Auxiliary power supply circuit for improving synchronous rectification efficiency of welding machine

Abstract

The utility model relates to an auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine, and relates to the technical field of auxiliary control circuits. The circuit comprises an input rectification unit; the auxiliary power supply unit comprises a transformer, a primary side driving module and a secondary synchronous rectification module, and the secondary synchronous rectification module is provided with a driving end; the input rectification unit is electrically connected with the primary side of the transformer, the primary side output end of the transformer is electrically connected to the input end of the primary side driving module, and the secondary side of the transformer is electrically connected with the secondary synchronous rectification module; the input end of the synchronous rectification driving unit is electrically connected to the output end, used for generating a synchronous rectification signal, of the primary side driving module, and the output end of the synchronous rectification driving unit is electrically connected to the input end of the secondary synchronous rectification module. The synchronous rectification device has the effect that the synchronous rectification efficiency of the welding machine can be improved.

Description

Technical Field

[0001] This application relates to the technical field of auxiliary control circuits, and in particular to an auxiliary power supply circuit for improving the synchronous rectification efficiency of a welding machine. Background Art

[0002] Currently, the integrated auxiliary power supply chips widely used in welding machines integrate all functions (control circuit, power switch tube, power supply circuit, secondary synchronous rectification circuit, drive circuit, etc.) in one chip, and only a few peripheral devices are required to achieve the function of the auxiliary power supply, which is very convenient to use, so they are welcomed by the majority of power supply development and design personnel.

[0003] However, the driving voltage of the secondary synchronous rectification switch tube provided by some integrated power supply chips is relatively low and the driving ability is weak, resulting in limited selection of synchronous rectification switch tubes. In practical applications, the driving voltage that the integrated power supply chip can provide usually cannot meet the rated driving voltage values of most common switch tubes, resulting in insufficient driving of many switch tubes. At this time, the on-state resistance of these switch tubes is relatively large, which in turn increases the loss of the switch tubes and affects the synchronous rectification efficiency of the auxiliary power supply output of the welding machine. Utility Model Content

[0004] In order to reduce the difficulty of selecting switch tubes and improve the synchronous rectification efficiency of a welding machine, this application provides a circuit for improving the synchronous rectification efficiency of the auxiliary power supply of a welding machine.

[0005] The auxiliary circuit for improving the synchronous rectification efficiency of a welding machine provided by this application adopts the following technical solutions:

[0006] An auxiliary power supply circuit for improving the synchronous rectification efficiency of a welding machine, including an input rectification unit for rectifying an external AC voltage into a DC voltage;

[0007] The auxiliary power supply unit includes a transformer T1, a primary side driving module, and a secondary side synchronous rectification module, and the secondary side synchronous rectification module is provided with an input end; the output end of the input rectification unit is electrically connected to the primary side input end of the transformer T1, the primary side output end of the transformer T1 is electrically connected to the input end of the primary side driving module, and a synchronous rectification signal can be generated inside the primary side driving module; the secondary side of the transformer T1 is electrically connected to the secondary side synchronous rectification module, and the secondary side of the transformer T1 is provided with an output winding N4, and the output end of the output winding N4 is set as the first power output end V1, and the secondary side synchronous rectification module is used for rectifying the output end of the output winding N4; and the secondary side of the transformer T1 is provided with an output winding N4 and an output winding N5, the output end of the output winding N4 is set as the first power output end V1, the output end of the output winding N5 is set as the second power output end V2, and the secondary side synchronous rectification module is used for rectifying the output ends of the output winding N4 and the output winding N5;

[0008] A synchronous rectification driving unit, the input end of the synchronous rectification driving unit is electrically connected to the output end of the primary side driving module for outputting the synchronous rectification signal, and the output end of the synchronous rectification driving unit is electrically connected to the driving end of the secondary side synchronous rectification module.

[0009] By adopting the above technical solution, the input rectification unit can output a DC voltage suitable for the operation of the subsequent circuit unit, and by setting the synchronous rectification driving unit, the output voltage of the output end of the primary side driving module for outputting the synchronous rectification signal can be increased, and the driving current is also increased synchronously, so that more types of switching tubes can be driven, which greatly facilitates the design and selection of the switching tubes. At the same time, it can also ensure that the switching tube enters the deep saturation state to achieve the lowest on-state resistance, thereby significantly improving the efficiency of synchronous rectification and further improving the efficiency of the power supply.

[0010] Preferably, the synchronous rectification driving unit includes a voltage stabilizing chip U1, an isolation driving chip U2 and their peripheral components. The grounding end of the voltage stabilizing chip U1 is grounded, the input end Vin of the voltage stabilizing chip U1 is electrically connected to the first power output end V1, and the output end OUT of the voltage stabilizing chip U1 is set as the third power output end V3;

[0011] The 5th pin of the isolation driving chip U2 is electrically connected to the third power output end V3, the third power output end V3 is also electrically connected to the 1st pin of the isolation driving chip U2 through a resistor R11, the 2nd pin of the isolation driving chip U2 is electrically connected to the output end of the primary side driving module, and the 6th pin of the isolation driving chip U2 is set as the output end of the synchronous rectification driving module.

[0012] By adopting the above technical solution, the voltage regulator chip U1 is used to enable the isolated drive chip U2 to obtain stable power supply. And when the isolated drive chip U2 receives a high-level signal, at this time, the pin 6 of the isolated drive chip U2 can output a high enough voltage and current, so that the switching transistor in the secondary synchronous rectification module can enter the deep saturation state. After voltage stabilization through the resistor R11 and the voltage regulator diode ZD1, the isolated drive chip U2 can match the output voltage of the primary drive module, that is, the isolated drive chip U2 can identify whether the signal received at pin 2 is a high-level signal or a low-level signal.

[0013] Preferably, the synchronous rectification drive unit further includes a voltage regulator diode ZD1. The negative electrode of the voltage regulator diode ZD1 is electrically connected to the third power output terminal V3, and the positive electrode of the voltage regulator diode ZD1 is grounded.

[0014] By adopting the above technical solution, the voltage regulator diode ZD1 is used to play a voltage stabilization role, so that the isolated drive chip U2 can match the output voltage of the primary drive module.

[0015] Preferably, the synchronous rectification drive unit further includes a capacitor C12. The positive terminal of the capacitor C12 is electrically connected to the third power output terminal V3 through a resistor R11, and the negative terminal of the capacitor C12 is grounded.

[0016] By adopting the above technical solution, the capacitor C12 is used to play a filtering role.

[0017] Preferably, the primary drive module includes a power management chip U3 and its peripheral components. The pin 6 of the transformer T1 is connected to the power supply pin of the power management chip U3 after being filtered by a diode D1, a capacitor C6 and a capacitor C7; the FB pin of the power management chip U3 is electrically connected to the second power output terminal V2, and the SR pin of the power management chip U3 is set as the output terminal of the primary drive module for outputting the synchronous rectification signal.

[0018] By adopting the above technical solution, the functions of the primary drive module are realized through the power management chip U3 and its peripheral components, so that the switching transistor can be driven through the synchronous rectification drive module.

[0019] Preferably, the secondary synchronous rectification module includes a first switching transistor Q1 and a second switching transistor Q2. The gates of the first switching transistor Q1 and the second switching transistor Q2 are both electrically connected to the output terminal of the synchronous rectification drive unit. The drain of the first switching transistor Q1 is electrically connected to the pin 9 of the transformer T1, the drain of the second switching transistor Q2 is electrically connected to the pin 7 of the transformer T1, the source of the first switching transistor Q1 is electrically connected to the source of the second switching transistor Q2, and the source of the first switching transistor Q1 is grounded.

[0020] By adopting the above technical solution, the synchronous rectification module composed of the first switching transistor Q1 and the second switching transistor Q2 can play a rectifying role, improve the stability of the first power output terminal V1, and can achieve a lower conduction voltage drop and switching loss, thereby improving the energy conversion efficiency.

[0021] Preferably, the source electrode of the first switching transistor Q1 is electrically connected to the drain electrode of the first switching transistor Q1 through a resistor R3 and a capacitor C2 in sequence.

[0022] By adopting the above technical solution, the resistor R3 and the capacitor C2 can absorb voltage spikes, ensuring that the voltage value between the source and drain electrodes of the first switching transistor Q1 does not exceed the rated voltage value.

[0023] Preferably, the source electrode of the second switching transistor Q2 is electrically connected to the drain electrode of the second switching transistor Q2 through a resistor R5 and a capacitor C5 in sequence.

[0024] By adopting the above technical solution, the resistor R5 and the capacitor C5 can absorb voltage spikes, ensuring that the voltage value between the source and drain electrodes of the second switching transistor Q2 does not exceed the rated voltage value.

[0025] Preferably, the input rectification unit includes an AC connector TN1, a thermistor RT1, and a rectifier bridge BD1. The pin 1 of the AC connector TN1 is electrically connected to the input terminal 2 of the rectifier bridge BD1 through the thermistor RT1. The pin 3 of the AC connector TN1 is electrically connected to the input terminal 3 of the rectifier bridge BD1. The ground terminal 1 of the rectifier bridge BD1 is grounded, and the output terminal 4 of the rectifier bridge BD1 is set as the output terminal of the input rectification unit.

[0026] By adopting the above technical solution, by setting the rectifier bridge BD1, the AC voltage can be rectified into a DC voltage, and by utilizing the characteristic that the resistance value of the thermistor RT1 decreases as the temperature increases, the function of reducing the inrush current at the moment of power-on can be achieved.

[0027] Preferably, the primary side pin 3 of the transformer T1 is electrically connected to the output terminal OUT1 through an absorption clamping module. The absorption clamping module includes a diode D2, a resistor R1, a resistor R2, and a capacitor C3. The positive electrode of the diode D2 is electrically connected to the pin 3 of the transformer T1. The negative electrode of the diode D2 is electrically connected to the output terminal of the input rectification unit through the resistor R2 and the resistor R1 in sequence. The capacitor C1 is connected in parallel across the two ends of the resistor R1.

[0028] By adopting the above technical solution, by setting the absorption clamping module, it can be ensured that the voltage spike applied to the power switching transistor does not exceed the safety value.

[0029] In summary, the present application includes at least one of the following beneficial technical effects: by providing a synchronous rectification drive module to increase the drive voltage and current input to the input end of the secondary synchronous rectification module, the first switching transistor Q1 and the second switching transistor Q2 in the secondary synchronous rectification module can more easily enter the deep saturation state, so as to achieve the lowest on-state resistance, which can facilitate the selection of more types of switching transistors, thereby significantly improving the efficiency of synchronous rectification and the power efficiency of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the principle block diagram of an embodiment of the present application;

[0031] Figure 2 is the circuit diagram of the input rectification unit in an embodiment of the present application;

[0032] Figure 3 is the circuit diagram of the auxiliary power supply unit in an embodiment of the present application;

[0033] Figure 4 is the circuit diagram of the synchronous rectification drive unit in an embodiment of the present application.

[0034] Reference numerals: 1, input rectification unit; 2, auxiliary power supply unit; 21, primary drive module; 22, secondary synchronous rectification module; 23, absorption clamping module; 3, synchronous rectification drive unit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following will further describe the present application in detail Figures 1-4 with reference to the accompanying drawings.

[0036] An embodiment of the present application discloses an auxiliary power supply circuit for improving the synchronous rectification efficiency of a welding machine.

[0037] Referring to Figure 1 , an auxiliary power supply circuit for improving the synchronous rectification efficiency of a welding machine includes an input rectification unit 1, an auxiliary power supply unit 2, and a synchronous rectification drive unit 3. The auxiliary power supply unit 2 includes a transformer, a primary drive module 21, and a secondary synchronous rectification module 22. The secondary synchronous rectification module 22 includes synchronous rectification switching transistors and is provided with a drive end. The output end of the input rectification unit 1 is electrically connected to the primary input end of the transformer. The secondary output end of the transformer is electrically connected to the input end of the secondary synchronous rectification module 22. The secondary synchronous rectification module 22 is used to output a synchronously rectified DC voltage signal. The primary output end of the transformer is sequentially electrically connected to the drive end of the secondary synchronous rectification module 22 through the primary drive module 21 and the synchronous rectification drive unit 3. Through the synchronous rectification drive unit 3, the output voltage and current of the primary drive module 21 can be increased, so as to provide higher drive capability for the switching transistors, enable the switching transistors to enter the deep saturation state, reduce the loss of the switching transistors, and improve the overall efficiency of the machine.

[0038] Referring to Figure 2 , the input rectification unit 1 includes an AC connector TN1, a negative temperature coefficient thermistor RT1, and a rectifier bridge BD1. The rectifier bridge BD1 is used to rectify the AC voltage into a DC voltage. The AC connector TN1 is provided with 3 pins, where the pin 2 is vacant, and the pins 1 and 3 of the AC connector TN1 are used to output the AC voltage. The pin 1 of the AC connector TN1 is electrically connected to the input terminal 2 of the rectifier bridge BD1 through the thermistor RT1. The characteristic that the resistance value of the thermistor RT1 becomes smaller as the temperature increases can play a role in reducing the inrush current instantaneously when power is applied; the pin 3 of the AC connector TN1 is electrically connected to the input terminal 3 of the rectifier bridge BD1. The ground terminal 1 of the rectifier bridge BD1 is grounded, and the output terminal 4 of the rectifier bridge BD1 is set as the output terminal OUT1 of the input rectification unit 1 for outputting the DC voltage. Preferably, the input rectification unit 1 further includes a filter capacitor C1. The positive electrode of the filter capacitor C1 is electrically connected to the output terminal 4 of the rectifier bridge BD1, and the negative electrode of the filter capacitor C1 is grounded. The filter capacitor C1 can improve the stability of the output voltage of the input rectification unit 1.

[0039] Referring to Figure 3 , the transformer T1 is set as an energy storage transformer, stores energy when the switching tube is turned on, and releases energy to the secondary side when the switching tube is turned off. The transformer T1 includes a primary coil N1, a primary auxiliary coil N2, a secondary winding N3, a secondary output winding N4, and a secondary output winding N5, and the secondary winding N3 is vacant. The pin 10 of the transformer T1 is set as the first power output terminal V1, and the pin 8 of the transformer T1 is set as the second power output terminal V2. The synchronous rectification module 22 is arranged on the secondary side of the transformer T1, and the primary side drive module 21 is arranged on the primary side of the transformer T1. At the same time, the inside of the primary side drive module 21 is communicatively connected to the secondary side of the transformer T1 and receives the feedback of the output voltage of the second power output terminal V2. The inside of the primary side drive module 21 can generate a synchronous rectification signal, and the primary side drive module 21 is provided with an output terminal for outputting the synchronous rectification signal.

[0040] The pin 1 of the transformer T1 is electrically connected to the output terminal OUT1 of the input rectification unit 1, and the pin 3 of the transformer T1 is electrically connected to the output terminal OUT1 through the absorption clamping module 23. The absorption clamping module 23 includes a diode D2, a resistor R1, a resistor R2, and a capacitor C3. The positive electrode of the diode D2 is electrically connected to the pin 3 of the transformer T1, the negative electrode of the diode D2 is sequentially electrically connected to the output terminal OUT1 through the resistor R2 and the resistor R1, and the capacitor C1 is connected in parallel across the resistor R1. By setting the absorption clamping module 23, it can be ensured that the voltage spike applied to the power switching tube does not exceed the safety value.

[0041] Pin 6 of the transformer T1 is electrically connected to the rectifying diode D1. The positive electrode of the rectifying diode D1 is electrically connected to pin 3 of the transformer T1, and the negative electrode of the rectifying diode D1 is electrically connected to the power supply terminal of the primary side driving module 21 through the resistor R7. Moreover, the negative electrode of the rectifying diode D1 is also electrically connected to the capacitors C6 and C7. One end of the capacitor C6 is electrically connected to the negative electrode of the rectifying diode D1, and the other end of the capacitor C6 is grounded. The positive terminal of the capacitor C7 is electrically connected to the negative electrode of the rectifying diode D1. The capacitors C6 and C7 play a filtering role, so that the output voltage of pin 6 of the transformer T1 can be more stable.

[0042] The primary side driving module 21 includes a power management chip U3 and its peripheral components. The power management chip U3 is responsible for performing functions such as multi-mode quasi-resonant control, high-voltage primary switching, synchronous rectification drive signal generation and output, etc. The BPP pin of the power management chip U3 is the power supply terminal of the primary side driving module 21. The D pin of the power management chip U3 is electrically connected to pin 3 of the transformer T1. The FWD pin of the power management chip U3 is electrically connected to pin 7 of the transformer T1 through the resistor R9. The FB pin of the power management chip U3 is electrically connected to the second power output terminal V2 through the resistor R12, and the second power output terminal V2 is also sequentially electrically connected to the FB pin of the power management chip U3 through the resistor R10 and the capacitor C11. The SR pin of the power management chip U3 is set as the output terminal of the primary side driving module 21 for outputting a synchronous rectification drive signal, and the output terminal of the primary side driving module 21 is electrically connected to the driving end of the secondary synchronous rectification module 22 through the synchronous rectification drive unit 3.

[0043] The secondary synchronous rectification module 22 includes a first switching transistor Q1 and a second switching transistor Q2. In this embodiment, both the first switching transistor Q1 and the second switching transistor Q2 are set as NMOS transistors, and the gates of the first switching transistor Q1 and the second switching transistor Q2 are electrically connected to the output terminal of the synchronous rectification driving unit 3. The drain of the first switching transistor Q1 is electrically connected to pin 9 of the transformer T1, and the drain of the second switching transistor Q2 is electrically connected to pin 7 of the transformer T1. The source of the first switching transistor Q1 is electrically connected to the source of the second switching transistor Q2, and the source of the first switching transistor Q1 is grounded. When the gates of the first switching transistor Q1 and the second switching transistor Q2 are powered on, the first switching transistor Q1 and the second switching transistor Q2 can be driven to be in the on state, so as to realize the rectification of the output current of the first power output terminal V1 and the second power output terminal V2. Moreover, the source of the first switching transistor Q1 is sequentially electrically connected to the drain of the first switching transistor Q1 through a resistor R3 and a capacitor C2. The resistor R3 and the capacitor C2 can absorb voltage spikes to ensure that the voltage value between the source and the drain of the first switching transistor Q1 does not exceed the rated voltage value. The source of the second switching transistor Q2 is sequentially electrically connected to the drain of the second switching transistor Q2 through a resistor R5 and a capacitor C5. The resistor R5 and the capacitor C5 can absorb voltage spikes to ensure that the voltage value between the source and the drain of the second switching transistor Q2 does not exceed the rated voltage value.

[0044] The secondary synchronous rectification module 22 further includes a resistor R4 and a capacitor C4. The positive terminal of the capacitor C4 is electrically connected to pin 10 of the transformer T1, and the negative terminal of the capacitor C4 is grounded. The capacitor C4 plays a filtering role, and the resistor R4 is connected in parallel across the capacitor C4 and is used as a fixed load to improve the stability of the voltage output of the first power output terminal V1. In this embodiment, the output voltage value of the first power output terminal V1 is set to 24V.

[0045] Preferably, a resistor R6 and a capacitor C8 are further electrically connected to pin 8 of the transformer T1. The positive terminal of the capacitor C8 is electrically connected to pin 8 of the transformer T1, and the negative terminal of the capacitor C8 is grounded. The capacitor C8 plays a filtering role, and the resistor R6 is connected in parallel across the capacitor C8 and is used as a fixed load to improve the stability of the voltage output of the second power output terminal V2. In this embodiment, the output voltage value of the second power output terminal V2 is set to 15V.

[0046] Refer to Figure 2 and Figure 3, the synchronous rectification drive unit 3 includes a voltage regulator chip U1, an isolation drive chip U2 and their peripheral components. The ground terminal of the voltage regulator chip U1 is grounded. The input terminal Vin of the voltage regulator chip U1 is electrically connected to the first power output terminal V1. The output terminal OUT of the voltage regulator chip U1 is set as the third power output terminal V3. The output terminal OUT of the voltage regulator chip U1 is also grounded through a capacitor C1, so as to improve the stability of the output voltage of the third power output terminal V3. In this embodiment, the output voltage value of the third power output terminal V3 is 15V. On this basis, by selecting different types of voltage regulator chips U1, the output voltage value of the third power output terminal V3 is different, so that the output voltage of the isolation chip U2 can be adjusted according to the driving characteristics of the first switching transistor Q1 and the second switching transistor Q2, and thus more types of switching transistors can be adapted.

[0047] The output terminal of the primary side drive module 21 for outputting the synchronous rectification signal is electrically connected to pin 2 of the isolation drive chip U2. When pin 2 of the isolation drive chip U2 receives a high-level signal, then pin 6 of the isolation drive chip U2 can output a sufficiently high voltage. Pin 5 of the isolation drive chip U2 is electrically connected to the third power output terminal V3. The third power output terminal V3 is also electrically connected to pin 1 of the isolation drive chip U2 through a resistor R11, so that the isolation drive chip U2 can be powered on and work. By using the current limiting function of the resistor R11 and the voltage stabilizing function of the voltage stabilizing diode ZD1, the supply voltage of pin 1 of the isolation drive chip in this embodiment is 5.1V, so that the isolation drive chip U2 can match the output voltage of the primary side drive module 21, that is, the isolation drive chip U2 can recognize whether the signal received at pin 2 is a high-level signal or a low-level signal. Pins 3, 4 and 8 of the isolation drive chip U2 are grounded, and pin 6 of the isolation drive chip U2 is electrically connected to the drive end of the secondary synchronous rectification module 22 through a resistor R8. At this time, the voltage input to the drive end of the secondary synchronous rectification module 22 is high enough and the current is large enough to meet the drive voltage values of more types of the first switching transistor Q1 and the second switching transistor Q2, so that the first switching transistor Q1 and the second switching transistor Q2 can enter the deep saturation state to achieve the lowest on-state resistance.

[0048] Preferably, the synchronous rectification drive unit 3 further includes a voltage stabilizing diode ZD1 and a capacitor C12. The negative electrode of the voltage stabilizing diode ZD1 is electrically connected to the third power output terminal V3 through a resistor R11, and the positive electrode of the voltage stabilizing diode ZD1 is grounded, playing a voltage stabilizing role; the positive end of the capacitor C12 is electrically connected to the third power output terminal V3, and the negative end of the capacitor C12 is grounded, playing a filtering role, so that the isolation drive chip U2 can work more stably.

[0049] The implementation principle of an auxiliary power supply circuit for improving the synchronous rectification efficiency of a welding machine in an embodiment of the present application is as follows: By setting the synchronous rectification drive unit 3, the output voltage of the primary drive module 21 can be boosted to a high enough level to drive more types of switching transistors, which greatly facilitates the design and selection of switching transistors. At the same time, it can also ensure that the switching transistors enter the deep saturation state to achieve the lowest on-state resistance, thereby significantly improving the synchronous rectification efficiency and further enhancing the power supply efficiency.

[0050] The above are all the preferred embodiments of the present application. Without restricting the protection scope of the present application based on this, therefore: Any equivalent changes made according to the structure, shape, and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. An auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine, characterized in that: include: An input rectifier unit (1) is used to rectify an external AC voltage into a DC voltage; An auxiliary power supply unit (2) comprises a transformer T1, a primary side drive module (21) and a secondary synchronous rectification module (22), wherein the secondary synchronous rectification module (22) is provided with an input end; the output end of the input rectification unit (1) is electrically connected to the primary side input end of the transformer T1, the primary side output end of the transformer T1 is electrically connected to the input end of the primary side drive module (21), and the primary side drive module is capable of generating a synchronous rectification signal; the secondary side of the transformer T1 is electrically connected to the secondary synchronous rectification module (22), and the secondary side of the transformer T1 is provided with an output winding N4 and an output winding N5, the output end of the output winding N4 is provided as a first power output end V1, the output end of the output winding N5 is provided as a second power output end V2, and the secondary synchronous rectification module (22) is used to rectify the output ends of the output winding N4 and the output winding N5; A synchronous rectification drive unit (3), wherein the input end of the synchronous rectification drive unit (3) is electrically connected to the output end of the primary side driving module (21) for outputting the synchronous rectification signal, and the output end of the synchronous rectification drive unit (3) is electrically connected to the input end of the secondary synchronous rectification module (22).

2. The auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine according to claim 1, characterized in that: The synchronous rectification drive unit (3) comprises a voltage stabilizing chip U1 and an isolation drive chip U2 and peripheral components thereof, the ground terminal of the voltage stabilizing chip U1 is grounded, the input terminal Vin of the voltage stabilizing chip U1 is electrically connected to the first power output terminal V1, and the output terminal OUT of the voltage stabilizing chip U1 is set as a third power output terminal V3; Pin 5 of the isolation driving chip U2 is electrically connected to the third power supply output terminal V3, and the third power supply output terminal V3 is also electrically connected to pin 1 of the isolation driving chip U2 through a resistor R11. Pin 2 of the isolation driving chip U2 is electrically connected to the output terminal of the primary side driving module (21) for outputting the synchronous rectification signal, and pin 6 of the isolation driving chip U2 is set as the output terminal of the synchronous rectification driving module.

3. The auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine according to claim 2, characterized in that: The synchronous rectification driving unit (3) further comprises a voltage stabilizing diode ZD1, a cathode of the voltage stabilizing diode ZD1 being electrically connected to the third power supply output terminal V3 via a resistor R11, and an anode of the voltage stabilizing diode ZD1 being grounded.

4. An auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine according to claim 2 or 3, characterized in that: The synchronous rectification drive unit (3) further comprises a capacitor C12, a positive terminal of the capacitor C12 being electrically connected to the third power supply output terminal V3 via a resistor R11, and a negative terminal of the capacitor C12 being grounded.

5. The auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine according to claim 1, characterized in that: The primary side drive module (21) comprises a power management chip U3 and peripheral components thereof; the 6th pin of the transformer T1 is electrically connected to the power supply pin of the power management chip U3 after filtering by a diode D1, a capacitor C6 and a capacitor C7; the FB pin of the power management chip U3 is electrically connected to the second power supply output terminal V2, and the SR pin of the power management chip U3 is set as the output terminal of the primary side drive module (21) for outputting the synchronous rectification signal.

6. The auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine according to claim 1, characterized in that: The secondary synchronous rectification module (22) comprises a first switch tube Q1 and a second switch tube Q2, wherein the gates of the first switch tube Q1 and the second switch tube Q2 are both electrically connected to the output end of the synchronous rectification drive unit (3), the drain of the first switch tube Q1 is electrically connected to pin 9 of the transformer T1, the drain of the second switch tube Q2 is electrically connected to pin 7 of the transformer T1, the source of the first switch tube Q1 is electrically connected to the source of the second switch tube Q2, and the source of the first switch tube Q1 is grounded.

7. The auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine according to claim 6, characterized in that: The source of the first switch tube Q1 is electrically connected to the drain of the first switch tube Q1 through the resistor R3 and the capacitor C2 in sequence.

8. The auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine according to claim 7, characterized in that: The source of the second switch tube Q2 is electrically connected to the drain of the second switch tube Q2 via the resistor R5 and the capacitor C5 in sequence.

9. The auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine according to claim 1, characterized in that: The input rectifier unit (1) comprises an AC connector TN1, a thermistor RT1 and a rectifier bridge BD1, wherein pin 1 of the AC connector TN1 is electrically connected to pin 2 of an input terminal of the rectifier bridge BD1 through the thermistor RT1, pin 3 of the AC connector TN1 is electrically connected to pin 3 of an input terminal of the rectifier bridge BD1, pin 1 of a ground terminal of the rectifier bridge BD1 is grounded, and pin 4 of an output terminal of the rectifier bridge BD1 is arranged as an output terminal of the input rectifier unit (1).

10. The auxiliary power supply circuit for improving synchronous rectification efficiency of a welding machine according to claim 1, characterized in that: The primary side pin 3 of the transformer T1 is electrically connected to the output end OUT1 through an absorption clamping module (23); the absorption clamping module (23) comprises a diode D2, a resistor R1, a resistor R2 and a capacitor C3; the positive electrode of the diode D2 is electrically connected to the pin 3 of the transformer T1; the negative electrode of the diode D2 is electrically connected to the output end of the input rectifying unit (1) through the resistor R2 and the resistor R1 in sequence; and the capacitor C1 is connected in parallel to both ends of the resistor R1.

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