Circuit for realizing bus voltage stabilization by welding machine power factor correction superimposed secondary feedback

Abstract

The application discloses a circuit for realizing bus voltage stabilization by welding machine power factor correction superimposed secondary feedback, which comprises a PFC chip, an input protection circuit, a PFC correction circuit, a topology structure circuit, a load resistor and a secondary voltage feedback circuit; the input protection circuit is connected with the PFC chip, an external AC zero line and an AC live line; the PFC correction circuit is connected with the PFC chip, the AC zero line and the AC live line; the topology structure circuit is connected with the PFC correction circuit; one end of the load resistor is connected with the topology structure circuit, and the other end is grounded; the secondary voltage feedback circuit is connected with the topology structure circuit and the PFC chip. In the moment of load mutation, the arc is disconnected, the load resistor becomes open circuit, the no-load voltage enters through the fifth capacitor and the voltage stabilizing tube, and then a feedback voltage is superimposed on the pin 6 of the PFC chip through the photoelectric coupler, namely VCC passes through the ninth resistor, at this time, the chip quickly adjusts the duty ratio, so that the output voltage is stabilized at VDC.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric welding machine circuit, and particularly relates to a circuit for realizing bus voltage stabilization through power factor correction and secondary feedback of an electric welding machine. BACKGROUND

[0002] In order to reduce the harmonic interference of the power grid, more and more countries and regions have put forward the requirement of power factor for electrical products, and there are various power factor correction chips on the market.

[0003] But in the use scene of the electric welding machine, the load RL is actually an electric arc, and since the load is intermittent during the welding process, there is a continuous switching from large load to small load or no load; when the user is welding, the output current is large, and at the moment when the welding is stopped, the machine enters the no-load state, at this time, the bus voltage VDC will suddenly rise due to the reflected voltage generated by the transformer energy storage, and the rising voltage may damage the diode D1, the capacitors C3 and C4 and the full-bridge inverter circuit. In order to reduce the influence, a circuit for realizing bus voltage stabilization through power factor correction and secondary feedback of an electric welding machine is designed. SUMMARY

[0004] According to the embodiment of the present application, a circuit for realizing bus voltage stabilization through power factor correction and secondary feedback of an electric welding machine is provided, which comprises a PFC chip, an input protection circuit, a PFC correction circuit, a topology structure circuit, a load resistor and a secondary voltage feedback circuit.

[0005] The input protection circuit is connected with the pin 5 of the PFC chip, an external AC neutral line and an AC live line, and is used for inputting a voltage signal to the PFC chip.

[0006] The PFC correction circuit is connected with the pins 1 and 8 of the PFC chip and the AC neutral line and the AC live line, and is used for correcting an input current.

[0007] The topology structure circuit is connected with the PFC correction circuit.

[0008] One end of the load resistor is connected with the topology structure circuit, and the other end is grounded.

[0009] The secondary voltage feedback circuit is connected with the topology structure circuit and the pin 6 of the PFC chip, and is used for superimposing a feedback voltage on the pin of the PFC chip.

[0010] Further, the input protection circuit comprises a first diode, a second diode, a first resistor, a second resistor, a third resistor and a first capacitor.

[0011] The anode of the first diode is connected with the AC neutral line.

[0012] Anode of the second diode is connected with the AC live wire, and the cathode of the second diode is connected with the cathode of the first diode, then sequentially passes through the first resistor, the second resistor and is connected with the pin 5 of the PFC chip;

[0013] One end of the third resistor is connected between the second resistor and the pin 5 of the PFC chip;

[0014] One end of the first capacitor is connected between one end of the third resistor and the pin 5 of the PFC chip, and the other end of the first capacitor is connected with the other end of the third resistor, and then is connected with the pin 2 of the PFC chip.

[0015] Further, it further comprises a fourth resistor and a second capacitor;

[0016] One end of the fourth resistor is connected with the pin 4 of the PFC chip, and the other end is connected with the other end of the third resistor, the other end of the first capacitor and the pin 2 of the PFC chip;

[0017] One end of the second capacitor is connected with the pin 3 of the PFC chip, and the other end is connected with the pin 2 of the PFC chip.

[0018] Further, the PFC correction circuit comprises a rectifier bridge, an inductor, a third diode, an IGBT device, a third capacitor, a fourth capacitor, a shunt resistor, a fifth resistor, a sixth resistor and a seventh resistor;

[0019] Two input ends of the rectifier bridge are connected with the AC live wire and the AC zero line respectively;

[0020] One end of the inductor is connected with one output end of the rectifier bridge;

[0021] Anode of the third diode is connected with the other end of the inductor, and the cathode of the third diode is connected with the topology structure circuit;

[0022] The third capacitor and the fourth capacitor are connected in parallel, and one end of the third capacitor and the fourth capacitor is connected between the cathode of the third diode and the topology structure circuit;

[0023] One end of the shunt resistor is connected with the other output end of the rectifier bridge, and the other end of the shunt resistor is sequentially connected with one end of the fifth resistor, the emitter of the IGBT device, the other end of the third capacitor, the other end of the fourth capacitor, and then is connected with the topology structure circuit;

[0024] The collector of the IGBT device is connected between the other end of the inductor and the anode of the third diode, and the gate of the IGBT device is connected with the pin 8 of the PFC chip through the sixth resistor;

[0025] The other end of the fifth resistor is connected between the gate of the IGBT device and the sixth resistor;

[0026] One end of the seventh resistor is connected between the other output end of the rectifier bridge and one end of the shunt resistor, and the other end of the seventh resistor is connected with the pin 1 of the PFC chip.

[0027] Further, the topology circuit comprises: a full-bridge inverter, a main transformer, a fourth diode and a fifth diode;

[0028] The full-bridge inverter is connected with the PFC correction circuit;

[0029] The pins 1 and 2 of the main transformer are connected with the full-bridge inverter, the pin 3 of the main transformer is connected with the anode of the fourth diode, the pin 4 of the main transformer is connected with the other end of the load resistor and then grounded, and the pin 5 of the main transformer is connected with the anode of the fifth diode;

[0030] The cathode of the fourth diode is connected with the cathode of the fifth diode and then connected with the other end of the load resistor and the secondary voltage feedback circuit.

[0031] Further, the secondary voltage feedback circuit comprises: a fifth capacitor, a voltage stabilizing diode, an eighth resistor, an optical coupler, a ninth resistor and a tenth resistor;

[0032] One end of the fifth capacitor is connected with the topology circuit and one end of the load resistor;

[0033] The cathode of the voltage stabilizing diode is connected with the other end of the fifth capacitor, and the other end of the voltage stabilizing diode is connected with the pin 1 of the optical coupler through the eighth resistor;

[0034] The pin 4 of the optical coupler is connected with the VCC terminal through the ninth resistor, the pin 2 of the optical coupler is connected with one end of the tenth resistor and then grounded, and the pin 3 of the optical coupler is connected with the pin 6 of the PFC chip;

[0035] The other end of the tenth resistor is connected between the pin 1 of the optical coupler and the eighth resistor.

[0036] Further, it further comprises: an eleventh resistor, a twelfth resistor and a thirteenth resistor;

[0037] One end of the eleventh resistor is connected between the topology circuit and the PFC correction circuit;

[0038] One end of the twelfth resistor is connected with the other end of the eleventh resistor;

[0039] One end of the thirteenth resistor is grounded, and the other end of the thirteenth resistor and the other end of the twelfth resistor are both connected between the pin 3 of the optical coupler and the pin 6 of the PFC chip.

[0040] According to an embodiment of the present invention, a circuit for achieving bus voltage stabilization by superimposing power factor correction on a welding machine and secondary feedback is configured such that, at the moment of a sudden load change, the arc is disconnected, the load resistor becomes an open circuit, and the no-load voltage enters the feedback loop through a fifth capacitor and a voltage-stabilizing diode. The feedback loop superimposes a feedback voltage, namely, VCC, on pin 6 of the PFC chip via an optocoupler, passing through a ninth resistor. At this point, the chip quickly adjusts the duty cycle to stabilize the output voltage at VDC.

[0041] It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the technology as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The present invention is a circuit diagram of a circuit for implementing bus voltage stabilization by superimposing power factor correction on a welding machine using secondary feedback according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to further illustrate the present invention.

[0044] First, combine Figure 1 A circuit for realizing bus voltage stabilization by power factor correction and secondary feedback of an electric welding machine according to an embodiment of the present invention is described. The circuit is used in an electric welding machine and has a wide range of application scenarios.

[0045] like Figure 1 As shown, a circuit for realizing bus voltage stabilization by power factor correction and secondary feedback of a welding machine according to an embodiment of the present invention comprises a PFC chip U1, an input protection circuit, a BOOST-type PFC correction circuit, a topology structure circuit, a load resistor RL, and a secondary voltage feedback circuit.

[0046] Specifically, if Figure 1 As shown, the VSENSE pin of the PFC chip U1 is a voltage feedback pin, which collects the VDC voltage as feedback and controls the VDC voltage to a constant value.

[0047] Specifically, if Figure 1As shown, the input protection circuit is connected with pin 5 of the PFC chip U1, external AC neutral line AC-N and AC live line AC-L, for inputting voltage signal to the PFC chip U1. The input protection circuit comprises: first diode D3, second diode D2, first resistor R1, second resistor R2, third resistor R3 and first capacitor C2. The anode of the first diode D3 is connected with the AC neutral line AC-N; the anode of the second diode D2 is connected with the AC live line AC-L, and the cathode of the second diode D2 is connected with the cathode of the first diode D3, then sequentially connected with the first resistor R1, the second resistor R2 and pin 5 of the PFC chip U1; one end of the third resistor R3 is connected between the second resistor R2 and pin 5 of the PFC chip U1; one end of the first capacitor C2 is connected between the one end of the third resistor R3 and pin 5 of the PFC chip U1, and the other end of the first capacitor C2 is connected with the other end of the third resistor R3 and then connected with pin 2 of the PFC chip U1.

[0048] Specifically, as shown in the figure, Figure 1 The PFC correction circuit is connected with pin 1, 8 of the PFC chip and AC neutral line AC-N and AC live line AC-L, for correcting input current. The PFC correction circuit comprises: rectifier bridge, inductor L1, third diode D1, IGBT device T1, third capacitor C3, fourth capacitor C4, shunt resistor Rshunt, fifth resistor R7, sixth resistor R6 and seventh resistor R4. Two input ends of the rectifier bridge are connected with the AC live line AC-L and the AC neutral line AC-N respectively; one end of the inductor L1 is connected with one output end of the rectifier bridge; the anode of the third diode D1 is connected with the other end of the inductor L1, and the cathode of the third diode D1 is connected with the topology circuit; the third capacitor C3 and the fourth capacitor C4 are connected in parallel, and one end of the third capacitor C3 and one end of the fourth capacitor C4 are connected between the cathode of the third diode D1 and the topology circuit; one end of the shunt resistor Rshunt is connected with the other output end of the rectifier bridge, and the other end of the shunt resistor Rshunt is sequentially connected with one end of the fifth resistor R7, the emitter of the IGBT device T1, the other end of the third capacitor C3, the other end of the fourth capacitor C4 and then connected with the topology circuit; the collector of the IGBT device T1 is connected between the other end of the inductor L1 and the anode of the third diode D1, and the gate of the IGBT device T1 is connected with pin 8 of the PFC chip U1 through the sixth resistor R6; the other end of the fifth resistor R7 is connected between the gate of the IGBT device T1 and the sixth resistor R6; one end of the seventh resistor R4 is connected between the other output end of the rectifier bridge and one end of the shunt resistor Rshunt, and the other end of the seventh resistor R4 is connected with pin 1 of the PFC chip U1.

[0049] Specifically, as shown in the figure, Figure 1As shown in the figure, the topology circuit is connected with the PFC correction circuit. The topology circuit comprises a full-bridge inverter, a main transformer TR1, a fourth diode D4 and a fifth diode D5. The full-bridge inverter is connected with the PFC correction circuit; a pin 1 and a pin 2 of the main transformer TR1 are connected with the full-bridge inverter, a pin 3 of the main transformer TR1 is connected with an anode of the fourth diode D4, a pin 4 of the main transformer TR1 is connected with the other end of the load resistor RL and then grounded, a pin 5 of the main transformer TR1 is connected with an anode of the fifth diode D5; a cathode of the fourth diode D4 and a cathode of the fifth diode D5 are connected and then connected with the other end of the load resistor RL and a secondary voltage feedback circuit.

[0050] Specifically, as shown in the figure, one end of the load resistor RL is connected with the topology circuit, and the other end is grounded. Figure 1

[0051] Specifically, as shown in the figure, the secondary voltage feedback circuit is connected with the topology circuit and a pin 6 of the PFC chip U1, and is used for superimposing a feedback voltage on the pin of the PFC chip U1. The secondary voltage feedback circuit comprises a fifth capacitor C5, a voltage stabilizing diode Z1, an eighth resistor R12, an optical coupler EL1, a ninth resistor R11 and a tenth resistor R13; one end of the fifth capacitor C5 is connected with the topology circuit and one end of the load resistor RL; a cathode of the voltage stabilizing diode Z1 is connected with the other end of the fifth capacitor C5, and the other end of the voltage stabilizing diode Z1 is connected with a pin 1 of the optical coupler EL1 through the eighth resistor R12; a pin 4 of the optical coupler EL1 is connected with a VCC terminal through the ninth resistor R11, a pin 2 of the optical coupler EL1 is connected with the other end of the tenth resistor R13 and then grounded, a pin 3 of the optical coupler EL1 is connected with the pin 6 of the PFC chip U1; the other end of the tenth resistor R13 is connected between the pin 1 of the optical coupler EL1 and the eighth resistor R12. Figure 1

[0052] Further, as shown in the figure, the circuit for realizing bus voltage stabilization of the welding machine power factor correction superimposed secondary feedback of the embodiment of the present application further comprises a fourth resistor R5 and a second capacitor C1; one end of the fourth resistor R5 is connected with the pin 4 of the PFC chip U1, the other end is connected with the other end of the third resistor R3, the other end of the first capacitor C2 and the pin 2 of the PFC chip U1; one end of the second capacitor C1 is connected with the pin 3 of the PFC chip U1, and the other end is connected with the pin 2 of the PFC chip U1. Figure 1

[0053] Further, as shown in the figure, the circuit for realizing bus voltage stabilization of the welding machine power factor correction superimposed secondary feedback of the embodiment of the present application further comprises a fourth resistor R5 and a second capacitor C1; one end of the fourth resistor R5 is connected with the pin 4 of the PFC chip U1, the other end is connected with the other end of the third resistor R3, the other end of the first capacitor C2 and the pin 2 of the PFC chip U1; one end of the second capacitor C1 is connected with the pin 3 of the PFC chip U1, and the other end is connected with the pin 2 of the PFC chip U1. Figure 1 ​​​As shown, the circuit for realizing bus voltage stabilization by power factor correction superimposed secondary feedback of the welding machine according to the embodiment of the application further comprises an eleventh resistor R8, a twelfth resistor R9 and a thirteenth resistor R10; one end of the eleventh resistor is connected between the topology circuit and the PFC correction circuit; one end of the twelfth resistor R9 is connected with the other end of the eleventh resistor R8; one end of the thirteenth resistor R10 is grounded, and the other end of the thirteenth resistor R10 and the other end of the twelfth resistor R9 are both connected between pin 3 of the optocoupler EL1 and pin 6 of the PFC chip U1.

[0054] The application focuses on designing a secondary voltage feedback circuit. At the moment of load mutation, the arc is disconnected, the load resistor RL becomes open circuit, the no-load voltage enters the feedback loop through the fifth capacitor C5 and the voltage stabilizing diode Z1, the feedback loop superimposes a feedback voltage at pin 6 of the PFC chip U1 through the optocoupler EL1, that is, VCC passes through the ninth resistor R11, at this time the chip will quickly adjust the duty cycle, so that the output voltage is stable at VDC unchanged. This superimposed feedback circuit cannot work for a long time, otherwise it will cause the bus voltage VDC to be too low, so a fifth capacitor C5 is passed to ensure that it is turned on only once each time.

[0055] It should be noted that in the present specification, the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or include elements inherent to such processes, methods, articles or devices. Without more limitations, the elements defined by the statement "comprising" do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0056] Although the content of the application has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the application. After reading the above content, various modifications and alternatives of the application will be obvious to those skilled in the art. Therefore, the protection scope of the application should be defined by the appended claims.

Claims

1. A circuit for realizing busbar voltage stabilization by superimposing power factor correction and secondary feedback on a welding machine, characterized in that: Includes: PFC chip, input protection circuit, PFC correction circuit, topology circuit, load resistor and secondary voltage feedback circuit; The input protection circuit is connected to pin 5 of the PFC chip, an external AC neutral line, and an AC live line, and is used to input a voltage signal to the PFC chip; The PFC correction circuit is connected to pins 1 and 8 of the PFC core and the AC neutral line and the AC live line, and is used to correct the input current; The topology structure circuit is connected to the PFC correction circuit; One end of the load resistor is connected to the topology structure circuit, and the other end is grounded; The secondary voltage feedback circuit is connected to the topology circuit and pin 6 of the PFC chip, and is used to superimpose a feedback voltage on the pin of the PFC chip; The PFC correction circuit includes: a rectifier bridge, an inductor, a third diode, an IGBT device, a third capacitor, a fourth capacitor, a shunt resistor, a fifth resistor, a sixth resistor and a seventh resistor; The two input ends of the rectifier bridge are respectively connected to the AC live wire and the AC neutral wire; One end of the inductor is connected to one of the output ends of the rectifier bridge; The anode of the third diode is connected to the other end of the inductor, and the cathode of the third diode is connected to the topology structure circuit; The third capacitor and the fourth capacitor are connected in parallel, and one end of the third capacitor and one end of the fourth capacitor are both connected between the cathode of the third diode and the topology structure circuit; One end of the shunt resistor is connected to the other output end of the rectifier bridge, and the other end of the shunt resistor is connected to one end of the fifth resistor, the emitter of the IGBT device, the other end of the third capacitor, and the other end of the fourth capacitor in sequence, and then connected to the topology circuit; The collector of the IGBT device is connected between the other end of the inductor and the anode of the third diode, and the gate of the IGBT device is connected to the pin 8 of the PFC chip through the sixth resistor; The other end of the fifth resistor is connected between the gate of the IGBT device and the sixth resistor; One end of the seventh resistor is connected between the other output end of the rectifier bridge and one end of the shunt resistor, and the other end of the seventh resistor is connected to pin 1 of the PFC chip; The secondary voltage feedback circuit comprises: a fifth capacitor, a voltage stabilizing diode, an eighth resistor, an optocoupler, a ninth resistor, and a tenth resistor; One end of the fifth capacitor is connected to the topology structure circuit and one end of the load resistor; The cathode of the voltage stabilizing diode is connected to the other end of the fifth capacitor, and the other end of the voltage stabilizing diode is connected to the pin 1 of the optocoupler via the eighth resistor; Pin 4 of the optocoupler is connected to the VCC terminal via a ninth resistor, pin 2 of the optocoupler is connected to one end of the tenth resistor and then to ground, and pin 3 of the optocoupler is connected to pin 6 of the PFC chip; The other end of the tenth resistor is connected between pin 1 of the optocoupler and the eighth resistor.

2. The circuit for realizing busbar voltage stabilization by power factor correction and secondary feedback of electric welding machine as claimed in claim 1, characterized in that: The input protection circuit includes: a first diode, a second diode, a first resistor, a second resistor, a third resistor and a first capacitor; The anode of the first diode is connected to the AC neutral line; The anode of the second diode is connected to the AC live wire, the cathode of the second diode is connected to the cathode of the first diode, and then connected to the pin 5 of the PFC chip through the first resistor and the second resistor in sequence; One end of the third resistor is connected between the second resistor and the pin 5 of the PFC chip; One end of the first capacitor is connected between one end of the third resistor and pin 5 of the PFC chip, and the other end of the first capacitor is connected to the other end of the third resistor and then to pin 2 of the PFC chip.

3. The circuit for realizing busbar voltage stabilization by power factor correction and secondary feedback of electric welding machine as claimed in claim 2, characterized in that: Also comprising: a fourth resistor and a second capacitor; One end of the fourth resistor is connected to pin 4 of the PFC chip, and the other end is connected to the other end of the third resistor, the other end of the first capacitor, and pin 2 of the PFC chip; One end of the second capacitor is connected to pin 3 of the PFC chip, and the other end is connected to pin 2 of the PFC chip.

4. The circuit for realizing busbar voltage stabilization by superimposing power factor correction and secondary feedback on a welding machine as claimed in claim 1, characterized in that: The topology structure circuit includes: a full-bridge inverter, a main transformer, a fourth diode and a fifth diode; The full-bridge inverter is connected to the PFC correction circuit; Pins 1 and 2 of the main transformer are connected to the full-bridge inverter, pin 3 of the main transformer is connected to the anode of the fourth diode, pin 4 of the main transformer is connected to the other end of the load resistor and then grounded, and pin 5 of the main transformer is connected to the anode of the fifth diode; After the cathode of the fourth diode is connected to the cathode of the fifth diode, it is connected to the other end of the load resistor and the secondary voltage feedback circuit.

5. The circuit for realizing busbar voltage stabilization by power factor correction and secondary feedback of electric welding machine as claimed in claim 1, characterized in that: Also comprising: an eleventh resistor, a twelfth resistor, and a thirteenth resistor; One end of the eleventh resistor is connected between the topology structure circuit and the PFC correction circuit; One end of the twelfth resistor is connected to the other end of the eleventh resistor; One end of the thirteenth resistor is grounded, and the other end of the thirteenth resistor and the other end of the twelfth resistor are both connected between the pin 3 of the optocoupler and the pin 6 of the PFC chip.

Images