Power supply protection circuit for reducing residual voltage

Abstract

The utility model relates to a power supply protection circuit capable of reducing residual voltage, comprising a voltage sampling module used for sampling an input voltage signal of an LED driving power supply and sending the input voltage signal to a voltage identification module; the voltage identification module is used for generating a closing signal when the input voltage signal is greater than a preset reference voltage signal, and generating a turn-off signal when the input voltage signal is smaller than the preset reference voltage signal; the switch control module responds to the closing signal to connect the discharge module and the protection ground, and responds to the turn-off signal to disconnect the discharge module and the protection ground; and the protection module and the discharge module discharge the input voltage to the protection ground. By adopting the scheme, when the surge voltage is input into the LED driving power supply, the discharge module is connected with the protection ground, and the surge voltage is discharged to the protection ground, so that the output residual voltage of the LED driving power supply can be effectively reduced. When an insulation and voltage resistance test is executed, the discharge module and the protection ground can be automatically disconnected, the requirements of the insulation and voltage resistance test are met, and potential safety hazards are reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of power protection especially relates to a power protection circuit that reduces residual voltage. BACKGROUND

[0002] The output residual voltage of the LED non-isolated drive power directly affects the reliability and safety of the LED lamp. In the work of the non-isolated power, the input and output are directly connected through electronic components, and the surge voltage suppression ability is poor. In the case of unstable grid voltage or lightning strike, the non-isolated power may generate a residual voltage of more than 3KV, which is directly output to the LED lamp, thereby damaging the aluminum substrate, chip and lamp bead of the lamp, and causing the lamp to be damaged.

[0003] At present, a gas discharge tube is generally used for discharge to reduce the output residual voltage. However, in the insulation voltage test, the voltage value between the drive power and the protection ground is not enough, and the gas discharge tube may be turned on, which cannot meet the safety certification standards such as UL1598 2018, IEC 60598-1:2014, GB 7000.1-2015 or IEC 60598-1:2014. In addition, the LED drive power can also reduce the output residual voltage by using double ground wire input and passing safety regulations. However, the ground wire switch needs to be manually switched when assembling the lamp, which cannot be prevented and has certain safety hazards. INVENTION CONTENTS

[0004] The technical problem to be solved by the utility model is to provide a power protection circuit that reduces residual voltage.

[0005] The technical scheme adopted by the utility model to solve its technical problem is: a power protection circuit that reduces residual voltage, comprising a voltage sampling module, a voltage identification module, a switch control module, a protection module and a discharge module.

[0006] The voltage sampling module is connected to the firewire and the zero line of the LED drive power and the voltage identification module respectively, the voltage identification module is connected to the switch control module, the protection module is connected to the discharge module, the firewire and the zero line respectively, and the discharge module is connected to the protection ground.

[0007] The protection module and the discharge module discharge the input voltage to the protection ground.

[0008] The voltage sampling module is used for sampling the input voltage signal of the LED drive power and sending it to the voltage identification module.

[0009] The voltage identification module is used for generating a closed signal when the input voltage signal is greater than the preset reference voltage signal, and generating an off signal when the input voltage signal is less than the preset reference voltage signal.

[0010] The switch control module connects the bleed module to the protective ground in response to the closing signal, and disconnects the bleed module from the protective ground in response to the turning-off signal.

[0011] Further, the voltage sampling module comprises a rectifier unit, a voltage dividing unit and a filter unit;

[0012] The rectifier unit is connected to the live wire, the neutral wire and the voltage dividing unit respectively, and the voltage dividing unit is connected to the voltage identification module through the filter unit.

[0013] Further, the rectifier unit comprises a diode D1 and a diode D2, the voltage dividing unit comprises resistors R1, R2, R3, R4, R5, R6, R7 and R8 connected in series, and the filter unit comprises a capacitor C1 and a resistor R9;

[0014] The anode of the diode D1 is connected to the live wire, the cathode of the diode D1 and the cathode of the diode D2 are connected to the resistor R1, and the anode of the diode D2 is connected to the neutral wire;

[0015] The capacitor C1 is connected in parallel with the resistor R7 and the resistor R8, one end of the capacitor C1 connected to the resistor R8 is grounded, and the other end of the capacitor C1 connected to the resistor R7 is connected to the voltage identification module through the resistor R9;

[0016] Among them, the resistors R1, R2, R3, R4, R5 and R6 are 1206 chip resistors, the resistors R7, R8 and R9 are 0603 chip resistors, and the capacitor C1 is a 0603 chip capacitor.

[0017] Further, the voltage identification module comprises a voltage follower unit, a comparator, a reference voltage unit and a positive feedback unit connected to the comparator;

[0018] The voltage follower unit is connected between the voltage sampling module and the inverting input terminal of the comparator, and the reference voltage unit is connected to the non-inverting input terminal of the comparator;

[0019] The input voltage signal is input to the comparator through the voltage follower unit, the reference voltage unit provides the preset reference voltage signal to the comparator, and the comparator compares the input voltage signal and the preset reference voltage signal and generates the closing signal or the turning-off signal.

[0020] Further, the voltage follower unit comprises an operational amplifier, a capacitor C2 and a diode D6, wherein the capacitor C2 is a 0603 chip capacitor;

[0021] The non-inverting input terminal of the operational amplifier is connected with the voltage sampling module, the output terminal of the operational amplifier is connected with the inverting input terminal of the operational amplifier through the diode D6, the positive power supply terminal of the operational amplifier is connected with the first power supply voltage, the negative power supply terminal of the operational amplifier is grounded, and the capacitor C2 is connected in parallel between the positive power supply terminal and the negative power supply terminal of the operational amplifier.

[0022] Further, the reference voltage unit comprises a resistor R12, a resistor R13, a resistor R14, a resistor R15, a capacitor C5 and a capacitor C6;

[0023] One end of the resistor R12 is connected with the second power supply voltage, the other end of the resistor R12 is grounded through the resistor R13, the resistor R14 and the capacitor C5 are connected in parallel with the resistor R13 respectively, one end of the resistor R15 is connected with one end of the capacitor C5, the other end of the resistor R15 is connected with the other end of the capacitor C5 through the capacitor C6, and the other end of the resistor R15 is also connected with the non-inverting input terminal of the comparator;

[0024] The resistor R12, the resistor R13, the resistor R14 and the resistor R15 are 0603 chip resistors, and the capacitor C5 and the capacitor C6 are 0603 chip capacitors.

[0025] Further, the voltage identification module further comprises a voltage division filter unit, wherein the voltage division filter unit comprises a resistor R10, a resistor R11, a capacitor C3 and a capacitor C4;

[0026] One end of the resistor R10 is connected with the output terminal of the voltage follower unit and grounded through the capacitor C3, and the other end of the resistor R10 is connected with the inverting input terminal of the comparator and grounded through the resistor R11 and the capacitor C4 respectively;

[0027] The resistor R10 and the resistor R11 are 0603 chip resistors, and the capacitor C3 and the capacitor C4 are 0603 chip capacitors.

[0028] Further, the switch control module comprises a switch tube Q1 and a coil of a relay;

[0029] The drain of the switch tube Q1 is connected with the first power supply voltage, the gate of the switch tube Q1 is connected with the voltage identification module, and the source of the switch tube Q1 is grounded through the coil of the relay.

[0030] Further, the discharge module comprises a discharge tube and the contact of the relay, and the discharge tube connects the protective earth through the contact of the relay.

[0031] The switch tube Q1 applies or removes power to the coil of the relay according to the closing signal or the opening signal, so as to trigger the contact of the relay to close or open.

[0032] Further, the protection module comprises a pressure sensitive resistor MOV1 and a pressure sensitive resistor MOV2.

[0033] The discharge tube connects the live wire and the zero wire through the pressure sensitive resistor MOV1 and the pressure sensitive resistor MOV2 respectively.

[0034] The power protection circuit for reducing residual voltage of the utility model has the following beneficial effects: the voltage identification module generates a closing signal or an opening signal according to the relationship between the input voltage signal and the preset reference voltage signal, so as to turn on or turn off the discharge module and the protective earth. When a surge voltage is input into the LED driving power supply, the discharge module and the protective earth are turned on, the surge voltage is discharged to the protective earth, and the output residual voltage of the LED driving power supply can be effectively reduced. When the insulation withstand voltage test is performed, the discharge module and the protective earth can be automatically turned off, the requirement of the insulation withstand voltage test is met, and the safety hidden danger is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0035] The utility model will be further described below in combination with the drawings and examples, and the drawings are as follows:

[0036] Figure 1 is the structure block diagram of the power protection circuit for reducing residual voltage of the utility model one embodiment;

[0037] Figure 2 is the circuit principle diagram of the power protection circuit for reducing residual voltage of the utility model one embodiment. DETAILED DESCRIPTION

[0038] In order to have more clear understanding of the technical features, objects and effects of the utility model, the specific implementation mode of the utility model will be described in detail by referring to the drawings. In the following description, the terms "first", "second" and the like are only for facilitating the description of the technical scheme, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features, therefore, the features with "first", "second" and the like can explicitly or implicitly include one or more features. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0039] As Figure 1As shown in the utility model discloses a reduce residual voltage's power supply protection circuit one embodiment, including voltage sampling module 11, voltage identification module 12, switch control module 13, protection module 15 and bleeder module 14.

[0040] Voltage sampling module 11 is connected with voltage identification module 12 and the fire line ACL of LED drive power supply, zero line ACN respectively, voltage identification module 12 is connected with switch control module 13, protection module 15 is connected with bleeder module 14, fire line ACL and zero line ACN respectively, and bleeder module 14 is connected with protection ground PE. Protection module 15 and bleeder module 14 discharge the input voltage of LED drive power supply to protection ground PE. Voltage sampling module 11 is used to sample the input voltage signal of LED drive power supply and sends to voltage identification module 12. Voltage identification module 12 is used to generate closing signal when input voltage signal is greater than preset reference voltage signal, and generates off signal when input voltage signal is less than preset reference voltage signal. Switch control module 13 is connected with bleeder module 14 and protection ground PE in response to closing signal, and is disconnected with bleeder module 14 and protection ground PE in response to off signal.

[0041] In the embodiment, protection module 15 and bleeder module 14 discharge the input voltage of LED drive power supply to protection ground PE together. Voltage sampling module 11 samples the input voltage signal of LED drive power supply input voltage from fire line ACL or zero line ACN. Voltage identification module 12 identifies and compares the input voltage signal provided by voltage sampling module 11, generates closing signal or off signal. Closing signal is used to control bleeder module 14 and protection ground PE to be connected. Off signal is used to control bleeder module 14 and protection ground PE to be disconnected, and stop discharging voltage. There is no direct electrical connection between switch control module 13 and bleeder module 14, and switch control module 13 triggers the on-off between bleeder module 14 and protection ground PE by induction.

[0042] When the surge voltage is input to LED drive power supply, input voltage signal is greater than preset reference voltage signal, and voltage identification module 12 generates closing signal, and bleeder module 14 and protection ground PE are connected. Surge voltage is discharged to protection ground PE through protection module 15 and bleeder module 14, effectively reduces the output residual voltage of LED drive power supply.

[0043] When the insulation withstand voltage test is performed on the LED driving power supply, a test voltage is applied between the live wire ACL and the protective earth PE, or between the neutral wire ACN and the protective earth PE. The test voltage is applied on the protection module 15 and the discharge module 14. The voltage sampling module 11 does not form a closed loop, and the input voltage signal sampled is close to 0, which is less than the preset reference voltage signal. The voltage identification module 12 generates an off signal, and the discharge module 14 is disconnected from the protective earth PE, so that the insulation withstand voltage value between the live wire ACL and the protective earth PE, and between the neutral wire ACN and the protective earth PE meets the regulatory requirements.

[0044] Compared with the existing residual voltage reduction method, the residual voltage reduction power supply protection circuit of the utility model can reduce the residual voltage when the input surge voltage is applied, and can automatically disconnect the discharge module 14 from the protective earth PE when the insulation withstand voltage test is performed. It meets the requirements of the insulation withstand voltage test, and can prevent mistakes and reduce safety hazards.

[0045] Further, the voltage sampling module 11 includes a rectifier unit, a voltage dividing unit and a filter unit. The rectifier unit is connected to the live wire ACL, the neutral wire ACN and the voltage dividing unit, respectively. The voltage dividing unit is connected to the voltage identification module 12 through the filter unit. The input voltage is rectified by the rectifier unit, and then divided by the voltage dividing unit to obtain the input voltage signal. The input voltage signal is filtered by the filter unit and then enters the voltage identification module 12.

[0046] Further, the voltage identification module 12 includes a voltage follower unit, a comparator U2, a reference voltage unit and a positive feedback unit connected to the comparator U2. The voltage follower unit is connected between the voltage sampling module 11 and the inverting input terminal of the comparator U2. The reference voltage unit is connected to the non-inverting input terminal of the comparator U2. The input voltage signal is input to the comparator U2 through the voltage follower unit. The reference voltage unit provides a preset reference voltage signal to the comparator U2. The comparator U2 compares the input voltage signal and the preset reference voltage signal and generates a closed signal or an off signal. The value of the preset reference voltage signal can be changed by adjusting the reference voltage unit, according to actual needs.

[0047] Further, the voltage identification module 12 further includes a voltage dividing and filtering unit. The voltage dividing and filtering unit is connected between the voltage follower unit and the comparator U2, and is used for dividing and filtering the input voltage signal. The input voltage signal passes through the voltage follower unit and the voltage dividing and filtering unit in sequence, and becomes a relatively smooth DC voltage, which improves the accuracy of the comparison result output by the comparator U2.

[0048] Further, when the voltage applied to the protection module 15 is lower than the voltage threshold value thereof, the protection module 15 is cut off. When the voltage applied to the protection module 15 exceeds the voltage threshold value, the protection module 15 is turned on. The protection module 15 can use a pressure sensitive resistor.

[0049] When a surge voltage is input to the LED driving power supply, the voltage applied to the protection module 15 exceeds the voltage threshold value thereof, and the protection module 15 is turned on. Both the protection module 15 and the leakage module 14 are turned on, thereby leaking the input voltage of the LED driving power supply to the protective earth PE. When the insulation withstand voltage test is performed on the LED driving power supply, the voltage applied to the protection module 15 exceeds the voltage threshold value thereof, and the protection module 15 is turned on. Since the leakage module 14 is disconnected from the protective earth PE, the safety requirement is still met. When the LED driving power supply is normally working, the protection module 15 is turned off, and the output voltage of the LED driving power supply can be prevented from being affected.

[0050] Further, the power supply protection circuit with reduced residual voltage further comprises a first fuse module arranged on the live wire ACL and a second fuse module arranged on the neutral wire ACN.

[0051] Reference Figure 2 The power supply protection circuit with reduced residual voltage is described below with a specific embodiment.

[0052] In this embodiment, the first fuse module comprises a fuse F1, and the second fuse module comprises a fuse F2.

[0053] In this embodiment, the rectifying unit comprises a diode D1 and a diode D2, the voltage dividing unit comprises resistors R1, R2, R3, R4, R5, R6, R7 and R8 connected in series, and the filtering unit comprises a capacitor C1 and a resistor R9. The anode of the diode D1 is connected to the live wire ACL, the cathode of the diode D1 and the cathode of the diode D2 are connected to the resistor R1, the anode of the diode D2 is connected to the neutral wire ACN. The capacitor C1 is connected in parallel with the resistor R7 and the resistor R8, one end of the capacitor C1 connected to the resistor R8 is connected to the ground GND, and the other end of the capacitor C1 connected to the resistor R7 is connected to the voltage recognition module 12 through the resistor R9.

[0054] In this embodiment, the voltage follower unit comprises an operational amplifier U1, a capacitor C2 and a diode D6. The non-inverting input terminal of the operational amplifier U1 is connected to the voltage sampling module 11, the output terminal of the operational amplifier U1 is connected to the inverting input terminal of the operational amplifier U1 through the diode D6, the positive power supply terminal of the operational amplifier U1 is connected to the first power supply voltage 12V, the negative power supply terminal of the operational amplifier U1 is connected to the ground GND, and the capacitor C2 is connected in parallel between the positive power supply terminal and the negative power supply terminal of the operational amplifier U1.

[0055] In this embodiment, the voltage dividing and filtering unit comprises a resistor R10, a resistor R11, a capacitor C3 and a capacitor C4. One end of the resistor R10 is connected to the output terminal of the voltage follower unit and connected to the ground GND through the capacitor C3, and the other end of the resistor R10 is connected to the inverting input terminal of the comparator U2 and connected to the ground GND through the resistor R11 and the capacitor C4 respectively.

[0056] In the embodiment, the reference voltage unit includes resistor R12, resistor R13, resistor R14, resistor R15, capacitor C5 and capacitor C6. One end of resistor R12 is connected to the second power supply voltage 5V, the other end of resistor R12 is connected to ground GND through resistor R13, resistor R14 and capacitor C5 are connected in parallel with resistor R13, one end of resistor R15 is connected to one end of capacitor C5, the other end of resistor R15 is connected to the other end of capacitor C5 through capacitor C6, and the other end of resistor R15 is also connected to the non-inverting input terminal of comparator U2.

[0057] In the embodiment, the positive feedback unit includes resistor R16. One end of resistor R16 is connected to the output terminal of comparator U2, and the other end of resistor R16 is connected to the non-inverting input terminal of comparator U2 through resistor R15.

[0058] In the embodiment, the switch control module 13 includes switch tube Q1 and the coil of relay K1. The drain of switch tube Q1 is connected to the first power supply voltage 12V, the gate of switch tube Q1 is connected to voltage identification module 12, and the source of switch tube Q1 is connected to ground GND through the coil of relay K1. The gate of switch tube Q1 is connected to the output terminal of comparator U2 through resistor R17. Switch tube Q1 is an NMOS tube.

[0059] In the embodiment, the discharge module 14 includes discharge tube FDG1 and the contact of relay K1, and discharge tube FDG1 is connected to protective earth PE through the contact of relay K1. Switch tube Q1 makes the coil of relay K1 energized or de-energized according to the off signal or the closing signal, so as to trigger the contact of relay K1 to close or open. The relay K1 is a normally closed relay K1.

[0060] In the embodiment, the protection module 15 includes pressure sensitive resistor MOV1 and pressure sensitive resistor MOV2. Discharge tube FDG1 is connected to live wire ACL and zero wire ACN through pressure sensitive resistor MOV1 and pressure sensitive resistor MOV2 respectively. Pressure sensitive resistor MOV1 is the same as pressure sensitive resistor MOV2.

[0061] Among them, resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, resistor R6 are 1206 chip resistors. Resistor R7, resistor R8, resistor R9, resistor R10, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15, resistor R16 and resistor R17 are 0603 chip resistors. Capacitor C1, capacitor C2, capacitor C3, capacitor C4, capacitor C5 and capacitor C6 are 0603 chip capacitors.

[0062] The specific working principle of the power protection circuit for reducing residual voltage in the embodiment is as follows:

[0063] In this embodiment, the preset reference voltage signal is adjusted so that the input voltage is greater than V MOV +V FDG1 when the leakage module 14 is turned on. Wherein, V MOV is the voltage across the voltage-sensitive resistor MOV1 or voltage-sensitive resistor MOV2 after conduction, and V FDG1 is the voltage across the discharge tube FDG1 after conduction.

[0064] When a waveform of a surge pulse voltage not less than 8MS is input from the live wire ACL, the voltage reaches the voltage sampling module 11 through the diode D1 to the voltage sampling module 11, and the input voltage signal is transmitted to the inverting input terminal of the comparator U2. The input voltage signal is greater than the preset reference voltage signal, and the comparator U2 outputs a low level (i.e. a closed signal), the switch tube Q1 is turned off, the coil of the relay K1 loses power, and the contacts of the relay K1 are triggered to close. Moreover, the voltage-sensitive resistor MOV1 is turned on, and the surge pulse voltage is discharged to the protective earth PE through the voltage-sensitive resistor MOV1 and the discharge tube FDG1. Without protection, the output residual voltage of the LED driving power supply can exceed 3KV, and after using the present scheme, the residual voltage is V MOV1 +V FDG1 , which greatly reduces the output residual voltage. V MOV1 is the voltage across the voltage-sensitive resistor MOV1 after conduction.

[0065] When a waveform of a surge pulse voltage not less than 8MS is input from the neutral wire ACN, the voltage reaches the voltage sampling module 11 through the diode D2 to the voltage sampling module 11, and the input voltage signal is transmitted to the inverting input terminal of the comparator U2. The input voltage signal is greater than the preset reference voltage signal, and the comparator U2 outputs a low level (i.e. a closed signal), the switch tube Q1 is turned off, the coil of the relay K1 loses power, and the contacts of the relay K1 are triggered to close. Moreover, the voltage-sensitive resistor MOV2 is turned on, and the surge pulse voltage is discharged to the protective earth PE through the voltage-sensitive resistor MOV2 and the discharge tube FDG1. Without protection, the output residual voltage of the LED driving power supply can exceed 3KV, and after using the present scheme, the residual voltage is V MOV2 +V FDG1 , which greatly reduces the output residual voltage. V MOV2 is the voltage across the voltage-sensitive resistor MOV2 after conduction.

[0066] When the insulation withstand voltage test is performed on the live wire ACL and the protective earth PE, a higher test voltage is applied between the live wire ACL and the protective earth PE, and the voltage-sensitive resistor MOV1 is turned on. The input voltage signal obtained by the voltage sampling module 11 is close to 0, which is less than the preset reference voltage signal, the comparator U2 outputs a high level (i.e. an off signal), the switch tube Q1 is turned on, the coil of the relay K1 gets power, and the contacts of the relay K1 are triggered to open. The live wire ACL and the protective earth PE are not conductive, which meets the regulatory requirements.

[0067] When the insulation withstand voltage test is performed between the neutral line ACN and the protective earth PE, a higher test voltage is applied between the neutral line ACN and the protective earth PE, and the voltage-sensitive resistor MOV2 is turned on. The input voltage signal obtained by the voltage sampling module 11 is close to 0, which is less than the preset reference voltage signal, and the comparator U2 outputs a high level (i.e. an off signal), the switch tube Q1 is turned on, the coil of the relay K1 is powered, and the contacts of the relay K1 are triggered to be disconnected. The neutral line ACN and the protective earth PE are not conductive, and the safety requirement is met.

[0068] When the LED driving power supply is normally working, if the input voltage exceeds V MOV +V FDG1 but is less than the voltage threshold of the voltage-sensitive resistor, the comparator U2 outputs a low level (i.e. a closed signal), the switch tube Q1 is turned off, the coil of the relay K1 is powered off, the contacts of the relay K1 are triggered to be closed, the discharge tube FDG1 is connected with the protective earth PE, and the voltage-sensitive resistor MOV1 and the voltage-sensitive resistor MOV2 are turned off.

[0069] The power supply protection circuit for reducing residual voltage of the utility model solves the problem of residual voltage of the LED non-isolated driving power supply, meets the safety requirement, reduces the risk caused by improper operation of the user, and can be widely applied in the high-power non-isolated LED driving power supply above 100W, such as the non-isolated LED driving power supply of the metal shell type I.

[0070] It can be understood that the above embodiments only express the preferred embodiments of the utility model, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the utility model; it should be pointed out that the above technical features can be freely combined without departing from the concept of the utility model, and a plurality of modifications and improvements can be made, which belong to the protection scope of the utility model; therefore, all equivalent transformations and modifications within the scope of the claims of the utility model should belong to the scope of the claims of the utility model.

Claims

1. A power supply protection circuit for reducing residual voltage, characterized in that, It includes a voltage sampling module, a voltage identification module, a switch control module, a protection module, and a discharge module; The voltage sampling module is connected to the voltage identification module and the live wire and neutral wire of the LED driver power supply respectively. The voltage identification module is connected to the switch control module. The protection module is connected to the discharge module, the live wire and the neutral wire respectively. The discharge module is connected to the protective ground. The protection module and the discharge module discharge the input voltage of the LED driver power supply to the protective ground; The voltage sampling module is used to sample the input voltage signal of the LED driver power supply and send it to the voltage recognition module; The voltage recognition module is used to generate a closing signal when the input voltage signal is greater than a preset reference voltage signal, and to generate a turning-off signal when the input voltage signal is less than the preset reference voltage signal. The switch control module connects the discharge module to the protective ground in response to the closing signal, and disconnects the discharge module from the protective ground in response to the closing signal.

2. The power supply protection circuit for reducing residual voltage according to claim 1, characterized in that, The voltage sampling module includes a rectification unit, a voltage divider unit, and a filtering unit; The rectifier unit is connected to the live wire, the neutral wire, and the voltage divider unit, respectively. The voltage divider unit is connected to the voltage identification module through the filter unit.

3. The power supply protection circuit for reducing residual voltage according to claim 2, characterized in that, The rectifier unit includes diodes D1 and D2, the voltage divider unit includes resistors R1, R2, R3, R4, R5, R6, R7 and R8 connected in series, and the filter unit includes capacitor C1 and resistor R9. The positive terminal of diode D1 is connected to the live wire, the negative terminal of diode D1 is connected to the resistor R1 and the negative terminal of diode D2, and the positive terminal of diode D2 is connected to the neutral wire. The capacitor C1 is connected in parallel with the resistors R7 and R8. One end of the capacitor C1 connected to the resistor R8 is grounded, and the other end of the capacitor C1 connected to the resistor R7 is connected to the voltage identification module through the resistor R9. Wherein, resistors R1, R2, R3, R4, R5, and R6 are 1206 surface mount resistors, resistors R7, R8, and R9 are 0603 surface mount resistors, and capacitor C1 is a 0603 surface mount capacitor.

4. The power supply protection circuit for reducing residual voltage according to claim 1, characterized in that, The voltage identification module includes a voltage follower unit, a comparator, a reference voltage unit, and a positive feedback unit connected to the comparator. The voltage follower unit is connected between the voltage sampling module and the inverting input of the comparator, and the reference voltage unit is connected to the non-inverting input of the comparator; The input voltage signal is input to the comparator through the voltage follower unit, and the reference voltage unit provides the preset reference voltage signal to the comparator. The comparator compares the input voltage signal and the preset reference voltage signal and generates the closing signal or the turning-off signal.

5. The power supply protection circuit for reducing residual voltage according to claim 4, characterized in that, The voltage follower unit includes an operational amplifier, a capacitor C2, and a diode D6. The capacitor C2 is a 0603 surface mount capacitor. The non-inverting input of the operational amplifier is connected to the voltage sampling module, the output of the operational amplifier is connected to the inverting input of the operational amplifier through the diode D6, the positive power supply of the operational amplifier is connected to the first power supply voltage, the negative power supply of the operational amplifier is grounded, and the capacitor C2 is connected in parallel between the positive power supply and the negative power supply of the operational amplifier.

6. The power supply protection circuit for reducing residual voltage according to claim 4, characterized in that, The reference voltage unit includes resistors R12, R13, R14, and R15, and capacitors C5 and C6. One end of resistor R12 is connected to the second power supply voltage, and the other end of resistor R12 is grounded through resistor R13. Resistor R14 and capacitor C5 are connected in parallel with resistor R13. One end of resistor R15 is connected to one end of capacitor C5, and the other end of resistor R15 is connected to the other end of capacitor C5 through capacitor C6. The other end of resistor R15 is also connected to the non-inverting input of the comparator. Resistors R12, R13, R14, and R15 are 0603 surface mount resistors, and capacitors C5 and C6 are 0603 surface mount capacitors.

7. The power supply protection circuit for reducing residual voltage according to claim 4, characterized in that, The voltage identification module also includes a voltage divider filter unit, which includes resistor R10, resistor R11, capacitor C3 and capacitor C4. One end of the resistor R10 is connected to the output terminal of the voltage follower unit and grounded through the capacitor C3; the other end of the resistor R10 is connected to the inverting input terminal of the comparator and grounded through the resistor R11 and the capacitor C4 respectively. Wherein, resistors R10 and R11 are 0603 surface mount resistors, and capacitors C3 and C4 are 0603 surface mount capacitors.

8. The power supply protection circuit for reducing residual voltage according to claim 1, characterized in that, The switch control module includes a switch transistor Q1 and a relay coil; The drain of the switching transistor Q1 is connected to the first power supply voltage, the gate of the switching transistor Q1 is connected to the voltage identification module, and the source of the switching transistor Q1 is grounded through the coil of the relay.

9. The power supply protection circuit for reducing residual voltage according to claim 8, characterized in that, The discharge module includes a discharge tube and the contacts of the relay, and the discharge tube is connected to the protective ground through the contacts of the relay; The switching transistor Q1 energizes or de-energizes the coil of the relay according to the off signal or the closed signal, thereby triggering the contacts of the relay to close or close.

10. The power supply protection circuit for reducing residual voltage according to claim 9, characterized in that, The protection module includes a varistor MOV1 and a varistor MOV2; The discharge tube is connected to the live wire and the neutral wire through the varistor MOV1 and the varistor MOV2, respectively.

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