A control circuit and arc welding power source

Abstract

The utility model discloses a control circuit and arc welding power supply. Control circuit includes sampling judgment unit, charge and discharge unit, reference voltage determination unit and photoelectric coupling unit, sampling judgment unit and reference voltage determination unit are accessed respectively in the positive output and negative output of arc welding power supply, and the control end of the control chip of photoelectric coupling unit is accessed in the arc welding power supply, sampling judgment unit is used to determine the state that arc welding power supply is in currently, photoelectric coupling unit is used to draw low control chip's control end potential when arc welding power supply is in no load state currently, reference voltage determination unit is used to control arc welding power supply output end's voltage less than or equal to the preset threshold when arc welding power supply is in no load state currently, and charge and discharge unit is used to reduce the time delay of arc welding power supply from the welding state to the switching of no load state. The scheme can draw low arc welding power supply output end's voltage when in no load state, thereby avoided the electric shock accident due to the mistake touch, improved the security of arc welding power supply.

Description

Technical Field

[0001] This utility model relates to the field of welding technology, and in particular to a control circuit and an arc welding power supply. Background Technology

[0002] An arc welding power source is a specialized power supply device that provides electrical energy for arc welding and meets the requirements of the welding process. It is an important component of arc welding. Therefore, the safety of the arc welding power source is crucial to safe production.

[0003] Current arc welding power supplies, once powered on, consistently output a DC voltage of 60V or higher, regardless of whether welding is being performed. Especially with manual arc welding power supplies, operators may accidentally touch the output terminal when not welding (i.e., in an unloaded state), leading to electric shock and posing a safety hazard. Utility Model Content

[0004] This invention provides a control circuit and an arc welding power supply that can lower the output voltage of the arc welding power supply when it is unloaded, thereby avoiding electric shock accidents caused by accidental contact and improving the safety of the arc welding power supply.

[0005] According to one aspect of this utility model, a control circuit is provided, comprising: a sampling and judgment unit, a charging and discharging unit, a reference voltage determination unit, and an optocoupler unit; wherein the optocoupler unit is electrically connected to the charging and discharging unit and the reference voltage determination unit, respectively, and the charging and discharging unit is electrically connected to the sampling and judgment unit; the sampling and judgment unit and the reference voltage determination unit are respectively connected to the positive output terminal and the negative output terminal of the arc welding power supply, respectively, and the optocoupler unit is connected to the control terminal of the control chip of the arc welding power supply; the sampling and judgment unit is used to determine the current state of the arc welding power supply; the optocoupler unit is used to lower the potential of the control terminal of the control chip when the arc welding power supply is currently in an unloaded state, so as to stop the arc welding power supply from working; the reference voltage determination unit is used to control the voltage of the output terminal of the arc welding power supply to be less than or equal to a preset threshold when the arc welding power supply is currently in an unloaded state; and the charging and discharging unit is used to reduce the time delay of the arc welding power supply switching from the welding state to the unloaded state.

[0006] Optionally, the sampling and judgment unit includes a first resistor and a first diode; wherein, one end of the first resistor is connected to the positive output terminal of the arc welding power supply, the other end of the first resistor is electrically connected to the output terminal of the first diode, and the input terminal of the first diode is electrically connected to the charging and discharging unit.

[0007] Optionally, the charging and discharging unit includes a second resistor, a third resistor, a first capacitor, and a second capacitor; wherein, one end of the second resistor is connected to a first DC power supply, the other end of the second resistor is electrically connected to the input terminal of the first diode and one end of the second capacitor, and the other end of the second capacitor is grounded; one end of the third resistor is electrically connected to one end of the second resistor, the other end of the third resistor is electrically connected to one end of the first capacitor, and the other end of the first capacitor is electrically connected to one end of the second capacitor and the optocoupler unit.

[0008] Optionally, the optocoupler unit includes an optocoupler, a fourth resistor, a fifth resistor, a switching transistor, and a third capacitor; wherein, the input terminal of the light-emitting diode in the optocoupler is electrically connected to the other end of the first capacitor, the output terminal of the light-emitting diode in the optocoupler is electrically connected to the reference voltage determination unit, the collector of the phototransistor in the optocoupler is electrically connected to one end of the fourth resistor, and the emitter of the phototransistor in the optocoupler is grounded; the other end of the fourth resistor is electrically connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to a second DC power supply; the base of the switching transistor is electrically connected to the other end of the fourth resistor, the collector of the switching transistor is grounded, and the emitter of the switching transistor is connected to the control terminal of the control chip; one end of the third capacitor is electrically connected to the emitter of the switching transistor, and the other end of the third capacitor is grounded.

[0009] Optionally, the reference voltage determination unit includes a Zener diode; wherein one end of the Zener diode is electrically connected to the output terminal of the light-emitting diode in the optocoupler, and the other end of the Zener diode is connected to the negative output terminal of the arc welding power supply, and the negative output terminal of the arc welding power supply is grounded.

[0010] Optionally, it may also include an isolation unit and / or a status indicator unit; the isolation unit is connected in series between the optocoupler unit and the control terminal of the control chip to protect the control circuit; the status indicator unit is connected in series between the optocoupler unit and the reference voltage determination unit to indicate the current status of the arc welding power supply.

[0011] Optionally, the isolation unit includes a second diode.

[0012] Optionally, the status indication unit includes a sixth resistor and an indication element connected in parallel.

[0013] Optionally, a switch is provided between one end of the first DC power supply and the second resistor; wherein, when the switch is open, the control circuit does not operate.

[0014] According to another aspect of the present invention, an arc welding power supply is provided, including a control chip and a control circuit of any of the above embodiments.

[0015] The technical solution of this utility model embodiment involves designing a control circuit between the output terminal of the arc welding power supply and the control terminal of the control chip. This control circuit includes a sampling and judgment unit, a charging and discharging unit, a reference voltage determination unit, and an optocoupler unit. On one hand, since the sampling and judgment unit can determine the current state of the arc welding power supply, the optocoupler unit pulls down the control terminal potential of the control chip when the arc welding power supply is in an unloaded state, causing the arc welding power supply to stop working. This ensures that once the arc welding power supply is not performing welding operations, the control chip will no longer output drive pulse signals, and therefore will no longer supply power to the positive and negative output terminals of the arc welding power supply. On the other hand, when the arc welding power supply is in an unloaded state, the reference voltage determination unit can control the voltage at the output terminal of the arc welding power supply to be less than or equal to a preset threshold, thereby ensuring that the output voltage of the arc welding power supply is always within a safe range in the unloaded state. Even if the operator accidentally touches it, there will be no danger, avoiding electric shock accidents and improving the safety of the arc welding power supply. Furthermore, the charging and discharging unit reduces the time delay of the arc welding power supply switching from the welding state to the unloaded state, which can further improve the safety of the arc welding power supply and lay the foundation for safe production. Furthermore, the control circuit has a simple structure, is easy to implement, and has low cost.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a control circuit provided in Embodiment 1 of this utility model;

[0019] Figure 2 This is a schematic diagram of another control circuit provided in Embodiment 1 of this utility model;

[0020] Figure 3 This is a schematic diagram of another control circuit provided in Embodiment 1 of this utility model;

[0021] Figure 4 This is a schematic diagram of another control circuit provided in Embodiment 1 of this utility model;

[0022] Figure 5This is a schematic diagram of the connection between a control circuit and a control chip provided in Embodiment 1 of this utility model. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] Example 1

[0026] Figure 1 This is a schematic diagram of a control circuit provided in Embodiment 1 of this utility model. The control circuit is applicable to various arc welding power supplies, such as inverter arc welding power supplies, manual arc welding power supplies, and inverter-manual arc welding power supplies. Figure 1 As shown, the control circuit includes: a sampling and judgment unit 100, a charging and discharging unit 200, a reference voltage determination unit 300, and an optocoupler unit 400.

[0027] Specifically, the optocoupler unit 400 is electrically connected to the charge / discharge unit 200 and the reference voltage determination unit 300, respectively. The charge / discharge unit 200 is electrically connected to the sampling and judgment unit 100. The sampling and judgment unit 100 and the reference voltage determination unit 300 are respectively connected to the positive output terminal U+ and the negative output terminal U- of the arc welding power supply. The optocoupler unit 400 is connected to the control terminal (such as the control pin of the control chip) of the arc welding power supply.

[0028] The sampling and judgment unit 100 samples the positive output terminal U+ of the arc welding power supply to determine the current state of the arc welding power supply, i.e., whether it is currently in an unloaded state or a welding state. When the sampling and judgment unit 100 determines that the arc welding power supply is currently in an unloaded state, the optocoupler unit 400 starts working. The optocoupler unit 400 is used to pull down the control terminal potential of the control chip, thereby causing the control chip to stop outputting pulse width modulation (PWM) drive pulse signals, and the arc welding power supply stops working. At this time, the reference voltage determination unit 300 controls the voltage at the output terminal of the arc welding power supply to be less than or equal to a preset threshold.

[0029] The voltage at the output terminal of the arc welding power supply refers to the voltage difference between the positive output terminal U+ and the negative output terminal U-. The preset threshold value can be set according to actual conditions. Typically, the preset threshold value is less than the "safe voltage" for the human body, ensuring that even if an operator accidentally touches the output terminal, no danger will occur, thus avoiding electric shock accidents. Optionally, the preset threshold value can be less than or equal to 24V, such as 24V, 20V, 16V, 5V, etc.

[0030] The discharge time of the charge-discharge unit 200 is only a few seconds. The charge-discharge unit 200 can reduce the time delay of the arc welding power supply switching from the welding state to the no-load state, so as to further improve the safety of the arc welding power supply.

[0031] In one embodiment, combined with Figure 1 , Figure 2 This is a schematic diagram of another control circuit provided in Embodiment 1 of this utility model. Figure 2 As shown, the control circuit may also include an isolation unit 500 and / or a status indication unit 600. Figure 2 The diagram is drawn using the control circuit, which includes the isolation unit 500 and the status indication unit 600, as an example.

[0032] Specifically, the isolation unit 500 is connected in series between the optocoupler unit 400 and the control terminal of the control chip to protect the control circuit and improve its reliability. The status indicator unit 600 is connected in series between the optocoupler unit 400 and the reference voltage determination unit 300 to indicate the current status of the arc welding power supply. In other words, the status indicator unit 600 serves as a prompt, allowing the operator to visually see the current status of the arc welding power supply.

[0033] In one embodiment, Figure 3 This is a schematic diagram of another control circuit provided in Embodiment 1 of this utility model. (See attached diagram.) Figure 3As shown, the sampling and judgment unit 100 includes a first resistor R1 and a first diode D1. One end of the first resistor R1 is connected to the positive output terminal U+ of the arc welding power supply, the other end of the first resistor R1 is electrically connected to the output terminal of the first diode D1, and the input terminal of the first diode D1 is electrically connected to the charging and discharging unit 200.

[0034] The charging / discharging unit 200 includes a second resistor R2, a third resistor R3, a first capacitor C1, and a second capacitor C2. One end of the second resistor R2 is connected to a first DC power supply V1, and the other end of the second resistor R2 is electrically connected to the input terminal of the first diode D1 and one end of the second capacitor C2, with the other end of the second capacitor C2 grounded. One end of the third resistor R3 is electrically connected to one end of the second resistor R2, and the other end of the third resistor R3 is electrically connected to one end of the first capacitor C1. The other end of the first capacitor C1 is electrically connected to one end of the second capacitor C2 and the optocoupler unit 400.

[0035] The optocoupler unit 400 includes an optocoupler U1, a fourth resistor R4, a fifth resistor R5, a switching transistor Q1, and a third capacitor C3. The input terminal of the light-emitting diode (LED) in optocoupler U1 is electrically connected to the other end of the first capacitor C1; the output terminal of the LED in optocoupler U1 is electrically connected to the reference voltage determination unit 300; the collector of the phototransistor in optocoupler U1 is electrically connected to one end of the fourth resistor R4; the emitter of the phototransistor in optocoupler U1 is grounded; the other end of the fourth resistor R4 is electrically connected to one end of the fifth resistor R5; the other end of the fifth resistor R5 is connected to the second DC power supply V2; the base of the switching transistor Q1 is electrically connected to the other end of the fourth resistor R4; the collector of the switching transistor Q1 is grounded; the emitter of the switching transistor Q1 is connected to the control terminal of the control chip; one end of the third capacitor C3 is electrically connected to the emitter of the switching transistor Q1; the other end of the third capacitor C3 is grounded.

[0036] An optocoupler U1 is a device that converts an electrical signal into an optical signal and then back into an electrical signal. The optocoupler U1 includes a light-emitting diode (LED) and a phototransistor. When a driving current flows through the LED in the optocoupler U1, it emits infrared light (an optical signal). This optical signal illuminates the base region of the phototransistor. The base current of the phototransistor is determined by the photogenerated carriers produced by the incident light; that is, the greater the current flowing through the LED, the greater the base current of the phototransistor. Thus, the input electrical signal of the LED is converted into the output electrical signal of the phototransistor through the optical signal, turning the phototransistor on.

[0037] In this invention, the first capacitor C1 is a polarized capacitor, and the second capacitor C2 and the third capacitor C3 are filter capacitors.

[0038] The reference voltage determination unit 300 includes a Zener diode Z1; one end of the Zener diode Z1 is electrically connected to the output terminal of the light-emitting diode in the optocoupler U1, and the other end of the Zener diode Z1 is connected to the negative output terminal U- of the arc welding power supply, which is grounded.

[0039] When the control circuit includes an isolation unit 500 and a status indication unit 600, the isolation unit 500 includes a second diode D2. The output terminal of the second diode D2 is electrically connected to the emitter of the switching transistor Q1, and the input terminal of the second diode D2 is connected to the control terminal of the control chip. The status indication unit 600 includes a sixth resistor R6 connected in parallel and an indicator element LED. One end of the sixth resistor R6 is electrically connected to the output terminal of the light-emitting diode in the optocoupler U1, and the other end of the sixth resistor R6 is electrically connected to one end of the Zener diode Z1. The indicator element LED is connected in parallel with the sixth resistor R6.

[0040] Optionally, the voltage of the first DC power supply V1 can be 24V, and the voltage of the second DC power supply V2 can be 15V.

[0041] Optional, Figure 4 This is a schematic diagram of another control circuit provided in Embodiment 1 of this utility model. Figure 4 As shown, a switch K1 is provided between one end of the first DC power supply V1 and the second resistor R2; wherein, when the switch K1 is open, the control circuit does not work, that is, the control circuit is ineffective when the switch K1 is open.

[0042] Normally, switch K1 is in the normally closed state.

[0043] Figure 5 This is a schematic diagram illustrating the connection between a control circuit and a control chip according to Embodiment 1 of this utility model. Figure 5As shown, the working principle of the control circuit is as follows: When the arc welding power supply is in an unloaded state (i.e., no welding operation is being performed), the switch K1 closes. The first DC power supply V1 passes through the charging and discharging unit 200 (the third resistor R3 is connected in series with the first capacitor C1 and then in parallel with the second resistor R2), the LED in the optocoupler U1, the status indicator unit 600 (the sixth resistor R6 and the indicator element LED are connected in parallel), and the Zener diode Z1 to ground, forming a current i1 loop. The indicator element LED lights up, indicating that the current arc welding power supply is in an unloaded state. The current i1 drives the LED in the optocoupler U1 to emit light, illuminating the base region of the phototransistor. The phototransistor in the optocoupler U1 forms a current i2, which drives the switch Q1 to conduct. After passing through the second diode D2, the control terminal (usually pin 1 of the control chip) is pulled low, so that the control chip (usually pins 11 and 14) no longer outputs PWM-OUTA and PWM-OUTB signals, that is, the main inverter circuit of the arc welding power supply stops working. At this point, the voltage at the output terminal of the arc welding power supply is determined by the voltage regulation value of the Zener diode Z1. Specifically, the first DC power supply V1 forms a voltage divider circuit through the second resistor R2, the LED in the optocoupler U1, the sixth resistor R6, and the Zener diode Z1. The voltage divided by the second capacitor C2 is then applied to the output terminal of the arc welding power supply via the first diode D1 and the first resistor R1. In other words, by changing the voltage regulation value of the Zener diode Z1, the voltage divider value can be changed, thereby altering the voltage across the unloaded output terminal of the arc welding power supply.

[0044] When the arc welding power supply is in welding mode (i.e., during welding operation), the positive output terminal U+ and the negative output terminal U- of the arc welding power supply are connected to the welding cable, and the positive output terminal U+ and the negative output terminal U- are short-circuited. The first DC power supply V1 flows through the charging and discharging unit 200 (the third resistor R3 is connected in series with the first capacitor C1 and then in parallel with the second resistor R2), the first diode D1, the first resistor R1, and the positive output terminal U+ and the negative output terminal U- of the arc welding power supply to ground, forming a current return. At this time, the current i1 loop cannot be generated, the optocoupler U1 will not conduct, the control terminal of the control chip (usually pin 1 of the control chip) is at a high level, the control chip is working normally, and pins 11 and 14 of the control chip output PWM-OUTA and PWM-OUTB signals, that is, the main inverter circuit of the arc welding power supply is working normally, and the output meets the current / voltage requirements during welding.

[0045] The technical solution of this utility model embodiment involves designing a control circuit between the output terminal of the arc welding power supply and the control terminal of the control chip. This control circuit includes a sampling and judgment unit, a charging and discharging unit, a reference voltage determination unit, and an optocoupler unit. On one hand, since the sampling and judgment unit can determine the current state of the arc welding power supply, the optocoupler unit pulls down the control terminal potential of the control chip when the arc welding power supply is in an unloaded state, causing the arc welding power supply to stop working. This ensures that once the arc welding power supply is not performing welding operations, the control chip will no longer output drive pulse signals, and therefore will no longer supply power to the positive and negative output terminals of the arc welding power supply. On the other hand, when the arc welding power supply is in an unloaded state, the reference voltage determination unit can control the voltage at the output terminal of the arc welding power supply to be less than or equal to a preset threshold, thereby ensuring that the output voltage of the arc welding power supply is always within a safe range in the unloaded state. Even if the operator accidentally touches it, there will be no danger, avoiding electric shock accidents and improving the safety of the arc welding power supply. Furthermore, the charging and discharging unit reduces the time delay of the arc welding power supply switching from the welding state to the unloaded state, which can further improve the safety of the arc welding power supply and lay the foundation for safe production. Furthermore, the control circuit has a simple structure, is easy to implement, and has low cost.

[0046] Example 2

[0047] This embodiment of the invention also provides an arc welding power supply. The arc welding power supply includes the control circuit described in the above embodiment, and also includes a control chip. The control chip can output PWM drive pulse signals. The specific structure of the control circuit and its connection relationship with the control chip can be referred to the description of Embodiment 1 above, and will not be repeated here for simplicity.

[0048] The technical solution of this utility model embodiment involves designing a control circuit between the output terminal of the arc welding power supply and the control terminal of the control chip. This control circuit includes a sampling and judgment unit, a charging and discharging unit, a reference voltage determination unit, and an optocoupler unit. On one hand, since the sampling and judgment unit can determine the current state of the arc welding power supply, the optocoupler unit pulls down the control terminal potential of the control chip when the arc welding power supply is in an unloaded state, causing the arc welding power supply to stop working. This ensures that once the arc welding power supply is not performing welding operations, the control chip will no longer output drive pulse signals, and therefore will no longer supply power to the positive and negative output terminals of the arc welding power supply. On the other hand, when the arc welding power supply is in an unloaded state, the reference voltage determination unit can control the voltage at the output terminal of the arc welding power supply to be less than or equal to a preset threshold, thereby ensuring that the output voltage of the arc welding power supply is always within a safe range in the unloaded state. Even if the operator accidentally touches it, there will be no danger, avoiding electric shock accidents and improving the safety of the arc welding power supply. Furthermore, the charging and discharging unit reduces the time delay of the arc welding power supply switching from the welding state to the unloaded state, which can further improve the safety of the arc welding power supply and lay the foundation for safe production.

[0049] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A control circuit, characterized in that, include: The system comprises a sampling and judgment unit, a charging and discharging unit, a reference voltage determination unit, and an optocoupler unit; among which, The optocoupler unit is electrically connected to the charging / discharging unit and the reference voltage determination unit, respectively. The charging / discharging unit is electrically connected to the sampling and judgment unit. The sampling and judgment unit and the reference voltage determination unit are respectively connected to the positive output terminal and the negative output terminal of the arc welding power supply. The optocoupler unit is connected to the control terminal of the control chip of the arc welding power supply. The sampling and judgment unit is used to determine the current state of the arc welding power source; The optocoupler unit is used to pull down the control terminal potential of the control chip when the arc welding power supply is currently in an unloaded state, so as to stop the arc welding power supply from working. The reference voltage determination unit is used to control the voltage at the output terminal of the arc welding power supply to be less than or equal to a preset threshold when the arc welding power supply is currently in an unloaded state. The charging and discharging unit is used to reduce the time delay of the arc welding power supply switching from the welding state to the no-load state.

2. The control circuit according to claim 1, characterized in that, The sampling and judgment unit includes a first resistor and a first diode; wherein... One end of the first resistor is connected to the positive output terminal of the arc welding power supply, the other end of the first resistor is electrically connected to the output terminal of the first diode, and the input terminal of the first diode is electrically connected to the charging and discharging unit.

3. The control circuit according to claim 2, characterized in that, The charging and discharging unit includes a second resistor, a third resistor, a first capacitor, and a second capacitor; wherein, One end of the second resistor is connected to the first DC power supply, and the other end of the second resistor is electrically connected to the input terminal of the first diode and one end of the second capacitor, respectively. The other end of the second capacitor is grounded. One end of the third resistor is electrically connected to one end of the second resistor, and the other end of the third resistor is electrically connected to one end of the first capacitor. The other end of the first capacitor is electrically connected to one end of the second capacitor and the optocoupler unit, respectively.

4. The control circuit according to claim 3, characterized in that, The optocoupler unit includes an optocoupler, a fourth resistor, a fifth resistor, a switching transistor, and a third capacitor; wherein, The input terminal of the light-emitting diode in the optocoupler is electrically connected to the other end of the first capacitor, the output terminal of the light-emitting diode in the optocoupler is electrically connected to the reference voltage determination unit, the collector of the phototransistor in the optocoupler is electrically connected to one end of the fourth resistor, and the emitter of the phototransistor in the optocoupler is grounded. The other end of the fourth resistor is electrically connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the second DC power supply. The base of the switching transistor is electrically connected to the other end of the fourth resistor, the collector of the switching transistor is grounded, and the emitter of the switching transistor is connected to the control terminal of the control chip. One end of the third capacitor is electrically connected to the emitter of the switching transistor, and the other end of the third capacitor is grounded.

5. The control circuit according to claim 4, characterized in that, The reference voltage determination unit includes a Zener diode; wherein... One end of the Zener diode is electrically connected to the output terminal of the light-emitting diode in the optocoupler, and the other end of the Zener diode is connected to the negative output terminal of the arc welding power supply, which is grounded.

6. The control circuit according to any one of claims 1-5, characterized in that, It also includes isolation units and / or status indication units; The isolation unit is connected in series between the optocoupler and the control terminal of the control chip to protect the control circuit. The status indication unit is connected in series between the optocoupler unit and the reference voltage determination unit to indicate the current status of the arc welding power supply.

7. The control circuit according to claim 6, characterized in that, The isolation unit includes a second diode.

8. The control circuit according to claim 6, characterized in that, The status indication unit includes a sixth resistor and an indication element connected in parallel.

9. The control circuit according to claim 3, characterized in that, A switch is provided between the first DC power supply and one end of the second resistor; wherein, When the switch is open, the control circuit does not work.

10. An arc welding power source, characterized in that, It includes a control chip and a control circuit as described in any one of claims 1-9.

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