CN115549032A

CN115549032A - Overvoltage protection circuit, PFC output system and air conditioner

Info

Publication number: CN115549032A
Application number: CN202110737097.4A
Authority: CN
Inventors: 薄传海; 赵新荣
Original assignee: Aux Air Conditioning Co Ltd; Ningbo Aux Electric Co Ltd
Current assignee: Aux Air Conditioning Co Ltd; Ningbo Aux Electric Co Ltd
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2022-12-30

Abstract

The application provides an overvoltage protection circuit, a PFC output system and an air conditioner, and relates to the technical field of overvoltage protection. The overvoltage protection circuit is applied to a PFC output system and comprises a voltage acquisition module, a voltage comparison module and a signal output module, wherein the voltage acquisition module, the voltage comparison module and the signal output module are electrically connected in sequence; the voltage acquisition module acquires the output voltage of the PFC output circuit; the voltage comparison module is used for controlling the signal output module to output a low level when the output voltage is greater than a preset voltage; the output end of the signal output module is electrically connected with the signal input port of the PFC driving circuit, and when the signal output module outputs a low level, the PFC driving circuit stops working so as to stop the PFC output circuit from working. The application has the advantages of preventing overvoltage and protecting devices such as capacitors.

Description

Overvoltage protection circuit, PFC output system and air conditioner

Technical Field

The application relates to the technical field of overvoltage protection, in particular to an overvoltage protection circuit, a PFC output system and an air conditioner.

Background

The existing variable frequency air conditioner technology is developed rapidly, and the variable frequency air conditioner basically adopts an active PFC (power factor correction) control technology so as to improve the power factor, inhibit harmonic current and reduce the interference on a power grid. However, the active PFC control scheme is complex, has high requirements on the control algorithm, and is liable to generate overvoltage due to improper control, resulting in bulge and explosion of the electrolytic capacitor at the output end or failure of the rear-stage load.

The output voltage control of the conventional PFC scheme completely depends on software adjustment, no relevant protection is provided for abnormal high output voltage, and if the amplitude and the adjustment speed of the software control, an electric network is unstable or a chip has poor anti-interference performance, the output voltage can be high and damage a rear-stage electrolytic capacitor or other loads.

In summary, there is a problem in the prior art that the output voltage of the PFC scheme may be too high.

Disclosure of Invention

The application aims to provide an overvoltage protection circuit, a PFC output system and an air conditioner, and aims to solve the problem that the output voltage of a PFC scheme in the prior art is possibly too high.

In a first aspect, an embodiment of the present application provides an overvoltage protection circuit, where the overvoltage protection circuit is applied to a PFC output system, the PFC output system further includes a PFC output circuit and a PFC drive circuit, and the PFC drive circuit is electrically connected to the PFC output circuit; the overvoltage protection circuit comprises a voltage acquisition module, a voltage comparison module and a signal output module, wherein the voltage acquisition module, the voltage comparison module and the signal output module are electrically connected in sequence; the voltage acquisition module is electrically connected with the PFC output circuit to acquire the output voltage of the PFC output circuit; the voltage comparison module is used for controlling the signal output module to output a low level when the output voltage is greater than a preset voltage; the output end of the signal output module is electrically connected with the signal input port of the PFC driving circuit, and when the signal output module outputs a low level, the PFC driving circuit stops working so as to stop the PFC output circuit from working.

When the output voltage of the PFC output circuit is greater than the preset voltage, the signal output module can output a low level, and the PFC driving circuit stops working at the moment, so that the PFC output circuit cannot receive the driving signal, the PFC output circuit stops working, the overvoltage condition is prevented, and devices such as a capacitor are protected.

Optionally, the comparison module includes a first comparator and a first diode, a non-inverting input terminal of the first comparator is electrically connected to the voltage acquisition module and a cathode of the first diode, respectively, an inverting input terminal of the first comparator is used to input the preset voltage, and an output terminal of the first comparator is electrically connected to an anode of the first diode, respectively;

when the output voltage acquired by the voltage acquisition module is smaller than the preset voltage, the first comparator outputs a low level to the signal output module so that the signal output module outputs a high level signal;

when the output voltage acquired by the voltage acquisition module is greater than the preset voltage, the first comparator outputs a high level to the signal output module so that the signal output module outputs a low level signal;

the first comparator is also used for self-locking through the first diode when outputting a high level.

Optionally, the overvoltage protection circuit further includes a main control chip, and the main control chip is electrically connected to a signal input port of the PFC driving circuit to input a control signal to the PFC driving circuit; the voltage comparison module further comprises a second diode, the anode of the second diode is electrically connected with the output end of the first comparator, and the cathode of the second diode is electrically connected with the unlocking end of the main control chip; wherein the content of the first and second substances,

and after the first comparator is self-locked, the main control chip is used for outputting a low level through an unlocking end so as to unlock the first comparator.

Optionally, the overvoltage protection circuit further includes a driving power supply, and the driving power supply is electrically connected to the first comparator and supplies power to the first comparator; the comparison module further comprises a first resistor, one end of the first resistor is electrically connected with the driving power supply, and the other end of the first resistor is electrically connected with the output end of the first comparator.

Optionally, the overvoltage protection circuit further includes a main control chip, and the main control chip is electrically connected to a signal input port of the PFC driving circuit to input a control signal to the PFC driving circuit; wherein the content of the first and second substances,

the output end of the signal output module is also electrically connected with the main control chip, so that when the signal output module outputs a low level, the main control chip stops inputting the control signal to the PFC driving circuit.

Optionally, the signal output module includes a second comparator and a third diode, an inverting input terminal of the second comparator is electrically connected to the output terminal of the voltage comparison module, a non-inverting input terminal of the second comparator is used for inputting a reference voltage, an output terminal of the second comparator is electrically connected to a cathode of the third diode, and an anode of the third diode is connected to the PFC driving circuit.

Optionally, the overvoltage protection circuit further includes a driving power supply, and the driving power supply is electrically connected to the second comparator and supplies power to the second comparator; the signal output module further comprises a second resistor, one end of the second resistor is electrically connected with the driving power supply, and the other end of the second resistor is electrically connected with the output end of the second comparator.

Optionally, the voltage acquisition module includes a third resistor and a fourth resistor, one end of the third resistor is electrically connected to the output end of the PFC output circuit, the other end of the third resistor is electrically connected to one end of the fourth resistor and the voltage comparison module, respectively, and the other end of the fourth resistor is grounded.

In a second aspect, an embodiment of the present application further provides a PFC output system, where the PFC output system includes the above overvoltage protection circuit.

In a third aspect, an embodiment of the present application further provides an air conditioner, where the air conditioner includes the above overvoltage protection circuit.

Drawings

Fig. 1 is a schematic circuit diagram of a PFC output circuit provided in the prior art.

Fig. 2 is a circuit diagram of a PFC driving circuit provided in the prior art.

Fig. 3 is a schematic block diagram of a PFC output system according to an embodiment of the present disclosure.

Fig. 4 is a block diagram of an overvoltage protection circuit according to an embodiment of the present application.

Fig. 5 is a schematic circuit diagram of an overvoltage protection circuit according to an embodiment of the present application.

Description of the reference numerals:

100-PFC output system; 110-a master control chip; 120-PFC output circuit; 130-PFC driver circuit; 140-overvoltage protection circuit; 141-a voltage acquisition module; 142-a voltage comparison module; 143-a signal output module; r1-a first resistance; r2-a second resistor; r3-a third resistor; r4-a fourth resistor; r5-a fifth resistor; r6-sixth resistor; r7 — seventh resistance; r8-an eighth resistor; IC 1-first comparator; IC 2-second comparator; d1-a first diode; d2-a second diode; d3-a third diode; c1-a first capacitor; c2-a second capacitor; c3-third capacitance; c4-fourth capacitance.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below.

As described in the background art, the output voltage control of the existing PFC scheme completely depends on software adjustment, and there is no relevant protection for abnormal high output voltage, and if the software control amplitude, the adjustment speed, the unstable power grid or the poor chip interference resistance may all cause high output voltage and damage the subsequent electrolytic capacitor or other loads.

For example, referring to fig. 1, fig. 1 shows a PFC output circuit, which includes a rectifier bridge BG1, a PFC inductor, an IGBT, a D1 diode, and two large electrolytic capacitors E1 and E2; the connection relationship is shown in the figure and will not be described herein. Wherein, R2, R3, R4 and C1 form alternating voltage detection; r5, R6, R7 and C2 form a direct-current voltage detection circuit, and the R1 current sampling resistor is not embodied any more.

Fig. 2 is a schematic circuit diagram of a PFC driving circuit for driving the IGBT shown in fig. 1. As can be seen from fig. 1 and fig. 2, the working principle of the PFC output system is as follows:

on the basis that a second pin and a fourth pin of a chip IC2 in the PFC drive circuit are connected with a PFC _ PWM pin of a main control chip together, the main control chip sends a PWM signal to the chip IC2, and a Driver port of the IC2 synchronously outputs the PWM control signal to the IGBT shown in the figure 1, so that the IGBT is switched on and off according to the high frequency of the PWM control signal, a PFC inductor is continuously charged and discharged, and the charging voltage is the sum of the output voltage of a rectifier bridge and the voltage of the PFC inductor when a large electrolytic capacitor is charged, thereby achieving the purpose of boosting.

However, in practical applications, the boosted voltage may be greater than the threshold, for example, the voltage required by the two large electrolytic capacitors E1 and E2 is 350V, but the boosted output voltage of the PFC output circuit may be greater than 350V, for example, the output voltage reaches 400V, which may damage the rear-stage electrolytic capacitor or the load.

In view of this, the present application provides an overvoltage protection circuit, and controls the PFC driving circuit to stop working when the output voltage of the PFC output circuit is too high, so that the PFC output circuit 120 also stops working synchronously, thereby achieving the purpose of protecting the subsequent load.

The following provides an exemplary description of an overvoltage protection circuit provided in an embodiment of the present application:

optionally, referring to fig. 3, the overvoltage protection circuit 140 is applied to the PFC output system 100, the PFC output system 100 further includes a PFC output circuit 120, a PFC driving circuit 130, and the PFC driving circuit 130 is electrically connected to the PFC output circuit 120. Referring to fig. 4, the overvoltage protection circuit 140 includes a voltage collecting module 141, a voltage comparing module 142 and a signal output module 143, and the voltage collecting module 141, the voltage comparing module 142 and the signal output module 143 are electrically connected in sequence.

The PFC output circuit 120 and the PFC driving circuit 130 described in this application are respectively the same as the circuits shown in fig. 1 and fig. 2, and therefore, the PFC output circuit 120 and the PFC driving circuit 130 are not described in detail in this application.

It should be noted that, the voltage collection module 141 is provided in the present application and electrically connected to the PFC output circuit 120 to collect the output voltage of the PFC output circuit 120, that is, the voltage collection module 141 is connected to two ends of the large electrolytic capacitor in fig. 1 to further collect the voltage at two ends of the large electrolytic capacitor, and as can be understood, the voltage at two ends of the large electrolytic capacitor is the output voltage.

After the voltage collecting module 141 collects the output voltage of the PFC output circuit 120, the output voltage is sent to the voltage comparing module 142, and the voltage comparing module 142 is configured to compare the output voltage with a preset voltage, where the preset voltage is a required voltage at two ends of the large electrolytic capacitor, and when the output voltage is greater than the preset voltage, the signal outputting module 143 is controlled to output a low level. The output terminal of the signal output module 143 is electrically connected to the signal input port of the PFC driving circuit 130, and when the signal output module 143 outputs a low level, the PFC driving circuit 130 stops operating, so that the PFC output circuit 120 stops operating. When the output voltage is lower than the preset voltage, the PFC output circuit 120 operates normally.

By the implementation mode, the PFC output circuit 120 can normally work only when the output voltage of the PFC output circuit 120 is not higher than the preset value; once the output voltage of the PFC output circuit 120 is higher than the preset value, the high voltage protection circuit stops the PFC driving circuit 130, and further stops the PFC output circuit 120, so as to protect the load at the rear end of the PFC output circuit 120, such as a large electrolytic capacitor.

Optionally, referring to fig. 5, the voltage collecting module 141 includes a third resistor R3 and a fourth resistor R4, one end of the third resistor R3 is electrically connected to the output end of the PFC output circuit 120, the other end of the third resistor R3 is electrically connected to one end of the fourth resistor R4 and the voltage comparing module 142, respectively, and the other end of the fourth resistor R4 is grounded. It is understood that the voltage collecting module 141 actually collects the voltage across the large electrolytic capacitor by using the voltage dividing principle, and the voltage Ua = R4/(R3 + R4) × DC + output to the voltage comparing module 142, where R4 represents the resistance of the fourth resistor R4, R3 represents the resistance of the third resistor R3, and DC + represents the voltage across the large electrolytic capacitor.

In addition, in order to make the voltage output to the voltage comparing module 142 more stable, optionally, the voltage collecting module 141 further includes a first capacitor C1, one end of the first capacitor C1 is electrically connected to the first resistor R1 and the second resistor R2, and the other end of the first capacitor C1 is grounded, so as to achieve the filtering effect.

As an optional implementation manner, the comparing module includes a first comparator IC1 and a first diode D1, a non-inverting input terminal of the first comparator IC1 is electrically connected to the voltage acquisition module 141 and a cathode of the first diode D1, respectively, an inverting input terminal of the first comparator IC1 is used for inputting a preset voltage, and an output terminal of the first comparator IC1 is electrically connected to an anode of the first diode D1, respectively.

Optionally, the overvoltage protection circuit 140 further includes a preset voltage supply circuit, the preset voltage supply circuit is configured to supply a preset voltage to the inverting input terminal of the first comparator IC1, the preset voltage supply circuit includes a fifth resistor R5 and a sixth resistor R6, one end of the fifth resistor R5 is electrically connected to the driving power supply, the other end of the fifth resistor R5 is electrically connected to the inverting input terminal of the first comparator IC1 and one end of the second resistor R2, and the other end of the second resistor R2 is grounded. That is, the preset voltage supply circuit also uses the voltage division principle to input the voltage to the inverting input terminal of the first comparator IC1, and the voltage output to the inverting input terminal of the first comparator IC1 is Ub = R6/(R5 + R6) × Vcc, where R6 is the resistance value of the sixth resistor R6 and R5 is the resistance value of the fifth resistor R5. Similarly, a second capacitor C2 may be disposed in the preset voltage supply circuit, one end of the second capacitor C2 is electrically connected to the fifth resistor R5 and the sixth resistor R6, and the other end of the second capacitor C2 is grounded to achieve the filtering effect.

It should be noted that the third resistor R3, the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 provided in the embodiment of the present application may be adjusted according to actual needs, where when Ua is smaller than Ub, it indicates that the output voltage of the PFC output circuit 120 does not exceed the preset voltage, and at this time, the PFC output circuit 120 may be controlled to continue to operate; when Ua is greater than Ub, it indicates that the output voltage of the PFC output circuit 120 exceeds the preset voltage, and at this time, the PFC output circuit 120 needs to be controlled to stop working. Meanwhile, when Ua = Ub, the critical point is set, and the voltage value DC + to be protected can be calculated according to this condition.

On the basis of the above implementation, it can be understood that when the PFC output circuit 120 operates normally, the first comparator IC1 outputs a low level, and when the PFC output circuit 120 outputs an overvoltage, the output of the first comparator IC1 is inverted and outputs a high level.

In addition, since the time for the PFC output circuit 120 to output the overvoltage may be short, in order to better reflect the overvoltage state of the PFC output circuit 120, the first diode D1 is provided in the present application, so that the first comparator IC1 performs self-locking when the PFC output circuit 120 is in overvoltage. The working principle is as follows:

when the PFC output circuit 120 normally operates, the first comparator IC1 outputs a low level, and at this time, due to the unidirectional conductive characteristic of the first diode D1, the low level signal does not affect the non-inverting input terminal of the first comparator IC 1. When the PFC output circuit 120 outputs an overvoltage, the output of the first comparator IC1 is inverted, and a high level is output at this time, and at this time, the first comparator IC1 outputs a high level signal which is also used as a feedback signal and is output to the non-inverting input terminal of the first comparator IC1, and it can be understood that the input voltage at the non-inverting input terminal of the first comparator IC1 is the sum of the voltage of the feedback signal and the voltage divided by the first resistor R1 and the second resistor R2, and is greater than the voltage Ub at the inverting input terminal, so that the first comparator IC1 always outputs a high level, and even if the output voltage of the PFC output circuit 120 is reduced, the first comparator IC1 cannot exit the state of outputting a high level, and the first comparator IC1 is in the self-locking state at this time.

Through the implementation mode, a user can timely know whether the situation that the PFC output circuit 120 outputs overvoltage occurs or not, and even if the situation that the overvoltage occurs is short, the first comparator IC1 can continuously output a high level due to the self-locking state of the first comparator IC 1.

Meanwhile, in order to achieve a better self-locking state, the overvoltage protection circuit 140 further includes a driving power supply, which is electrically connected to the first comparator IC1 and supplies power to the first comparator IC 1; the comparison module further comprises a first resistor R1, one end of the first resistor R1 is electrically connected with the driving power supply, and the other end of the first resistor R1 is electrically connected with the output end of the first comparator IC 1. By providing the first resistor R1, a part of the voltage outputted from the driving power supply is also used as the feedback voltage. It will be appreciated that the non-inverting terminal voltage Ua ≧ (Vcc-0.7) × R4/(R1 + R4) of the first comparator IC1 after self-locking and Ua > Ub.

In order to facilitate unlocking after self-locking, as an implementation manner, the overvoltage protection circuit 140 further includes a main control chip 110, where the main control chip 110 is electrically connected to a signal input port of the PFC driving circuit 130 to input a control signal to the PFC driving circuit 130; the voltage comparison module 142 further includes a second diode D2, an anode of the second diode D2 is electrically connected to the output terminal of the first comparator IC1, and a cathode of the second diode D2 is electrically connected to the unlock terminal of the main control chip 110; after the first comparator IC1 is self-locked, the main control chip 110 is configured to output a low level through the unlocking terminal to unlock the first comparator IC 1.

In a normal operating state, the unlock terminal of the main control chip 110 outputs a high level, so that the second diode D2 is not turned on even when the first comparator IC1 outputs a high level. When the self-locking mode needs to be exited, the master control chip 110 only needs to output the low level first and then output the high level.

It can be understood that when the unlock terminal of the main control chip 110 outputs a low level, a current flows through a path with the minimum impedance, that is, the voltage at the output terminal of the first comparator IC1 is transmitted to the signal output module 143, and at the same time, flows to the main control chip 110 through a path of the second diode D2, and at this time, the feedback signal is not generated. Returning to the original reference point. Therefore, when the output voltage of the PFC output circuit 120 is lower than the preset voltage, the first comparator IC1 outputs a low level again to unlock the circuit, and the unlocking terminal of the main control chip 110 continues to output a high level for the next round of detection.

In order to make the signal output to the signal output module 143 more accurate, the voltage comparison module 142 may further include a third capacitor C3, one end of the third capacitor C3 is electrically connected to the output end of the first comparator IC1, and the other end of the third capacitor C3 is grounded, so as to implement filtering.

As one implementation manner, the signal output module 143 includes a second comparator IC2 and a third diode D3, an inverting input terminal of the second comparator IC2 is electrically connected to the output terminal of the voltage comparison module 142, a non-inverting input terminal of the second comparator IC2 is used for inputting a reference voltage, an output terminal of the second comparator IC2 is electrically connected to a cathode of the third diode D3, and an anode of the third diode D3 is connected to the PFC driving circuit 130.

Through this implementation, when the first comparator IC1 outputs a low level, the voltage of the non-inverting input terminal of the second comparator IC2 is greater than the voltage of the inverting input terminal, and the second comparator IC2 outputs a high level, which does not affect the PFC driving circuit 130 due to the unidirectional conduction characteristic of the third diode D3. When the first comparator IC1 outputs a high level, the voltage of the non-inverting input terminal of the second comparator IC2 is lower than the voltage of the inverting input terminal, and the second comparator IC2 outputs a low level. Since the main control chip 110 is connected to the control pin of the driving chip in the PFC driving circuit 130, and the anode of the third diode D3 is also connected to the control pin, when the second comparator IC2 outputs a low level, the control pin equivalent to the driving chip in the PFC driving circuit 130 is grounded, and even if the main control chip 110 outputs a PWM control signal, the control pin of the driving chip in the PFC driving circuit 130 does not receive the control signal, so that the PFC driving circuit 130 stops working, and the PFC output circuit 120 also stops working, thereby protecting a rear stage load.

It should be noted that, optionally, the overvoltage protection circuit 140 includes a reference voltage generation circuit, the reference voltage generation circuit includes a seventh resistor R7 and an eighth resistor R8, one end of the seventh resistor R7 is electrically connected to the driving power supply, and the other end of the seventh resistor R7 is electrically connected to one end of the eighth resistor R8 and the non-inverting input end of the second comparator IC2, respectively. It can be understood that, by the voltage division of the seventh resistor R7 and the eighth resistor R8, the reference voltage of the second comparator IC2 is obtained, and the voltage value of the reference voltage is any value greater than the low-level voltage and less than the high-level voltage, which is not limited herein.

Meanwhile, in order to realize filtering, the reference voltage generating circuit further comprises a fourth capacitor C4, one end of the fourth capacitor C4 is electrically connected with the seventh resistor R7 and the eighth resistor R8 respectively, and the other end of the fourth capacitor C4 is grounded.

In addition, the driving voltage described in this application may be the same voltage, or different driving voltages may be set for different circuit modules, which is not limited herein.

Optionally, the overvoltage protection circuit 140 further includes a driving power supply, which is electrically connected to the second comparator IC2 and supplies power to the second comparator IC 2; the signal output module 143 further includes a second resistor R2, one end of the second resistor R2 is electrically connected to the driving power supply, and the other end of the second resistor R2 is electrically connected to the output end of the second comparator IC 2.

As one implementation manner, the main control chip 110 is electrically connected to a signal input port of the PFC driving circuit 130 to input a control signal to the PFC driving circuit 130; the output end of the signal output module 143 is further electrically connected to the main control chip 110, so that when the signal output module 143 outputs a low level, the main control chip 110 stops inputting the control signal to the PFC driving circuit 130.

That is, when the second comparator IC2 outputs a low level, the receiving pin of the main control chip 110 receives a low level signal, so that the main control chip 110 can determine that the PFC output circuit 120 outputs an overvoltage, and further stop outputting the PWM control signal to the PFC driving circuit 130. In other words, the present application ensures that the PFC driving circuit 130 stops working through two ways, so as to stop the PFC output circuit 120, the first way is that the main control chip 110 stops outputting the PWM control signal to the PFC driving circuit 130, and the second way is that the port voltage of the PFC driving circuit 130 is pulled down, so as to further ensure the accuracy of controlling the PFC output circuit 120 to stop working.

On the basis of the foregoing implementation manner, an embodiment of the present application further provides a PFC output system 100, where the PFC output system 100 includes the foregoing overvoltage protection circuit 140.

In addition, the present application further provides an air conditioner, which includes the overvoltage protection circuit 140 mentioned above

In summary, the embodiment of the application provides an overvoltage protection circuit, a PFC output system and an air conditioner, wherein the overvoltage protection circuit is applied to the PFC output system, the PFC output system further includes a PFC output circuit and a PFC driving circuit, and the PFC driving circuit is electrically connected with the PFC output circuit; the overvoltage protection circuit comprises a voltage acquisition module, a voltage comparison module and a signal output module, wherein the voltage acquisition module, the voltage comparison module and the signal output module are electrically connected in sequence; the voltage acquisition module is electrically connected with the PFC output circuit to acquire the output voltage of the PFC output circuit; the voltage comparison module is used for controlling the signal output module to output a low level when the output voltage is greater than a preset voltage; the output end of the signal output module is electrically connected with the signal input port of the PFC driving circuit, and when the signal output module outputs a low level, the PFC driving circuit stops working so as to stop the PFC output circuit from working. When the output voltage of the PFC output circuit is greater than the preset voltage, the signal output module can output a low level, and the PFC driving circuit stops working at the moment, so that the PFC output circuit cannot receive the driving signal, the PFC output circuit stops working, the overvoltage condition is prevented, and devices such as a capacitor are protected.

Although the present application is disclosed above, the present application is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present disclosure, and it is intended that the scope of the present disclosure be defined by the appended claims.

Claims

1. An overvoltage protection circuit (140), wherein the overvoltage protection circuit (140) is applied to a PFC output system (100), the PFC output system (100) further comprises a PFC output circuit (120) and a PFC drive circuit (130), and the PFC drive circuit (130) is electrically connected with the PFC output circuit (120); the overvoltage protection circuit (140) comprises a voltage acquisition module (141), a voltage comparison module (142) and a signal output module (143), wherein the voltage acquisition module (141), the voltage comparison module (142) and the signal output module (143) are electrically connected in sequence; wherein, the first and the second end of the pipe are connected with each other,

the voltage acquisition module (141) is electrically connected with the PFC output circuit (120) to acquire the output voltage of the PFC output circuit (120);

the voltage comparison module (142) is used for controlling the signal output module (143) to output a low level when the output voltage is greater than a preset voltage;

the output end of the signal output module (143) is electrically connected with the signal input end of the PFC driving circuit (130), and when the signal output module (143) outputs a low level, the PFC driving circuit (130) stops working so as to stop the PFC output circuit (120).

2. The overvoltage protection circuit (140) according to claim 1, wherein the comparison module comprises a first comparator (IC 1) and a first diode (D1), a non-inverting input terminal of the first comparator (IC 1) is electrically connected to the voltage acquisition module (141) and a cathode of the first diode (D1), respectively, a inverting input terminal of the first comparator (IC 1) is used for inputting the preset voltage, and an output terminal of the first comparator (IC 1) is electrically connected to an anode of the first diode (D1), respectively;

when the output voltage acquired by the voltage acquisition module (141) is less than the preset voltage, the first comparator (IC 1) outputs a low level to the signal output module (143), so that the signal output module (143) outputs a high level signal;

when the output voltage acquired by the voltage acquisition module (141) is greater than the preset voltage, the first comparator (IC 1) outputs a high level to the signal output module (143), so that the signal output module (143) outputs a low level signal;

the first comparator (IC 1) is also used for self-locking through the first diode (D1) when outputting a high level.

3. The overvoltage protection circuit (140) according to claim 2, wherein the overvoltage protection circuit (140) further comprises a main control chip (110), the main control chip (110) is electrically connected with the signal input port of the PFC drive circuit (130) to input a control signal to the PFC drive circuit (130); the voltage comparison module (142) further comprises a second diode (D2), the anode of the second diode (D2) is electrically connected with the output end of the first comparator (IC 1), and the cathode of the second diode (D2) is electrically connected with the unlocking end of the main control chip (110); wherein the content of the first and second substances,

when the first comparator (IC 1) is self-locked, the main control chip (110) is used for outputting a low level through an unlocking end so as to unlock the first comparator (IC 1).

4. The overvoltage protection circuit (140) of claim 2, wherein the overvoltage protection circuit (140) further comprises a drive power supply electrically connected to the first comparator (IC 1) and powering the first comparator (IC 1); the comparison module further comprises a first resistor (R1), one end of the first resistor (R1) is electrically connected with the driving power supply, and the other end of the first resistor (R1) is electrically connected with the output end of the first comparator (IC 1).

5. The overvoltage protection circuit (140) according to claim 1, wherein the overvoltage protection circuit (140) further comprises a main control chip (110), the main control chip (110) is electrically connected with a signal input port of the PFC driving circuit (130) to input a control signal to the PFC driving circuit (130); wherein, the first and the second end of the pipe are connected with each other,

the output end of the signal output module (143) is also electrically connected with the main control chip (110), so that when the signal output module (143) outputs a low level, the main control chip (110) stops inputting the control signal to the PFC driving circuit (130).

6. The overvoltage protection circuit (140) according to claim 1, wherein the signal output module (143) comprises a second comparator (IC 2) and a third diode (D3), an inverting input terminal of the second comparator (IC 2) is electrically connected to the output terminal of the voltage comparison module (142), a non-inverting input terminal of the second comparator (IC 2) is used for inputting a reference voltage, an output terminal of the second comparator (IC 2) is electrically connected to a cathode of the third diode (D3), and an anode of the third diode (D3) is connected to the PFC driving circuit (130).

7. The overvoltage protection circuit (140) of claim 6, wherein the overvoltage protection circuit (140) further comprises a drive power supply electrically connected to the second comparator (IC 2) and powering the second comparator (IC 2); the signal output module (143) further comprises a second resistor (R2), one end of the second resistor (R2) is electrically connected to the driving power supply, and the other end of the second resistor (R2) is electrically connected to an output end of the second comparator (IC 2).

8. The overvoltage protection circuit (140) according to claim 1, wherein the voltage acquisition module (141) comprises a third resistor (R3) and a fourth resistor (R4), one end of the third resistor (R3) is electrically connected to the output terminal of the PFC output circuit (120), the other end of the third resistor (R3) is electrically connected to one end of the fourth resistor (R4) and the voltage comparison module (142), respectively, and the other end of the fourth resistor (R4) is grounded.

9. A PFC output system (100), characterized in that the PFC output system (100) comprises an overvoltage protection circuit (140) according to any one of claims 1 to 8.

10. An air conditioner, characterized in that it comprises an overvoltage protection circuit (140) according to any one of claims 1 to 8.