Grounding detection circuit for PFC (Power Factor Correction) circuit, controller and electric equipment

Abstract

The utility model relates to a grounding detection circuit for a PFC circuit, a controller and an electric device, a grounding signal induction circuit is arranged in a working loop of the PFC circuit, and a grounding signal isolation circuit is arranged at the output end of the grounding signal induction circuit, so that the grounding signal induction circuit is isolated from the grounding signal isolation circuit in the high-speed switching working process of a switching tube of the PFC circuit. The grounding signal induction circuit outputs an induced first detection voltage to the ground, generates a second detection voltage to the circuit reference ground through the grounding signal isolation circuit, and inputs the second detection voltage to the MCU, so that the MCU detects whether a controller where the PFC circuit is located is effectively grounded or not, thereby ensuring that the controller is effectively grounded, and improving the reliability of the PFC circuit. And the working reliability of the whole controller is improved.

Description

Technical Field

[0001] The utility model relates to a grounding detection circuit, a controller and electrical equipment for a PFC circuit, and belongs to the field of grounding protection control circuits. Background Art

[0002] At present, most of the controllers of household appliances with variable frequency loads, such as variable frequency air conditioners, washing machines, refrigerators, etc., use PFC circuits to improve electrical efficiency. However, PFC circuits often introduce a lot of noise interference into the electrical circuit, affecting the stability of the circuit. To solve this problem, the controller is generally grounded. During the operation of the PFC circuit, how to effectively detect whether it is effectively grounded has become a problem to be solved. Utility Model Content

[0003] The technical problem to be solved by the utility model is how to effectively detect whether the PFC circuit of the controller of the existing household appliance with variable frequency load is effectively connected to the ground during the operation of the PFC circuit.

[0004] The utility model proposes a ground detection circuit for a PFC circuit, the ground detection circuit comprises a ground signal sensing circuit, a ground signal isolation circuit and an MCU; wherein

[0005] The input end of the ground signal sensing circuit is connected in series in the working loop of the PFC circuit to sense the switching action signal of the PFC switch tube in the PFC circuit and output an induced voltage relative to the ground. The output end of the ground signal sensing circuit is connected to the input end of the ground signal isolation circuit, and the output end of the ground signal isolation circuit is connected to the MCU.

[0006] Optionally, the PFC circuit includes a PFC switching circuit and a rectifier circuit, the output end of the rectifier circuit is connected to the PFC switching circuit, the input end of the rectifier circuit is connected to the AC power input end, and the ground signal sensing circuit is connected in series between the output end of the PFC switching circuit and the rectifier circuit, or the ground signal sensing circuit is connected in series between the AC power input end and the input end of the rectifier circuit.

[0007] Optionally, the ground signal sensing circuit includes a high-frequency transformer, a first diode and a second electrolytic capacitor, wherein

[0008] The two primary input ends of the high-frequency transformer are the input ends of the ground signal sensing circuit, the first secondary output end of the high-frequency transformer is connected to the anode of the first diode, and the second secondary of the high-frequency transformer is connected to the ground; the cathode of the first diode and the positive electrode of the second electrolytic capacitor are connected to the output end of the ground signal sensing circuit, and the negative electrode of the second electrolytic capacitor is connected to the ground.

[0009] Optionally, when the ground signal sensing circuit is connected in series between the input end of the AC power supply and the input end of the rectifier circuit, the ground signal sensing circuit includes a high-frequency transformer, a first diode, a fourth diode, a fifth diode, a sixth diode and a second electrolytic capacitor, wherein

[0010] The two primary input ends of the high-frequency transformer are the input ends of the ground signal sensing circuit, the first secondary output end of the high-frequency transformer is commonly connected to the anode of the first diode and the cathode of the sixth diode, the second secondary of the high-frequency transformer is commonly connected to the anode of the fourth diode and the cathode of the fifth diode, the cathode of the first diode, the cathode of the fourth diode and the positive electrode of the second electrolytic capacitor are commonly connected to the output end of the ground signal sensing circuit, and the anode of the fifth diode, the anode of the sixth diode and the negative electrode of the second electrolytic capacitor are commonly connected to the ground.

[0011] Optionally, the ground signal isolation circuit includes a first optical coupler and a fifth resistor, wherein

[0012] The anode of the first optocoupler is the input end of the ground signal isolation circuit, the cathode of the first optocoupler is connected to the ground, the collector of the first optocoupler and one end of the fifth resistor are connected to the output end of the ground signal isolation circuit, the other end of the fifth resistor is connected to the positive electrode of the low-voltage direct current, and the emitter of the first optocoupler is connected to the circuit reference ground.

[0013] Optionally, the ground signal isolation circuit further includes a fourth resistor, one end of the fourth resistor is connected to the cathode of the first optocoupler, and the other end of the fourth resistor is connected to the ground.

[0014] Optionally, the PFC switch circuit includes a PFC switch unit, a third rectifier diode and a first electrolytic capacitor; wherein

[0015] The anode of the third rectifier diode and the output end of the PFC switch unit are connected to the positive input end of the PFC switch circuit, the control end of the PFC switch unit is connected to the MCU, the cathode of the third rectifier diode is connected to the positive electrode of the first electrolytic capacitor and the positive output end of the PFC switch circuit, and the negative electrode of the first electrolytic capacitor is the negative electrode of the PFC switch circuit.

[0016] Optionally, the PFC circuit also includes an output voltage detection circuit, the input end of the output voltage detection circuit is connected to the positive output end of the PFC circuit, and the output end of the output voltage detection circuit is connected to the MCU, wherein the output voltage detection circuit includes a second resistor and a third resistor, one end of the second resistor is the input end of the output voltage detection circuit, the other end of the second resistor and one end of the third resistor are commonly connected to the output end of the output voltage detection circuit, and the other end of the third resistor is connected to the circuit reference ground.

[0017] The utility model also provides a controller, which is provided with the above-mentioned grounding detection circuit for the PFC circuit.

[0018] The utility model also provides an electrical device, characterized in that the electrical device comprises the above-mentioned controller.

[0019] The grounding detection circuit for the PFC circuit of the utility model is adopted, by arranging a grounding signal sensing circuit in the working loop of the PFC circuit, and arranging a grounding signal isolation circuit at the output end of the grounding signal sensing circuit, so that during the high-speed switching operation of the switch tube of the PFC circuit, the grounding signal sensing circuit outputs a first detection voltage sensed to the ground, and generates a second detection voltage to the circuit reference ground through the grounding signal isolation circuit, and inputs it to the MCU, so that the MCU detects whether the controller where the PFC circuit is located is effectively grounded, thereby ensuring that the controller is effectively grounded and improving the working reliability of the entire controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a circuit schematic diagram of an embodiment of a ground detection circuit for a PFC circuit of the utility model;

[0021] Figure 2 This is a circuit schematic diagram of a second embodiment of a ground detection circuit for a PFC circuit of the utility model;

[0022] Figure 3 This is a circuit schematic diagram of a third embodiment of a ground detection circuit for a PFC circuit according to the present utility model. DETAILED DESCRIPTION

[0023] It should be noted that, in the case where the structures or functions do not conflict, the embodiments and features in the embodiments of the present utility model can be combined with each other. The present utility model is described in detail below based on examples.

[0024] The utility model proposes a ground detection circuit for a PFC circuit, such as Figure 1 As shown, the ground detection circuit includes a ground signal sensing circuit 10, a ground signal isolation circuit 20 and an MCU 30; wherein the input end of the ground signal sensing circuit 10 is connected in series to the working loop of the PFC circuit 40 to sense the switching action signal of the PFC switch tube in the PFC circuit 40 and output an induced voltage relative to the earth PE, the output end of the ground signal sensing circuit 10 is connected to the input end of the ground signal isolation circuit 20, and the output end of the ground signal isolation circuit 20 is connected to the MCU 30.

[0025] When the MCU30 controls the high-speed switching of the PFC switch tube of the PFC circuit 40, the working loop of the PFC circuit 40 generates a changing current, and then the ground signal sensing circuit 10 senses and outputs a corresponding induced voltage relative to the earth PE, that is, a first detection voltage. The detection voltage is a voltage relative to the earth PE, and then the ground signal isolation circuit 20 is used to generate a second detection voltage relative to the circuit reference ground GND. The second detection voltage is input to a pin of the MCU30, so that it is detected by the MCU30. In this way, when the PFC circuit 40 is working, the MCU30 detects whether the controller where the PFC circuit 40 is located is effectively connected to the earth PE. When it is detected that the controller is not effectively connected to the earth PE, the ground signal sensing circuit 10 cannot output a valid first detection voltage, and finally the MCU30 cannot detect a valid second detection voltage. At this time, the MCU30 can output a corresponding display or sound alarm information to prompt the user, or can control the PFC circuit 40 to stop working to remind the user to correctly and effectively connect the controller to the earth PE, so that the system noise generated during the operation of the PFC circuit 40 can be effectively released by connecting to the earth PE, thereby improving the working reliability of the entire controller.

[0026] The ground detection circuit for the PFC circuit 40 of the utility model is provided with a ground signal sensing circuit 10 in the working loop of the PFC circuit 40, and a ground signal isolation circuit 20 is provided at the output end of the ground signal sensing circuit 10, so that during the high-speed switching operation of the switch tube of the PFC circuit 40, the ground signal sensing circuit 10 outputs a sensed first detection voltage to the earth PE, and generates a second detection voltage to the circuit reference ground GND through the ground signal isolation circuit 20, and inputs the second detection voltage to the MCU 30, so that the MCU 30 detects whether the controller where the PFC circuit 40 is located is effectively connected to the earth PE, thereby ensuring that the controller is effectively connected to the earth PE, and improving the working reliability of the entire controller.

[0027] In some embodiments of the present invention, the PFC circuit 40 includes a PFC switch circuit 41 and a rectifier circuit 42, the output end of the rectifier circuit 42 is connected to the PFC switch circuit 41, the input end of the rectifier circuit 42 is connected to the AC power input end, and the ground signal sensing circuit 10 is connected in series between the output ends of the PFC switch circuit 41 and the rectifier circuit 42, or the ground signal sensing circuit 10 is connected in series between the AC power input end and the input end of the rectifier circuit 42. The rectifier circuit 42 is used to rectify the AC voltage input from the AC input end, and generally adopts a full-bridge rectifier circuit 42 to output a pulsating DC voltage. The PFC switch circuit 41 is used to perform power factor correction on the pulsating DC voltage to output a stable DC voltage. The PFC switch circuit 41 generally includes a PFC switch unit 411, a rectifier diode, a PFC inductor and an energy storage capacitor, wherein the PFC switch unit 411 includes a PFC switch tube, which performs high-speed switching action under the control of MCU30 to achieve high-speed energy storage and discharge state switching of the PFC inductor. The rectifier diode is used to perform unidirectional rectification on the discharge of the PFC inductor, and the energy storage capacitor is used to store the discharge of the PFC inductor.

[0028] Specifically, as a specific circuit of the ground detection circuit, the ground detection circuit is connected in series between the PFC switch circuit 41 and the rectifier circuit 42. Figure 1 As shown, the ground signal sensing circuit 10 includes a high-frequency transformer L1, a first diode D1 and a second electrolytic capacitor E2, wherein the two primary input terminals of the high-frequency transformer L1 are the input terminals of the ground signal sensing circuit 10, the first secondary output terminal of the high-frequency transformer L1 is connected to the anode of the first diode D1, and the second secondary output terminal of the high-frequency transformer L1 is connected to the earth PE; the cathode of the first diode D1 and the positive electrode of the second electrolytic capacitor E2 are connected to the output terminal of the ground signal sensing circuit 10, and the negative electrode of the second electrolytic capacitor E2 is connected to the earth PE.

[0029] Furthermore, the ground signal sensing circuit 10 may further include a first resistor R1, one end of which is connected to the cathode of the first diode D1, and the other end of which is the output end of the ground signal sensing circuit 10. The ground signal sensing circuit 10 may further include a second capacitor, which is connected in parallel to both ends of the second electrolytic capacitor E2, and is generally a non-polar small-capacity capacitor such as a ceramic capacitor, to filter out high-frequency clutter.

[0030] Specifically, as a specific circuit of the ground signal isolation circuit 20, such as Figure 1As shown, the ground signal isolation circuit 20 includes a first optocoupler IC1 and a fifth resistor R5, wherein the anode of the first optocoupler IC1 is the input end of the ground signal isolation circuit 20, the cathode of the first optocoupler IC1 is connected to the ground PE, the collector of the first optocoupler IC1 and one end of the fifth resistor R5 are connected to the output end of the ground signal isolation circuit 20, the other end of the fifth resistor R5 is connected to the positive electrode of the low-voltage direct current, and the emitter of the first optocoupler IC1 is connected to the circuit reference ground GND.

[0031] Furthermore, the ground signal isolation circuit 20 further includes a fourth resistor R4 , one end of the fourth resistor R4 is connected to the cathode of the first optical coupler IC1 , and the other end of the fourth resistor R4 is connected to the ground PE.

[0032] The working principle of the ground signal sensing circuit 10 and the ground detection circuit is as follows: when the MCU30 controls the high-speed switching of the PFC switch tube of the PFC circuit 40, the working loop of the PFC circuit 40 generates a changing current, and this changing current passes through the primary of the high-frequency transformer L1, and then generates an induced voltage at the secondary of the high-frequency transformer L1, that is, a first detection voltage. This first detection voltage is half-wave rectified by the first diode D1 and filtered by the second electrolytic capacitor E2 to form a stabilized DC first detection voltage VRef. Because the secondary of the high-frequency transformer L1 is connected to the earth PE, the first detection voltage is a voltage relative to the earth PE. Because the high-frequency transformer L1 is used, the earth PE and the circuit reference ground GND in the controller and the AC live wire or neutral wire are isolated, so that the PFC circuit 40 circuit can work for a long time without being connected to the earth PE to generate overcurrent and cause leakage protection at the AC input end of the controller. By reasonably setting the primary and secondary turns ratio of the high-frequency transformer L1, the output first detection voltage can be a lower safety voltage. Furthermore, a first resistor R1 may be provided, one end of which is connected to the cathode of the first diode D1, and the other end of which is the output end of the ground signal sensing circuit 10. The first resistor R1 serves to limit the current formed by the first detection voltage in the circuit. The first detection voltage is then loaded on the anode of the first optocoupler IC1, so that the light-emitting diode inside the first optocoupler IC1 is turned on, thereby causing conduction between the collector and the emitter of the first optocoupler IC1. Since the emitter of the first optocoupler IC1 is connected to the circuit reference ground GND, the collector of the first optocoupler IC1 outputs a low level relative to the circuit reference ground GND, i.e., an effective ground signal. Furthermore, a fourth resistor R4 may be included, one end of which is connected to the cathode of the first optocoupler IC1, and the other end of which is connected to the earth PE. The fourth resistor R4 serves to further limit the current passing through the light-emitting diode of the first optocoupler IC1.

[0033] It is worth noting that, in addition to realizing the induction of the working loop of the PFC circuit 40 to generate a changing current, the primary coil of the high-frequency transformer L1 also serves as a PFC inductor, which plays a role in high-speed energy storage and discharge during the high-speed switching operation of the switch tube of the PFC circuit 40.

[0034] In addition to being connected in series between the PFC switch circuit 41 and the rectifier circuit 42, the ground detection circuit can also be connected as follows: Figure 2 As shown, it is connected in series between the input end of the AC power supply and the input end of the rectifier circuit 42. At this time, the primary of the high-frequency transformer L1 also serves as a PFC inductor, and the secondary of the high-frequency transformer L1 is AC, and the corresponding low-voltage AC is induced in its secondary, and then converted into a low-voltage DC first detection voltage through half-wave rectification of the first diode D1 and filtering of the second electrolytic capacitor E2. The other working principles are the same as the working principles of the ground detection circuit introduced in the above embodiment.

[0035] In some embodiments of the present invention, Figure 3 As shown, when the ground signal sensing circuit 10 is connected in series between the input end of the AC power supply and the input end of the rectifier circuit 42, as another specific implementable circuit, the ground signal sensing circuit 10 includes a high-frequency transformer L1, a first diode D1, a fourth diode D4, a fifth diode D5, a sixth diode D6 and a second electrolytic capacitor E2, wherein the two primary input ends of the high-frequency transformer L1 are the input ends of the ground signal sensing circuit 10, the first secondary output end of the high-frequency transformer L1 is commonly connected to the anode of the first diode D1 and the cathode of the sixth diode D6, the second secondary end of the high-frequency transformer L1 is commonly connected to the anode of the fourth diode D4 and the cathode of the fifth diode D5, the cathode of the first diode D1, the cathode of the fourth diode D4 and the positive electrode of the second electrolytic capacitor E2 are commonly connected to the output end of the ground signal sensing circuit 10, and the anode of the fifth diode D5, the anode of the sixth diode D6 and the negative electrode of the second electrolytic capacitor E2 are commonly connected to the earth PE.

[0036] The ground signal sensing circuit 10 is relatively Figure 1 and Figure 2 The main difference of the ground signal sensing circuit 10 mentioned in the above embodiment is that the secondary output of the high-frequency transformer L1 is rectified by a full-bridge rectifier, specifically a full-bridge rectifier circuit 42 composed of a first diode D1, a fourth diode D4, a fifth diode D5 and a sixth diode D6. Figure 1 and Figure 2 In the scheme, the full-bridge rectifier circuit 42 outputs a voltage twice as high as the half-wave rectifier. Therefore, when the output voltage is the same, the number of turns of the secondary coil can be relatively reduced, which is beneficial to reducing the volume of the high-frequency transformer L1 and reducing the cost. The other working principles of the ground signal sensing circuit 10 are similar to Figure 1 and Figure 2 The corresponding scheme is the same.

[0037] In some embodiments of the present invention, as a specific circuit of the PFC switch circuit 41, such as Figures 1 to 3 As shown, the PFC switch circuit 41 includes a PFC switch unit 411, a third rectifier diode D3 and a first electrolytic capacitor E1, wherein the anode of the third rectifier diode D3 and the output end of the PFC switch unit 411 are connected to the positive input end of the PFC switch circuit 41, the control end of the PFC switch unit 411 is connected to the MCU30, the cathode of the third rectifier diode D3 is connected to the positive electrode of the first electrolytic capacitor E1 and the positive output end of the PFC switch circuit 41, and the cathode of the first electrolytic capacitor E1 is the negative electrode of the PFC switch circuit 41. The positive output end and the negative electrode of the PFC switch circuit 41 are connected to the electrical load, that is, Figures 1 to 3 The Load in the controller can be other power circuits in the controller, or externally controlled power loads such as motors, etc.

[0038] As a specific circuit of the PFC switch unit 411, Figures 1 to 3As shown, the PFC switch unit 411 includes a second NMOS transistor Q1, a third PNP transistor Q3, a fourth diode D7, a fourteenth resistor R14, an eleventh resistor R11, a tenth resistor R10, a seventh resistor R7 and a ninth resistor R9, wherein one end of the ninth resistor R9 and one end of the seventh resistor R7 are commonly connected to the control end of the PFC switch unit 411, the other end of the ninth resistor R9 is commonly connected to the anode of the fourth diode D7 and the base of the third PNP transistor Q3, the other end of the ninth resistor R9 is commonly connected to the cathode of the fourth diode D7, one end of the fourteenth resistor R14, the emitter of the third PNP transistor Q3 and the gate of the second NMOS transistor Q1, the collector of the third PNP transistor Q3 is connected to one end of the tenth resistor R10, the other end of the tenth resistor R10 is commonly connected to one end of the eleventh resistor R11, the source of the second NMOS transistor Q1 and the other end of the fourteenth resistor R14, and the drain of the second NMOS transistor Q1 is the output end of the PFC switch unit 411. The second NMOS transistor Q1 is the main switch of the PFC switch unit 411. When the third PNP transistor Q3 is turned on, the second NMOS transistor Q1 is quickly pulled down, so that the second NMOS transistor Q1 is quickly turned off. The ninth resistor R9 is the base current limiting resistor of the third PNP transistor Q3. When the second NMOS transistor Q1 is turned on, the seventh resistor R7 plays the role of gate current limiting of the second NMOS transistor Q1. The eighth resistor can be further connected in parallel to the seventh resistor R7 to adjust the conduction speed of the second NMOS transistor Q1. The fourteenth resistor R14 is further used to accelerate the cutoff of the second NMOS transistor Q1. The fourth diode D7 is used to clamp the node voltage of the third PNP transistor Q3 to prevent the voltage between its base and emitter from being too high and damaged. The PFC switch unit 411 may further include a fifth capacitor C5, a twelfth resistor R12 and a thirteenth resistor R13, wherein the twelfth resistor R12 and the thirteenth resistor R13 are connected in parallel, one end of the twelfth resistor R12 and the thirteenth resistor R13 is connected to one end of the fifth capacitor C5, the other end of the twelfth resistor R12 and the thirteenth resistor R13 is connected to the source of the second NMOS transistor Q1, and the other end of the fifth capacitor C5 is connected to the drain of the second NMOS transistor Q1. The twelfth resistor R12, the thirteenth resistor R13 and the fifth capacitor C5 are used for EMC filtering to reduce the switching noise of the second NMOS transistor Q1.

[0039] Specifically, for the above Figure 1 and Figure 2For the ground signal sensing circuit 10 and the PFC switch circuit 41 shown, the first detection voltage can be calculated as follows: Vref = U5-8*D / (1-D)*N-Ud, wherein: U5-8 is the voltage on the primary winding 5-8 of the high-frequency transformer L1, D is the duty cycle of the switch tube of the PFC circuit, i.e., the second NMOS tube Q1, when it is turned on, N is the turns ratio of the primary coil and the secondary coil of the high-frequency transformer L1, and Ud is the conduction voltage drop of the rectifier diode of the PFC circuit 40, i.e., the third diode D3.

[0040] Further, the PFC circuit 40 also includes an output voltage detection circuit, the input end of the output voltage detection circuit is connected to the output positive electrode of the PFC circuit 40, and the output end of the output voltage detection circuit is connected to the MCU30, wherein the output voltage detection circuit includes a second resistor R2 and a third resistor R3, one end of the second resistor R2 is the input end of the output voltage detection circuit, the other end of the second resistor R2 and one end of the third resistor R3 are connected to the output end of the output voltage detection circuit, and the other end of the third resistor R3 is connected to the circuit reference ground GND. The bus voltage output by the PFC switch circuit 41 for driving the load to work enters the voltage divider circuit composed of the second resistor R2 and the third resistor R3, and outputs the low voltage detection voltage to the MCU30, so that the MCU30 can monitor the bus voltage in real time, thereby realizing corresponding control.

[0041] The utility model also proposes a controller, which is provided with the grounding detection circuit for the PFC circuit mentioned in the above embodiment. By providing the grounding detection circuit, the controller has the ability to detect in real time whether it is effectively grounded, thereby improving its working reliability.

[0042] The utility model also proposes an electrical device, which includes the controller mentioned in the above embodiment, wherein the electrical device can be an air conditioner, a washing machine, a refrigerator, a heat pump device such as a heat pump water heater, a heat pump heating device, a heat pump air conditioner, etc., or a water pump device with variable frequency operation, etc. By adopting the controller, these electrical devices can detect whether the grounding is good in real time, remind the user to make corrections and limit the operation of the device, thereby ensuring the reliability of its operation.

[0043] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0044] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0045] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A ground detection circuit for a PFC circuit, characterized in that: The ground detection circuit includes a ground signal sensing circuit, a ground signal isolation circuit and an MCU; wherein The input end of the ground signal sensing circuit is connected in series in the working loop of the PFC circuit to sense the switching action signal of the PFC switch tube in the PFC circuit and output an induced voltage relative to the ground. The output end of the ground signal sensing circuit is connected to the input end of the ground signal isolation circuit, and the output end of the ground signal isolation circuit is connected to the MCU.

2. The ground detection circuit according to claim 1, characterized in that: The PFC circuit includes a PFC switch circuit and a rectifier circuit, the output end of the rectifier circuit is connected to the PFC switch circuit, the input end of the rectifier circuit is connected to the AC power input end, and the ground signal sensing circuit is connected in series between the PFC switch circuit and the output end of the rectifier circuit, or the ground signal sensing circuit is connected in series between the AC power input end and the input end of the rectifier circuit.

3. The ground detection circuit according to claim 2, characterized in that: The ground signal sensing circuit includes a high-frequency transformer, a first diode and a second electrolytic capacitor, wherein The two primary input ends of the high-frequency transformer are the input ends of the ground signal sensing circuit, the first secondary output end of the high-frequency transformer is connected to the anode of the first diode, and the second secondary of the high-frequency transformer is connected to the ground; the cathode of the first diode and the positive electrode of the second electrolytic capacitor are connected to the output end of the ground signal sensing circuit, and the negative electrode of the second electrolytic capacitor is connected to the ground.

4. The ground detection circuit according to claim 2, characterized in that: When the ground signal sensing circuit is connected in series between the input end of the AC power supply and the input end of the rectifier circuit, the ground signal sensing circuit includes a high-frequency transformer, a first diode, a fourth diode, a fifth diode, a sixth diode and a second electrolytic capacitor, wherein The two primary input ends of the high-frequency transformer are the input ends of the ground signal sensing circuit, the first secondary output end of the high-frequency transformer is commonly connected to the anode of the first diode and the cathode of the sixth diode, the second secondary of the high-frequency transformer is commonly connected to the anode of the fourth diode and the cathode of the fifth diode, the cathode of the first diode, the cathode of the fourth diode and the positive electrode of the second electrolytic capacitor are commonly connected to the output end of the ground signal sensing circuit, and the anode of the fifth diode, the anode of the sixth diode and the negative electrode of the second electrolytic capacitor are commonly connected to the ground.

5. The ground detection circuit according to claim 1, characterized in that: The ground signal isolation circuit includes a first optical coupler and a fifth resistor, wherein The anode of the first optocoupler is the input end of the ground signal isolation circuit, the cathode of the first optocoupler is connected to the ground, the collector of the first optocoupler and one end of the fifth resistor are connected to the output end of the ground signal isolation circuit, the other end of the fifth resistor is connected to the positive electrode of the low-voltage direct current, and the emitter of the first optocoupler is connected to the circuit reference ground.

6. The ground detection circuit according to claim 5, characterized in that: The ground signal isolation circuit further includes a fourth resistor, one end of the fourth resistor is connected to the cathode of the first optical coupler, and the other end of the fourth resistor is connected to the ground.

7. The ground detection circuit according to claim 2, characterized in that: The PFC switch circuit includes a PFC switch unit, a third rectifier diode and a first electrolytic capacitor; wherein The anode of the third rectifier diode and the output end of the PFC switch unit are commonly connected to the positive input end of the PFC switch circuit, the control end of the PFC switch unit is connected to the MCU, the cathode of the third rectifier diode is commonly connected to the positive electrode of the first electrolytic capacitor and the positive output end of the PFC switch circuit, and the cathode of the first electrolytic capacitor is the negative electrode of the PFC switch circuit.

8. The ground detection circuit according to claim 2, characterized in that: The PFC circuit also includes an output voltage detection circuit, wherein an input end of the output voltage detection circuit is connected to the positive output end of the PFC circuit, and an output end of the output voltage detection circuit is connected to the MCU, wherein the output voltage detection circuit includes a second resistor and a third resistor, one end of the second resistor is the input end of the output voltage detection circuit, the other end of the second resistor and one end of the third resistor are commonly connected to the output end of the output voltage detection circuit, and the other end of the third resistor is connected to a circuit reference ground.

9. A controller, characterized in that: The controller is provided with a ground detection circuit for a PFC circuit according to any one of claims 1 to 8.

10. An electrical device, characterized in that: The electric device comprises the controller as claimed in claim 9.

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