Overcurrent protection circuit and method, PFC (Power Factor Correction) device and electronic equipment

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By introducing an overcurrent protection circuit of the detection module and control module into the PFC circuit, the overcurrent fault problem caused by the short circuit of the thermistor during power failure or secondary power-on is solved, and effective protection of the impact current and safe operation of the circuit are achieved.

CN119891080APending Publication Date: 2025-04-25HEFEI KUTEAN TECH CO LTD

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Patent Information

Application Number: CN202311394533.8
Authority / Receiving Office: CN · China
Patent Type: Applications(China)
Current Assignee / Owner
Filing Date: 2023-10-24
Publication Date: 2025-04-25

AI Technical Summary

Technical Problem

When the existing PFC circuit suddenly loses power or is powered on again in a short time, the thermistor is easily short-circuited, resulting in PFC overcurrent failure.

Method used

An overcurrent protection circuit is provided, including a detection module and a control module. The detection module is used to detect the power failure of the PFC circuit. The control module controls the relay to pull in when the trigger signal is received, short-circuits the thermistor, controls the relay to disconnect when the trigger signal is not received, and transfers the thermistor into the main circuit of the PFC circuit in series.

Benefits of technology

It effectively prevents excessive impact current during secondary power-on, protects the PFC circuit, and avoids the occurrence of overcurrent failures. At the same time, the circuit structure is simple and has cost advantages.

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Abstract

The invention relates to the technical field of PFC protection, in particular to an overcurrent protection circuit and method, a PFC device and electronic equipment. The circuit comprises a detection module and a control module, the input end of the detection module is connected with the input end of the PFC circuit, the input end of the control module is connected with the output end of the detection module, the detection module can detect the power failure condition of the PFC circuit, when it is detected that the PFC circuit is powered on, a trigger signal is output to the control module, and the control module controls the PFC circuit to be powered on. When the control module receives a trigger signal, the relay RL1 can be controlled to be closed, and the thermistor PTC1 is short-circuited, so that a post-stage load normally starts to work. When the power failure of the PFC circuit is detected, the detection module stops outputting a trigger signal, and the control module controls the relay RL1 to be switched off when not receiving the trigger signal, so that the thermistor PTC1 is connected into the PFC main loop in series, the device damage caused by overlarge impact current of secondary power-on is prevented, and the circuit is simple in circuit structure, has the cost advantage and is suitable for popularization and application.

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Description

Technical Field

[0001] The present application relates to the field of PFC protection technology, and in particular to an overcurrent protection circuit, method, PFC device and electronic equipment. Background Art

[0002] In the home appliance industry, PFC (i.e., power factor correction) circuits are usually used to improve the conversion efficiency of power supplies, in which thermistors are usually connected to the main circuit through switch devices such as relays. Taking the variable frequency drive board in home appliances as an example, when the variable frequency drive board with a PFC circuit is powered off, since the bus capacitor is generally very large, the output bus VBUS voltage drops slowly, which is not enough to reach the threshold voltage for the soft start relay to disconnect. The relay is in the energized state, which will cause the thermistor to be short-circuited and unable to function. In addition, if the power supply is powered on again in a short time, since there is a certain voltage difference between the input voltage peak and the current bus voltage value at this time, the voltage difference will charge the bus energy storage capacitor. At this time, the relay still has no time to disconnect, and the thermistor is still short-circuited and unable to function, resulting in a large charging current in the main circuit, which is very likely to trigger a PFC overcurrent fault. The current solution is mainly to increase the PFC overcurrent point or increase the filtering time for PFC overcurrent protection, but such a method of relying on device resistance cannot solve the above problems from the root. Summary of the invention

[0003] The embodiments of the present application mainly solve the technical problem that when the existing PFC circuit is suddenly powered off or powered on again in a short period of time, the thermistor is short-circuited and easily triggers a PFC overcurrent fault.

[0004] In order to solve the above technical problems, a technical solution adopted in the embodiment of the present application is: to provide an overcurrent protection circuit for protecting a PFC circuit, wherein the PFC circuit includes a thermistor PTC1, wherein the thermistor PTC1 is connected in parallel with a relay control circuit, wherein the relay control circuit is used to control the thermistor PTC1 to be connected in series with a main circuit of the PFC circuit when the relay is disconnected, and comprises:

[0005] a detection module, wherein an input end of the detection module is connected to an input end of the PFC circuit, and the detection module is used to detect a power failure of the PFC circuit, and output a trigger signal if the PFC circuit is powered on, and stop outputting the trigger signal if the PFC circuit is powered off;

[0006] A control module, wherein the input end of the control module is connected to the output end of the detection module, and the control module is used to control the relay to be attracted when the trigger signal is received, and the control module is also used to control the relay to be disconnected when the trigger signal is not received.

[0007] Optionally, the control module is further connected to a controller;

[0008] The control module is used to output a square wave signal to the controller when the trigger signal is received, so that the controller controls the relay to be closed according to the square wave signal, and is also used to output a continuous high level signal to the controller when the trigger signal is not received, so that the controller controls the relay to be opened according to the continuous high level signal.

[0009] Optionally, the detection module includes a current limiting resistor R6, a diode D4 and an optocoupler U1, the anode of the diode D4 is connected to the first input end of the PFC circuit through the current limiting resistor R6, the cathode of the diode D4 is connected to the first input end of the optocoupler U1, the second input end of the optocoupler U1 is connected to the second input end of the PFC circuit, and the output end of the optocoupler U1 is connected to the input end of the control module.

[0010] Optionally, the detection module further includes a resistor R8, a first end of the resistor R8 is connected to the first input end of the optocoupler U1, a second end of the resistor R8 is connected to the second input end of the optocoupler U1, and the resistor R8 is used to provide a bias voltage for the optocoupler U1.

[0011] Optionally, the detection module further includes a diode D5, a cathode of the diode D5 is connected to the first input terminal of the optocoupler U1, an anode of the diode D5 is connected to the second input terminal of the optocoupler U1, and the diode D5 is used for voltage clamping to protect the optocoupler U1.

[0012] Optionally, the detection module includes a power supply, a resistor R4, a resistor R9, a resistor R10, a switch tube Q3 and a signal output port, the first end of the switch tube Q3 is connected to the first output end of the detection module through the resistor R4, the first end of the switch tube Q3 is also connected to the power supply through the resistor R4, the second end of the switch tube Q3 is grounded, the control end of the switch tube Q3 is connected to the second output end of the detection module through the resistor R9, the control end of the switch tube Q3 is also connected to the second end of the switch tube Q3 through the resistor R10, and the first end of the switch tube Q3 is also connected to the signal output port.

[0013] Optionally, the detection module also includes a filtering unit, which includes a resistor R5 and a capacitor C2, the switch tube Q3 is connected to the signal output port through the resistor R5, the first end of the capacitor C2 is connected to the signal output port, and the second end of the capacitor C2 is connected to the second end of the switch tube Q3.

[0014] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present application is: providing a PFC device, including a PFC circuit and the overcurrent protection circuit mentioned above, wherein the overcurrent protection circuit is used to control the relay to disconnect when the PFC circuit loses power, so that the thermistor PTC1 is connected in series with the main circuit of the PFC circuit.

[0015] In order to solve the above technical problems, another technical solution adopted by the embodiment of the present application is: to provide an overcurrent protection method for protecting a PFC circuit, wherein the PFC circuit includes a thermistor PTC1, and the thermistor PTC1 is connected in parallel with a relay control circuit, and the relay control circuit is used to control the thermistor PTC1 to be connected in series with the main circuit of the PFC circuit when the relay is disconnected, and the method includes:

[0016] Obtaining a power failure condition of the PFC circuit;

[0017] When the PFC circuit is powered on, controlling the relay to be closed to short-circuit the thermistor PTC1;

[0018] When the PFC circuit loses power, the relay is controlled to be disconnected so that the thermistor PTC1 is connected in series to the main loop of the PFC circuit.

[0019] In order to solve the above technical problem, another technical solution adopted in the implementation manner of the present application is: to provide an electronic device, comprising the above-mentioned PFC device.

[0020] Different from the related art, the embodiments of the present application provide an overcurrent protection circuit, method, PFC device and electronic device. The device comprises a PFC circuit and an overcurrent protection circuit. The PFC circuit comprises a thermistor PTC1. The thermistor PTC1 is connected in parallel with a relay control circuit. The relay control circuit is used to control the thermistor PTC1 to be connected in series with the main circuit of the PFC circuit when the relay RL1 is disconnected. The overcurrent protection circuit comprises a detection module and a control module. The input end of the detection module is connected to the input end of the PFC circuit, and the input end of the control module is connected to the output end of the detection module. The detection module can detect the power failure of the PFC circuit. When the power-on of the PFC circuit is detected, a trigger signal will be output to the control module. When the control module receives the trigger signal, the relay RL1 can be controlled to be attracted to short-circuit the thermistor PTC1 so that the subsequent load starts to work normally. When the power failure of the PFC circuit is detected, the detection module will stop outputting the trigger signal. When the control module does not receive the trigger signal, the relay RL1 will be controlled to be disconnected, thereby connecting the thermistor PTC1 in series with the PFC main circuit to prevent the device from being damaged due to excessive impact current of the secondary power-on. In addition, the circuit structure of the circuit is simple, cost-effective, and suitable for popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0022] Figure 1 is a circuit structure example diagram of an existing PFC circuit provided in an embodiment of the present application;

[0023] Figure 2 is a structural schematic diagram of an overcurrent protection circuit provided in an embodiment of the present application;

[0024] Figure 3 is a circuit structure diagram of an overcurrent protection circuit provided in an embodiment of the present application;

[0025] Figure 4 is a circuit structure diagram of another overcurrent protection circuit provided in an embodiment of the present application;

[0026] Figure 5 It is a flow chart of an overcurrent protection method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. It should be noted that, if there is no conflict, the various features in the embodiments of the present application can be combined with each other, all within the scope of protection of the present application. In addition, although the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in an order different from that in the flow chart. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0029] In the home appliance industry, PFC circuits are usually used to improve the conversion efficiency of power supplies. The thermistor is usually connected to the main circuit through switch devices such as relays. Take the variable frequency drive board in home appliances as an example. Figure 1 As shown in the figure, when the variable frequency drive board is powered off (AC_L and AC_N are powered off in the figure), the PFC circuit ( Figure 1 In the bold dashed box in the figure, since the output capacitor C1 has a large capacitance, the output bus VBUS voltage drops slowly. For example, the bus voltage drops from 400V in normal working state to 200V, especially in standby state. It is difficult for the bus voltage to drop to the threshold voltage of the soft start relay RL1 disconnection in a short time, for example, it is preset to 50V, resulting in the relay RL1 on the main circuit still being in the energized state, and the thermistor PTC1 is short-circuited and cannot function. In addition, if the power supply is powered on again at this time, since there is a certain voltage difference between the input voltage peak and the current bus voltage value, the voltage difference will charge the bus energy storage capacitor, and at this time the relay RL1 is still in the energized state, the soft start PTC1 resistor will be short-circuited, which is equivalent to the charging resistor on the charging circuit being extremely small, resulting in a large charging current in the main circuit, which is very easy to trigger a PFC overcurrent fault, and the impact current will also cause damage to the diode D1 and the rectifier bridge D2. The current solution is to increase the PFC overcurrent point or increase the filtering time to perform PFC overcurrent protection, for example, by increasing the specifications of the diode D1 and the rectifier bridge D2 to avoid damage, but this method of relying on the hard resistance of the device cannot solve the above problem from the root. Based on this, the embodiment of the present application proposes the following solution:

[0030] The embodiments of this application are Figure 1 The present application provides a PFC device, including a PFC circuit and an overcurrent protection circuit, wherein: Figure 1 For example, the PFC circuit includes a thermistor PTC1, and the thermistor PTC1 is connected in parallel with a relay control circuit. The relay control circuit is used to control the thermistor PTC1 to be connected in series with the main circuit of the PFC circuit when the relay RL1 is disconnected, and the overcurrent protection circuit is used to protect the PFC circuit.

[0031] For details, please combine Figure 2 , Figure 2 Schematic diagram of an example of a structural block diagram of an overcurrent protection circuit provided in an embodiment of the present application. Figure 2 As shown, the overcurrent protection circuit 100 includes a detection module 11 and a control module 12, wherein the input end of the detection module 11 is connected to the input end of the PFC circuit, that is, Figure 1 At AC_L and AC_N shown in the figure, the input end of the control module 12 is connected to the output end of the detection module 11. Wherein, AC_L and AC_N may refer to the sinusoidal alternating current provided by the power grid.

[0032] Specifically, the detection module 11 can detect the power failure of the PFC circuit. When it is detected that the PFC circuit is powered on, it will output a trigger signal to the control module 12. When receiving the trigger signal, the control module 12 can control the relay RL1 to be energized, and short-circuit the thermistor PTC1, so that the subsequent load starts to work normally; when it is detected that the PFC circuit is powered off, the detection module 11 will stop outputting the trigger signal. When the control module 12 does not receive the trigger signal, it will control the relay RL1 to be disconnected, thereby connecting the thermistor PTC1 in series with the PFC main circuit to prevent the impact current of the secondary power-on from being too large and causing damage to the device.

[0033] Specifically, if the power is turned on for the second time in a short period of time, although there is a voltage difference between the input voltage peak and the bus VBUS voltage at this time, since the relay RL1 is disconnected when the power is off, the thermistor PTC1 is working normally at this time, and the process from the overcurrent protection circuit detecting the second power-on to re-controlling the relay RL1 to re-engage is not instantaneous control, but requires a short period of time, and this short period of time is enough to fully charge the bus capacitor C1, so there will be no charging impact current, thereby protecting the PFC circuit. It can be understood that the power-off situation described in the embodiment of the present application refers to the situation where the PFC circuit is abnormally powered off, and not the situation where the entire device is actively powered off. For example, when the PFC circuit is working normally, it suddenly loses power abnormally for a few seconds and then returns to normal, which belongs to the situation of powering on twice in a short period of time mentioned in the embodiment of the present application.

[0034] In some embodiments, the overcurrent protection circuit can control the closing and opening of the relay by connecting to a controller, such as a single-chip microcomputer MCU or other similar controller, and the output end of the control module 12 is connected to the controller. Specifically, when the control module 12 receives a trigger signal, it outputs a square wave signal to the controller, so that the controller controls the relay to close according to the square wave signal. That is, when the controller receives the square wave signal, it controls the relay to close, for example, Figure 1 The example relay control circuit provides a drive signal AC_RL to drive the relay RL1 to close; when the control module 12 does not receive (or stops receiving) a trigger signal, it outputs a continuous high-level signal to the controller, so that the controller controls the relay to open according to the continuous high-level signal. This design uses the feedback and response time of the controller to provide charging time for the bus capacitor during the secondary power-on in a short period of time, so as to avoid the situation where the impact current of the secondary power-on is too large and causes damage to the device.

[0035] Please combine Figure 3The detection module 11 includes a current limiting resistor R6, a diode D4 and an optical coupler U1, and the detection module 12 includes a power supply (represented as 5V in the figure), a resistor R4, a resistor R9, a resistor R10, a switch tube Q3 and a signal output port (represented as ZERO in the figure).

[0036] Specifically, the anode of the diode D4 is connected to the first input terminal of the PFC circuit through the current limiting resistor R6, that is, AC_L shown in the figure, the cathode of the diode D4 is connected to the first input terminal (U1_1) of the optocoupler U1, the second input terminal (U1_2) of the optocoupler U1 is connected to the second input terminal of the PFC circuit, that is, AC_N shown in the figure, the first end of the switch tube Q3 is connected to the first output terminal (U1_4) of the optocoupler U1 through the resistor R4, the first end of the switch tube Q3 is also connected to the power supply through the resistor R4, that is, 5V in the figure, the second end of the switch tube Q3 is grounded, represented as SGND in the figure, the control end of the switch tube Q3 is connected to the second output terminal (U1_3) of the optocoupler U1 through the resistor R9, the control end of the switch tube Q3 is also connected to the second end of the switch tube Q3 through the resistor R10, and the first end of the switch tube Q3 is also connected to the signal output port, represented as ZERO in the figure.

[0037] It can be understood that the signal output port ZERO is a port that provides a square wave signal or a continuous high level signal to the controller. Figure 1 In the relay control circuit shown in FIG. 1 , the controller can provide a driving signal AC_RL to the relay control circuit according to a square wave signal or a continuous high level signal to control the closing and opening of the relay RL1 .

[0038] Based on this, Figure 3 The overcurrent protection circuit shown works as follows:

[0039] When the PFC device is powered on for the first time, AC_L and AC_N provide AC power to the overcurrent protection circuit. After rectification by diode D4 and isolation by optocoupler U1, combined with the power supply, a trigger signal is provided to the control end of switch tube Q3 through the output end of optocoupler U1, and switch tube Q3 is controlled to conduct-disconnect-conduct-disconnect in a cycle, and then a square wave signal is provided to the controller through the signal output port ZERO. The controller can determine that the PFC circuit is working normally at this time through the square wave signal, and then control the relay to attract by providing a drive signal AC_RL, so as to short-circuit the thermistor PTC1, and the subsequent load starts to work normally.

[0040] When the PFC device loses power, AC_L and AC_N stop supplying power, the output end of the optocoupler U1 is disconnected, and the switch tube Q3 is disconnected. At this time, the signal output port ZERO provides a continuous high-level signal to the controller. The controller can determine that the PFC circuit is powered off at this time through the continuous high-level signal, and then stop providing the drive signal AC_RL to control the relay to disconnect, and connect the thermistor PTC1 in series to the main circuit of the PFC circuit, thereby preventing the impact current of the secondary power-on from being too large and causing damage to the device.

[0041] If the PFC device is powered on again within a short period of time after power failure, since the thermistor PTC1 has been connected in series to the main circuit of the PFC circuit, although there is a voltage difference between the input voltage peak and the bus VBUS voltage when the power is turned on again, the thermistor PTC1 can also protect the PCT circuit and prevent the impact current from damaging the device. At the same time, the overcurrent protection circuit takes a short time from detecting the second power-on to feeding back to the controller to drive the control relay RL1 to re-close, and this short time is enough to fully charge the bus capacitor C1, so there will be no charging impact current, thereby protecting the PFC circuit.

[0042] In some embodiments, the detection module 11 further includes a resistor R8. Figure 4 , the first end of the resistor R8 is connected to the first input end (U1_1) of the optical coupler U1, and the second end of the resistor R8 is connected to the second input end (U1_2) of the optical coupler U1, wherein the resistor R8 can provide a bias voltage for the optical coupler U1 to avoid the optical coupler U1 from being mis-conducted. In addition, in some cases, the voltage corresponding to the conduction of the optical coupler U1 can be set by changing the resistance value of the resistor R8.

[0043] In some embodiments, the detection module further includes a diode D5. Figure 4 The cathode of the diode D5 is connected to the first input terminal (U1_1) of the optocoupler U1, and the anode of the diode D5 is connected to the second input terminal (U1_2) of the optocoupler U1. The diode D5 can clamp the voltage within 1V. For example, a common diode can clamp the voltage at about 0.7V to prevent the interference voltage from reversely breaking through the diode inside the optocoupler U1 and causing damage to the device.

[0044] In some embodiments, the detection module 12 further includes a filter unit, which includes a resistor R5 and a capacitor C2. Figure 4 , the switch tube Q3 is connected to the signal output port ZERO through the resistor R5, the first end of the capacitor C2 is connected to the signal output port ZERO, and the second end of the capacitor C2 is connected to the second end of the switch tube Q3. The filter unit can filter out the clutter in the square wave signal or the continuous high level signal, reducing the possibility of false alarm of the controller.

[0045] The embodiment of the present application provides a PFC device, which includes a PFC circuit and an overcurrent protection circuit. The PFC circuit includes a thermistor PTC1. The thermistor PTC1 is connected in parallel with a relay control circuit. The relay control circuit is used to control the thermistor PTC1 to be connected in series with the main circuit of the PFC circuit when the relay RL1 is disconnected. The overcurrent protection circuit includes a detection module and a control module. The input end of the detection module is connected to the input end of the PFC circuit, and the input end of the control module is connected to the output end of the detection module. The detection module can detect the power failure of the PFC circuit. When the power-on of the PFC circuit is detected, the trigger signal will be output to the control module. When the control module receives the trigger signal, the relay RL1 can be controlled to be attracted to short-circuit the thermistor PTC1, so that the subsequent load starts to work normally. When the power failure of the PFC circuit is detected, the detection module will stop outputting the trigger signal. When the control module does not receive the trigger signal, the relay RL1 will be controlled to be disconnected, thereby connecting the thermistor PTC1 in series with the PFC main circuit to prevent the device from being damaged due to excessive impact current of the secondary power-on. In addition, the circuit structure of the circuit is simple, cost-effective, and suitable for popularization and use.

[0046] The embodiment of the present application provides an electronic device, which includes the PFC device described in the above embodiment. It can be understood that the above electronic device has the structure and functional modules and beneficial effects of the PFC device embodiment. For technical details not fully described in the electronic device embodiment, refer to the PFC device provided in the embodiment of the present application.

[0047] Please combine Figure 5 The embodiment of the present application provides an overcurrent protection method for protecting a PFC circuit, wherein the PFC circuit includes a thermistor PTC1, the thermistor PTC1 is connected in parallel with a relay control circuit, and the relay control circuit is used to control the thermistor PTC1 to be connected in series with a main circuit of the PFC circuit when the relay RL1 is disconnected. The method includes:

[0048] S11, obtaining the power-off status of the PFC circuit. In an embodiment of the present application, the power-off status of the PFC circuit can be obtained by the overcurrent protection circuit in the above embodiment, wherein the overcurrent protection circuit includes a detection module and a control module, and the input end of the detection module is connected to the input end of the PFC circuit, thereby obtaining the power-off status of the PFC circuit.

[0049] S12, when the PFC circuit is powered on, the relay is controlled to be closed to short-circuit the thermistor PTC1. The controller can provide a driving signal to control the relay to be closed or disconnected. When the PFC circuit is detected to be powered on, the control module of the overcurrent protection circuit provides a square wave signal to the controller, and the controller outputs a driving signal AC_RL according to the square wave signal to control the relay RL1 to be closed, short-circuiting the thermistor PTC1 in the PFC circuit, so that the subsequent load starts to work normally.

[0050] S13, when the PFC circuit loses power, the control relay is disconnected so that the thermistor PTC1 is connected in series to the main circuit of the PFC circuit. When the PFC circuit loses power, the detection module of the overcurrent protection circuit is disconnected, and the control module provides a high-level signal to the controller in combination with the power supply. The controller stops outputting the drive signal AC_RL according to the continuous high-level signal, so that the relay RL1 is disconnected, thereby connecting the thermistor PTC1 in series to the PFC main circuit. If the power is turned on again in a short period of time, since the thermistor PTC1 has been connected in series to the main circuit of the PFC circuit and works normally, although there is a voltage difference between the input voltage peak and the bus VBUS voltage when the power is turned on for the second time, the thermistor PTC1 can also achieve the function of protecting the PCT circuit and prevent the impact current from damaging the device.

[0051] The above overcurrent protection method can achieve the functions and beneficial effects of the PFC device embodiment. For technical details not fully described in the overcurrent protection method embodiment, please refer to the PFC device provided in the embodiment of the present application.

[0052] Through the description of the above implementation methods, ordinary technicians in this field can clearly understand that the method implementation method can be implemented by means of software plus a general hardware platform, and of course, it can also be implemented by hardware. Ordinary technicians in this field can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An overcurrent protection circuit for protecting a PFC circuit, the PFC circuit comprising a thermistor PTC1, the thermistor PTC1 being connected in parallel with a relay control circuit, the relay control circuit being used to control the thermistor PTC1 to be connected in series with a main circuit of the PFC circuit when the relay is disconnected, characterized in that: include: a detection module, wherein an input end of the detection module is connected to an input end of the PFC circuit, and the detection module is used to detect a power failure of the PFC circuit, and output a trigger signal if the PFC circuit is powered on, and stop outputting the trigger signal if the PFC circuit is powered off; A control module, wherein the input end of the control module is connected to the output end of the detection module, and the control module is used to control the relay to be attracted when the trigger signal is received, and the control module is also used to control the relay to be disconnected when the trigger signal is not received.

2. The overcurrent protection circuit according to claim 1, characterized in that: The control module is also connected to a controller; The control module is used to output a square wave signal to the controller when the trigger signal is received, so that the controller controls the relay to be closed according to the square wave signal, and is also used to output a continuous high level signal to the controller when the trigger signal is not received, so that the controller controls the relay to be opened according to the continuous high level signal.

3. The overcurrent protection circuit according to claim 1, characterized in that: The detection module includes a current limiting resistor R6, a diode D4 and an optical coupler U1, the anode of the diode D4 is connected to the first input end of the PFC circuit through the current limiting resistor R6, the cathode of the diode D4 is connected to the first input end of the optical coupler U1, the second input end of the optical coupler U1 is connected to the second input end of the PFC circuit, and the output end of the optical coupler U1 is connected to the input end of the control module.

4. The overcurrent protection circuit according to claim 3, characterized in that: The detection module further includes a resistor R8, a first end of the resistor R8 is connected to the first input end of the optical coupler U1, a second end of the resistor R8 is connected to the second input end of the optical coupler U1, and the resistor R8 is used to provide a bias voltage for the optical coupler U1.

5. The overcurrent protection circuit according to claim 3, characterized in that: The detection module further includes a diode D5, a cathode of the diode D5 is connected to the first input terminal of the optocoupler U1, an anode of the diode D5 is connected to the second input terminal of the optocoupler U1, and the diode D5 is used for voltage clamping to protect the optocoupler U1.

6. The overcurrent protection circuit according to claim 1, characterized in that: The detection module includes a power supply, a resistor R4, a resistor R9, a resistor R10, a switch tube Q3 and a signal output port. The first end of the switch tube Q3 is connected to the first output end of the detection module through the resistor R4, the first end of the switch tube Q3 is also connected to the power supply through the resistor R4, the second end of the switch tube Q3 is grounded, the control end of the switch tube Q3 is connected to the second output end of the detection module through the resistor R9, the control end of the switch tube Q3 is also connected to the second end of the switch tube Q3 through the resistor R10, and the first end of the switch tube Q3 is also connected to the signal output port.

7. The overcurrent protection circuit according to claim 6, characterized in that: The detection module also includes a filtering unit, which includes a resistor R5 and a capacitor C2. The switch tube Q3 is connected to the signal output port through the resistor R5, the first end of the capacitor C2 is connected to the signal output port, and the second end of the capacitor C2 is connected to the second end of the switch tube Q3.

8. A PFC device, characterized in that: It comprises a PFC circuit and an overcurrent protection circuit as claimed in any one of claims 1 to 7, wherein the overcurrent protection circuit is used to control the relay to disconnect when the PFC circuit loses power, so that the thermistor PTC1 is connected in series to the main circuit of the PFC circuit.

9. An overcurrent protection method for protecting a PFC circuit, wherein the PFC circuit comprises a thermistor PTC1, wherein the thermistor PTC1 is connected in parallel with a relay control circuit, wherein the relay control circuit is used to control the thermistor PTC1 to be connected in series with a main circuit of the PFC circuit when the relay is disconnected, wherein: The method comprises: Obtaining a power failure condition of the PFC circuit; When the PFC circuit is powered on, controlling the relay to be closed to short-circuit the thermistor PTC1; When the PFC circuit loses power, the relay is controlled to be disconnected so that the thermistor PTC1 is connected in series to the main loop of the PFC circuit.

10. An electronic device, characterized in that: Comprising the PFC device as claimed in claim 8.