CN112091369A

CN112091369A - Inverter welding machine protection circuit and electric welding machine

Info

Publication number: CN112091369A
Application number: CN202010994843.3A
Authority: CN
Inventors: 王科海; 黎波
Original assignee: Shenzhen Jasic Technology Co ltd
Current assignee: Shenzhen Jasic Technology Co ltd
Priority date: 2020-09-21
Filing date: 2020-09-21
Publication date: 2020-12-18

Abstract

An inverter welding machine protection circuit and an electric welding machine detect an input voltage signal through an input voltage detection circuit to generate an input voltage detection signal; the control circuit generates a switch control signal, a correction enabling signal and an inversion control signal according to the input voltage detection signal; the overvoltage protection circuit generates a first protection signal to cut off the first direct current according to the condition that the input voltage signal is greater than a first voltage threshold value, and controls the on-off state of the first direct current according to the switch control signal; the current regulating circuit regulates a rectified voltage signal output by the rectifying circuit according to the disconnection of the first direct current; the power correction circuit performs power correction on the rectified voltage signal according to the correction enable signal and the second direct current to generate a correction voltage signal; the inversion rectifying circuit performs inversion rectification on the correction voltage signal according to the inversion control signal to generate a driving voltage signal; the starting surge protection is realized, the dual overvoltage protection of hardware and software is realized, and the stability and the reliability of the overvoltage protection are improved.

Description

Inverter welding machine protection circuit and electric welding machine

Technical Field

The application belongs to the technical field of circuit protection, especially relates to an contravariant welding machine protection circuit and electric welding.

Background

The inverter welding machine refers to an arc welding Power supply adopting an inverter technology, and the operating principle of the inverter welding machine is that alternating-current voltage of a mains supply is rectified by a rectifying module, Power Factor Correction (PFC) circuit Power Correction and capacitance filtering energy storage are changed into high-voltage direct current, the direct current is changed into high-frequency alternating-current square wave by an inverter unit, and the alternating-current square wave is subjected to voltage reduction by a main transformer and then is converted into low-voltage high-current direct current for output by diode rectification and inductance filtering.

At present, the conventional inverter welding machine with the PFC circuit generally has a complex time sequence, an improper power-on time sequence or untimely control easily causes circuit damage, and for this reason, a PFC inductor is generally connected in series with a boost diode and then connected in parallel with a protection diode to realize the protection of the circuit, but the boost diode is a fast recovery diode, so the capacity of bearing surge current is weak; in addition, at the moment of starting up, the voltage of the filter capacitor is not established, the current passing through the PFC inductor is large due to the fact that the large capacitor is charged, the maximum value of the sine wave is possible at the moment of switching on, the PFC inductor is easy to be magnetically saturated at the moment of large current, once the PFC circuit works due to magnetic saturation, the current of the PFC switching tube is not limited, and the PFC switching tube is burnt out.

Therefore, the protection diode needs to be designed to protect the boost diode in the traditional technical scheme, and the problems of poor protection stability, low power utilization safety and single protection function exist.

Disclosure of Invention

An object of the application is to provide an inverter welding machine protection circuit and electric welding machine, aim at solving the traditional need that exists among the inverter welding machine technical scheme who takes the PFC circuit and design protection diode and protect boost diode, and protection stability is poor, and power consumption security is low to and protect function singleness's problem.

The first aspect of the embodiment of the application provides an inverter welding machine protection circuit, is connected with input power, inverter welding machine protection circuit includes:

the alternating current rectifying circuit is connected with the input power supply and is configured to rectify an input voltage signal provided by the input power supply to generate a rectified voltage signal;

an input voltage detection circuit connected with the input power supply and configured to detect the input voltage signal to generate an input voltage detection signal;

the control circuit is connected with the input voltage detection circuit and is configured to generate a switch control signal, a correction enabling signal and an inversion control signal according to the input voltage detection signal;

the overvoltage protection circuit is connected with the input power supply, the control circuit and the alternating current rectification circuit, is configured to detect the input voltage signal, generates a first protection signal to disconnect a first direct current according to the condition that the input voltage signal is greater than a first voltage threshold value, and controls the on-off state of the first direct current according to the switch control signal;

the current regulating circuit is connected with the input power supply, the overvoltage protection circuit and the alternating current rectifying circuit and is configured to regulate the current corresponding to the rectified voltage signal according to the disconnection state of the first direct current;

the power correction circuit is connected with the alternating current rectification circuit and the control circuit and is configured to carry out power factor correction on the rectified voltage signal according to the correction enabling signal and second direct current to generate a corrected voltage signal;

and the inversion rectifying circuit is connected with the control circuit and the power correcting circuit and is configured to invert and rectify the correcting voltage signal according to the inversion control signal so as to generate a driving voltage signal.

In one embodiment, the control circuit is further configured to generate an alarm prompt signal according to the input voltage detection signal, and the inverter welder protection circuit further includes:

and the display alarm circuit is connected with the control circuit and is configured to display for alarm prompt according to the alarm prompt signal.

In one embodiment, the inverter welder protection circuit further comprises:

an auxiliary power supply circuit connected to the input power supply, the input voltage detection circuit, the overvoltage protection circuit, and the power correction circuit, and configured to generate a feedback voltage signal, the first direct current, and the second direct current according to the input voltage signal; the input voltage detection circuit is further configured to detect the feedback voltage signal to generate the input voltage detection signal.

In one embodiment, the overvoltage protection circuit comprises:

the reverse connection preventing unit is connected with the input power supply and the alternating current rectifying circuit and is configured to prevent the input voltage signal from being reversely connected;

the overvoltage detection unit is connected with the reverse connection prevention unit and is configured to detect the input voltage signal and conduct the input voltage signal when the input voltage signal is larger than the first voltage threshold;

and the isolating switch unit is connected with the overvoltage detection unit, the input power supply, the current regulation circuit, the control circuit and the alternating current rectification circuit and is configured to generate the first protection signal according to the input voltage signal so as to disconnect the first direct current.

In one embodiment, the power correction circuit includes:

the driving switch unit is connected with the control circuit and is configured to control the on and off states of the second direct current according to the correction enabling signal;

the correction control unit is connected with the driving switch unit and is configured to generate a correction control signal according to the second direct current;

and the power correction unit is connected with the alternating current rectification circuit, the correction control unit and the inversion rectification circuit and is configured to carry out power factor correction on the rectified voltage signal according to the correction control signal so as to generate a corrected voltage signal.

In one embodiment, the current regulating circuit includes: a thermistor; the first end of the thermistor is connected with the overvoltage protection circuit and the input power supply, and the second end of the thermistor is connected with the overvoltage protection circuit and the alternating current rectification circuit.

In one embodiment, the disconnecting switch unit includes: the circuit comprises a first photoelectric coupler, a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a first diode, a second diode, a first triode, a second triode and a first relay; wherein a first end of the first capacitor, a cathode of the first diode, and an anode end of the first photocoupler are commonly connected to the overvoltage detection unit, a second end of the first capacitor, an anode of the first diode, and a cathode end of the first photocoupler are connected to a first end of the first resistor, a second end of the first resistor is connected to a first end of the second resistor, a second end of the second resistor is connected to the current regulation circuit, an emitter end of the first photocoupler is connected to a power ground, a collector end of the first photocoupler is connected to a first end of the third resistor and a base of the first triode, a second end of the third resistor, a first end of the fourth resistor, and a first end of the second capacitor are commonly connected to the power correction circuit, and a second end of the fourth resistor and a second end of the second capacitor are connected to the power ground, the emitter of the first triode is connected with the base of the second triode, the collector of the first triode is connected with the first end of the relay coil of the first relay, the anode of the second diode and the collector of the second triode, the emitter of the second triode is connected with a power ground, the second end of the relay coil and the cathode of the second diode are connected to a first direct current end in a common mode, the first end of the relay normally open switch of the first relay is connected with the second end of the second resistor, and the second end of the relay normally open switch is connected with the alternating current rectification circuit.

In one embodiment, the driving switching unit includes: the third diode is connected with the third resistor, the fourth resistor, the sixth resistor, the seventh resistor, the third diode, the first field effect transistor, the third triode and the second photoelectric coupler; wherein an anode of the third diode is connected to the second dc terminal, a cathode of the third diode is connected to a drain of the first field effect transistor, a source of the first field effect transistor and a first terminal of the fifth resistor are commonly connected to the power correction circuit, a gate of the first field effect transistor is connected to a first terminal of the seventh resistor, a second terminal of the seventh resistor and a second terminal of the fifth resistor are connected to a second terminal of the second photocoupler, an emitter terminal of the second photocoupler is connected to a ground, an anode terminal of the second photocoupler is connected to a second terminal of the sixth resistor, a first terminal of the sixth resistor is connected to the first dc terminal, a cathode terminal of the second photocoupler is connected to a collector of the third triode, and an emitter of the third triode is connected to the ground, and the base electrode of the third triode is connected with the control circuit.

In one embodiment, the input voltage detection circuit includes: a fourth diode, a fifth diode, an eighth resistor, and a ninth resistor; the anode of the fourth diode and the cathode of the fifth diode are connected to the auxiliary power supply circuit in common, the cathode of the fourth diode is connected to the first end of the eighth resistor, the second end of the eighth resistor and the first end of the ninth resistor are connected to the control circuit in common, and the second end of the ninth resistor is connected to the power ground.

A second aspect of embodiments of the present application provides a welding bug comprising an inverter welder protection circuit as defined in any one of the above.

Compared with the prior art, the embodiment of the invention has the following beneficial effects: in the inverter welding machine protection circuit, an input voltage signal provided by an input power supply is rectified by an alternating current rectification circuit to generate a rectified voltage signal; the input voltage detection circuit detects an input voltage signal to generate an input voltage detection signal; the control circuit generates a switch control signal, a correction enabling signal and an inversion control signal according to the input voltage detection signal; the overvoltage protection circuit detects the input voltage signal, generates a first protection signal to cut off the first direct current according to the condition that the input voltage signal is greater than a first voltage threshold value, and controls the on-off state of the first direct current according to the switch control signal; the current regulating circuit regulates the current corresponding to the rectifying voltage signal according to the disconnection state of the first direct current; the power correction circuit performs power factor correction on the rectified voltage signal according to the correction enable signal and the second direct current to generate a correction voltage signal; the inversion rectifying circuit inverts and rectifies the correction voltage signal according to the inversion control signal to generate a driving voltage signal; the protection of the startup surge is realized, so that the circuit components are damaged by the very large surge current generated by the voltage mutation of the large electrolytic capacitor in the initial inversion rectifying circuit of the startup of the non-return transformer welder, the dual overvoltage protection of hardware and software can be realized, a protection diode is not needed, and the stability and the safety reliability of the overvoltage protection are improved.

Drawings

FIG. 1 is a schematic diagram of an inverter welding machine protection circuit according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of another structure of a protection circuit of an inverter welding machine according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of another structure of a protection circuit of an inverter welding machine according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of another structure of a protection circuit of an inverter welding machine according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of another structure of a protection circuit of an inverter welding machine according to an embodiment of the present application;

fig. 6 is a schematic circuit diagram of an example of an inverter welder protection circuit according to an embodiment of the present application.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship illustrated in the drawings for convenience in describing the present application and to simplify description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

Fig. 1 shows a schematic structural diagram of an inverter welder protection circuit provided in a first embodiment of the present application, and for convenience of description, only the parts related to the present embodiment are shown, and detailed descriptions are as follows:

referring to fig. 1, an inverter welding machine protection circuit is connected to an input power supply 01, and includes: an input voltage detection circuit 11, a control circuit 12, an overvoltage protection circuit 13, a current regulation circuit 14, an alternating current rectification circuit 15, a power correction circuit 16, and an inverter rectification circuit 17.

An ac rectifier circuit 15 connected to the input power supply 01 and configured to rectify an input voltage signal supplied from the input power supply 01 to generate a rectified voltage signal; an input voltage detection circuit 11 connected to the input power supply 01 and configured to detect an input voltage signal to generate an input voltage detection signal; a control circuit 12 connected to the input voltage detection circuit 11 and configured to generate a switching control signal, a correction enable signal, and an inversion control signal according to the input voltage detection signal; the overvoltage protection circuit 13 is connected with the input power supply 01, the control circuit 12 and the alternating current rectification circuit 15, and is configured to detect an input voltage signal, generate a first protection signal to disconnect the first direct current when the input voltage signal is greater than a first voltage threshold value, and control the on-off state of the first direct current according to a switch control signal; a current adjusting circuit 14 connected to the input power supply 01, the overvoltage protection circuit 13, and the ac rectifying circuit 15, and configured to adjust a current corresponding to the rectified voltage signal according to a disconnection state of the first dc power; a power correction circuit 16 connected to the ac rectification circuit 15 and the control circuit 12, and configured to perform power factor correction on the rectified voltage signal according to the correction enable signal and the second dc power to generate a corrected voltage signal; and an inverter rectification circuit 17 connected to the control circuit 12 and the power correction circuit 16, and configured to perform inversion and rectification processing on the correction voltage signal according to the inversion control signal to generate a driving voltage signal.

In a specific implementation, optionally, the input power supply 01 is an alternating current, the alternating current is rectified by the alternating current rectifying circuit 15 to generate a rectified voltage signal, the rectified voltage signal is subjected to power factor correction and other processing by the power correction circuit 16 to generate a corrected voltage signal, the inversion rectifying circuit 17 is subjected to inversion and rectification and other processing by the power correction circuit 16 to generate a driving voltage signal, and the driving voltage signal is a low-voltage high-current direct current to drive a load. The current regulating circuit 14 is specifically connected to the negative output terminal of the input power supply 01, the second terminal and the third terminal of the overvoltage protection circuit 13, and the negative input terminal of the ac rectifying circuit 15. A first end of the overvoltage protection circuit 13 is connected to a positive output end of the input power supply 01 and a positive input end of the ac rectification circuit 15. When the inverter welding machine is started, the overvoltage protection circuit 13 disconnects the first direct current according to that the switch control signal is not received and the first protection signal is not generated, namely, the overvoltage protection circuit 13 is in a state of keeping disconnecting the first direct current by default when the inverter welding machine is started, and the surge current of the inverter is absorbed by the current adjusting circuit 14 which is connected between the negative input end of the alternating current rectifying circuit 15 and the negative output end of the input power supply 01 in series, so that the input current is adjusted, the current corresponding to the rectifying voltage signal is adjusted, and the startup surge protection of components in the circuit is realized. After the starting process is finished, the control circuit 12 generates and outputs a first switch control signal, a first correction enabling signal and a first inversion enabling signal according to the condition that the input voltage detection signal is smaller than the second voltage threshold, and the overvoltage protection circuit 13 controls to conduct first direct current according to the first switch control signal, so that the overvoltage protection circuit 13 short circuits the current regulation circuit 14, and disconnects the current regulation circuit 14 from regulating the rectified voltage signal; meanwhile, the power correction circuit 16 is communicated with the second direct current according to the first correction enabling signal, power factor correction is carried out on the rectified voltage signal according to the second direct current to generate a corrected voltage signal, and the inversion rectification circuit 17 carries out inversion, rectification and other processing on the corrected voltage signal according to the first inversion control signal to generate a driving voltage signal, so that normal work under the condition that the input voltage signal is not overvoltage is achieved. In the normal working process, on one hand, the overvoltage protection circuit 13 detects the magnitude of an input voltage signal, and generates a first protection signal to disconnect a first direct current when the input voltage signal is greater than a first voltage threshold (namely, overvoltage), the overvoltage protection circuit 13 does not short a current regulation circuit 14, and current corresponding to the input voltage signal is absorbed by the current regulation circuit 14, so that the rectified voltage signal is regulated, when the rectified voltage signal is regulated to be very small (close to zero), the alternating current rectification circuit 15 is considered to be an open circuit, and at the moment, a rear-stage power correction circuit 16, an inversion rectification circuit 17 and the like cannot be damaged by overvoltage of the input voltage signal, so that hardware overvoltage protection is realized; at this time, on the other hand, when the control circuit 12 determines that the input voltage signal is too large (i.e., overvoltage) according to the fact that the input voltage detection signal generated by the input voltage detection circuit 11 is greater than or equal to the second voltage threshold, the control circuit 12 generates and outputs a second switch control signal, a second correction enable signal and a second inversion control signal according to the fact that the input voltage detection signal is greater than or equal to the second voltage threshold, and the overvoltage protection circuit 13 disconnects the first direct current according to the second switch control signal, so that the current regulation circuit 14 absorbs the current corresponding to the input voltage signal, and the purpose of regulating the rectified voltage signal is achieved; meanwhile, the power correction circuit 16 disconnects the connection with the second direct current according to the second correction enable signal, that is, the power supply of the second direct current to the power correction circuit 16 is disconnected, the power factor correction processing on the rectified voltage signal is stopped, and the generation of the corrected voltage signal is stopped; the inversion rectifying circuit 17 stops performing inversion processing on the correction voltage signal according to the second inversion control signal, stops generating the driving voltage signal, and achieves software-controlled overvoltage protection.

Optionally, the switch control signal includes a first switch control signal and a second switch control signal, the calibration enable signal includes a first calibration enable signal and a second calibration enable signal, and the inversion control signal includes a first inversion control signal and a second inversion control signal. The first switch control signal and the second switch control signal may be switch control signals with different levels, for example, the first switch control signal is a high-level switch control signal, and the second switch control signal is a low-level switch control signal. Alternatively, the first voltage threshold and the second voltage threshold may be the same or different.

The embodiment of the application utilizes the overvoltage protection circuit and the current regulation circuit to combine the input voltage detection circuit and the control circuit to realize protecting the startup surge, so that the circuit components and parts can be damaged by the very large surge current which can be generated by the sudden change of the voltage of the large electrolytic capacitor in the initial inversion rectifying circuit of the startup of the inverter welding machine, the dual overvoltage protection of hardware and software can be realized, a protection diode is not needed, and the stability and the safety and reliability of the overvoltage protection are improved.

Referring to fig. 2, in one embodiment, the control circuit 12 is further configured to generate an alarm prompting signal according to the input voltage detection signal, and the inverter welder protection circuit further includes: an alarm circuit 18 is displayed.

And the display alarm circuit 18 is connected with the control circuit 12 and is configured to display for alarm prompt according to the alarm prompt signal.

In specific implementation, the display alarm circuit 18 includes a display screen, and can display alarm prompt information, such as alarm prompt characters, alarm prompt flashing pages, and alarm prompt lights, through the display screen, so as to remind the user of abnormal situations such as overvoltage, so that the user can take safety measures conveniently, thereby reducing potential safety hazards of power utilization and improving the reliability and practicability of the inverter welding machine protection circuit.

Referring to fig. 3, in one embodiment, the inverter welding machine protection circuit further includes: and an auxiliary power supply circuit 19.

An auxiliary power supply circuit 19 connected to the input power supply 01, the input voltage detection circuit 11, the overvoltage protection circuit 13, and the power correction circuit 16, and configured to generate a feedback voltage signal, a first direct current, and a second direct current from the input voltage signal; the input voltage detection circuit 11 is further configured to detect the feedback voltage signal to generate an input voltage detection signal.

In a specific implementation, the auxiliary power supply circuit 19 rectifies and transforms the input voltage signal to generate a feedback voltage signal, a first direct current, and a second direct current. The first direct current is used for supplying power to the overvoltage protection circuit 13 and the like; the second direct current is used to power the power correction circuit 16. In the present embodiment, the input voltage detection circuit 11 detects the feedback voltage signal output by the auxiliary power supply circuit 19 to generate an input voltage detection signal and output the input voltage detection signal to the control circuit 12, so as to achieve the purpose of detecting and monitoring the input voltage. The feedback voltage signal generated after the input voltage signal is rectified and transformed is a direct current signal, and the voltage value is smaller than the voltage value corresponding to the input voltage signal, so that the feedback voltage signal is detected to realize the detection of the input voltage signal, and the precision and the safety of the detection of the input voltage are improved.

In one embodiment, the first direct current and the second direct current may also be provided by other voltage conversion circuits or power adapters.

Referring to fig. 4, in one embodiment, the overvoltage protection circuit 13 includes: an anti-reverse connection unit 131, an overvoltage detection unit 132, an isolation switch unit 133, and an inrush suppression unit 134.

An anti-reverse connection unit 131 connected to the input power supply 01 and the ac rectification circuit 15 and configured to prevent reverse connection of the input voltage signal; an overvoltage detection unit 132 connected to the reverse connection preventing unit 131, configured to detect the input voltage signal and turn on the input voltage signal when the input voltage signal is greater than a first voltage threshold; and an isolation switch unit 133 connected to the overvoltage detection unit 132, the input power supply 01, the current regulation circuit 14, the control circuit 12, and the ac rectification circuit 15, and configured to generate a first protection signal to disconnect the first dc power according to the input voltage signal.

In specific implementation, the reverse connection preventing unit 131 has unidirectional conductivity and can prevent the reverse connection of the input voltage signal, so that the reverse connection protection of the inverter welding machine protection circuit and the input power supply 01 is performed. When the inverter welding machine is started, overvoltage does not occur, the overvoltage detection unit 132 does not conduct an input voltage signal, the isolating switch unit 133 is in a state of disconnecting the first direct current, and the current regulating circuit 14 absorbs the startup surge current to realize startup surge protection of components in the circuit. In the normal working process after the start-up is finished, when the overvoltage detection unit 132 detects the input voltage signal and conducts the input voltage signal to the isolating switch unit 133 according to the condition that the input voltage signal is greater than the first voltage threshold, the isolating switch unit 133 generates a first protection signal according to the input voltage signal to disconnect the first direct current, so that the switch in the isolating switch unit 133 is in a disconnected state, the current regulation circuit is not short-circuited, the current corresponding to the input voltage signal is absorbed through the current regulation circuit 14, and the rectified voltage signal is regulated; at this time, the control circuit 12 generates a first switching control signal of a low level or does not generate a switching control signal according to the input voltage detection signal so as to keep the first direct current in an off state; when the current regulating circuit 14 regulates the rectified voltage signal to be very small (close to zero), the alternating current rectifying circuit 15 can be regarded as an open circuit, and the power correcting circuit 16, the inverter rectifying circuit 17 and the like at the later stage cannot be damaged by overvoltage of the input voltage signal at the moment, so that hardware overvoltage protection is realized.

In one embodiment, referring to fig. 6, the reverse connection preventing unit 131 includes: a diode D7; an anode of the diode D7 is connected to the positive output terminal of the input power supply 01, and a cathode of the diode D7 is connected to the overvoltage detection unit 132. The diode D7 has the characteristics of forward conduction and reverse cut-off, so that the input current can be ensured to be conducted in a single phase, and the current can be prevented from flowing backwards and damaging components in the circuit due to the reverse connection of the input power supply 01.

In one embodiment, referring to fig. 6, the overvoltage detection unit 132 includes: a voltage dependent resistor RV 1; wherein, the first end of piezo-resistor RV1 is connected with preventing joining unit 131, specifically is: a first terminal of the varistor RV1 is connected to the cathode of the diode D7, and a second terminal of the varistor RV1 is connected to the disconnecting switch unit 133. The voltage dependent resistor RV1 has a nonlinear current-voltage characteristic, the voltage threshold of the voltage dependent resistor RV1 is a first voltage threshold, when the voltage applied to the voltage dependent resistor RV1 is lower than the voltage threshold, the voltage dependent resistor RV1 is equivalent to an open-state switch, and when the input voltage signal exceeds the voltage threshold (i.e., overvoltage), the voltage dependent resistor RV1 is equivalent to a closed-state switch, thereby conducting the input voltage signal to the isolation switch unit 133.

In one embodiment, referring to fig. 6, the isolation switch unit 133 includes: the circuit comprises a first photoelectric coupler U1, a first capacitor C3, a second capacitor C4, a first resistor R3, a second resistor R4, a third resistor R5, a fourth resistor R6, a first diode D6, a second diode D8, a first triode Q1, a second triode Q2 and a first relay RLY 1; wherein, the first end of the first capacitor C3, the cathode of the first diode D6 and the anode end of the first photocoupler U1 are commonly connected to the overvoltage detection unit 132, the second end of the first capacitor C3, the anode of the first diode D6 and the cathode end of the first photocoupler U1 are connected to the first end of the first resistor R3, the second end of the first resistor R3 is connected to the first end of the second resistor R4, the second end of the second resistor R4 is connected to the current regulation circuit 14, the emitter end of the first photocoupler U1 is connected to the power ground, the collector end of the first photocoupler U1 is connected to the first end of the third resistor R5 and the base of the first triode Q1, the second end of the third resistor R5, the first end of the fourth resistor R6 and the first end of the second capacitor C4 are commonly connected to the power correction circuit 16, the second end of the fourth resistor R6 and the second end of the second capacitor C4 are connected to the power ground, an emitter of the first triode Q1 is connected with a base of the second triode Q2, a collector of the first triode Q1 is connected with a first end of a relay coil RLY1A of the first relay RLY1, an anode of a second diode D8 and a collector of the second triode Q2, an emitter of the second triode Q2 is connected with a power ground, a second end of the relay coil RLY1A and a cathode of a second diode D8 are connected with a first direct current end in common, a first end of a relay normally open switch RLY1B of the first relay RLY1 is connected with a second end of a second resistor R4, and a second end of the relay normally open switch RLY1B is connected with the alternating current rectifying circuit 15.

In a specific implementation, the first dc terminal outputs a first dc voltage, and the voltage of the first dc voltage may be + 24V. A first terminal of the first capacitor C3, a cathode of the first diode D6, and an anode terminal of the first photocoupler U1 are connected to a second terminal of the varistor RV 1. Wherein, first diode D6 and second diode D8 can carry out the protection of coupling conversely to first photoelectric coupler U1, and first resistance R3 and second resistance R4 are the current-limiting resistor, can carry out current-limiting protection to first photoelectric coupler U1 and current regulator circuit 14 etc. and first electric capacity C3 carries out filtering noise reduction to the input voltage signal to improve the stability of circuit. The first relay RLY1 is a medium for controlling slow start, and the two triodes of the first triode Q1 and the second triode Q2 form a Darlington tube enhanced switch control signal so as to enhance the driving capability of the first relay RLY 1. The third resistor R5 is used as a resistor for driving the first transistor Q1 and the second transistor Q2, and also has a voltage-dividing current-limiting protection function. The fourth resistor R6 and the second capacitor C4 jointly form an RC filter circuit, filtering and noise reduction processing is carried out on the switch control signal, and the triodes (namely the first triode Q1 and the second triode Q2) are prevented from misoperation, so that the control precision of overvoltage protection is improved. The first photocoupler U1 and the first relay RLY1 play a role in photoelectric isolation and overvoltage control and overvoltage protection on hardware.

In one embodiment, referring to fig. 6, the ac rectification circuit 15 includes a rectifier bridge BR1 and a rectifier bridge BR2 to rectify the input voltage signal to generate a rectified voltage signal.

In one embodiment, the current regulation circuit 14 includes: at least one thermistor; the first end of at least one thermistor is connected with the overvoltage protection circuit 13 and the input power supply 01, and the second end of at least one thermistor is connected with the overvoltage protection circuit 13 and the alternating current rectification circuit 13.

For example, referring to fig. 6, the current adjusting circuit 14 includes three parallel thermistors, that is, a thermistor RT1, a thermistor RT2 and a thermistor RT3, a first end of the thermistor RT1, a first end of the thermistor RT2 and a first end of the thermistor RT3 are commonly connected to a second end of the second resistor R4, a first end of the relay normally-open switch RLY1B and a negative output end of the input power supply 01, a second end of the thermistor RT1, a second end of the thermistor RT2 and a second end of the thermistor RT3 are commonly connected to a second end of the relay normally-open switch RLY1B and a negative input end of the ac rectifying circuit 15, and the three parallel thermistors can reduce the heat value of the circuit while limiting the surge current, and adjust the current corresponding to the input voltage signal, thereby adjusting the current corresponding to the rectified voltage signal.

Referring to fig. 5, in one embodiment, the power calibration circuit includes: a drive switching unit 161, a correction control unit 162, and a power correction unit 163.

A driving switch unit 161 connected to the control circuit 12 and configured to control on and off states of the second direct current according to the correction enable signal; a correction control unit 162 connected to the drive switch unit 161 and configured to generate a correction control signal according to the second direct current; and a power correction unit 163 connected to the ac rectification circuit 15, the correction control unit 162, and the inverter rectification circuit 17, and configured to perform power factor correction on the rectified voltage signal according to the correction control signal to generate a corrected voltage signal.

In a specific implementation, the control circuit 12 generates and outputs a first switch control signal, a first correction enable signal and a first inversion enable signal according to the condition that the input voltage detection signal is smaller than the second voltage threshold; the control circuit 12 generates and outputs a second switching control signal, a second correction enable signal, and a second inversion control signal according to the input voltage detection signal being greater than or equal to a second voltage threshold (i.e., overvoltage). The driving switch unit 161 controls the power supply communicated with the second direct current to the correction control unit 162 according to the first correction enable signal, so that the correction control unit 162 generates a correction control signal according to the communicated second direct current, controls the power correction unit 163 to perform power factor correction and other processing on the corrected voltage signal to generate a correction voltage signal and output the correction voltage signal to the inverter rectification circuit 17, and the inverter rectification circuit 17 performs inversion and rectification processing on the correction voltage signal according to the first inversion enable signal to generate a driving voltage signal; the drive switching unit 161 disconnects the second dc power supply to the correction control unit 162 in accordance with the second correction enable signal, so that the correction control unit 162 does not generate the correction control signal, the power correction unit 163 does not perform processing such as power factor correction on the rectified voltage signal, and stops generating the correction voltage signal, and the inverter rectifier circuit 17 stops outputting the drive voltage signal in accordance with the second inverter enable signal.

In a specific implementation, the control circuit 12 may further stop generating the second inverter control signal according to that the input voltage detection signal is greater than or equal to the second voltage threshold, so as to control the inverter rectification circuit 17 to stop inverting and rectifying the correction voltage signal, and stop generating and outputting the driving voltage signal.

Referring to fig. 6, in one embodiment, the driving switch unit 161 includes: a fifth resistor R7, a sixth resistor R8, a seventh resistor R9, a third diode D9, a first field effect transistor VT1, a third triode Q3 and a second photoelectric coupler U2; an anode of the third diode D9 is connected to the second dc terminal, a cathode of the third diode D9 is connected to a drain of the first field effect transistor VT1, a source of the first field effect transistor VT1 and a first end of the fifth resistor R7 are commonly connected to the power correction circuit 16, a gate of the first field effect transistor VT1 is connected to a first end of the seventh resistor R9, a second end of the seventh resistor R9 and a second end of the fifth resistor R7 are connected to a collector end of the second photocoupler U2, an emitter end of the second photocoupler U2 is connected to the power ground, an anode end of the second photocoupler U2 is connected to a second end of the sixth resistor R8, a first end of the sixth resistor R8 is connected to the first dc terminal, a cathode end of the second photocoupler U2 is connected to a collector of the third triode Q3, an emitter of the third triode Q3 is connected to the power ground, and a base of the third triode Q3 is connected to the control circuit 12.

In specific implementation, the second direct current end outputs a second direct current, and the voltage of the second direct current is + 15V. The anode of the third diode D9 is connected to the second dc power, and can rectify and output the second dc power, the source of the first fet VT1 and the first end of the fifth resistor R7 are connected to the calibration control unit 162, and the rectified second dc power is output from the source of the first fet VT1 to power the calibration control unit 162. The base of the third triode Q3 is connected in series with the resistor R01 and then connected with the control circuit 12, the base of the third triode Q3 is connected with the first end of the resistor R01 and the first end of the resistor R02, the second end of the resistor R01 is connected with the control circuit 12, the second end of the resistor R02 is connected with the power ground, and voltage division and current limitation protection can be performed on the third triode Q3 through the resistor R01 and the resistor R02.

In one embodiment, the correction control unit 162 includes a PFC control chip, such as ICE3PCS03G, capable of generating a correction control signal under the power supply of the second direct current, and controlling the power correction unit 163 to perform power factor correction and the like on the rectified voltage signal through the correction control signal to generate a corrected voltage signal.

In one embodiment, referring to fig. 6, the power calibration unit 163 includes: a first inductor L1, a boost diode D2, a resistor R1, a resistor R2, and a first IGBT tube G3 and a second IGBT tube G4; the first IGBT tube G3 and the second IGBT tube G4 are used as power correction switching tubes, the control end of the first IGBT tube G3 and the control end of the second IGBT tube G4 are connected to the power correction control unit 162, the rectified voltage signal after flowing through the first inductor L1 is subjected to power factor correction and other processing according to the correction control signal to generate an original correction voltage signal, and the original correction voltage signal is subjected to boost processing by the boost diode D2 to generate a correction voltage signal and output to the inverter rectification circuit 17.

Alternatively, the boost diode D2 may be replaced by a boost diode group in which a plurality of diodes are connected in parallel.

Referring to fig. 6, in one embodiment, the input voltage detecting circuit 11 includes: a fourth diode D10, a fifth diode D11, an eighth resistor R10, and a ninth resistor R11; the anode of the fourth diode D10 and the cathode of the fifth diode D11 are commonly connected to the auxiliary power circuit 19, the cathode of the fourth diode D10 is connected to the first end of the eighth resistor R10, the second end of the eighth resistor R10 and the first end of the ninth resistor R11 are commonly connected to the control circuit 12, and the second end of the ninth resistor R11 is connected to the power ground.

In a specific implementation, the anode of the fourth diode D10 and the cathode of the fifth diode D11 together form a feedback voltage signal input terminal of the input voltage detection circuit 11, the fourth diode D10 and the fifth diode D11 rectify the feedback voltage signal to generate rectified positive and negative voltages, and the eighth resistor R10 and the ninth resistor R11 limit and divide the rectified positive voltage to generate the input voltage detection signal, so that the input voltage detection signal is within the allowable voltage range of the control circuit 12.

Referring to fig. 6, in one embodiment, the inverter rectification circuit 17 includes a filtering energy storage capacitor C1, an inverter IGBT (e.g., an IGBT G1, an IGBT G2, an IGBT G5, and an IGBT G6), a transformer T1, a rectifier diode D4 and a rectifier diode D6, and the connection relationship between the components is shown in fig. 6; the filtering energy storage capacitor C1 is an electrolytic capacitor with large capacitance capacity. In a specific implementation, the control circuit 12 may send the inversion control signal to the control end of each inversion IGBT through a bus communication manner, such as an I2C bus, to control the inversion IGBT to perform the inversion processing on the correction voltage signal.

In one embodiment, the control circuit 12 may be a single chip or a PLC, and is capable of calculating, analyzing, comparing, and judging the input voltage detection signal, and generating a switch control signal, a calibration enable signal, and an inversion control signal according to the input voltage detection signal and other control signals, so as to perform relevant control on a normal operating state, an overvoltage abnormal state, and the like, and perform display control on an abnormal state such as overvoltage, and the like to prompt an alarm.

The working principle of the inverter welder protection circuit will be briefly explained with reference to fig. 6 as follows:

during starting, since the relay coil RLY1A of the first relay RLY1 is not energized, the normally open relay switch RLY1B is in an off state, so that the current corresponding to the input voltage signal firstly flows through the thermistors (RT1, RT2, RT3) in the current regulating circuit 14, the input current is limited by the thermistors, the surge current is suppressed, the current flowing through the rectifier bridge BR1 and the rectifier bridge BR2 is reduced, and the current flowing through the first inductor L1, the boost diode D1 and the power correction switching tube (i.e. the first IGBT tube G3 and the second IGBT tube G4) is correspondingly reduced, thereby protecting the components in the alternating current rectifying circuit 15, the power correction unit 163 and the inverter rectifying circuit 17 from being damaged by the overcurrent or surge current.

After the starting process is finished, the singlechip outputs a first switch control signal to control the conduction of the first triode Q1 and the second triode Q2, and the relay coil RLY1A of the first relay RLY1 conducts first direct current, so that the normally open switch RLY1B of the relay is closed, and the short-circuit thermistor (RT1, RT2 and RT3) enters a normal working state. In the normal working process after starting, the singlechip generates a first switch control signal, a first correction enabling signal and a first inversion enabling signal according to the condition that the input voltage detection signal is smaller than a second voltage threshold (namely, not overvoltage); the first switch control signal is used for controlling the relay coil RLY1A to be electrified (namely, conducting first direct current) so as to close the relay normally open switch RLY1B, and therefore the thermistors (RT1, RT2 and RT3) are short-circuited; the first correction enable signal enables the third triode Q3 to be conducted, so that the second photocoupler U2 drives the first field effect transistor VT1 to conduct the second direct current (+15V) to the correction control unit 162 to supply power to the correction control unit 162 (such as a PFC control chip), the correction control unit 162 generates a power correction control signal according to the power supply of the second direct current to control the power correction switching tube (i.e., the first IGBT tube G3 and the second IGBT tube G4) to perform power factor correction and other processing on the rectified voltage signal after flowing through the first inductor L1 to generate an original correction voltage signal, and the original correction voltage signal is subjected to boosting processing by the boost diode D2 to generate a correction voltage signal; the first inversion enabling signal is used for controlling an inversion IGBT (namely an IGBT tube G1, an IGBT tube G2, an IGBT tube G5 and an IGBT tube G6) to perform inversion processing on the correction voltage signal so as to generate an inversion voltage signal, the inversion voltage signal is transformed through a transformer T1, and then rectified through a rectifier diode D4 and a rectifier diode D6 to output a driving voltage signal.

In the normal working process after starting, when the input voltage signal is greater than the first voltage threshold, that is, overvoltage occurs, the voltage-sensitive RV1 is turned on, the primary light-emitting diode of the first photocoupler U1 is turned on, the first protection signal is output from the collector terminal of the first photocoupler U1, the first protection signal rapidly pulls down the base level of the first triode Q1, so that the first triode Q1 and the second triode Q2 are turned off, thereby rapidly disconnecting the connection between the first direct current and the power ground, causing the relay coil RLY1A of the first relay RLY1 to be powered down, the relay normally open switch RLY1B to be disconnected, the current corresponding to the input voltage signal flows through the thermistors (RT1, RT2, RT3), because the resistance of the thermistors increases with the rise of temperature, the charging speed is greatly slowed down through the thermistors, when the thermistors reach the level of megabytes, the transformer rectifier circuit 15 can be considered as an open circuit, at this time, the subsequent circuits (such as the power correction circuit 16 and the inverter rectification circuit 17) cannot be damaged, and the hardware overvoltage protection is realized; meanwhile, when the control circuit 12 determines that the input voltage signal is too large (i.e., overvoltage) according to the fact that the input voltage detection signal is greater than or equal to the second voltage threshold, a second switch control signal, a second correction enable signal and a second inversion control signal are generated and output; the second switch control signal pulls down the base level of the first triode Q1, the relay coil RLY1A is controlled to be powered off so that the relay normally-open switch RLY1B is switched off, and therefore current corresponding to the input voltage signal flows through the thermistors (RT1, RT2 and RT3), and is limited through the thermistors, and therefore current corresponding to the rectification voltage signal is adjusted; the second correction enable signal enables the third triode Q3 to be cut off, so that the first field effect transistor VT1 is cut off through the second photoelectric coupler U2, the power supply of the second direct current (+15V) to the correction control unit 162 (such as a PFC control chip) is cut off, the generation of the power correction control signal is stopped after the power failure of the correction control unit 162, the power factor correction and other processing to the rectified voltage signal after flowing through the first inductor L1 are stopped, and the generation of the correction voltage signal is stopped; the second inversion control signal controls the inversion IGBT (namely IGBT tube G1, IGBT tube G2, IGBT tube G5 and IGBT tube G6) to stop performing inversion processing on the correction voltage signal and stop outputting the driving voltage signal, so that software-controlled overvoltage protection is realized.

A second aspect of the application provides a welding bug comprising an inverter welder protection circuit as claimed in any preceding claim.

In specific implementation, the electric welding machine can be an inverter electric welding machine, and can process input commercial power to generate low-voltage large-current direct current so as to be loaded on a device to be welded for welding.

This application embodiment can realize protecting the start-up surge in order to prevent that the start-up surge from damaging circuit components and parts, effectively avoids the circuit damage that the power-on time sequence is improper or control untimely leads to, can also realize the dual overvoltage protection of hardware and software, need not use the protection diode, has improved overvoltage protection's stability and fail safe nature.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the functional units, modules and circuits described above are illustrated as being divided into different functional units, modules and circuits, and in practical applications, the functions may be divided into different functional units, modules and circuits according to different requirements, that is, the internal structure of the device may be divided into different functional units, modules or circuits to complete all or part of the functions described above. In the embodiments, each functional unit, module, and circuit may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units, modules and circuits are only used for distinguishing one from another, and are not used for limiting the protection scope of the present application. In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims

1. The utility model provides an contravariant welding machine protection circuit, is connected with input power supply, its characterized in that contravariant welding machine protection circuit includes:

2. The inverter welder protection circuit of claim 1, wherein the control circuit is further configured to generate an alarm prompt signal based on the input voltage detection signal, the inverter welder protection circuit further comprising:

3. The inverter welder protection circuit of claim 1, wherein the inverter welder protection circuit further comprises:

4. The inverter welder protection circuit of claim 1, characterized in that the overvoltage protection circuit comprises:

5. The inverter welder protection circuit of claim 1, characterized in that the power correction circuit comprises:

6. The inverter welder protection circuit of claim 1, characterized in that the current regulation circuit comprises: at least one thermistor; the first end of the at least one thermistor is connected with the overvoltage protection circuit and the input power supply, and the second end of the at least one thermistor is connected with the overvoltage protection circuit and the alternating current rectification circuit.

7. The inverter welder protection circuit of claim 4, characterized in that the isolation switch unit comprises: the circuit comprises a first photoelectric coupler, a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a first diode, a second diode, a first triode, a second triode and a first relay; wherein a first end of the first capacitor, a cathode of the first diode, and an anode end of the first photocoupler are commonly connected to the overvoltage detection unit, a second end of the first capacitor, an anode of the first diode, and a cathode end of the first photocoupler are connected to a first end of the first resistor, a second end of the first resistor is connected to a first end of the second resistor, a second end of the second resistor is connected to the current regulation circuit, an emitter end of the first photocoupler is connected to a power ground, a collector end of the first photocoupler is connected to a first end of the third resistor and a base of the first triode, a second end of the third resistor, a first end of the fourth resistor, and a first end of the second capacitor are commonly connected to the power correction circuit, and a second end of the fourth resistor and a second end of the second capacitor are connected to the power ground, the emitter of the first triode is connected with the base of the second triode, the collector of the first triode is connected with the first end of the relay coil of the first relay, the anode of the second diode and the collector of the second triode, the emitter of the second triode is connected with a power ground, the second end of the relay coil and the cathode of the second diode are connected to a first direct current end in a common mode, the first end of the relay normally open switch of the first relay is connected with the second end of the second resistor, and the second end of the relay normally open switch is connected with the alternating current rectification circuit.

8. The inverter welder protection circuit of claim 5, characterized in that the drive switch unit comprises: the third diode is connected with the third resistor, the fourth resistor, the sixth resistor, the seventh resistor, the third diode, the first field effect transistor, the third triode and the second photoelectric coupler; wherein an anode of the third diode is connected to the second dc terminal, a cathode of the third diode is connected to a drain of the first field effect transistor, a source of the first field effect transistor and a first terminal of the fifth resistor are commonly connected to the power correction circuit, a gate of the first field effect transistor is connected to a first terminal of the seventh resistor, a second terminal of the seventh resistor and a second terminal of the fifth resistor are connected to a second terminal of the second photocoupler, an emitter terminal of the second photocoupler is connected to a ground, an anode terminal of the second photocoupler is connected to a second terminal of the sixth resistor, a first terminal of the sixth resistor is connected to the first dc terminal, a cathode terminal of the second photocoupler is connected to a collector of the third triode, and an emitter of the third triode is connected to the ground, and the base electrode of the third triode is connected with the control circuit.

9. The inverter welder protection circuit of claim 3, characterized in that the input voltage detection circuit comprises: a fourth diode, a fifth diode, an eighth resistor, and a ninth resistor; the anode of the fourth diode and the cathode of the fifth diode are connected to the auxiliary power supply circuit in common, the cathode of the fourth diode is connected to the first end of the eighth resistor, the second end of the eighth resistor and the first end of the ninth resistor are connected to the control circuit in common, and the second end of the ninth resistor is connected to the power ground.

10. A welding machine comprising an inverter welder protection circuit as claimed in any one of claims 1 to 9.