CN210172764U

CN210172764U - IGBT contravariant manual electric arc welding machine

Info

Publication number: CN210172764U
Application number: CN201920363279.8U
Authority: CN
Inventors: Min Sun; 孙敏; Jikun Wei; 魏继昆; Xuandong Zhu; 朱宣东; Faqing Chen; 陈法庆; Xuanhui Zhu; 朱宣辉
Original assignee: Zhejiang Kende Mechanical and Electrical CO Ltd
Current assignee: Zhejiang Kende Mechanical and Electrical CO Ltd
Priority date: 2019-03-21
Filing date: 2019-03-21
Publication date: 2020-03-24
Anticipated expiration: 2029-03-21

Abstract

The utility model relates to an IGBT contravariant manual electric arc welding machine, which adopts the mode that an IGBT and a fast recovery diode are sleeved in a pin sheath and then welded on a main circuit board, insulating paint is coated on the manufactured main circuit board, and a digital display meter and a control panel thereof are put into a protective cover thereof and epoxy potting material is poured for dustproof protection treatment, thereby preventing the circuit from losing efficacy due to the invasion of conductive dust; the cooling efficiency of key parts of heating main power is improved by configuring a high-air-volume and high-speed direct-current cooling fan and utilizing a good air duct formed among a main circuit board, a radiator of an IGBT (insulated gate bipolar transistor) and a radiator of an output fast recovery diode, so that the load duration of a welding machine is improved, and the problem of short welding time is solved; by adopting the novel control circuits such as the power-on buffer and overvoltage protection, the IGBT drive, the switching power supply, the overheat protection, the output voltage and the like, the control and protection functions of the welding machine are better realized.

Description

IGBT contravariant manual electric arc welding machine

Technical Field

The utility model relates to a structure and circuit design of IGBT contravariant manual electric arc welding machine. Belongs to the technical field of inverter welding machines.

Technical Field

The manual arc welding machine has large sales volume and wide application range. However, in such a welding machine, different circuit, circuit board and whole machine structural designs are adopted, the control principle and mode are different, the layout and connection mode of the circuit board and the whole machine or the connection complexity is different, and the production procedures and manufacturing processes of the product are completely different. These all affect the performance, reliability, production efficiency, transportation costs, etc. of the product, ultimately affecting the market competitiveness of the product.

At present, in the markets at home and abroad, the rated current of the small IGBT tube inversion type manual electric arc welding machine is generally at the level of 80-200A (load duration rate is 100-20%). For such welder products, if the design is not good, the following problems can occur: 1) the net pressure fluctuation resistance is poor. For example, when the input supply voltage of the power grid is low, such as below 180VAC, the welder cannot perform normal welding even with thin welding electrodes. This limits the range of applications of the welder. When the power supply voltage is too large, if the power supply voltage is connected with 380V by mistake, the welding machine is burnt out; 2) the load duration rate is low, and some welding machines can only reach 10-25%. The reason is as follows: the configuration of the cooling fan of the welding machine and the design of the cooling air duct of key devices (such as the IGBT and the radiator thereof, the fast recovery diode and the radiator thereof, the main transformer and the like) are not reasonable. This results in a reduced duty cycle for the welder to work, i.e., a shorter time to weld. Serious problems can also cause the explosion or damage of the IGBT or the fast recovery diode and the burning out of the inverter transformer; 3) the dustproof performance is poor, so that the working reliability of the welding machine is reduced. After the inverter welding machine is used for a long time, some conductive metal-containing dust on a working site can be adsorbed between pins of the IGBT and the fast recovery diode device, so that the creepage distance is reduced, and the device and the control circuit are invalid. Therefore, how to solve the problems and develop a welding machine with good structure and performance and high reliability is the problem and the purpose of the utility model.

SUMMERY OF THE UTILITY MODEL

The utility model relates to a manual electric arc welding machine of IGBT contravariant, the utility model discloses the spare part of the front panel partial installation of welding machine mainly has: the intelligent control system comprises a positive output quick connector and connector base assembly, a negative output quick connector and connector base assembly, a front plastic mask, a working power supply indicator lamp (white) and a thermal protection indicator lamp (yellow) on a digital display meter and a front control circuit board, a current regulation potentiometer and a knob. The front control circuit board assembly has many other electronic components besides a current display meter, a power supply and an overheat protection indication LED. The circuit board is called a control board. The control board is provided with an output current adjusting potentiometer, a UC3846PWM control chip, an operational amplifier LM324 chip and a circuit consisting of a plurality of other electronic components. The digital display meter and the control panel thereof are put into the protective cover, and epoxy potting material is poured. Thus, the control board can play a good dustproof protection role and prevent the control board from losing efficacy due to the invasion of conductive dust. And the front control board part is connected with part of the circuit of the welding machine through the sockets or connectors designed on the board and the connecting wires of the sockets or connectors.

The utility model discloses spare part of installation mainly has on the rear panel of welding machine: power switch, power supply line, cooling blower, back plastic face guard. And cold air is conducted from an air inlet hole at the rear part of the welding machine case. Can make some heating devices or spare parts in the welding machine have good cooling effect.

The utility model discloses the shell part of welding machine, including enclosing cover, bottom plate, braces or handle.

The utility model discloses inside spare part of welding machine, including rectifier bridge, IGBT and the A radiator of fast recovery diode, main circuit board, the B radiator of fast recovery diode, digital display table and front control panel, output fast recovery diode pass through screw fixation at components and parts and spare parts such as radiator, contravariant main transformer, filter electrolytic capacitor, switching power supply transformer, driving transformer, output reactor.

The utility model discloses the dustproof performance problem of welding machine is solved through one of the above-mentioned modes to the welding machine after the pin of four IGBT and fast recovery diode of welding machine adopts the pin sheath to embolia, welds to main circuit board again, and device installation and welding on the main circuit board are accomplished, apply paint insulating varnish with a brush; by adopting the technical measures, the phenomenon that some conductive metal dust on a working site is adsorbed between pins of an IGBT (insulated gate bipolar transistor) tube and a fast recovery diode device and on a control circuit board after the inverter welding machine is used for a long time can be avoided. The creepage distance is not reduced, and the device and the control circuit are not easy to lose efficacy. This improves the reliability of the welder operation.

The utility model discloses rectifier bridge, IGBT and the fast recovery diode of welding machine are respectively through respective screw fixation on the A radiator. And then, the radiator A is fixed on the main circuit board through screws. The radiator B of the IGBT and the fast recovery diode is fixed on the main circuit board through two screws. The output fast recovery diode is fixed on the radiator through screws. And a radiator of the output fast recovery diode is fixed on the main circuit board through screws. The inversion main transformer, the filtering electrolytic capacitor, the control transformer and the driving transformer are welded on the main circuit board. The output reactor is connected in an output loop of the welding machine through screws. Through the above assembling and connecting mode, the main parts of the inverter welding machine of the utility model form a whole. Thus, a "wind tunnel" is formed between the main circuit board, the IGBT heat sink A, B, and the output fast recovery diode heat sink. Due to the fact that the direct-current cooling fan with large air volume and high speed (4000-5500 rpm/min) and the air channel exist, the cooling efficiency of key parts of heating main power (such as all IGBTs, all fast recovery diodes, all radiators, a rectifier bridge, an inverter main transformer, an output reactor and the like) can be improved. The load continuous rate when the welder outputs is also improved. If the output current of the welder is small, the load hold up rate will be higher, and even continuous welding can be performed. Therefore, the problem of short welding time is solved. Meanwhile, the failure rate of devices or parts such as IGBT (insulated gate bipolar transistor) or fast recovery diode, inverter transformer and the like is effectively reduced.

On the main circuit board and the front control board, there are many electronic components and their control circuits, such as resistors, capacitors, diodes, voltage regulator tubes, relays, power-on buffer and overvoltage protection control circuits, IGBT drive control circuits, pulse width modulator circuits, switching power supply control circuits, overheat protection control circuits, etc.

The utility model discloses the welding machine does not have like the welding machine of other multicircuit board structures, has a lot of control connection lines between the circuit board, and not only the preparation process is many and production technology is complicated, and the circuit board still occupies space moreover greatly, makes the complete machine size big, weight heavy. And adopt the utility model discloses structure, circuit board and circuit design of welding machine then can reduce the size of circuit board and complete machine, reduce product weight, production and cost of transportation. Because the control lines are few, the production and processing procedures of the welding machine are few, the manufacturing process is greatly simplified, and the production is more convenient.

From the control function of the circuit, the control method mainly completes the work of input power-on buffering and overvoltage protection control, input rectification and filtering, the generation of the DC power supply voltage of the switching power supply, PWM pulse width regulation, IGBT tube drive control and inversion, the inverter circuit output parameter (current and voltage) control of the manual welding method, protection control and the like. Finally, under the action of the control circuit, various control requirements of manual electric arc welding are met.

The utility model discloses, solve the problem of "anti net pressure fluctuation ability is poor" through the design that adopts novel control circuit. Under the action of a new control circuit, when the input power voltage of a power grid is lower, such as 130VAC, a thin welding rod is adopted, and a welding machine can also carry out normal welding; if the power supply voltage rises to no more than 270VAC, the welding performance of the welder is not affected. Even if the voltage exceeds the predetermined voltage, the power supply overvoltage protection control can be realized. Therefore, the network voltage fluctuation resistance of the welding machine is improved, and the application range of the welding machine is expanded.

The utility model discloses welding machine, a small amount of spare part specification parameter on the accessible adjustment circuit board form the product of different output rated current and load persistence rate to different current classes and load persistence rate requirements. For example, the current rating, number (e.g., two in parallel as one is used; circuit board design needs to be modified at the same time) and heat sink size of the IGBT devices are changed; changing the model and parameters of the 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 rated current specifications can be easily formed. Such as 160A/26.4V, 140A/25.6V, 120A/24.8V, etc. The smaller the rated current, the higher the rated load duration. The purpose of these variations is, of course, to match the production costs of the product to the specifications and performance specifications of the respective machine. In this way, each specification type of welder can achieve optimal cost control. This improves the market competitiveness of the product. The utility model discloses the circuit principle of welding machine, circuit board and complete machine structural design have own unique part. This is also the fundamental object of the patent protection.

Description of the drawings

FIG. 1 is a schematic structural view of an exemplary manual arc welding machine made in accordance with the present invention;

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

FIG. 3 is a schematic diagram of a control circuit of the electric buffer relay on the welding machine of the present invention;

FIG. 4 is a schematic circuit diagram of a portion of the switching power supply circuit of the welder of the present invention;

FIG. 5 is a schematic diagram of a part of the circuit of the switch power circuit and the driving circuit of the welding machine of the present invention;

FIG. 6 is a schematic diagram of the control circuit of the welding machine of the present invention;

the names of the components in the drawings are as follows: 1. a harness; 2. a housing; 3. m4 self-tapping screw; 4. a rectifier bridge; 5. a fast recovery diode; 6. an IGBT; 7. an IGBT; 8. a fast recovery diode; 9. an IGBT; 10. an IGBT; 11. b, a radiator; 12. a reactor; 13. an inverting main transformer; 14. a, a radiator; 15. a main circuit board; 16. a switching power supply transformer; 17. a drive transformer; 18. an electrolytic capacitor; 19. an electrolytic capacitor; 20. a heat sink for the fast recovery diode; 21. a fast recovery diode; 22. a fast recovery diode; 23. a fast recovery diode; 24. a front plastic face shield; 25. a digital display meter and a front circuit board; 26. a front panel; 27. a white indicator light; 28. a yellow indicator light; 29. a current adjustment potentiometer and a knob; 30. a red quick connector; 31. a black quick connector; 32. a base plate; 33. a cooling fan; 34. a rear plastic face shield; 35 the power line is not pulled off; 36. a power line; 37. and a power switch.

Detailed Description

Utilize as shown in fig. 1 the utility model discloses the structural design schematic diagram of the IGBT contravariant welding machine of making, its major constituent includes: a front panel portion. The device mainly comprises a positive output quick connector and connector seat assembly 30, a negative output quick connector and connector seat assembly 31, a front plastic mask 24, a working power supply white indicator lamp 27 on a digital display meter and a front control panel 25, a thermal protection yellow indicator lamp 28, a current regulation potentiometer, a knob 29 and the like.

The front circuit board assembly has a current display meter, a power supply and an overheat protection indicating LED, and many other electronic components. The circuit board is called a control board. The control board is provided with an output current adjusting potentiometer, a UC3846PWM control chip, an operational amplifier LM324 chip and a plurality of other electronic components. The digital display meter and the control panel thereof are put into the protective cover, and epoxy potting material is poured. Thus, the control board can play a good dustproof protection role and prevent the control board from losing efficacy due to the invasion of conductive dust.

And the front control board part is connected with part of the circuit of the welding machine through the sockets or connectors designed on the board and the connecting wires of the sockets or connectors.

The back panel part is mainly provided with a power switch 37, a power supply line 36, a cooling fan 33, a back plastic mask 34 and the like, and cold air enters from an air inlet hole at the back part of the welding machine, so that some heating devices or parts in the welding machine can have good cooling effect.

A housing part including an outer cover 2, a bottom plate 32, a strap or a handle 1, etc.;

the parts inside the welding machine comprise components and parts such as a rectifier bridge 4, an IGBT6, an A radiator 14 of an IGBT 7 and a fast recovery diode 5, a main circuit board 15, a B radiator 11 of a fast recovery diode 8, a digital display meter and a front control board 25, output fast recovery diodes 21, 22 and 23 which are fixed on a radiator 20, an inverter main transformer 13, filter electrolytic capacitors 18 and 19, a switching power supply transformer 16, a driving transformer 17, an output reactor 12 and the like through screws.

The pins of the four

IGBTs

6, 7, 9, 10 and the two

fast recovery diodes

5, 8 are sleeved by pin sheaths and then welded on the main circuit board 15. Digital display table and front control panel 25 are put into its protecting cover to pouring epoxy potting material, the utility model discloses an above-mentioned mode solves the dustproof performance problem of welding machine, and the device installation on main circuit board 15 is accomplished with the welding after, applies paint insulating varnish with a brush. By adopting the technical measures, the phenomenon that some conductive metal-containing dust on a working site is adsorbed between pins of an IGBT (insulated gate bipolar transistor) tube and a fast recovery diode device and on a control circuit board after the inverter welding machine is used for a long time can be avoided, the creepage distance can not be reduced, and the devices and the control circuit are not easy to lose efficacy. This improves the reliability of the operation of the welder.

The rectifier bridge 4, the

IGBTs

6, 7, and the fast recovery diode 5 are fixed to the a heat sink 14 by respective screws, and thereafter, the a heat sink 14 is fixed to the main circuit board 15 by screws. The

IGBTs

9, 10 and the B heat sink 11 of the fast recovery diode 8 are fixed on the main circuit board 15 by two screws. The output fast recovery diodes 21, 22, 23 are fixed to the heat sink 20 by screws. The heat sink 20 of the output fast recovery diodes 21, 22, 23 is fixed to the main circuit board 15 by screws. The inverter main transformer 13, the filter electrolytic capacitors 18 and 19, the control transformer 16 and the drive transformer 17 are welded on the main circuit board 15. The output reactor 12 is connected in the output loop of the welding machine through screws, and the main parts of the inverter welding machine form a whole through the above assembling and connecting modes. Thus, an "air duct" is formed among the main circuit board 15, the radiators A and B of the IGBT and the radiator 20 of the output fast recovery diodes 21, 22 and 23, and due to the arrangement of the direct current cooling fan 33 with large air volume and high speed (4000-5500 rpm/min), the cooling efficiency of key parts of the heating main power (such as each IGBT, each fast recovery diode, each radiator, a rectifier bridge, an inverter main transformer, an output reactor and the like) can be improved. The load continuous rate when the welder outputs is also improved. If the output current of the welder is small, the load hold up rate will be higher, and even continuous welding can be performed. Therefore, the problem of short welding time is solved. Meanwhile, the failure rate of devices or parts such as IGBT (insulated gate bipolar transistor) or fast recovery diode, inverter transformer and the like is effectively reduced.

On the main circuit board 15, the digital display meter and the front control board 25, there are many electronic components and their control circuits, such as resistors, capacitors, diodes, voltage regulator tubes, relays, power-on buffer and overvoltage protection control circuits, IGBT drive control circuits, pulse width modulator circuits, switching power supply control circuits, overheat protection control circuits, etc.

The utility model discloses unlike the welding machine of other multicircuit board structures, there are a lot of connecting wires between the circuit board, and not only the preparation process is many and production technology is complicated, and the circuit board still occupies space greatly, makes the whole size big, weight heavy. And adopt the utility model discloses a circuit board structure and circuit design, then the size of reducible circuit board and complete machine reduces product weight, production and cost of transportation. Because the control lines are few, the production and processing procedures of the welding machine are few, the manufacturing process is greatly simplified, and the production is more convenient.

The utility model discloses the theory of operation of above-mentioned each part circuit of welding machine is briefly described as follows:

fig. 2 is a schematic diagram of the main circuit part of the welding machine of the present invention. The circuit schematic diagrams of other relevant control parts are shown in figures 3-6. As shown in fig. 2, the main circuit portion of the welding machine mainly includes a power-on buffer control circuit composed of a rectifier or a rectifier bridge BG1, a Q5 thyristor, a relay contact JDQB, etc., an IGBT1 (one symbol represents 1 or 2 IGBTs, which will be described below, and will not be described again), an IGBT2 (one symbol represents 1 or 2 IGBTs, which will be described below, which will not be described again), a driving circuit thereof, a single-ended forward inverter circuit composed of fast recovery diodes D1 and D2, an inverter main transformer T2, fast recovery diodes D3 to D5 rectification output circuit, a filter 12, a cooling FAN, a reactor switch 37, etc.

The rectifier or rectifier bridge BG1 is used to convert the ac from the power supply network into dc.

The power-on buffering and overvoltage protection control circuit part comprises a circuit with two parts, and is shown in the attached figures 2 and 3. Part of the circuit consists of thyristors or thyristors Q5, an RT1 thermistor, a contact of a relay JDQA (shown in figure 3) which is JDQB, a triode Q1, an optocoupler U9, a voltage regulator tube ZD6, and resistors R5, R9, R21, R25 and R53. The method is characterized in that: the contact JDQB of the relay is connected in series in an input direct-current bus of the inverter main circuit, the front end of the contact JDQB is connected to the output positive polarity end of the rectifier BG1, and the rear end of the contact JDQB is connected to the positive polarity ends of the filtering electrolytic capacitors EC 1-EC 2. At both ends of the contact, a series circuit of a thyristor or thyristor Q5 and an RT1 thermistor is connected in parallel. Two branches are connected in parallel at two output ends of a rectifier bridge or a rectifier BG1, wherein one branch is a series circuit of two resistors R5 and R9, and the other branch is a series circuit of a resistor R21, a light emitting diode (anode) of an optocoupler U9, a variable resistor R53, a triode Q1 (collector) and a voltage regulator tube ZD6 (cathode). The base of the transistor Q1 is connected between the two resistors R5 and R9 of the previous branch. The trigger electrode of the thyristor or thyristor Q5 is connected with one end of a resistor R25, and the other end of the resistor is connected with the anode of a light emitting diode of the optocoupler U9. The other part of the circuit is shown in figure 3 and consists of a relay JDQA, a triode Q2, a voltage regulator tube ZD2, a diode D28, an electrolytic capacitor C32, a resistor R50 and a resistor R70. The part of the circuit is powered by + 15V-12V power supply voltage provided by the switching power supply circuit. The method is characterized in that: the collector of the transistor Q2 is connected to one end of a relay JDQA (coil), the other end of which is connected to the supply voltage + 15V. The emitter of transistor Q2 is connected to the supply voltage-12V. The base of the triode Q2 is connected with a series branch which is composed of a resistor R50, a resistor R70 and a voltage regulator tube ZD 2. One end of the resistor R70 is connected to the supply voltage +15V, and the other end is connected to the cathode of the voltage regulator ZD 2. The cathode of the voltage regulator ZD2 is connected to one end of a resistor R50, and the other end of the resistor is connected to the base of a transistor Q2. The anode of the electrolytic capacitor C32 is connected to the cathode of the voltage regulator tube ZD2, and the cathode of the electrolytic capacitor C32 is connected to the power supply voltage-12V. And the two ends of the electrolytic capacitor C32 are connected in parallel with an output stage triode of an optocoupler U9, the emitter of the optocoupler triode is connected to the power supply voltage of-12V, and the collector of the optocoupler triode is connected to the anode end of the electrolytic capacitor C32.

Referring to fig. 2 and 3, the JDQA relay (whose contacts are JDQB in fig. 2) selects a relay of 30A/24V. The JDQA relay is controlled by a transistor Q2 and its peripheral circuits, including the photocoupler U9 and the transistor Q1 shown in fig. 2. The working process of the power-on buffer circuit is as follows: when a power supply switch (37) of the welding machine is turned on, during the period that a light emitting diode U9A of an optocoupler U9 does not emit light and an output triode U9B of the optocoupler U9 is cut off or not conducted, control current flows through a resistor connected in series with a trigger pole loop of a thyristor or a thyristor Q5, the current can enable the thyristor or the thyristor Q5 to be conducted, and then after the current flows through an RT1 thermistor, EC 1-EC 2 electrolytic capacitors (470 mu F/400V) (18, 19) are charged. The voltage VCC on the electrolytic capacitors EC 1-EC 2 gradually rises. Meanwhile, as the output stage triode U9B of the optocoupler U9 is turned off or not turned on, the electrolytic capacitor C32 and the resistor R70 form an RC delay charging circuit, and the voltage at the two ends of the electrolytic capacitor C32 is gradually increased. When the voltage at the two ends of the electrolytic capacitor C32 is increased to a certain value, the voltage stabilizing tube ZD2 breaks down and stabilizes the voltage, and a larger current flows into the base electrode of the triode Q2, so that the triode Q2 is conducted, and the JDQA relay can only act. It can be seen that the action time of the JDQA relay lags behind the closing time of the power switch (37), i.e. the JDQA relay is delayed in action. When the JDQA relay acts, the contact (JDQB in figure 2) closes the branch of the RT1 thermistor, so that the utility model discloses when the welder normally inverts and works, the heavy current on the bus flows through from the contact (JDQB in figure 2) of relay. Such a circuit is called a power-on buffer circuit. The power switch (37) is mainly prevented from being burnt out due to the fact that voltage does not exist on the electrolytic capacitors (18 and 19) of EC 1-EC 2 at the moment when the power switch (37) is switched on, which is equivalent to short circuit, and large surge current is formed. The function of the power-on buffer circuit is to limit surge current by means of switching on the thyristor Q5 at the moment of switching on and connecting the thyristor Q5 in series with the RT1 thermistor. The resistance of the RT1 thermistor increases as the temperature increases. Therefore, the power-on buffer circuit can play a better protection role.

Referring to fig. 2 and fig. 3, if the power supply voltage of the welding machine is too high, that is, when the charging voltage VCC of the electrolytic capacitors EC 1-EC 2 increases to a certain value, the transistor Q1 is turned on, and the voltage regulator ZD6 is broken down and regulated. At this time, the light emitting diode U9A in the photocoupler U9 emits light, and the transistor U9B in the photocoupler U9 is turned on. Therefore, the triode Q2 is cut off or not conducted, no current flows through the coil of the relay JDQA, the relay JDQA stops operating, the contact JDQB is disconnected, the inverter circuit stops inverting, and overvoltage protection of the supply voltage is achieved.

Switching power supply circuit, characterized by: for generating +15V, -12V supply voltages. The switching power supply control circuit part comprises a two-part circuit, which is shown in fig. 4 and 5. A part of circuits of the switching power supply comprise a B3 switching power supply transformer (16) (provided with four windings, namely N1 and N4 windings of N1 (B3A), N2 and N3 (B3B in figure 5) and N4 (B3C), N1 is a primary winding, and the others are secondary windings), a TVS1 voltage regulator tube, D16-D17 diodes, a U10 switching power supply control chip (TOP 264 VG), and resistors (R +1, TS, R35) and capacitors (C19-21) around the N1 and the N4 windings. Between the power supply 310V of the switching power supply circuit and the ground, a branch of a capacitor C17 and a resistor TS are connected in series. The terminal S, the terminal F and the terminal V of a U10 switching power supply control chip (TOP 264 VG) are connected between a capacitor C17 and a resistor TS branch. Two branches are connected in parallel between the D end of the U10 switching power supply control chip (TOP 264 VG) and 310V. One branch is the N1 winding of the B3 switching power transformer (16). The other branch is a series circuit of TVS1, a Z voltage regulator and a D16 diode, the TVS1 and the Z voltage regulator are connected in series with reversed polarity, the cathode of the TVS1 is connected to 310V, and the anode of the TVS1 is connected to the anode of the voltage regulator Z. The cathode of the stabilivolt Z is connected to the cathode of D16. The winding N4 of the B3 switching power supply transformer (16) is connected with the anode of a D17 diode at the upper end, and connected with the S end, the F end and the V end of a U10 switching power supply control chip (TOP 264 VG) and the cathodes of a capacitor C21 and an electrolytic capacitor C29 at the lower end. The other end of the capacitor C21 is connected to the cathode of the D17 diode and the collector of the output transistor in the optocoupler U5. The emitter of the output triode in the optocoupler U5 is connected with the series branch of the resistor R35 and the electrolytic capacitor C29. In addition, the emitter of the output stage triode in the optocoupler U5 is also connected with the C end of the U10 switching power supply control chip (TOP 264 VG). A capacitor C20 is connected between the C terminal and the S terminal of the U10 switching power supply control chip (TOP 264 VG). And a resistor R +1 is connected between the X end and the S end of the U10 switching power supply control chip (TOP 264 VG). The other part of the circuit of the switching power supply consists of N2 and N3 secondary windings of a B3 switching power supply transformer (16), voltage-stabilizing tubes Z2-Z3, D21 and D23 diodes, a U5 optical coupler, and resistors (R1-R2, R38 and the like) and capacitors (EC 3-EC 4, C2-C3 and C34) around the light-stabilizing tubes. The secondary windings of the N2 and N3 of the B3 switch power supply transformer (16) are connected in series, and the middle connecting point is the ground end for outputting direct-current voltage. The upper end of the winding of N2 is connected with the anode of diode D21, and the electrolytic capacitors EC3 and EC4, capacitor C2 and resistor R38 are connected in parallel between the cathode of diode D21 and the ground of the partial power supply. The cathode terminal of the diode D21 outputs + 15V. A branch circuit is connected in parallel between the +15V voltage and the ground of the part of the power supply, and the branch circuit consists of resistors R1 and R2, a light emitting diode U5A in an optocoupler U5, and voltage regulators Z2 and Z3. The voltage regulators Z2 and Z3 are connected in series in positive polarity, the anode end of Z2 is connected to the ground end of the part of power supply, and the cathode of Z3 is connected with the cathode of the light emitting diode U5A in the optocoupler U5 and the resistor R2. R2 is connected to the +15V terminal. The anode of the light emitting diode U5A in the optocoupler U5 is connected to the resistor R1, and the other end of the R1 is connected to the +15V terminal. The lower end of the winding of N3 is connected with the cathode of diode D23, and the electrolytic capacitor C34, capacitor C3 and resistor R are connected in parallel between the anode of diode D23 and the ground of the partial power supply. The anode terminal of the diode D23 is the output-12V.

Referring to fig. 4, 310V dc power is supplied to the switching power supply circuit. A primary winding N1 of a B3 switching power supply transformer, TVS1 voltage regulator tubes around the primary winding, a D16 diode and the like form a circuit, the circuit is connected to 310V, and the circuit belongs to a high-voltage loop. To ensure the safety of the control circuit, in fig. 4, isolation is performed by using a U5 (EL 817) photocoupler. The core control chip of the switching power supply is U10, namely TOP264VG chip. For further detailed understanding of the operation principle of this part of the circuit of the switching power supply, it is necessary to understand the operation principle and knowledge of the switching power supply and the TOP264VG switching power supply control chip. The relationship between sections is only a brief description. In summary, the switching power supply control circuit part can respectively obtain +15V and-12V power supply voltages at 2 voltage output circuit parts of B3. For use with various other devices and circuits. For example, 12V supply fans Fan1 and Fan 2; the +15V is supplied to a drive control circuit and other control circuits, etc. According to the circuit and principle of the switching power supply part, the utility model does not adopt a general control transformer and a related voltage conversion circuit to generate the two power supply voltages. The circuit takes 310V from the main loop. The volume and size, the weight of switching transformer are far less than general control transformer, and this just reduces the utility model discloses the cost of welding machine has promoted the technological added value of welding machine.

The utility model discloses switching power supply circuit, following advantage: under the condition of power grid voltage fluctuation, even in the voltage fluctuation range of 130 VAC-270 VAC, the switching power supply circuit can still generate stable + 15V-12V power supply voltage. This ensures the normal operation of other control circuits of the welder. Experiments show that: under the action of the control circuit of the utility model, when the input power voltage of the power grid is lower, such as 130VAC, even if a thin welding electrode is adopted, the welding machine can carry out normal welding; if the power supply voltage rises to no more than 270VAC, the welding performance of the welder is not affected. Therefore, the network voltage fluctuation resistance of the welding machine is improved, and the application range of the welding machine is expanded. Therefore, the problem of poor net pressure fluctuation resistance is solved.

The IGBT drive control circuit realizes drive control of the IGBT1 and the IGBT2 under the control action of a PWM (pulse width modulation) signal generated by the control panel circuit, and finally realizes conversion from direct current to dozens of KHz alternating current through the single-ended forward inverter circuit.

The IGBT drive control circuit part comprises a two-part circuit, and is shown in the accompanying figures 5 and 2. The method is characterized in that: a part of the circuit of the IGBT drive control circuit is composed of a primary MCA (N1 winding) of a drive transformer (17), a Q6 drive chip (4606), resistors R28, R29 and R61 and a capacitor C1. The upper end of the primary MCA (N1 winding) of the driving transformer (17) is connected to +15V, and the lower end thereof is connected to the two D2 terminals of the driving chip Q6. A series circuit of a resistor R61 and a capacitor C1 is connected between the two terminals D1 and D2 of the driver chip Q6. The terminals G1 and G2 of the driver chip Q6 are connected to the terminal S2 thereof, and the terminal S2 thereof is connected to the ground terminal through a resistor R29 and to the PWM control signal terminal through a resistor R28. The S1 terminal of the driver chip Q6 is connected to the +15V terminal. And the other part of the circuit of the IGBT drive control circuit is arranged between the G pole and the E pole of the IGBT. A voltage regulator tube (such as ZD 5) and a resistor (such as R15) are connected in parallel between the G pole and the E pole of the IGBT. The G pole of the IGBT is connected in series with two parallel resistors (such as R63 and R64), and the other ends of the two parallel resistors are connected with the E pole (such as Q3) of a PNP type triode and the cathode of a diode (such as D7). The PNP transistor has its C-pole (e.g., Q3) connected to the E-pole of the IGBT. The B pole (such as Q3) of the PNP type triode is connected to the cathode of a diode (such as D6), two series resistors (such as R60 and R59) are connected in parallel to two ends of the diode (such as D6), and the anode of the diode (such as D6) is connected with the upper end of the secondary winding (such as N2) of the driving transformer. The upper end of the secondary winding is connected to the anode of a diode (e.g., D7), and the lower end is connected to the E-pole of the IGBT.

Referring to fig. 2 and 5, a driving transformer (17) of the IGBT (in fig. 5) is divided into a primary MCA, a secondary MCB (N2) and an MCC (N3), and peripheral diodes D6 to D9, resistors R13, R15 and R59 to R66, voltage regulators ZD4 to ZD5, and triodes Q3 and Q6 form a driving circuit of the IGBT1 and the IGBT 2. The drive circuit form of each section is uniform. The signal output by the chip (4606) of Q6 in fig. 5 controls the operating state of the IGBT through the drive transformer (17) of the IGBT and the drive circuit around the IGBT. In fig. 5, the control signal input by the driving circuit is the control signal output by the IC1 Pulse Width Modulation (PWM) chip (UC 3845) in fig. 6. These signals are a set of square wave pulse signals. The square wave pulse signal has a fixed frequency. Is one of important parameters for guaranteeing the work of the IGBT switch. The time is determined by the peripheral device parameter setting of the UC3845 chip. As to how to determine, the relevant usage data or description of UC3845 needs to be checked. The description of the relationship between the sections is not repeated here. It should be noted that: the PWM signal is a signal for determining the output voltage and current of the main inverter circuit of the welding machine.

The inversion main transformer T2 realizes voltage reduction and current transformation; then the output fast recovery diodes D3-D5 are used for rectifying and outputting, and low-voltage and large-current signals of dozens of KHz alternating current are rectified and converted into direct current signals required by welding.

OUT (+) represents the positive polarity output of the welder. The filter reactor (12) connected in series between the OUT + and the output positive polarity terminal converts pulsating direct current into more stable direct current, which is convenient for welding.

FIG. 6 is a schematic diagram of the control circuit of the welder of the present invention. In fig. 6, IC1 (UC 3845) is a PWM pulse width control chip; u2 is a four operational amplifier chip. The terminals "1" to "6" are connected to the KZ plug in fig. 5, respectively. Wherein, the terminal No. 4 is actually the IF of the primary current transformer connected to the main inverter transformer in the main inverter circuit. The primary current of the inverter main transformer is detected through the current transformer, and a current feedback control signal IF required by output control of the welding machine is obtained. The "6" terminal or OUT + is connected to the positive output terminal of the welder. "3" of the KZ plug in fig. 5 (also "3" in fig. 6) outputs a PWM control signal, which is an input control signal of the IGBT driving circuit, that is, a PWM signal for on/off controlling the IGBT in the inverter main circuit. The RT plug is connected to both terminals of the overheat protector. One terminal of the RT is connected to "5" of the KZ plug in fig. 5 (also "5" in fig. 6). The overheat protector is installed on an aluminum radiator of the IGBT on the power board. D1 is an overheat protection indicator lamp (yellow). D2 is a power indicator. When the welder switching power supply circuit generates +15V, the D2 power indicator lamp is lightened to indicate that the welder works in an electrified way. The +5V supply voltage is derived from pin 8 of IC1 (UC 3845), is the voltage output by the internal reference power supply (Vre) of the chip, and is available to the associated control circuit. RP1 is the current regulating potentiometer of the welder. VR2 is a calibrated adjustment potentiometer for the output current of the welder. The circuit composed of the U2A operational amplifier and peripheral devices thereof is a PI control circuit, which is one of the core parts of the control circuit. As shown in fig. 6, a Ug current setting signal given by the RP1 current regulation potentiometer is input to the input terminal of the PI operational amplifier via R15 or the like; the current negative feedback signal IF detected by the current transformer T3 is rectified and transformed by D9 and the like to obtain a negative feedback Ufi signal controlled by output current. The current negative feedback Ufi signal is input to the other input of the PI operational amplifier through D12, R10, etc., and compared with the Ug current set signal. Then, through the PI control link, the Uk control signal output by the U2A operational amplifier determines the time width of the PWM pulse signal output by the IC1 (UC 3845) chip. When the Ug current given signal and the current negative feedback Ufi signal change, the time width of the PWM pulse signal changes, and finally, the change of the output voltage and the current of the welding machine is realized through the inverter main circuit so as to meet the performance control requirement of manual arc welding.

In fig. 6, it was previously mentioned that the "5" terminal signal of the KZ plug is ultimately connected to the over-temperature protection signal of the welder. The U2C operational amplifier and its peripheral circuit constitute an overheat protection control circuit. The method is characterized in that: the inverting input of the U2C operational amplifier is connected to a resistor (R13) to +5V, and the input is also connected to an over-temperature protector RT. And the other end of the RT is connected to ground level. In order to reduce interference, a capacitor (C5) is also connected between the inverting input terminal of the U2C operational amplifier and ground. The non-inverting input of the U2C operational amplifier is connected to a feedback resistor R11 to the output of the operational amplifier, and the non-inverting input is connected to the midpoint of two resistors R22 and R21, the other end of the resistor R22 is connected to +5V, and the other end of the resistor R21 is connected to ground. The output end of the U2C operational amplifier is connected with the anode of a light-emitting diode (D1), which is an overheat protection indicator lamp (yellow) arranged on the panel of the welding machine. The cathode of the light emitting diode is connected with a resistor (R17) which is connected with the base of an NPN type triode (Q3). A resistor (R18) is connected between the base and emitter of the transistor, and the emitter of the transistor is connected to ground. And the collector of the triode is connected to the current set potential signal of the welding machine. In the welding process, when the heat radiator of the IGBT is overheated or a thermal protector in the welding machine works, the output state of the U2C operational amplifier is changed, on one hand, a D1 overheating protection indicator lamp (yellow) is lightened, on the other hand, a control signal enables a triode Q3 to be conducted through a resistor R17, and a given current signal is limited. The circuit can control the pulse width output of the PWM chip to limit the output current of the welding machine. Meanwhile, the welder cannot weld. Under the effect of the cooling fan, when the temperature of the IGBT radiator is reduced to a certain degree, or when the overheating phenomenon in the welding machine is eliminated and the thermal protector is recovered, the control circuit can continue to output the PWM control signal. While the D1 overheat indicator light (yellow) was off. This achieves over-temperature protection of the welder.

In FIG. 6, the "6" terminal is signal connected to the output voltage of the welder. The U2D, the U2B operational amplifier and the peripheral circuit thereof form an output voltage control circuit of the welding machine. The method is characterized in that: the U2D operational amplifier and its peripheral circuits constitute a voltage comparator. The inverting input terminal of the U2D operational amplifier is connected with a voltage division circuit. The voltage divider circuit is composed of two resistors, one resistor R27 connected with the inverting input end of the U2D operational amplifier is connected to +15V, and the other resistor R28 connected with the inverting input end of the U2D operational amplifier is connected to the ground. The output end of the U2D operational amplifier is connected with a resistor R9. At the rear end of the resistor R9, two branches are connected, one branch being connected to the base of an NPN transistor (Q5). A resistor (R3) is connected between the base and emitter of the transistor, and the emitter of the transistor is connected to ground. And the collector of the triode is connected to a 1-pin control signal end of a welding machine PWM control chip UC 3845. The other branch is connected to the anode of a regulator tube Z1, and the cathode of the regulator tube is connected with a resistor R19 and is connected to the positive polarity OUT + end of the output of the welder through the resistor. The non-inverting input of the U2D operational amplifier is connected to the non-inverting input of the U2B operational amplifier. Since the resistor R19 is connected to the positive OUT + output terminal of the welder, the output level of the U2D operational amplifier is controlled by the output voltage of the welder. The U2B operational amplifier and its peripheral circuits constitute a voltage comparator. The non-inverting input of the U2B operational amplifier is connected to +5V through a resistor R23. The non-inverting input terminal of the U2B operational amplifier is further connected to two branches, one is connected to the non-inverting input terminal of the U2D operational amplifier, and the other is connected to ground through a resistor R30. The inverting input of the U2B operational amplifier is connected to two branches, one of which is connected to the anode of a diode D13, the cathode of which is connected to + 5V. The other branch is connected with a resistor R24, and after passing through the resistor R24, the other branch is connected to the ground through a resistor R20 on one hand, and is connected to the middle junction point of the voltage regulator tube Z1 and the resistor R19 on the other hand. Since the resistor R19 is connected to the positive OUT + output terminal of the welder, the output level of the U2B operational amplifier is controlled by the output voltage of the welder. In addition, in order to improve the anti-interference performance, a capacitor C7 is connected between the middle node of the voltage regulator tube Z1 and the resistor R19 and the ground. The output of the U2B operational amplifier is connected to the anode of a diode D10, and the cathode of the diode is connected to the collector of an NPN transistor (Q3) through a resistor. Since the collector of the transistor is connected to the welder current set potential signal, the output level of the U2B op amp has an effect on the welder output current. On the other hand, a parallel circuit is connected, which has two branches, one is a resistor R25, and the other is a series connection of a resistor R26 and a diode D15. The cathode of the diode D15 is connected to the resistor R26 and then to the output of the U2B operational amplifier. The anode of the diode D15 and the connection point of the resistor R25 are connected to the anode of an electrolytic capacitor C8, the cathode of the capacitor is connected to the ground, and the connection point is connected to a resistor R29 and then to the base of an NPN transistor (Q3). Electrolytic capacitor C8 is also an integrating capacitor, having the effect of time delay. It can be seen from the above description that the two operational amplifier circuit segments are controlled by the output voltage signal of the welding machine, and can respectively control the operating states of the transistors Q5 and Q3, and finally control the PWM pulse signal output by the IC1 (UC 3845) chip. This also controls the output of the welder. For example, if the outputs OUT + and OUT-of the welder are shorted for a long time, U2B outputs a high level, the control signal turns on transistor Q3 via R29, pulling the potential at the midpoint of VR2 low to ground (low), thereby limiting the current set signal. The control circuit limits the output current of the welding machine by controlling the pulse width output of the PWM chip. Meanwhile, the welding machine cannot weld, so that the short-circuit protection function is realized; if a high voltage is output across OUT + and OUT-terminals of the welder, then the U2B operational amplifier outputs a low level. The U2D operational amplifier outputs a high level. The regulator tube of Z1 is broken down and regulated, the transistor Q5 is conducted, which will pull down the control signal of "1" pin of IC1 (UC 3845) chip to approach "ground", thus realize the limitation to the output voltage.

The further working principle is illustrated as follows: after the welder is powered on, the power switch (37) is connected with the power supply of the power grid. Alternating current from a power grid is rectified by a BG1 rectifier bridge (4) and then is converted into pulsating direct current. Current flows through the RT1 thermistor by turning on the thyristor or thyristor Q5, and then EC 1-EC 2 electrolytic capacitors (470 muF/400V) (18, 19) are charged. The voltage on the electrolytic capacitor of EC 1-EC 2 gradually rises and finally becomes more stable direct current of 310V. The EC 1-EC 2 electrolytic capacitor plays a role in filtering. During charging of the electrolytic capacitors of EC 1-EC 2, the relay JDQA is in delayed action due to the control action of the power-on buffer circuit. The power-on buffer circuit can play a role in preventing the surge current from burning out the power supply switch. After the delay, relay JDQA is activated and its contact JDQB is connected to the bus loop. The 310V direct current is supplied to a single-ended forward inverter main circuit consisting of an IGBT1, an IGBT2 tube, a D1, a D2 fast recovery diode, a T2 inverter main transformer, D3-D5 fast recovery diode, a T3 primary bus current detection mutual inductor and the like, the function of the main circuit is mainly that high-voltage direct current is converted into medium-frequency (dozens of KHz) alternating current, the T2 inverter transformer realizes voltage reduction and large current output conversion, and the D3-D5 fast recovery diode converts the medium-frequency alternating current output by the inverter transformer into direct current.

The simple control process of the manual electric arc welding output characteristic of the welding machine of the utility model is briefly described as follows:

after the switch of the rear panel of the welding machine is closed and the power supply source is connected for a short time (in the period, the welding machine circuit is subjected to power-on buffering control and has certain time delay control), all the control panels in the welding machine work in an electrified mode. The power indicator D2 on the front panel lights up to indicate that the welder is live. An IGBT PWM pulse width control circuit in the welding machine generates a pulse signal with a large duty ratio, so that a drive circuit of the IGBT works, the IGBT is in an alternate conduction state, and finally the inverter main circuit outputs no-load voltage. When the operator adjusts the potentiometer of the welding current on the front panel and performs welding, the control circuit can detect an output current signal through the T3 current transformer. And performing signal processing, and taking the signal as a current negative feedback control Ufi signal to be compared with a welding current given Ug signal. And performing PI (proportional and integral) regulation control on the compared difference signals, inputting the difference signals into a welding machine output PWM control circuit, controlling the pulse width or duty ratio of a welding machine output PWM chip by the output result, determining the magnitude of output current and voltage of the welding machine, and realizing accurate control of output current parameters. And the output characteristic of the welding machine meets the requirement of manual arc welding. Further, when the welding current given signal is unchanged, the current detected by the welding machine circuit increases, and after the given set value is reached, the difference value between the welding current given signal and the current negative feedback control signal decreases along with the increase of the current, and after the PI control, the pulse width or the duty ratio of the welding machine output PWM chip is reduced, and the output voltage of the welding machine is reduced. This process, the so-called negative feedback control of current cut-off, is a feedback control which is active only when the current has reached the set value Ug of the welding current potentiometer. Thereafter, as the current increases slightly, the output voltage decreases much. When the voltage drops below a certain value, the control circuit can increase the pulse width or duty ratio of the output PWM chip of the welding machine along with the reduction of the voltage, so that the welding current is increased according to the set parameters, thrust current control is generated, and finally the dropping characteristic of constant current band dragging is formed. The practical test result shows that: if the output voltage is low (such as short circuit for a long time) and high, the control circuit can realize corresponding protection or control; if the main device is overheated, overheating protection is achieved and an overheating protection lamp indicates the overheating protection. The utility model discloses the thrust current of welding machine can make the striking easy. Meanwhile, when the welding current gives a change in the Ug signal, the current cut-off negative feedback set value is different, but the other control processes are similar. In this way, between the minimum and maximum potentiometer settings, numerous droop characteristics can be obtained. Such control is also a basic requirement for satisfying manual arc welding.

The utility model discloses above-mentioned control circuit of welding machine, through actual performance test, the functional. Even if a layperson without welding training operates the welder for manual arc welding, the welding arc is easily stabilized.

As can be seen from the above description, the present invention has its own unique design ideas and methods. Not only realized control such as manual welding method output of welding machine, moreover, the control circuit who designs, including their circuit board and mutual relation of connection to and the complete machine structural design of welding machine, all make the utility model discloses the welding machine product has the root cause place of technical advantages such as control performance is good, welding machine compact structure, also is the important guarantee that satisfies product high efficiency and low-cost production, high reliability, manufacturing process technical advance. The protection content of the utility model discloses a patent application just lies in protecting the structural design of this kind of welding machine.

The above is a detailed description of the present invention in connection with specific welder configurations and circuit boards and control functions, and it should not be construed that the practice of the present invention is limited to these descriptions. It is right other technical personnel in technical field do not deviate from the utility model discloses under the prerequisite of design, can also make a plurality of other deductions and transform, these all should regard as belonging to the utility model discloses the scope of protection.

Claims

1. The utility model provides a manual electric arc welding machine of IGBT contravariant, includes shell and inside spare part, and the shell includes enclosing cover, bottom plate, front panel and rear panel, its characterized in that: the front panel part of the welding machine is provided with a positive output quick connector and a connector base assembly, a negative output quick connector and a connector base assembly, a front plastic mask, a working power indicator, a thermal protection indicator, a current regulation potentiometer and a knob on a digital display meter and a front control circuit board; the front control circuit board is provided with a current display meter, a power supply, an overheat protection indication light-emitting diode, and a circuit consisting of an output current regulation potentiometer, a PWM control chip, an operational amplifier chip and peripheral electronic components; the front control circuit board is placed in the protective cover of the front control circuit board, and epoxy potting material is poured, so that a good dustproof protection effect is achieved, and the control board is prevented from being invalid due to invasion of conductive dust; the connector and the connecting wire designed on the board are connected with other part of circuits of the welding machine; the internal parts of the welding machine comprise a rectifier bridge, an A radiator of an IGBT and a fast recovery diode, a main circuit board, a B radiator of the fast recovery diode, a digital display table and a front control board, wherein the output fast recovery diode is fixed on the radiator, an inversion main transformer, a filter electrolytic capacitor, a switching power supply transformer, a driving transformer and an output reactor through screws; the radiator B of the IGBT and the fast recovery diode is fixed on the main circuit board through two screws, the output fast recovery diode is fixed on the radiator through the screws, and the radiator is fixed on the main circuit board through the screws; the inversion main transformer, the filtering electrolytic capacitor, the control transformer and the driving transformer are welded on the main circuit board; the output reactor is connected in an output loop of the welding machine through screws; the air duct is formed among the main circuit board, the radiator A, B of the IGBT and the radiator of the output fast recovery diode, and the large-air-volume direct-current cooling fan is configured on the rear panel; a plurality of control circuits are arranged on the main circuit board and the front control board, and each control circuit comprises an upper electricity buffer and overvoltage protection control circuit, an IGBT drive control circuit, a pulse width modulator circuit, a switching power supply control circuit and an overheating protection control circuit; the circuit mainly completes input power-on buffering and overvoltage protection control, input rectification and filtering, generation of direct current power supply voltage of a switching power supply, PWM pulse width regulation, IGBT tube drive control, inversion circuit output parameter control, output voltage control and overheating protection control work of manual welding methods.

2. The IGBT inverter manual electric arc welder of claim 1, wherein: in the power-on buffering and overvoltage protection control circuit, a part of circuits consist of a silicon controlled rectifier or a thyristor, a thermistor, a contact of a relay, a first triode, an optocoupler, a first voltage regulator tube, a first resistor, a second resistor, a third resistor, a fourth resistor and a variable resistor; the contact of the relay is connected in series in an input direct current bus of the main inverter circuit, the front end of the relay is connected to the output positive polarity end of the rectifier bridge or the rectifier, and the rear end of the relay is connected to the positive polarity end of the filter electrolytic capacitor; two ends of the contact are connected with a series circuit of a silicon controlled rectifier or a thyristor and a thermistor in parallel, two branches are connected in parallel at two output ends of a rectifier bridge or a rectifier, one branch is a series circuit of two resistors I and two resistors II, and the other branch is a series circuit of a resistor III, an anode of a light emitting diode of an optical coupler, a variable resistor, a collector of a triode and a cathode of a voltage regulator tube; the base electrode of the triode I is connected between the first resistor I and the second resistor II of the previous branch circuit; the trigger electrode of the controlled silicon or the thyristor is connected with one end of a resistor IV, and the other end of the resistor is connected with the anode of the light-emitting diode of the optocoupler; the other part of the circuit consists of a relay, a second triode, a second voltage regulator tube, a first diode, a first electrolytic capacitor, a fifth resistor and a sixth resistor; the circuit is powered by + 15V-12V power supply voltage provided by a switching power supply circuit, a collector of a second triode is connected to one end of a relay coil, the other end of the relay coil is connected to the +15V power supply voltage, an emitter of the second triode is connected to the-12V power supply voltage, a base of the second triode is connected with a series branch circuit which consists of a fifth resistor, a sixth resistor and a second voltage regulator tube, one end of the sixth resistor is connected to the +15V power supply voltage, the other end of the sixth resistor is connected to a cathode of the second voltage regulator tube, a cathode of the second voltage regulator tube is connected to one end of the fifth resistor, the other end of the resistor is connected to a base of the second triode, an anode of a first electrolytic capacitor is connected to a cathode of the second voltage regulator tube, a cathode of the first electrolytic capacitor is connected to the-12V power supply voltage, and two ends, the emitter of the optical coupling triode is connected to the power supply voltage of-12V, the collector of the optical coupling triode is connected to the anode end of the first electrolytic capacitor, and the action of the relay is controlled by the second triode and a peripheral circuit thereof.

3. The IGBT inverter manual electric arc welder of claim 2, wherein: the switching power supply circuit is used for generating +15V and-12V power supply voltage, the switching power supply circuit comprises two parts of circuits, wherein one part of the circuits comprises four windings of a switching power supply transformer, namely N1, N2, N3 and N4, N1 is a primary winding, the other parts of the circuits are secondary windings, N1 and N4 windings of the switching power supply transformer, a voltage regulator tube A and a voltage regulator tube B, a diode A, a diode B, a switching power supply control chip, a resistor A, a resistor B, a resistor C, a capacitor A, a capacitor B and a capacitor C which are arranged around the switching power supply transformer, a branch of the capacitor D and the resistor B is connected between a power supply 310V of the switching power supply circuit and an input rectifying and filtering circuit in series, an S end, an F end and a V end of the switching power supply control chip are connected between the branch of the capacitor D and the branch of the resistor B in parallel, and two branches of the D end of the switching power supply control chip, one branch is an N1 winding of a switching power supply transformer, the other branch is a series circuit of a voltage regulator tube A, a voltage regulator tube B and a diode A, the voltage regulator tube A and the voltage regulator tube B are connected in series in a reversed polarity mode, the cathode of the voltage regulator tube A is connected to 310V, the anode of the voltage regulator tube A is connected to the anode of the voltage regulator tube B, the cathode of the voltage regulator tube B is connected to the cathode of the diode A, the upper end of the N4 winding of the switching power supply transformer is connected to the anode of the diode B, the lower end of the N4 winding of the switching power supply transformer is connected to the S end, the F end and the V end of a switching power supply control chip, the cathode of a capacitor C and the cathode of an electrolytic capacitor A, the other end of the capacitor C is connected to the cathode of the diode B and the collector of an output stage triode in an optocoupler A, the emitter of the output stage triode in the optocoupler A is connected, a capacitor B is connected between the end C and the end S of the switching power supply control chip, and a resistor A is connected between the end X of the switching power supply control chip and the end S thereof; the other part of the circuit of the switch power supply consists of secondary windings of N2 and N3 of a switch power supply transformer, a voltage regulator tube M, a voltage regulator tube N, a diode P, a diode Q, an optical coupler A, and a resistor, an electrolytic capacitor and a capacitor which are arranged around the diode P, the diode Q and the optical coupler A; the N2 and N3 secondary windings of the switch power supply transformer are connected in series, the middle connection point is the ground end for outputting direct current voltage, the upper end of the N2 winding is connected with the anode of the diode P, the cathode of the diode P is connected with the ground of the partial power supply in parallel with the electrolytic capacitor X, the electrolytic capacitor Y, the capacitor F and the resistor H, the cathode end of the diode P is +15V voltage, a branch circuit is connected between the +15V voltage and the ground of the partial power supply in parallel, the branch circuit is composed of the resistor F and the resistor G, the light emitting diode in the optical coupler A, the voltage regulator tube M and the voltage regulator tube N, the positive polarity of the voltage regulator tube M is connected in series, the anode end of the voltage regulator tube M is connected to the ground end of the partial power supply, the cathode of the voltage regulator tube N is connected with the cathode of the light emitting diode in the optical coupler A and the resistor G, the resistor G is connected to the +15V end, the other end of the resistor F is connected to a +15V end, the lower end of the winding N3 is connected with the cathode of a diode Q, an electrolytic capacitor H, a capacitor G and a resistor R are connected in parallel between the anode of the diode Q and the ground of the partial power supply, the anode end of the diode Q is the voltage of-12V output, and a circuit consisting of a primary winding N1 of the switching power supply transformer, a voltage stabilizing tube A and a diode A on the periphery of the primary side of the switching power supply transformer is connected to 310V and belongs to a high-voltage loop; in order to ensure the safety of the control circuit, an optical coupler A is adopted for isolation.

4. The IGBT inverter manual electric arc welder of claim 1, wherein: the IGBT drive control circuit comprises a circuit with two parts, wherein one part of the circuit consists of a primary N1 winding of a drive transformer, a drive chip, three resistors and a capacitor, the upper end of the primary N1 winding of the drive transformer is connected to +15V, the lower end of the primary N1 winding of the drive transformer is connected to two D2 ends of the drive chip, a series circuit of the resistors and the capacitor is connected between the two D1 ends and a D2 end of the drive chip, G1 and G2 ends of the drive chip are connected with an S2 end of the drive chip, and an S2 end of the drive chip is connected to the ground end through another resistor and is connected to a PWM control signal end through another resistor; the S1 end of the driving chip is connected with the +15V end; the other part of the IGBT drive control circuit is arranged between a G pole and an E pole of the IGBT and consists of a drive transformer of the IGBT and a diode, a resistor, a voltage-regulator tube and a triode which are arranged at the periphery of the drive transformer, wherein the drive circuit of each part is in the same form; the signal output by the driving chip controls the working state of the IGBT through a driving transformer of the IGBT and a driving circuit at the periphery of the driving transformer, and the control signal input by the driving circuit is the control signal output by the pulse width modulation PWM chip.

5. The IGBT inverter manual electric arc welder of claim 1, wherein: the overheating protection control circuit consists of an operational amplifier and peripheral circuits thereof, wherein the inverting input end of the operational amplifier is connected with a resistor to +5V, the input end is also connected with an overheating protector, the other end of the overheating protector is connected to the ground level, a capacitor is also connected between the inverting input end of the operational amplifier and the ground in order to reduce interference, the non-inverting input end of the operational amplifier is connected with a feedback resistor to the output end of the operational amplifier, the non-inverting input end of the operational amplifier is connected to the middle point of two resistors, the other end of one resistor is connected to +5V, the other end of the other resistor is connected to the ground, the output end of the operational amplifier is connected with the anode of a light-emitting diode, the light-emitting diode is an overheating protection indicator lamp installed on a panel of the welding machine, and the cathode of the light-emitting diode is connected, the circuit is connected to the base electrode of a triode through the resistor, a resistor is connected between the base electrode and the emitting electrode of the triode, the emitting electrode of the triode is connected to the ground, the collector electrode of the triode is connected to a current given potential signal of a welding machine, in the welding process, when an IGBT radiator generates an overheating phenomenon or when a thermal protector in the welding machine works, the output state of the operational amplifier changes, on one hand, an overheating protection indicator lamp is lightened, on the other hand, the control signal enables the triode to be conducted through the resistor, the current given signal is limited, the circuit can control the pulse width output of the PWM chip, and the output current of the welding machine is limited.

6. The IGBT inverter manual electric arc welder of claim 1, wherein: the output voltage control circuit consists of two operational amplifiers and peripheral circuits thereof, wherein a voltage comparator consists of a first operational amplifier and the peripheral circuits thereof, the inverting input end of the first operational amplifier is connected with a voltage division circuit, the voltage division circuit consists of two resistors, one resistor connected with the inverting input end of the first operational amplifier is connected to +15V, the other resistor connected with the inverting input end of the first operational amplifier is connected to the ground, the output end of the first operational amplifier is connected with one resistor, the rear end of the resistor is connected with two branches, one branch is connected to the base electrode of a triode, a resistor is connected between the base electrode and the emitter electrode of the triode, the emitter electrode of the triode is connected to the ground, and the collector electrode of the triode is connected to the 1-pin control signal end of the welding machine PWM control chip; the other branch is connected to the anode of a voltage regulator tube Z1, and the cathode of the voltage regulator tube is connected with a resistor and is connected to the positive output polarity OUT + end of the welding machine through the resistor; the non-inverting input end of the operational amplifier I is connected to the non-inverting input end of the operational amplifier II, the resistor is connected to the positive output polarity OUT + end of the welding machine, and the output level of the operational amplifier I is controlled by the output voltage of the welding machine; the second operational amplifier and the peripheral circuit thereof form a voltage comparator, the non-inverting input end of the second operational amplifier is connected to +5V through a resistor, the non-inverting input end of the second operational amplifier is also connected with two branches, one is connected to the non-inverting input end of the first operational amplifier, the other is connected to the ground through a resistor, the inverting input end of the second operational amplifier is connected with the two branches, one branch is connected with the anode of a diode, and the cathode of the diode is connected to + 5V; the other branch is connected with a resistor, after passing through the resistor, the other branch is connected to the ground through the other resistor on one hand, and is connected to a voltage regulator tube Z1 and a middle node of the resistor on the other hand, the resistor is connected to an output positive polarity OUT + end of the welding machine, and the output level of the second operational amplifier is controlled by the output voltage of the welding machine; meanwhile, a capacitor is connected between the voltage regulator tube Z1 and the middle junction point of the resistor to the ground, the output end of the second operational amplifier is connected with the anode of a diode on the one hand, the cathode of the diode is connected to the collector of the triode through a resistor, and the collector of the triode is connected to a current given potential signal of the welding machine, so the output level of the second operational amplifier influences the output current of the welding machine; on the other hand, a parallel circuit is connected, the parallel circuit is provided with two branches, one branch is a resistor, the other branch is a series connection of another resistor and a diode, and the cathode of the diode is connected with the resistor and then connected to the output end of the operational amplifier II; the anode of the diode is connected with the anode of an electrolytic capacitor, the cathode of the capacitor is connected to the ground, and the connection point is connected with a resistor and then connected to the base of the NPN type triode.