of the alternating driving signal of the MOS tube group, the two ends of OUTPUT1 and OUTPUT2, namely the two OUTPUT ends of the welding machine, can obtain alternating current, the alternating frequency depends on the alternating control frequency of the driving signal of the MOS tube, namely the control of alternating current argon arc welding (TIG); if the MOS tube driving signal is also controlled by the cleaning width in the alternating process, the control of asymmetric alternating current argon arc welding can be formed; if the VT1-1 to VT1-4 tube group and the VT3-1 to VT3-4 tube group are always conducted, and the VT2-1 to VT2-4 tube group and the VT4-1 to VT4-4 tube group are not conducted, the OUTPUT1 end is positive polarity OUTPUT, the OUTPUT2 end is negative polarity OUTPUT, and the OUTPUT1 end and the OUTPUT2 end are respectively connected with the positive polarity OUTPUT end and the negative polarity OUTPUT end of the front panel of the welding machine, which is the control of direct current manual welding and direct current argon arc welding. The secondary inversion control board mainly has the function of realizing control of direct current, (square wave) alternating current, alternating frequency and cleaning width in a post-stage circuit at the ends of OUTPUT1 and OUTPUT2 under the action of a control circuit.

3) The Hall sensor detection circuit for outputting current is shown in the attached figures 5 and 3 and consists of a Hall current sensor HECGQ and a + 15V-15V power supply thereof. As mentioned above, the Hall sensor HECGQ is connected to the output loop of the secondary inverter, i.e. the welding loop of the welding machine, after penetrating into the connecting piece, and is used for detecting the output current of the welding machine. The 1 pin of the Hall current sensor HECGQ is connected with +15V, the 2 pin of the HECGQ is connected with-15V, and the 4 pin of the HECGQ is grounded. The connection wires and the plugs of the hall current sensor HECGQ are connected to the P4 socket in fig. 3, and therefore, the 3-pin output signal terminal of the HECGQ is connected to the secondary inverting hall sensor output current detection and conversion and current feedback circuit thereof in fig. 3. The output current signal of the welding machine can be obtained through the detection of the Hall current sensor HECGQ and the processing of a post-stage circuit.

4) An output current filtering and high-frequency arc striking boosting circuit, as shown in fig. 5, L2 is connected in series in a secondary inverter output circuit of the welding machine, on one hand, the output current is filtered by using an inductor of L2, so that the current becomes smooth and stable, on the other hand, the above description also mentions: the L2 inductance winding is also wound with some windings in the high frequency arc striking generating circuit. Thus, the wound winding also has a problem of transformation ratio or turns ratio with the winding of L2. Since the number of turns of the winding is less than that of the L2 inductor winding, a step-up transformer is constructed. This is the meaning of the high frequency arc starting and voltage boosting circuit.

5) The control circuit of the alternating current arc stabilization pulse is shown in a figure 5 and comprises a U5 optical coupler, an IGBT tube VT1 (FGH 40N60 SFD), a T1 transformer, diodes D6-D8, D15 and D21, a RL1 high-power resistor (50W 33 RJ), voltage-stabilizing tubes ZD1, ZD5 and ZD9, resistors R1, R2, R4, R7, sockets P1 and P3, a fuse tube RT1, an inductor L1, a capacitor C8, an electrolytic capacitor CE8 and CE 9; a fuse tube RT1 is connected in series in a primary loop of the T1 transformer, and then the T1 transformer is connected to a P1 socket and is connected to a P5 socket of a primary inverter circuit part in the attached drawing through a plug and a control line thereof, namely, a power supply accessed by the P1 socket is a primary high-frequency alternating power supply of a primary inverter main transformer T5; the secondary output voltage of the T1 transformer is filtered by a full-wave rectifier bridge circuit consisting of D6-D8 and D15 and series electrolytic capacitors CE8 and CE9 which are connected to two ends of the rectifier bridge in parallel to obtain higher direct-current voltage; r4 is also connected in parallel across the output of the rectifier bridge; the D end of VT1 is also connected to the positive OUTPUT end of the rectifier bridge, the S end of VT1 is connected to the 3 pin of P3 socket and the cathode of D21, the anode of D21 and the anode of ZD9 are connected to the negative OUTPUT end of the rectifier bridge, the negative OUTPUT end is also connected to the IN-end, the cathode of ZD9 is connected to the anode of ZD5, the cathode of ZD5 is connected to the 1 pin of socket P3 and one end of inductor L1, and the other end of inductor L1 is connected to the OUTPUT2 OUTPUT end. The plug and its connection line through P3 are connected to RL1 high power resistor. ZD1 and R2 are connected in parallel between the G pole and the S end of VT1, and the cathode of ZD1 is connected with the G pole of VT 1; one end of R1 is connected with the G pole of VT1, and the other end 2G5 of R1 is connected with the 6-pin 2G5 end of U5; the 5-pin 2E5 terminal of U5 is connected to the S terminal of VT 1. The U5 opto-coupler is a driving chip of an IGBT tube VT1, and is the same as the U1-U4 opto-couplers. The 8 feet of the U5 optocoupler are connected with a + V5 power supply, the 2 feet of the U5 optocoupler are connected with R7, the other end of the R7 is connected with the 9 feet of the socket P2, and the 3 feet of the U5 optocoupler are connected with the 10 feet of the socket P2 and also are ground ends; the

pins

9 and 10 of the P2 jack are connected to the

pins

9 and 10 of the P4 jack of the main control board of fig. 7 through its plug and its control lines. The output of the main control board U7 chip, i.e. the output signals of

pins

9 and 10 of the P4 socket, controls the U5 chip in fig. 5, so that

pins

6 and 5 of the U5 output control signals to control the operating state of the VT 1.

6) The filter circuit of the output loop is shown in figure 5, and the filter circuit consists of filter capacitors C19, C17 and C28, wherein C19 is connected in parallel at two output ends of a full-bridge inverter circuit consisting of four groups of MOS (metal oxide semiconductor) tubes; one end of each of the C17 and C28 is also connected to the output end of the full bridge inverter circuit, and the other end of each of the C17 and C28 is connected to the protective ground or the frame of the welder. The filter capacitor is arranged for preventing the interference of high-frequency signals to the control circuit and preventing the interference from entering the secondary inverter circuit to burn out devices.

For the operating and display control panel section, on the left above the panel, a nixie tube U1 is provided for displaying parameters and error codes. On the right side of nixie tube U1, near nixie tube U1, four parameter unit symbol indicator lights of "A", "S", "%" and "Hz" are arranged from top to bottom. On the right side of the four unit symbol indicating lamps, welding parameter indicating lamps which are different from left to right in height and position and correspond to current waveform time sequences in different stages are arranged, and the welding parameters comprise air supply advance time, arc striking (or hot start) current, arc thrust (or thrust current) or spot welding time, (current) rise time, welding current or pulse peak current, alternating current frequency, base current, (alternating current) cleaning width, (current) attenuation time, arc receiving (or fire hole filling) current, pulse frequency or pulse width (or pulse time) and lagging air closing time. A VRD ON indicator lamp and a VRD OFF indicator lamp are arranged below the nixie tube U1, the VRD function is a function which can be selected during manual welding, and the VRD function represents a manual welding no-load low-voltage output function. For the operation and display control panel part, when the welding machine works, when a welding method selection key is pressed down, an indicator lamp corresponding to the selected welding method is lightened to indicate that the welding method corresponding to the lightened indicator lamp is selected, and when the welding method key is pressed in sequence, indicator lamps of different welding methods are lightened in sequence and change in a circulating mode.

The welding parameters and functions that can be selected and set are different for different welding methods, for the operating and display control panel parts. For example, when selecting the manual MMA method, welding parameters that may be selected are welding current, thrust current, and electrode diameter. Under the condition of selecting the manual welding method, the indicator lamps corresponding to the parameters of the welding current, the thrust current and the diameter of the welding rod can be selected in sequence by pressing down the keys of the encoder. When one indicator light is selected to be lightened, the corresponding parameter can be adjusted through the encoder. For example, when the corresponding welding current or peak current indicator lamp is turned on, it indicates that the welding current parameter is selected, and at this time, the welding current can be adjusted by the encoder; when the corresponding arc thrust (or thrust current) or spot welding time indicator lamp is lightened, the thrust current parameter is selected, and the thrust current can be adjusted through the encoder; when the corresponding tungsten electrode or welding rod diameter indicating lamp is lighted, the diameter of the welding rod is selected, and at the moment, the diameter of the welding rod corresponding to actual use can be selected through adjustment of the encoder. In addition, when a certain parameter (not including the electrode diameter) is selected, the corresponding unit indicating lamp is lighted. For example, if the selected welding parameter is a current parameter, then the current unit A indicator lights will be illuminated at the same time, indicating that the selected parameter is a current parameter; when the key of the encoder is operated, if the 'certain' indicator lamp cannot be lightened, the parameter corresponding to the indicator lamp is not the welding parameter under the selected welding method, so that the indicator lamp cannot be lightened or selected for operation.

For the operation and display control panel part, under the condition of selecting the direct current argon arc welding method, three welding gun switch operation mode options of 2T/4T and SPOT SPOT welding are available. By pressing a key of the encoder, the 2T or 4T welding gun switch operation mode can be selected, and the 2T or 4T indicator lamp is turned on correspondingly; a SPOT welding SPOT mode can be selected, and a corresponding SPOT indicating lamp is lightened. The welding parameters that may be selected may be different for different modes.

The circuit for operating and displaying the control panel part, see fig. 6, is composed of drive chip U2 (TM 1638) of the nixie tube display, U1 (CPS 05631 AG) nixie tube, indicator light D1 in Hz (hertz) of Frequency unit of AC or Pulse CURRENT, indicator light D2 in% of the AC cleaning width or Pulse time ratio (or Pulse duty), indicator light D3 in S (seconds) of time, indicator light D4 in a (ampere) of CURRENT, indicator light D5 in Pre-flow time, indicator light D6 for ARC striking (or hot START) CURRENT (START CURRENT), indicator light D7 for rise time (incorporated) of CURRENT, indicator light D8 for Welding CURRENT or Pulse peak CURRENT (Welding CURRENT) of ARC striking (or thrust) or Spot Welding time (ARC) of ARC 9, indicator light D10 for AC Frequency (AC) of Frequency, Basic current (Background current) indicator lamp D11, (alternating current) cleaning width (clear width) indicator lamp D12, (current) decay time (depletion time) indicator lamp D13, Pulse Frequency or Pulse width (or Pulse time) (Pulse Frequency or Pulse time) indicator lamp D14, arc (or fire filling) current (Final or spike current) indicator lamp D15, lagging closing time (Post-flow time) indicator lamp D16, 2T welding gun switch operation mode (2T mode) indicator lamp D17, 4T welding gun switch operation mode (4T mode) indicator lamp D18, SPOT welding mode (SPOT) indicator lamp D19, Alternating Current (AC) argon arc welding (AC) indicator lamp D20, alternating current Pulse welding (AC PULSE) indicator lamp D364, argon arc welding DC (TIG) indicator lamp D22, direct current (TIG) arc welding (TIG) indicator lamp D22, A manual welding (MMA) indicator lamp D24, an overheating or overcurrent Protection (Protection of O.H or O.C) indicator lamp D25, a Tungsten Electrode or Electrode diameter (Tungsten Electrode diameter) indicator lamp D26, a Remote control (Remote control) indicator lamp D27, a VRD function OFF (VRD OFF) indicator lamp D28, a VRD function ON (VRD ON) indicator lamp D29, a welding parameter adjusting encoder BMQ1, a welding parameter selection key B1 (note that it is a self-contained key of BMQ 1), a selection key S1 of an alternating current/alternating current pulsed argon arc welding/direct current pulsed argon arc welding/manual welding (TIG-AC/TIG-AC PULSE/TIG-DC/TIG-DC PULSE/MMA) welding method, a selection key S1 of a 2T, 4T and TIG mode (2T/4T/SPOT) of welding gun switch operation 2, the operation and display control panel part is connected with a socket P1 of an external circuit, capacitors C1-C5 and resistors R1-R8; the 4 pins of U2 are connected with + 5V; pins 18 and 25 of U2 are grounded; the +5V comes from the 1 pin of the P1 socket, and a C4 capacitor is connected between the +5V and the ground; the pins 2, 3, 5, 7, 9, 13 and 15 of the P1 receptacle are grounded, the lower end of which is connected to the chassis of the welder, i.e., the protective ground of the power supply system of the welder, through capacitor C5; 5-12 pins (corresponding to SEG 1-SEG 8) of U2 are respectively connected to anodes of light emitting diodes D1-D8, D9-D16 and D17-D24, and cathodes of light emitting diodes D1-D8, D9-D16 and D17-D24 are respectively connected with 20 pins (GRID 5), 19 pins (GRID 6) and 24 pins (GRID 1) of U2; 5-9 pins (corresponding to SEG 1-SEG 5) of U2 are respectively connected to anodes of D25-D29 light-emitting diodes, and cathodes of D25-D29 light-emitting diodes are connected with a 17 pin (GRID 7) of U2; the 5-12 pins (corresponding to SEG 1-SEG 8) of the U2 are respectively connected to the 11 pins, 7 pins, 4 pins, 2 pins, 1 pin, 10 pins, 5 pins and 3 pins of the nixie tube U1; the 12 pin (GRID 2), the 9 pin (GRID 3) and the 8 pin (GRID 4) of the nixie tube U1 are respectively connected to the 23 pin, the 22 pin and the 21 pin of the U2; the 28-pin (STB) of U2 is connected to the 4-pin of C1, R1 and P1 sockets, the other end of R1 is connected with +5V, and the other end of C1 is grounded; the 27 pin (CLK) of U2 is connected to the 6 pins of the C2, R2 and P1 sockets, the other end of R2 is connected with +5V, and the other end of C2 is grounded; a 26 pin (DIN) of U2 is connected to 8 pins of a C3, R3 and P1 socket, the other end of R3 is connected with +5V, and the other end of C3 is grounded; one end of the S1 key is grounded, the other end of the S1 key is connected to the 10 pins of the R4 and P1 sockets, and the other end of the R4 is connected with + 5V; one end of the S2 key is grounded, the other end of the S2 key is connected to the 12 pins of the R5 and P1 sockets, and the other end of the R5 is connected with + 5V; the encoder BMQ1 is grounded at one end with a B1 key, the other end of the encoder BMQ1 is connected to the 11 pins of the R6 and P1 sockets, and the other end of R6 is connected with + 5V; the 3 feet of the encoder BMQ1 are grounded, the 2 feet of the encoder BMQ1 are connected to the 14 feet of the R8 and P1 sockets, the other end of the R8 is connected with +5V, the 1 foot of the encoder BMQ1 is connected to the 16 feet of the R7 and P1 sockets, and the other end of the R7 is connected with + 5V; the nixie tube U1 is used for displaying parameters and error codes; four unit symbol indicating lamps of 'A', 'S', 'percent' and 'Hz' are arranged on the right side of the nixie tube U1 from top to bottom; the DIO of U2 is the data input/output interface, STB of U2 is the chip select signal control, CLK is the clock signal; the circuits of the operating and display control panel part interface with the P1 socket to enable control contact and data exchange with external circuits.

Referring to fig. 7, the circuit schematic diagram of the Main Control board (Main Control-PCB) portion is composed of a U4 microprocessor (STM 32F051R8T 6), a U3 (LC 4032V) ultrafast high-density programmable logic device with 48 pins, a buffer or driver with two inputs and two outputs of U7 and U8 (SN 74LVC2G34 DBVR), a voltage regulator circuit composed of U1, U5 and U6 integrated voltage regulators and filter capacitors thereof, a J1 program programming interface circuit, a P5 socket and a capacitor filter circuit thereof, a P2 socket and a capacitor filter and diode limiter circuit thereof, a P4 socket interface circuit, a light emitting diode indication and abnormality alarm circuit, and an overheat protection circuit composed of J3 and J4 sockets and capacitors, resistors thereof and temperature relays. The circuit operation principle of the main control board part is further explained as follows:

1) a voltage stabilizing circuit is shown in figure 7 and comprises a U1, U5 and U6 integrated voltage stabilizer and a filter capacitor thereof. The +5V power supply is obtained by the +15V power supply from the P2 socket and the voltage stabilizing and filtering circuit consisting of U6 and the surrounding capacitor, electrolytic capacitor, filtering inductor L1 and diode D2, and is supplied to the circuit using the +5V power supply on the circuit board, and then the +5V power supply is supplied to the circuit of the operation and display control board part to work through the socket P5 and the plug and control line thereof; the +3.3V power supply is obtained by a +5V power supply and a voltage stabilizing and filtering circuit consisting of U5, a capacitor around the U5 and an electrolytic capacitor, and is supplied to the circuit work of a U3 buffer using the +3.3V power supply, a U4 microprocessor and the like on the circuit board; the power supply of (+) REF is obtained by a +3.3V power supply and a voltage stabilizing and filtering circuit consisting of U1 and a capacitor around the U1, and is supplied to a U4 microprocessor using the REF power supply on the circuit board to work; the circuit of the overheating protection part on the circuit board is supplied to work through a +3.3V power supply. The voltage stabilizing circuit is a relatively common and typical circuit, and the circuit principle of the voltage stabilizing circuit is not further elaborated.

2) The microprocessor circuit and its programming interface circuit, see fig. 7, are composed of the J1 interface circuit, the U4 microprocessor and the circuit of the U3 section, and the circuit of the U7 and U8 buffer section. The J1 interface circuit is used for the U4 to control the programming or writing of programs. The other circuit part is a core part of the control circuit in the figure 7, the U4 microprocessor can obtain more control information by monitoring and sampling information of parts such as pins 54-59, pins 61 and 62, and the like, and the circuit mainly sends control information and provides control parameters to the primary inverter circuit part through a control system of the U4 microprocessor and also receives information from the primary inverter circuit part. Secondly, providing a control signal for controlling an alternating current arc stabilizing circuit in the secondary inverter circuit; and providing a MOS tube group driving control signal in the secondary inverter circuit.

3) The P5 jack and its capacitive filter circuit, see fig. 7, are connected to the P1 jack of the operation and display control circuit of fig. 6 via the plug of the P5 jack and its control lines. The circuit portion connects the operating and display control circuitry to the U4 microprocessor control system of fig. 7.

4) The P2 jack and its capacitive filtering and diode limiter circuit, see fig. 7, are connected via a plug and its control lines to the P1 jack of the primary inverter circuit portion of fig. 3. In the circuit of the part, capacitors such as C28-C30, C34-C38 and the like connected between the control line and the ground play a role in resisting interference; diodes connected between the control line and the ground and between the control line and the +3.3V, such as D3-D6 double diodes, play a role in amplitude limiting of the level of the control line.

5) The P4 socket interface circuit, see fig. 7, the socket is connected with the P2 socket of the secondary inverter circuit board part through the plug and the control line thereof, mainly providing +15V, +5V power supply for the circuit of the secondary inverter circuit board; providing a control signal for controlling an alternating current arc stabilizing circuit in a secondary inverter circuit; the driving control signals of the MOS tube group in the secondary inverter circuit are provided, and of course, the driving control signals of the different welding methods are output through a U3 programmable logic device and then through a U7 and U8 buffer or driver after being detected by a U4 system through a U4 microprocessor control system according to control information provided by an operation and display control circuit part connected to a P5 socket in the figure 7.

6) The LED indication and abnormity warning circuit is shown in figure 7, and comprises a D19 LED, an alarm BZ1, an NPN type triode Q1, a resistor R6 and a resistor R8, wherein the output levels of a pin 53 and a pin 52 of a microprocessor U4 respectively control the display of D19 and the warning circuit of BZ 1; when the 53 pin of the U4 outputs low level, the D19 lights up and emits light; otherwise, D19 does not indicate. When the pin 52 of the U4 outputs high level, the Q1 is conducted, and the BZ1 gives out alarm sound; otherwise, BZ1 does not alarm. The circuit of the part is mainly used for monitoring the abnormity of the program control program of the microprocessor.

7) An overheat protection circuit, see fig. 7, consists of J3 and J4 sockets and their capacitors, resistors and temperature relays WKQ1, WKQ 2. The overheat detection protector or the temperature controller is closely attached to the radiator of the IGBT and is connected to a J3 socket in the figure 7; the J4 socket and the circuit thereof are used as the connecting interface of the overheat protector of the secondary inverter circuit, and the overheat protector is also closely attached to the aluminum radiator in the secondary inverter. The microprocessor detects the working states of the two protectors simultaneously, namely the high and low levels of the

pins

26 and 27 of the U4. As long as one overheating phenomenon occurs, overheating protection can be performed. For example, when the heat sink of the IGBT is overheated during the output of the welder, the microprocessor U4 controls the system to scan the level of pin 27 of U4 to determine whether the overheat detection protector or the thermostat is activated. If the operation is performed, the overheating phenomenon is shown to be generated, at the moment, the microprocessor U4 control system can emit a control command, on one hand, under the control action of the operation and display circuit, a O.H overheating indicator lamp is lightened to display an overheating state, on the other hand, a Shutdown PWM signal is emitted through a pin 21 of the U4, the output of the U2 PWM signal in the attached figure 3 is closed, and finally the current output of the welding machine is closed; under the action of the cooling fan, after the overheating phenomenon is eliminated, the control system can automatically recover, the U2 PWM control circuit in the attached figure 3 can continue to output PWM control signals, and meanwhile, the overheating O.H indicator light of the operation and display circuit is turned off, so that the welding machine is allowed to perform welding operation again. Thus realizing the overheating protection of the welding machine; and if the argon arc welding is in the argon arc welding state, the electromagnetic gas valve is closed, and the protective gas is stopped being conveyed to the welding gun.

The circuit has unique design thought and method, and the designed control circuit and the whole structure of the welding machine can ensure that the welding machine product meets the requirement of safety certification, has good control performance, and is also an important guarantee for meeting the requirements of high efficiency, low cost production, high reliability and advanced manufacturing process technology of the product. The present patent application claims protection of the structure and circuit design of such a welder.

In addition, the circuit boards of the invention are simple to connect, and a plurality of devices on the circuit boards are processed by adopting an automatic chip mounter and a component inserter, so that the manufacturing process and the production process are greatly simplified, and the product weight, the production cost and the transportation cost are reduced.

The foregoing is a detailed description of the invention in conjunction with specific welder structures and circuit boards and control functions and is not intended to limit the practice of the invention to these descriptions. Numerous other deductions and alterations may be made by those skilled in the art without departing from the spirit of the invention, which should be considered as falling within the scope of the invention.

Claims

1. The utility model provides a multi-functional argon arc welding machine of alternating current-direct current contravariant of microprocessor control which characterized in that: the welding machine comprises a shell part and an inner part of the welding machine, wherein the shell part comprises a handle, a shell cover plate, a shell bottom plate, a rear panel, a front panel and a shell screw;

the outer side of the front panel of the welding machine is provided with a negative polarity output quick joint component, a positive polarity output quick joint component, an argon arc welding gun switch, a remote control socket, an air outlet nozzle connected with an argon arc welding gun and an operation and display control panel;

a power switch, an electromagnetic valve, an argon gas inlet nozzle thereof, a power supply wire, a plug, a power cord pull-off and cooling fan are arranged on the rear panel of the welding machine;

a primary inversion control panel, a secondary inversion control panel, a main control panel, an insulating plate, two circuit board supports supported at the bottom, two plastic supports supported at the bottom, a connecting piece connected with an output end, a Hall current sensor penetrating through the connecting piece, and an air pipe connected with a gas-electricity integrated interface of a welding gun are arranged in the welding machine; electronic components and parts on the primary inversion control board face the center of the welding machine; the primary inversion control board is connected with one circuit board support through a connecting screw, and then the circuit board support is fixed on the bottom plate of the machine shell through the connecting screw; electronic components and parts on the secondary inverter control panel also face the center of the welding machine; the secondary inversion control board is connected with the other circuit board bracket through a connecting screw, and then the circuit board bracket is fixed on the bottom plate of the shell through the connecting screw; the plastic supports of the two auxiliary supports are respectively fixed with the secondary inversion control plate and the primary inversion control plate through screws, and the plastic supports and the bottom plate of the machine shell are fixed through screws to play an auxiliary support role in reinforcing the fixation of the two circuit boards; an insulating plate is arranged above the two circuit boards of the secondary inversion control board and the primary inversion control board, and the insulating plate and the two circuit boards below the insulating plate are connected into a whole by screws; a cooling air channel is formed among the primary inversion control plate, the secondary inversion control plate, the insulating plate and the bottom plate of the shell; the main control board is fixedly arranged above the insulating board, one end of a power switch on the rear panel of the welding machine is connected to a power supply, and the other end of the power switch is connected to the input end of the primary inversion control board; the socket P1 of the primary inversion control board is connected to the socket P2 of the main control board through a plug and a control line thereof; the IN + and IN-ends of the primary inversion control board are respectively connected to the IN + and IN-ends of the secondary inversion control board; the socket P5 of the primary inversion control board is connected to the socket P1 of the secondary inversion control board through a plug and a control line thereof; the socket P3 of the primary inverter control board is connected to the cooling fan on the back panel of the welding machine through a plug and a control line thereof; the socket P4 of the primary inversion control board is connected to a Hall sensor of the welding machine output loop detection current through a plug and a control line thereof; the socket P7 of the primary inversion control board is connected to the electromagnetic air valve of the welding machine through a plug and a control line thereof; the socket P6 of the primary inversion control board is connected to a welding gun switch on the front panel of the welding machine and a control line of a remote control socket through a plug and the control line thereof;

the primary inversion control board obtains direct current and power-on buffer control IN the post-stage circuits at IN + and IN-ends under the action of the control circuit of the main control board; the switching power supply circuit generates +15V, -15V and-24V; detecting a primary inversion direct current bus current signal, a primary inversion circuit output direct current voltage signal, a secondary inversion circuit output current signal, a welding gun switch and a remote control signal, and controlling a cooling fan, a high-frequency arc striking and an electromagnetic gas valve;

the input end of the secondary inverter circuit is connected with the output IN + and IN-ends of the primary inverter circuit; the OUTPUT end of the secondary inversion control plate is connected to the positive polarity OUTPUT end and the negative polarity OUTPUT end of the front panel part of the welding machine and the electric OUTPUT interface end of the argon arc welding gun; the secondary inversion control board realizes the control of direct current, alternating frequency and cleaning width in a post-stage circuit at the OUTPUT end under the action of a control circuit of the main control board;

the socket P5 of the main control board is connected to the P1 socket of the operation and display control board through a plug and a control line thereof; the socket P4 of the main control board is connected to the socket P2 of the secondary inversion control board through a plug and a control line thereof; the operation and display control panel realizes the selection and adjustment control of corresponding welding parameters under different welding methods, different operation modes and different welding methods and the display of various states and parameters under the action of a control circuit of the operation and display control panel and a main control panel circuit;

the main control board control circuit controls the work of the primary and secondary inverter circuits according to the operation information obtained from the operation and display control board, so that the primary and secondary inverter circuits output corresponding current and voltage according to the control requirement, control various parameters and output states of different welding methods according to the requirement of time sequence control is realized, and parameter display and various state indication are carried out on the corresponding information through the operation and display control board.

2. The microprocessor-controlled AC/DC inversion multifunctional argon arc welding machine according to claim 1, wherein: the circuit on the operation and display control panel comprises a drive chip U2 of a nixie tube display, a nixie tube U1, a frequency unit indicator lamp D1 of alternating current or pulse current, a percentage indicator lamp D2 of alternating cleaning width or pulse time ratio, a unit indicator lamp D3 of time, a unit indicator lamp D4 of current, an advanced air supply time indicator lamp D5, an arc striking current indicator lamp D6, a rise time indicator lamp D7, a welding current or pulse peak current indicator lamp D8, an arc thrust or spot welding time indicator lamp D9, an alternating current frequency indicator lamp D10, a base current indicator lamp D11, a cleaning width indicator lamp D12, a decay time indicator lamp D13, a pulse frequency or pulse width indicator lamp D14, an arc receiving current indicator lamp D15, a lagging air-off time indicator lamp D16, a 2T welding gun switch operation mode indicator lamp D17, a 4T switch operation mode indicator lamp D18, a spot welding mode indicator lamp D19, An alternating current argon arc welding indicator lamp D20, an alternating current pulse argon arc welding indicator lamp D21, a direct current argon arc welding indicator lamp D22, a direct current pulse argon arc welding indicator lamp D23, a manual welding indicator lamp D24, an overheating or overcurrent protection indicator lamp D25, a tungsten electrode or welding rod diameter indicator lamp D26, a remote control indicator lamp D27, a VRD function closing indicator lamp D28, a VRD function opening indicator lamp D29, a welding parameter adjusting encoder BMQ1, a welding parameter selection key B1, a selection key S1 of an alternating current argon arc welding/alternating current pulse argon arc welding/direct current pulse argon arc welding/manual welding method, a welding gun switch operation and spot welding mode selection key S2, an operation and display panel part, a socket P1, capacitors C1-C5 and resistors R1-R8; the 4 pins of the driving chip U2 are connected with + 5V; pins 18 and 25 of the driving chip U2 are grounded; +5V from socket P1, and capacitor C4 connected between +5V and ground; pins 2, 3, 5, 7, 9, 13 and 15 of socket P1 are grounded, and the low end is connected to the chassis of the welder through capacitor C5; 5-12 pins of the driving chip U2 are respectively connected to anodes of the light emitting diodes D1-D8, D9-D16 and D17-D24, and cathodes of the light emitting diodes D1-D8, D9-D16 and D17-D24 are respectively connected with 20 pins, 19 pins and 24 pins of the U2; pins 5-9 of the driving chip U2 are also respectively connected to anodes of the light emitting diodes D25-D29, and cathodes of the light emitting diodes D25-D29 are connected with pins 17 of the driving chip U2; pins 5-12 of the driving chip U2 are also respectively connected to pins 11, 7, 4, 2, 1, 10, 5 and 3 of the nixie tube U1; the 12 pin, the 9 pin and the 8 pin of the nixie tube U1 are respectively connected to the 23 pin, the 22 pin and the 21 pin of the drive chip U2; a pin 28 of the driving chip U2 is connected to a capacitor C1, a resistor R1 and a pin 4 of the socket P1, the other end of the resistor R1 is connected with +5V, and the other end of the capacitor C1 is grounded; the pin 27 of the driving chip U2 is connected to the capacitor C2, the resistor R2 and the pin 6 of the socket P1, the other end of the resistor R2 is connected with +5V, and the other end of the capacitor C2 is grounded; a pin 26 of the driving chip U2 is connected to a capacitor C3, a resistor R3 and a pin 8 of the socket P1, the other end of the resistor R3 is connected with +5V, and the other end of the capacitor C3 is grounded; one end of the key S1 is grounded, the other end is connected to the resistor R4 and the 10 feet of the socket P1, and the other end of the resistor R4 is connected with + 5V; one end of the key S2 is grounded, the other end is connected to the resistor R5 and the 12 feet of the socket P1, and the other end of the resistor R5 is connected with + 5V; one end of the encoder BMQ1 with a key B1 is grounded, the other end of the encoder BMQ1 is connected to a resistor R6 and the 11 feet of a socket P1, and the other end of the resistor R6 is connected with + 5V; the 3 feet of the encoder BMQ1 are grounded, the 2 feet are connected to a resistor R8 and a 14 foot of a socket P1, the other end of the resistor R8 is connected with +5V, the 1 foot of the resistor R8 is connected to a resistor R7 and a 16 foot of a socket P1, and the other end of the resistor R7 is connected with + 5V.

3. The microprocessor-controlled AC/DC inversion multifunctional argon arc welding machine according to claim 1, wherein: the control circuit of the primary inversion control board part comprises an input filter circuit, an upper electricity buffer circuit and a control circuit thereof, an IGBT full-bridge inversion main circuit, an output rectification and overvoltage protection circuit, a primary inversion direct current bus current detection and rectification conversion and current feedback circuit thereof, an IGBT driving circuit, a switch power supply circuit, a cooling Fan control circuit and an electromagnetic gas valve DCF control circuit, the control circuit comprises an HF high-frequency arc striking control circuit, a primary inversion output voltage detection and feedback circuit, a secondary inversion Hall sensor output current detection and conversion and current feedback circuit, a primary inversion output current setting and signal conversion circuit, a primary inversion output characteristic control circuit, a detection control circuit for the input power supply voltage signal level, a welding gun switch signal detection and output signal control circuit and a remote control signal detection and output signal control circuit;

the input filter circuit comprises a mode inductor T1, a capacitor C77, a capacitor C4, a capacitor C1 and a capacitor C8; the capacitor C77 is connected in parallel at two ends of an input stage of the common-mode inductor T1, the capacitor C4 is connected in parallel at the rear stage of the common-mode inductor T1, one end of the common-mode inductor T1 is connected with the capacitor C8, the other end of the common-mode inductor T1 is connected with the capacitor C1, and the other ends of the capacitor C8 and the capacitor C1 are connected to a PE end of a protective grounding end of a welding machine frame; the input filter circuit is used for inhibiting electromagnetic noise and clutter signals of an input power supply, preventing interference on a welding power supply control circuit and simultaneously preventing interference of high-frequency clutter generated by the welding power supply on a power grid; the capacitor C1 and the capacitor C8 are safety capacitors; the input filter circuit enables the welding machine to have EMC electromagnetic compatibility;

the power-on buffer circuit comprises a thermistor RT1, a thermistor RT2 and a contact K2-1 of a relay K2 which are connected in parallel; the control circuit of the relay K2 is composed of a field effect transistor VT5, an optocoupler U11, a light emitting diode D13, a voltage regulator tube Z4, resistors R54-R56 and R59, a capacitor C55 and a 24V power supply; the cathode of a light emitting diode in the optocoupler U11 is grounded, the anode of the light emitting diode is connected with a resistor R55, the other end of the resistor R55 is connected with the signal end of a relay K2 of an 18-pin P1 socket, the signal end is connected with the 18-pin P2 of a main control panel socket through a plug P1 and a control line thereof, and is finally connected with a 24-pin of a microprocessor U4, and the signal end of the relay K2 is controlled by a microprocessor U4; the collector of a triode in the optocoupler U11 is grounded, the emitter of the triode is connected with the resistor R54, the other end of the resistor R54 is connected with the anode of the light emitting diode D13, the cathode of the light emitting diode D13 is connected with the capacitor C55, the cathode of the voltage regulator tube Z4 and the resistor R56, and the other ends of the cathodes of the capacitor C55 and the voltage regulator tube Z4 are connected with a-24V power supply; the other end of the resistor R56 is connected with a resistor R59 and a G-end control electrode of the field effect transistor VT5, and the other end of the resistor R59 is connected with a-24V power supply; the S end of the field effect transistor VT5 is connected with a-24V power supply, the D end of the field effect transistor VT5 is connected with the anode of the diode D10 and one end of the coil of the relay K2, and the other end of the coil of the relay K2 and the cathode of the diode D10 are grounded; -the 24V power supply is from a switching power supply circuit; the contact K2-1 of the relay K2 is connected with the thermistor RT1 and the thermistor RT2 which are connected in parallel, and the contact K2-1 is connected between the power supply of the welding machine and the input end of the rectifier bridge B1 in series;

the primary inversion output voltage detection and feedback circuit comprises a linear optocoupler U3, an operational amplifier U15C, an operational amplifier U20, diodes D8 and D40, resistors R19, R20, R27-R30, R57, R102, R110 and R134, and capacitors C19, C27 and C54; the working power supply is VCC-Uf, +15V comes from the switching power supply circuit; the linear optical coupler U3 is not only an isolation optical coupler, but also a data transmission linear optical coupler for sampling voltage signals; the circuit of the operational amplifier U15C is a synchronous follower; the circuit of the operational amplifier U20 is an integrating circuit; a pin 6 of the linear optocoupler U3 is connected with a +15V power supply, a pin 5 of the linear optocoupler U3 is connected with a pin 10 non-inverting input end of an operational amplifier U15C, a resistor R19 and a capacitor C27, and the other ends of the resistor R19 and the capacitor C27 are grounded; the output of the operational amplifier U15C is connected with a resistor R29, and the other end of the resistor R29 is connected with a resistor R30 and U_1fThe other end of the resistor R30 is grounded; u shape_1fThe voltage detection signal is output for primary inversion, the voltage detection signal is connected to a pin 7 of a socket P1 and is finally transmitted to a microprocessor U4 control system, a pin 1 of a linear optocoupler U3 is grounded, and a pin 2 of the linear optocoupler U3 is connected with a pin 4 output end of an operational amplifier U20 through a resistor R20; a pin 3 of the linear optocoupler U3 is connected with VCC-Uf, a pin 4 of the linear optocoupler U3 is connected with a resistor R110 and a pin 3 inverting input end of the operational amplifier U20, and the other end of the resistor R110 is grounded; the non-inverting input end of a pin 1 of an operational amplifier U20 is connected with a resistor R57, the other end of a resistor R57 is connected with the anode of a diode D40, a capacitor C19, a resistor R134 and a resistor R27, the cathode of a diode D40 is connected with VCC-Uf, the other ends of the capacitor C19 and the resistor R134 are grounded, the other end of the resistor R27 is connected with a resistor R28, the other end of the resistor R28 is connected with the output IN + end after primary inversion rectification, the output IN + end is also connected with the cathode of a diode D8, the anode of the diode D8 is connected with a resistor R102, and the other end of the resistor R102 is connected;

the IGBT driving circuit comprises a low-voltage side driving circuit and a high-voltage side driving circuit, 4 IGBTs are arranged on the primary inverter circuit part, 4 high-voltage side IGBT driving circuits are arranged, and the form of each high-voltage side driving circuit is consistent; the driving transformer T7 has 4 independent secondary windings, and the IGBT driving circuit is divided into a low-voltage side driving circuit and a high-voltage side driving circuit through the driving transformer T7; high-voltage side drive circuit: the cathode of the fast recovery diode D30 is connected with the resistor R93, the dotted terminal of the secondary winding N2 of the driving transformer T7, and the anode of the recovery diode D30 is connected with the resistor R89; the other end of the resistor R89 is connected with the other end of the resistor R93 and is connected with the G1 grid of the IGBT 1; a N2 synonym terminal of a secondary winding of the driving transformer T7 is connected with an E1 drain electrode of the IGBT 1; a capacitor C42 and a resistor R77 are connected in parallel between the G1 and the E1 poles of the IGBT 1; the cathode of the fast recovery diode D31 is connected with the resistor R96, the dotted terminal of the secondary winding N3 of the driving transformer T7, and the anode of the fast recovery diode D31 is connected with the resistor R92; the other end of the resistor R92 is connected with the other end of the resistor R96 and is connected with the G3 grid of the IGBT 3; the N3 synonym terminal of a secondary winding of the driving transformer T7 is connected with the E3 drain of the IGBT 3; a capacitor C43 and a resistor R87 are connected in parallel between the G3 and the E3 poles of the IGBT 1; the cathode of the fast recovery diode D32 is connected with the resistor R94, the synonym terminal of the other secondary winding N4 of the driving transformer T7, and the anode of the fast recovery diode D32 is connected with the resistor R90; the other end of the resistor R90 is connected with the other end of the resistor R94 and the G2 grid of the IGBT2, the same-name end of the secondary winding N4 of the driving transformer T7 is connected with the E2 drain of the IGBT2, and a capacitor C44 and a resistor R80 are connected between the G2 pole and the E2 pole of the IGBT2 in parallel; the cathode of the fast recovery diode D33 is connected with a resistor R95, the synonym end of the other secondary winding N5 of the driving transformer T7, the anode of the fast recovery diode D33 is connected with a resistor R91, the other end of the resistor R91 is connected with the other end of the resistor R95 and is connected with the G4 grid of the IGBT4, the synonym end of the secondary winding N5 of the driving transformer T7 is connected with the E4 drain of the IGBT4, and a capacitor C41 and a resistor R88 are connected between the G4 and the E4 poles of the IGBT4 in parallel; the IGBT low-voltage side driving circuit comprises a P-channel field effect transistor VT6, a P-channel field effect transistor VT2, an N-channel field effect transistor VT7, an N-channel field effect transistor VT8, resistors R3, R22, R98-R101, a capacitor C50, a capacitor C48, an electrolytic capacitor CE18, and a primary winding N1 and a +15V power supply of a driving transformer T7; the +15V power supply is connected with a filter inductor L3, the other end of the filter inductor L3 is connected with the anode of an electrolytic capacitor CE18 and a resistor R99, the cathode of the electrolytic capacitor CE18 is grounded, the other end of the resistor R99 is connected with a capacitor C50 and the D ends of a P-channel field effect transistor VT6 and the P-channel field effect transistor VT2, and the other end of the capacitor C50 is grounded; the S end of the P-channel field effect transistor VT2 and the D end of the N-channel field effect transistor VT8 are connected with a capacitor C48 and a resistor R98 which are connected in parallel, the other end of the parallel circuit of the capacitor C48 and the resistor R98 is connected with one end of a primary winding N1 of a driving transformer T7, and the other end of a primary winding N1 of the driving transformer T7 is connected with the S end of the P-channel field effect transistor VT6 and the D end of the N-channel field effect transistor VT 7; the S end of the N-channel field effect transistor VT7 is grounded; the G end of a P-channel field effect transistor VT6 is connected with a resistor R101, the G end of an N-channel field effect transistor VT7 is connected with a resistor R22, the other ends of the resistor R101 and the resistor R22 are connected with an 11 pin of a driving chip U2, the G end of the P-channel field effect transistor VT2 is connected with a resistor R100, the G end of the N-channel field effect transistor VT8 is connected with a resistor R3, the S end of the P-channel field effect transistor VT8 is grounded, the other ends of the resistor R100 and the resistor R3 are connected with a 14 pin of the driving chip U2, and the 11 pin and the 14 pin of the driving chip U2 are output ends of PWM pulse; the PWM pulse signal output can form PWM square wave pulse in a primary winding of a driving transformer T7, and square wave pulse signals required by driving the IGBT can be generated in 4 driving circuits on the high-voltage side of the IGBT after the coupling and the isolation of the driving transformer T7;

the cooling Fan control circuit comprises a socket P3, a direct-current high-speed cooling Fan; one end of the resistor R62 is connected to the 16 pin of the socket P1, the plug of the plug P1 and the control line thereof are connected to the 22 pin of the microprocessor U4, the other end of the resistor R62 is connected with the anode of the light emitting diode in the optocoupler U12, and the cathode of the light emitting diode in the optocoupler U12 is grounded; the collector of an output triode in the optocoupler U12 is grounded, the emitter of the output triode in the optocoupler U10 is connected with the resistor R61, the other end of the resistor R61 is connected with the anode of the light emitting diode D18, the cathode of the light emitting diode D18 is connected with the capacitor C56, the cathode of the voltage regulator tube Z6 and the resistor R64, the anode of the voltage regulator tube Z6 and the other end of the capacitor C56 are connected with a-24V power supply, the other end of the resistor R64 is connected with the resistor R66 and the G end or the control electrode of the field effect tube VT3, the other end of the resistor R66 and the S end of the field effect tube VT3 are connected with the-24V power supply, the D end of the field effect tube VT 68623 is connected with the pin 1 of the; a pin 2 of the socket P3 is connected with the anode of the direct-current high-speed cooling Fan Fan, and a pin 1 of the socket P3 is connected with the cathode of the direct-current high-speed cooling Fan Fan;

the control circuit of the electromagnetic air valve DCF comprises a socket P7, the electromagnetic air valve DCF connected with the socket P7, a field effect tube VT1, an optocoupler U10, a voltage stabilizing tube Z2, a diode D14, a light emitting diode D9, resistors R48-R49, a resistor R51, a resistor R45 and a capacitor C26; one end of the resistor R48 is connected to a pin 17 of the socket P1, the plug of the socket P1 and a control line thereof are connected to a pin 23 of the microprocessor U4, the other end of the resistor R48 is connected with the anode of a light emitting diode in the optocoupler U10, and the cathode of the light emitting diode in the optocoupler U10 is grounded; the collector of an output triode in the optocoupler U10 is grounded, the emitter of the output triode in the optocoupler U10 is connected with a resistor R45, the other end of the resistor R45 is connected with the anode of a light-emitting diode D9, the cathode of the light-emitting diode D9 is connected with a capacitor C26, the cathode of a voltage regulator tube Z2 and a resistor R49, the anode of the voltage regulator tube Z2 and the other end of the capacitor C26 are connected with a-24V power supply, the other end of the resistor R49 is connected with a resistor R51 and the G end or the control electrode of a field-effect tube VT1, the other end of the resistor R51 and the S end of the field-effect tube VT1 are connected with the-24V power supply, the D end of the field-effect tube VT1 is connected with the anode of a diode D14 and the pin 1 of the; the 2 pin of the socket P7 is connected with the anode of the electromagnetic air valve DCF, and the 1 pin of the socket P7 is connected with the cathode of the electromagnetic air valve DCF;

the HF high-frequency arc striking control circuit comprises a high-frequency arc striking generating circuit, a field effect transistor VT4, an optocoupler U13, a voltage regulator tube Z5, a light emitting diode D21, resistors R68-R71 and a capacitor C58; the high-frequency arc striking generating circuit consists of a secondary winding N4 of a main transformer T5 in the inverter main circuit, a relay K1, a high-frequency transformer T6, a spark amplifier FD1, an output filter reactor L2, a winding N1 wound on the output filter reactor L2, a high-voltage ceramic chip capacitor C45, a high-voltage ceramic chip capacitor C47, a capacitor C46, a resistor R132 and a diode D20; the high-frequency arc striking generating circuit is powered by a secondary winding N4 of a main transformer T5, and when a primary inversion process is carried out, a certain high-frequency high-voltage power supply output is arranged at two ends of the secondary winding N4; one end of a secondary winding N4 is connected with one end of a contact K1-2 of a relay K1 or a pin 3 of the relay, the other end of the secondary winding N4 is connected with a capacitor C46, the other end of the capacitor C46 is connected with an 8 pin of a primary side of a high-frequency transformer T6 or one end of a contact K1-1 of the K1 relay or a pin 2 of the relay, and a pin 5 of a primary side of a high-frequency transformer T6 is connected with a common node of the contact K1-1 and the contact K1-2 or the pin 1 of the relay; the contact K1-1 is normally closed, and the contact K1-2 is normally open; one end or 9 feet of the secondary side of the high-frequency transformer T6 is connected with a spark amplifier FD1, a high-voltage ceramic chip capacitor C47 and a high-voltage ceramic chip capacitor C45 which are connected in parallel, the other ends of the two ceramic chip capacitors are output to one end of an N1 winding on a filter reactor L2, the other end of an N1 winding is connected with the other end of a spark amplifier FD1 and a resistor R132, and the other end of the resistor R132 is connected with the other end of the secondary side of the high-frequency transformer T; the inductor L2 is connected in series in the secondary inverter output loop of the welding machine; the 4 feet of the relay K1 are connected with the cathode of the diode D20 and the ground terminal, and the 5 feet of the relay K1 are connected with the anode of the diode D20 and the D terminal of the field effect transistor VT4 in the high-frequency arc striking control circuit; the S end of the field effect transistor VT4 is connected with a-24V power supply;

the detection control circuit for the high and low of the input power supply voltage signal comprises an operational amplifier U5A, a diode D36, resistors R44, R46, R60, R72 and R112, capacitors C3, C53, C60 and C64, wherein the power supply of the operational amplifier U5A is + 15V-15V and comes from a switching power supply circuit; a capacitor C60 and a capacitor C3 are respectively connected between +15V and-15V and the ground; the resistor R44 is connected in parallel between the output and the inverting input end of the operational amplifier U5A, the non-inverting input end of the operational amplifier U5A is grounded, and the circuit of the operational amplifier U5A is a proportioner; the cathode of the diode D36 is connected with the anodes of the diode D3 and the diode D2 in the switching power supply circuit, the cathode of the diode D36 is connected with the resistor R72, the resistor R60 and the capacitor C53 which are connected in parallel, the other ends of the resistor R60 and the capacitor C53 which are connected in parallel are grounded, the other end of the resistor R72 is connected with the resistor R46, and the other end of the resistor R46 is connected with the inverting input end of the operational amplifier U5A; the input voltage signal of the resistor R72 is the voltage across the resistor R60 and the capacitor C53 which are connected in parallel; the output of the operational amplifier U5A is connected to the resistor R112, and is capacitively filtered by the capacitor C64 connected between the rear stage and ground to obtain a signal, which is connected to pin 11 of the socket P1 and to pin 16 of the microprocessor U4 via the plug of the socket P1 and its control line.

4. The microprocessor-controlled AC/DC inversion multifunctional argon arc welding machine according to claim 1, wherein: the circuit of the secondary inversion control board part comprises: the device comprises six parts, namely a full-bridge inverter circuit consisting of four groups of MOS field effect tube groups, a switching power supply and a driving circuit for controlling MOS tubes, a Hall sensor detection circuit for outputting current, an output current filter and high-frequency arc striking booster circuit, a control circuit for alternating current arc stabilization pulse and a filter circuit for an output loop; the IN + and IN-input ends of the secondary inverter control panel are connected to the IN + and IN-output ends of the primary inverter circuit part; the OUTPUT1 and OUTPUT2 ends of the secondary inversion control plate are connected to a positive polarity OUTPUT end and a negative polarity OUTPUT end of the front panel part of the welding machine and an electric OUTPUT interface end of the argon arc welding gun; in the subsequent stage circuits at the ends of OUTPUT1 and OUTPUT2, the control of direct current, alternating frequency and cleaning width is realized;

in the full-bridge inverter circuit consisting of the four groups of MOS field effect tube groups, field effect tubes VT 1-1-VT 1-4 are in one group, field effect tubes VT 2-1-VT 2-4 are in one group, field effect tubes VT 3-1-VT 3-4 are in one group, field effect tubes VT 4-1-VT 4-4 are in one group, and each MOS tube is an N-channel field effect tube; four MOS tubes in each group are in parallel connection, the D ends and the S ends of the MOS tubes are respectively connected together, and the G ends or the grid electrodes of the MOS tubes are controlled by a driving signal; in the four groups of MOS tube groups, when a field effect tube VT 1-1-VT 1-4 tube group, a field effect tube VT 3-1-VT 3-4 tube group, a field effect tube VT 2-1-VT 2-4 tube group and a field effect tube VT 4-1-VT 4-4 tube group are alternately conducted under the action of a driving signal, the two OUTPUT ends of OUTPUT1 and OUTPUT2 can obtain alternating current, the alternating current frequency depends on the alternating control frequency of the driving signal of the MOS tube, and the control is the control of alternating current argon arc welding; if the MOS tube driving signal is also controlled by the cleaning width in the alternating process, the control of asymmetric alternating current argon arc welding can be formed; if the field effect tubes VT 1-1-VT 1-4 and VT 3-1-VT 3-4 are always conducted, and the field effect tubes VT 2-1-VT 2-4 and the field effect tubes VT 4-1-VT 4-4 are not conducted, the OUTPUT1 end is positive polarity OUTPUT, the OUTPUT2 end is negative polarity OUTPUT, and the OUTPUT1 end and the OUTPUT2 end are respectively connected with the positive polarity OUTPUT end and the negative polarity OUTPUT end of the front panel of the welding machine, so that the control of direct current manual welding and direct current argon arc welding is realized; the secondary inverter control board is mainly used for realizing control of direct current, alternating frequency and cleaning width in a post-stage circuit at the ends of OUTPUT1 and OUTPUT2 under the action of the control circuit;

the switching POWER supply circuit of the MOS tube comprises a PWM chip U6, an N-channel field effect tube Q10, a switching POWER supply transformer T2, a PNP triode Q20, a PNP triode Q21, a light emitting diode POWER-3, a voltage stabilizing tube ZD10, a fast recovery diode D1, a fast recovery diode D3, a fast recovery diode D9, a fast recovery diode D18, a peripheral resistor, a peripheral capacitor and an electrolytic capacitor; a control field effect transistor Q10 of a PWM chip U6 works, a switching power supply transformer T2 is provided with four secondary windings, and fast recovery diodes, capacitors and electrolytic capacitors which are connected with the four windings are completely consistent in circuit structure; five groups of direct current power supply outputs can be respectively obtained through the output of the four secondary windings, the rectification action of the four fast recovery diodes and the filtering of a rear-stage capacitor and an electrolytic capacitor, and the five groups of direct current power supply outputs are respectively connected to the driving circuits of the corresponding MOS tube groups;

the driving circuit of the MOS tube group comprises a double-non-inverting high-speed MOS tube driving chip U7, optical couplers U1-U4, a voltage-regulator tube ZD6, a voltage-regulator tube ZD7, resistors R3, R6-R9, capacitors C1, C3-C6 and C8; pins 2 of the optical couplers U1-U4 are anodes of light emitting diodes in chips, pins 3 of the optical couplers U1-U4 are cathodes of the light emitting diodes, pins 8 of the optical couplers U1-U4 are working power supply ends, pins 6 and pins 5 of the optical couplers U1-U4 are output signal ends, the pins 6 of the optical couplers U1-U4 are respectively connected with the ends 2G1, 2G2, 2G3 and 2G4 of double-non-inverse-phase high-speed MOS tube groups, and pins 5 of the optical couplers U1-U4 are respectively connected with the ends 2E1, 2E2, 2E3 and 2E4 of; 8 pins and 5 pins of the U1-U4 optocouplers are respectively connected with a capacitor C3, a capacitor C4, a capacitor C6 and a capacitor C5; the one end of resistance R8 connects the 2 feet of opto-coupler U1 and opto-coupler U3, opto-coupler U2 and the 3 feet of opto-coupler U4, and the other end of resistance R8 connects two non-anti-phase high-speed MOS pipe drive chip U7's 5 feet: one end of the resistor R6 is connected with a pin 2 of the optocoupler U2 and the optocoupler U4, a pin 3 of the optocoupler U1 and the optocoupler U3, and the other end of the resistor R6 is connected with a pin 7 of the double-non-reversed-phase high-speed MOS tube driving chip U7; the 6 pins of the double non-inverting high-speed MOS tube driving chip U7 are connected with a power supply end, and a capacitor C1 is connected between the power supply end and the ground; the 3 pins of the double non-inverting high-speed MOS tube driving chip U7 are grounded; a pin 2 of the double non-inverting high-speed MOS tube driving chip U7 is a control signal input end output by a pin 7 of the double non-inverting high-speed MOS tube driving chip U7, the control signal input end is connected with a cathode of a voltage regulator tube ZD6 and a resistor R9, an anode of the voltage regulator tube ZD6 is grounded, and the other end of the resistor R9 is connected with a pin 8 of a socket P2; the 4 feet of the double non-inverting high-speed MOS tube driving chip U7 are control signal input ends output by the 5 feet of the double non-inverting high-speed MOS tube driving chip U7, the control signal input ends are connected with the cathode of the voltage regulator tube ZD7 and the resistor R3, the anode of the voltage regulator tube ZD7 is grounded, and the other end of the resistor R3 is connected with the 7 feet of the socket P2; the 7 pins and the 8 pins of the socket P2 are connected to the 7 pins and the 8 pins of the socket P4 of the main control board through plugs and control wires thereof; the output of the main control panel chip U8 controls the double non-inverting high-speed MOS tube driving chip U7 chip, so that the 5 pins and the 7 pins of the double non-inverting high-speed MOS tube driving chip U7 output two columns of opposite control signals;

the control circuit of the alternating current arc stabilizing pulse comprises an optocoupler U5, an IGBT tube VT1, a transformer T1, diodes D6-D8, D15, D21, a high-power resistor RL1, a voltage stabilizing tube ZD1, ZD5, ZD9, resistors R1, R2, R4, R7, a socket P1, a socket P3, a fuse RT1, an inductor L1, a capacitor C8, electrolytic capacitors CE8 and CE 9; a fuse tube RT1 is connected in series in a primary circuit of the transformer T1 and then connected to a socket P1, the socket P1 is connected to a socket P5 of a primary inverter circuit part through a plug and a control line thereof, and the secondary output voltage of the transformer T1 is filtered by a full-wave rectifier bridge circuit consisting of diodes D6-D8 and D15 and series electrolytic capacitors CE8 and CE9 connected in parallel at two ends of the rectifier bridge to obtain higher direct-current voltage; a resistor R4 is also connected in parallel across the output of the rectifier bridge; the D end of an IGBT tube VT1 is also connected to the positive OUTPUT end of the rectifier bridge, the S end of the IGBT tube VT1 is connected with the 3 pin of a socket P3 and the cathode of a diode D21, the anode of the diode D21 and the anode of a voltage regulator tube ZD9 are connected to the negative OUTPUT end of the rectifier bridge, the negative OUTPUT end is also connected with the IN-end, the cathode of the voltage regulator tube ZD9 is connected with the anode of a voltage regulator tube ZD5, the cathode of the voltage regulator tube ZD5 is connected with the 1 pin of the socket P3 and one end of an inductor L1, and the other end of the inductor L1 is connected with the OUTPUT end of an; the plug P3 is connected to the RL1 high-power resistor through the plug and a connecting wire thereof; a voltage regulator tube ZD1 and a resistor R2 are connected in parallel between the G pole and the S end of the IGBT tube VT1, and the cathode of the voltage regulator tube ZD1 is connected with the G pole of the IGBT tube VT 1; one end of the resistor R1 is connected with the G pole of the IGBT tube VT1, and the other end of the resistor R1 is connected with the 6 feet of the optocoupler U5; the 5 feet of the optocoupler U5 are connected with the S end of an IGBT tube VT 1; the 8 feet of the U5 optocoupler are connected with a + V5 power supply, the 2 feet of the U5 optocoupler are connected with a resistor R7, the other end of the resistor R7 is connected with the 9 feet of the socket P2, the 3 feet of the U5 optocoupler are connected with the 10 feet of the socket P2, and the 9 feet and the 10 feet of the socket P2 are connected with the 9 feet and the 10 feet of the socket P4 of the main control board through plugs and control lines thereof; the output of the main control panel U7 chip is used for controlling the optocoupler U5 chip, so that the pins 6 and 5 of the optocoupler U5 output control signals to control the working state of the IGBT tube VT 1.