380VAC protection circuit and charger and usage

Abstract

The present invention relates to the field of power electronics technology, and specifically to a 380VAC protection circuit and a charger and a method for using the same, which are reliable in operation, highly safe and cost-effective. The invention is characterized in that an input lightning protection circuit, an input power supply interlocking circuit, an input filtering and rectifying circuit, a high-voltage auxiliary power supply circuit and a high-voltage voltage sampling circuit are provided; wherein the input lightning protection circuit is arranged at the front end of the input power supply interlocking circuit, the rear end of the input power supply interlocking circuit is connected to the input rectifying and filtering circuit, the electrical signal output terminal of the high-voltage auxiliary power supply circuit is connected between the input lightning protection circuit and the input power supply interlocking circuit, and the sampling signal input terminal of the high-voltage voltage sampling circuit is connected to the front end of the input power supply interlocking circuit. Through the implementation of the present solution, the application scope of the product is expanded, the safe working performance of the product under complex working conditions is improved, and the market return rate of the product can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a 380VAC protection circuit and a charger and a use method thereof which are reliable in operation, highly safe and reasonably cost-effective. Background Art

[0002] At present, small and medium power switching power supply products are basically powered by single-phase 220VAC. In terms of device application, the withstand voltage of the device on the AC side of the input stage is selected according to 300VAC; in terms of protection design, a fuse is generally connected in series on the live wire or neutral wire of the input stage. This circuit design has a low probability of problems under normal use, but in some special industrial application scenarios, there are both single-phase and three-phase power supply lines on site, and it is very easy for users on site to connect three-phase electricity to the charger product, which causes the charger product to malfunction and damage. Summary of the invention

[0003] In view of the shortcomings and deficiencies in the prior art, the present invention proposes a 380VAC protection circuit and a charger and applications thereof when connected to a 380VAC power supply.

[0004] The present invention can be achieved through the following technical solutions:

[0005] A 380VAC protection circuit, characterized in that it is provided with an input lightning protection circuit, an input power supply interlocking circuit, an input filtering and rectifying circuit, a high-voltage auxiliary power supply circuit, and a high-voltage voltage sampling circuit; wherein the input lightning protection circuit is arranged at the front end of the input power supply interlocking circuit, the rear end of the input power supply interlocking circuit is connected to the input rectifying and filtering circuit, the electrical signal output terminal of the high-voltage auxiliary power supply circuit is connected between the input lightning protection circuit and the input power supply interlocking circuit, and the sampling signal input terminal of the high-voltage voltage sampling circuit is connected to the front end of the input power supply interlocking circuit.

[0006] The input lightning protection circuit is provided with a first varistor MOV1, a second varistor MOV2 and a third varistor MOV3, wherein the first varistor MOV1 is connected between the input power supply neutral line and the live line, the second varistor MOV2 is connected between the input power supply live line and the ground line, and the third varistor MOV3 is connected between the input power supply neutral line and the ground line;

[0007] The input power supply interlock circuit is provided with a first relay K1, a second relay K2, a first thermistor NTC resistor RT1 and a second thermistor NTC resistor RT2, wherein the normally open contact of the first relay K1 is connected in series with the power supply input live wire; the soft start component is connected in series with the first thermistor NTC resistor RT1 and the second thermistor NTC resistor RT2 and the normally open contact of the second relay K2; the soft start component is connected in parallel with the first relay K1;

[0008] The input filter and rectifier circuit is located after the input power supply interlocking circuit; the input filter and rectifier circuit includes a first X capacitor C1, a first Y capacitor C2, a second Y capacitor C3, an input common mode inductor and an input rectifier bridge; the first X capacitor C1 is connected between the LN lines, the first Y capacitor C2 and the second Y capacitor C3 are respectively located after the first X capacitor C1, and the first Y capacitor C2 is connected between the live wire and the ground wire, the second Y capacitor C3 is connected between the neutral wire and the ground wire, the front end of the input common mode inductor is connected after the first Y capacitor C2 and the second Y capacitor C3, and the rear end of the input common mode inductor is connected to the input rectifier bridge;

[0009] The high-voltage auxiliary power supply circuit is provided with a cross power supply component, a balanced filter component and an auxiliary power supply power conversion component; the cross power supply component includes a first filter inductor L1, a diode D1, a diode D2, a diode D3, a diode D4, a diode D5 and a diode D6, wherein one end of the first filter inductor L1 is connected to the node between the second thermistor NTC resistor RT2 and the second relay K2 in the input power supply interlocking circuit, the other end of the first filter inductor L1 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the anode of the diode 3, the cathode of the diode D3 is connected to the anode of the diode D4, and the cathode of the third diode D3 is connected to the anode of the fourth diode D4; the anode of the fifth diode D5 is connected to the positive bus of the PFC boost circuit, the cathode of the fifth diode D5 is connected to the anode of the sixth diode D6, the cathode of the fourth diode D4 is connected to the cathode of the sixth diode D6, and both are connected to the input end of the balanced filter component;

[0010] The balancing filter component includes a voltage-equalizing resistor R1, a voltage-equalizing resistor R2, a voltage-equalizing resistor R3, a voltage-equalizing resistor R4, a first filter electrolytic capacitor C7, a second filter electrolytic capacitor C5 and a first filter ceramic capacitor C6. One end of the first voltage-equalizing resistor R1, the positive electrode of the first filter electrolytic capacitor C7 and one end of the first filter ceramic capacitor C6 are connected as the input end of the balancing filter component. The voltage-equalizing resistor R1, the voltage-equalizing resistor R2, the voltage-equalizing resistor R3 and the voltage-equalizing resistor R4 are connected in series. The other end of the voltage-equalizing resistor R4, the negative electrode of the second filter electrolytic capacitor C5 and the other end of the first filter ceramic capacitor C6 are connected and then connected to the negative bus of the PFC boost circuit. The connection point of the voltage-equalizing resistor R2 and the voltage-equalizing resistor R3 is connected to the negative electrode of the first filter electrolytic capacitor C7 and the negative electrode of the second filter electrolytic capacitor C5.

[0011] The auxiliary power conversion component of the present invention is a multi-winding output flyback switching power supply, and the power supply is designed according to the AC input 530Vac design to meet the normal operation of the power supply under high voltage conditions.

[0012] The high-voltage voltage sampling circuit of the present invention includes an AC rectifier component, a step-down average component and an isolated sampling component; the AC rectifier component includes a rectifier diode D7, a rectifier diode D8, a rectifier diode D9 and a rectifier diode D10, wherein the anode of the rectifier diode D9 is connected to the input N line, the cathode of the rectifier diode D9 is connected to the anode of the rectifier diode D10, the anode of the rectifier diode D7 is connected to the anode connection point of the first filter inductor L1 and the diode D1, the cathode of the rectifier diode D7 is connected to the anode of the rectifier diode D8, the cathode of the rectifier diode D10 is connected to the cathode of the rectifier diode D8, and then connected to the input end of the step-down average component;

[0013] The step-down average value component includes six step-down resistors R9, R10, R11, R12, R13, R14, four equipotential resistors R5, R6, R7, R8, and a first average value capacitor C4. The six step-down resistors are connected in series in sequence, the other end of the step-down resistor R9 is connected to the connection point between the cathode of the diode D10 and the cathode of the diode D8, and the other end of the step-down resistor R14 is grounded; the four equipotential resistors are connected in series in sequence, the front end of the resistor R5 and the front end of the step-down resistor R9 are simultaneously connected to the connection point between the cathode of the diode D10 and the cathode of the diode D8, and the rear end of the resistor R8 is connected to the PFC bus The first average value capacitor C4 is connected in parallel to the two ends of the step-down resistor R14; the isolated sampling component includes a triangular wave generating circuit, a voltage comparison circuit, an optocoupler isolation transmission circuit and an MCU sampling circuit, wherein the output end of the triangular wave generating circuit is connected to one input end of the voltage comparison circuit, the output end of the step-down average component is connected to another input end of the voltage comparison circuit, the output end of the voltage comparison circuit is connected to the input end of the optocoupler isolation transmission circuit, the output end of the optocoupler isolation transmission circuit is connected to the MCU sampling circuit, and the MCU sampling circuit is connected to the control unit.

[0014] It can be seen from the above scheme that the scheme described in this case can effectively electrically isolate the voltage of the AC input port and accurately sample the voltage value.

[0015] A charger, characterized in that it is provided with the above-mentioned 380VAC protection circuit, AC-DC conversion circuit and control unit, wherein the rear end of the input rectifier and filter circuit in the 380VAC protection circuit is connected to the AC-DC conversion circuit, and the control unit is respectively connected to the AC-DC conversion circuit and the high-voltage auxiliary power supply circuit and the high-voltage voltage sampling circuit in the 380VAC protection circuit.

[0016] The 380VAC protection circuit of the present invention is the circuit in the above scheme or a modified circuit thereof.

[0017] The AC / DC conversion circuit of the present invention comprises: a PFC active power factor conversion circuit, which is used to convert the externally provided AC mains power into high-voltage bus DC power and improve the power factor of the whole machine; a DC / DC conversion circuit, which is used to realize the conversion of DC voltage and convert the high-voltage bus DC power into the level voltage required for battery charging.

[0018] The control unit of the present invention comprises: a main control MCU unit, which is used to implement the whole machine control algorithm, control the whole machine working timing logic and respond to the protection action; an internal indicator light driving circuit, which is used to receive the control signal output by the main control MCU unit and drive the indicator light on the charger body to display; an external indicator light driving circuit, which is used to receive the control signal output by the main control MCU unit and drive the indicator light outside the charger to display;

[0019] The first temperature sampling circuit is used to sample the internal temperature of the charger product;

[0020] The second temperature sampling circuit is used for sampling the external environment temperature of the charger product;

[0021] A first driving circuit, used for driving a first relay in the input power supply interlocking circuit;

[0022] A second driving circuit, used for driving a second relay in the input power supply interlocking circuit;

[0023] The third driving circuit is used to drive the output relay in the AC / DC conversion circuit.

[0024] It can be seen from the above scheme that when the input power supply voltage is within the normal working voltage range of the charger product, the 380VAC protection circuit does not perform an action, and the AC power supply provided by the power grid is converted into the DC power supply required for charging the power battery through the AC-DC conversion circuit. When the wrong power supply system is connected, resulting in excessive system voltage, the 380VAC protection circuit performs a protective action, isolates the high-voltage power grid, and protects the AC-DC conversion circuit.

[0025] A method for using a charger, characterized by comprising the following steps:

[0026] Step 1: The control unit is powered by a high-voltage auxiliary power circuit to ensure that it can work normally under any power supply voltage;

[0027] Step 2: The control unit samples the power supply voltage through the high voltage voltage sampling circuit. In order to ensure the accuracy of the sampled AC power supply voltage, the least squares linear fitting algorithm is used to calibrate the internal curve. The implementation method of this algorithm is:

[0028] The formula to be calibrated is:

[0029] ,

[0030] Actual N tests U samp and U ac , respectively denoted as U sampi and U aci , i=1, 2,…,N.

[0031] Let U0=a, cU0=b be two parameters to be estimated, then the error formula can be written as:

[0032] ,

[0033] According to the error equation, the normal equation is listed:

[0034] ,

[0035] By inputting the AC voltage value to be calibrated, the coefficients a, b, c and U0 can be obtained.

[0036] After detecting the input AC power supply voltage, when the input power supply voltage Uac is within the normal operating voltage range of the charger product, that is, Uac < 280V, the control unit issues a control instruction to drive the second relay K2 in the input power supply interlock circuit to close, and the soft start charging of the PFC active power factor conversion circuit in the AC-DC conversion circuit is performed through the input filter rectifier circuit; after a delay of 1 second, the control unit issues a control instruction to drive the first relay K1 in the input power supply interlock circuit to close, and provide energy to the AC-DC conversion circuit through the input filter rectifier circuit; when the input power supply voltage is not within the normal operating voltage range of the charger product, the control unit issues a control instruction not to drive the first relay K1 and the second relay K2 in the input power supply interlock circuit to operate, then the external risk voltage is isolated from the AC-DC conversion circuit, which can play an absolute protective role for the AC-DC conversion circuit, and at the same time outputs an alarm prompt signal to the outside, and waits for the AC input voltage to be normal.

[0037] It can be seen from the above scheme that through the implementation of the least squares algorithm, the compensation effect of the error is fully utilized, which can effectively reduce the influence of random errors, so the fitting results are the most reliable. The implementation of this algorithm effectively ensures the accuracy of the isolated AC sampling voltage and provides reliable data support for the logical judgment of the control unit. The control unit blocks the high-voltage dangerous circuit from entering the main power circuit through logical judgment. The implementation of this scheme provides a safe and reliable 380VAC AC protection circuit.

[0038] When the charger of the present invention is in use, the control unit collects the internal ambient temperature of the charger and the external ambient temperature of the charger product through the first temperature sampling circuit and the second temperature sampling circuit; the control unit calibrates the charging curve according to the collected ambient temperature; the calibration algorithm is: taking 20°C as the reference, the output voltage of the charger is normalized to a decrease or increase of 4mV or 3mV for each 1°C increase / decrease in ambient temperature; the control unit controls the DC output of the AC / DC conversion circuit according to the calibrated charging curve to reach the voltage and current points required by the charged battery.

[0039] It can be seen from the above scheme that by implementing the method of using this scheme and realizing the implementation of the linear fitting control algorithm, the sampling accuracy and linearity of the AC power supply voltage are improved. By controlling the action of the two relays in the input interlocking circuit according to the input power supply voltage state, the physical isolation of the input power supply voltage and the electrical circuit of the AC / DC conversion circuit can be effectively achieved, thereby achieving a certain protective effect. At the same time, the control unit can be safely powered by the high-voltage auxiliary power supply circuit to ensure that the control unit circuit can be powered under any voltage state. By implementing the method of using the charger described in this scheme, it can be ensured that the charging curve meets the charging requirements of the battery at any temperature, avoiding the occurrence of overcharging and undercharging.

[0040] Through the implementation of this plan, the application scope of the product has been expanded, the product's safe working performance under complex working conditions has been improved, and the product market return rate can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Attached Figure 1 It is a structural block diagram of the present invention.

[0042] Attached Figure 2 It is a circuit schematic diagram of the 380VAC protection circuit of the present invention.

[0043] Attached Figure 3 It is a working flow chart of the 380VAC protection circuit in the present invention.

[0044] Attached Figure 4 It is a control logic schematic diagram of the present invention.

[0045] Attached Figure 5 This is the charging curve of the first charger.

[0046] Attached Figure 6 This is the charging curve of the second charger.

[0047] Figure numerals: 1 Input lightning protection circuit; 2 Input power supply interlock circuit; 3 High-voltage auxiliary power supply circuit; 4 High-voltage voltage sampling circuit; 5 Input filter rectifier circuit. DETAILED DESCRIPTION

[0048] Reference Figure 2 The 380VAC protection circuit proposed in the present invention includes: an input lightning protection circuit 1, an input power supply interlocking circuit 2, a high-voltage auxiliary power supply circuit 3, a high-voltage voltage sampling circuit 4 and an input filter rectifier circuit 5; the input lightning protection circuit 1 is placed in parallel on the input power supply port, and the input power supply interlocking circuit 2 is connected in series to the power supply L line; the input of the high-voltage auxiliary circuit 3 is connected to the power supply L line and the DC bus after PFC boosting; the high-voltage voltage sampling circuit 4 is connected to the input LN line and the ground line of the DC bus after PFC boosting.

[0049] In the input lightning protection circuit 1 , the first varistor MOV1 is connected in parallel between the input power supply LN line, the second varistor MOV2 is connected in parallel between the input power supply L line and the Earth line, and the third varistor MOV3 is connected in parallel between the input power supply N line and the Earth line.

[0050] The normally open contact of the first relay K1 in the power supply interlock circuit 2 is connected in series to the input L line; the first thermistor NTC resistor RT1, the second thermistor NTC resistor RT2 are connected in series with the normally open contact of the second relay K2 to form a soft start component; the soft start component is connected in parallel with the first relay K1.

[0051] The input filter rectifier circuit 5 is located after the input power supply interlock circuit; the first X capacitor C1 is connected in parallel between the LN lines; the first Y capacitor C1 and the second Y capacitor C2 are connected in series and then connected in parallel before the LN line, and the node of the first Y capacitor C1 and the second Y capacitor C2 in series is connected to the grounding point Earth.

[0052] The cross-power supply component of the high-voltage auxiliary power supply 3 includes a first filter inductor L1 and first to sixth diodes D1-D6. One end of the first filter inductor L1 is connected to the node where the second thermistor NTC resistor RT2 and the second relay K2 are connected in series in the input power supply interlocking circuit, and the other end of the first filter inductor L1 is connected to the anode of the first diode D1, the cathode of the first diode D1 is connected to the anode of the second diode D2, the cathode of the second diode D2 is connected to the anode of the third diode D3, and the cathode of the third diode D3 is connected to the anode of the fourth diode D4; the anode of the fifth diode D5 is connected to the positive bus of the PFC boost circuit, and the cathode of the fifth diode D5 is connected to the anode of the sixth diode D6; the cathode of the fourth diode D4 is connected to the cathode of the sixth diode D6, and is connected to the input end of the balancing filter component.

[0053] The balanced filter component of the high-voltage auxiliary power supply 3 includes the first to fourth voltage-equalizing resistors R1-R4, the first filter electrolytic capacitor C7, the second filter electrolytic capacitor C5 and the first filter ceramic capacitor C6. One end R1 of the first voltage-equalizing resistor, the positive electrode of the first filter electrolytic capacitor C7 and one end of the first filter ceramic capacitor C6 are connected as the input end of the balanced filter component. One end of the fourth voltage-equalizing resistor R4, the negative electrode of the second filter electrolytic capacitor C2 and one end of the first filter ceramic capacitor C6 are connected, and then connected to the negative bus of the PFC boost circuit. The connection point of the second voltage-equalizing resistor R2 and the third voltage-equalizing resistor R3 is connected to the negative electrode of the first filter electrolytic capacitor C7 and the negative electrode of the second filter electrolytic capacitor C5.

[0054] The auxiliary power conversion component of the high-voltage auxiliary power supply 3 is a multi-winding output flyback switching power supply. This power supply is designed according to the AC input 530Vac design to meet the high voltage condition, and this power supply works normally.

[0055] The AC rectifier component of the high voltage sampling circuit 4 includes the seventh to tenth rectifier diodes D7-D10. The anode of the seventh rectifier diode D7 is connected to the input N line, and the cathode of the seventh rectifier diode D7 is connected to the anode of the eighth rectifier diode D8. The anode of the ninth rectifier diode D9 is connected to the connection point between the first filter inductor L1 and the anode of the first diode D1, the cathode of the ninth rectifier diode D9 is connected to the anode of the tenth rectifier diode D10, and the cathode of the tenth rectifier diode D10 is connected to the cathode of the eighth rectifier diode D8, and then connected to the input end of the step-down average component.

[0056] The step-down average component of the high voltage sampling circuit 4 includes the first to sixth step-down resistors R9-R14, the first average capacitor C4 and the first to fourth equipotential resistors (R5-R8). The first step-down resistor to the sixth step-down resistor (R9-R14) are connected in series in sequence, wherein one end of the first step-down resistor R9 is connected to the node where the cathode of the tenth rectifier diode D10 and the cathode of the eighth rectifier diode D8 are connected, and one end of the sixth step-down resistor R14 is connected to the negative ground of the PFC bus; the first average capacitor C4 is connected in parallel to the sixth step-down resistor R14. The first to fourth equipotential resistors (R5-R8) are connected in sequence, wherein one end of the first equipotential resistor R5 is connected to the node where the cathode of the tenth rectifier diode D10 and the cathode of the eighth rectifier diode D8 are connected, and one end of the fourth equipotential resistor R8 is connected to the negative ground of the PFC bus.

[0057] The isolated sampling component of the high voltage sampling circuit 4 includes a triangle wave generating circuit, a voltage comparison circuit, an optocoupler isolation transmission circuit and an MCU sampling circuit.

[0058] Reference Figure 1 and Figure 3, the control method of the 380Vac protection charger is explained.

[0059] Control method of 380Vac protection charger:

[0060] The control unit includes an MCU single-chip controller, which is powered by a high-voltage auxiliary power circuit 3 to ensure that it can work normally under any power supply voltage conditions.

[0061] The control unit samples the AC mains supply voltage through the high-voltage voltage sampling circuit 4. When the input mains supply voltage is within the normal working voltage range of the charger product, the main control MCU unit in the control unit issues a control instruction to drive the second relay K2 in the input power supply interlock circuit 2 to close through the second drive circuit, and charges the soft start of the PFC active power factor conversion circuit in the AC / DC conversion circuit through the input filter rectifier circuit 5. Figure 3 As shown, after a delay of 1 second, the main control MCU unit issues a control instruction to drive the first relay K1 in the input power supply interlock circuit 2 to close through the first drive circuit, and provide energy to the AC / DC conversion circuit through the input filter rectifier circuit 5.

[0062] The control unit samples the power supply voltage through the high-voltage voltage sampling circuit 4. When the input power supply voltage is not within the normal working voltage range of the charger product, the main control MCU unit in the control unit issues a control instruction and does not drive the first relay K1 and the second relay K2 in the input power supply interlock circuit 5 to operate. At this time, the external risk voltage is isolated from the AC-DC conversion circuit, which can provide absolute protection for the AC-DC conversion circuit.

[0063] The control unit samples the supply voltage through the high-voltage voltage sampling circuit 4, and the main control MCU unit drives the indicator light outside the charger through the external indicator light driving circuit according to the sampled external voltage;

[0064] It can be seen from the circuit of the above embodiment that the control unit controls the actions of the two relays in the input interlock circuit according to the input power supply voltage state, which can effectively achieve physical isolation between the input power supply voltage and the electrical circuit of the AC / DC conversion circuit, thereby achieving a certain protection effect. At the same time, the control unit can be safely powered by the high-voltage auxiliary power supply circuit, ensuring that the control unit circuit can be powered under any voltage state.

Claims

1. A 380VAC protection circuit, characterized in that: An input lightning protection circuit, an input power supply interlocking circuit, an input filtering and rectifying circuit, a high-voltage auxiliary power supply circuit, and a high-voltage voltage sampling circuit are provided; wherein the input lightning protection circuit is arranged at the front end of the input power supply interlocking circuit, the rear end of the input power supply interlocking circuit is connected to the input rectifying and filtering circuit, the electrical signal output terminal of the high-voltage auxiliary power supply circuit is connected between the input lightning protection circuit and the input power supply interlocking circuit, and the sampling signal input terminal of the high-voltage voltage sampling circuit is connected to the front end of the input power supply interlocking circuit. The input lightning protection circuit is provided with a first varistor MOV1, a second varistor MOV2 and a third varistor MOV3, wherein the first varistor MOV1 is connected between the input power supply neutral line and the live line, the second varistor MOV2 is connected between the input power supply live line and the ground line, and the third varistor MOV3 is connected between the input power supply neutral line and the ground line; The input power supply interlock circuit is provided with a first relay K1, a second relay K2, a first thermistor NTC resistor RT1 and a second thermistor NTC resistor RT2, wherein the normally open contact of the first relay K1 is connected in series with the power supply input live wire; the soft start component is connected in series with the first thermistor NTC resistor RT1 and the second thermistor NTC resistor RT2 and the normally open contact of the second relay K2; the soft start component is connected in parallel with the first relay K1; The input filter and rectifier circuit is located after the input power supply interlocking circuit; the input filter and rectifier circuit includes a first X capacitor C1, a first Y capacitor C2, a second Y capacitor C3, an input common mode inductor and an input rectifier bridge; the first X capacitor C1 is connected between the LN lines, the first Y capacitor C2 and the second Y capacitor C3 are respectively located after the first X capacitor C1, and the first Y capacitor C2 is connected between the live wire and the ground wire, the second Y capacitor C3 is connected between the neutral wire and the ground wire, the front end of the input common mode inductor is connected after the first Y capacitor C2 and the second Y capacitor C3, and the rear end of the input common mode inductor is connected to the input rectifier bridge; The high-voltage auxiliary power supply circuit is provided with a cross power supply component, a balanced filter component and an auxiliary power supply power conversion component; the cross power supply component includes a first filter inductor L1, a diode D1, a diode D2, a diode D3, a diode D4, a diode D5 and a diode D6, wherein one end of the first filter inductor L1 is connected to the node between the second thermistor NTC resistor RT2 and the second relay K2 in the input power supply interlocking circuit, the other end of the first filter inductor L1 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the anode of the diode 3, the cathode of the diode D3 is connected to the anode of the diode D4, and the cathode of the third diode D3 is connected to the anode of the fourth diode D4; the anode of the fifth diode D5 is connected to the positive bus of the PFC boost circuit, the cathode of the fifth diode D5 is connected to the anode of the sixth diode D6, the cathode of the fourth diode D4 is connected to the cathode of the sixth diode D6, and both are connected to the input end of the balanced filter component; The balancing filter component includes a voltage-equalizing resistor R1, a voltage-equalizing resistor R2, a voltage-equalizing resistor R3, a voltage-equalizing resistor R4, a first filter electrolytic capacitor C7, a second filter electrolytic capacitor C5 and a first filter ceramic capacitor C6. One end of the first voltage-equalizing resistor R1, the positive electrode of the first filter electrolytic capacitor C7 and one end of the first filter ceramic capacitor C6 are connected as the input end of the balancing filter component. The voltage-equalizing resistor R1, the voltage-equalizing resistor R2, the voltage-equalizing resistor R3 and the voltage-equalizing resistor R4 are connected in series. The other end of the voltage-equalizing resistor R4, the negative electrode of the second filter electrolytic capacitor C5 and the other end of the first filter ceramic capacitor C6 are connected and then connected to the negative bus of the PFC boost circuit. The connection point of the voltage-equalizing resistor R2 and the voltage-equalizing resistor R3 is connected to the negative electrode of the first filter electrolytic capacitor C7 and the negative electrode of the second filter electrolytic capacitor C5.

2. A 380VAC protection circuit according to claim 1, characterized in that: The auxiliary power supply power conversion component is a multi-winding output flyback switching power supply, and this power supply is designed according to the AC input 530Vac design to meet the normal operation of this power supply under high voltage conditions.

3. A 380VAC protection circuit according to claim 1, characterized in that: The high voltage sampling circuit comprises an AC rectifier component, a step-down average component and an isolation sampling component; The rectifier assembly includes rectifier diodes D7, D8, D9 and D10, wherein the anode of rectifier diode D9 is connected to the input N line, the cathode of rectifier diode D9 is connected to the anode of rectifier diode D10, the anode of rectifier diode D7 is connected to the anode connection point of the first filter inductor L1 and the diode D1, the cathode of rectifier diode D7 is connected to the anode of rectifier diode D8, and the cathode of rectifier diode D8 is connected to the anode of rectifier diode D10. The cathode of the rectifier diode D10 is connected to the cathode of the rectifier diode D8, and then connected to the input end of the step-down average component; The voltage-dropping average component includes six voltage-dropping resistors R9, R10, R11, R12, R13, R14, The six voltage-dropping resistors are connected in series in series. The other end of the step-down resistor R9 is connected to the connection point between the cathode of the diode D10 and the cathode of the diode D8, and the other end of the step-down resistor R14 is grounded; the four equipotential resistors are connected in series in sequence, the front end of the resistor R5 and the front end of the step-down resistor R9 are simultaneously connected to the connection point between the cathode of the diode D10 and the cathode of the diode D8, and the rear end of the resistor R8 is connected to the negative ground wire of the PFC bus; the first average value capacitor C4 is connected in parallel to the step-down resistor The isolated sampling component includes a triangular wave generating circuit, a voltage comparison circuit, an optocoupler isolation transmission circuit and an MCU sampling circuit, wherein the output end of the triangular wave generating circuit is connected to one input end of the voltage comparison circuit, and the output end of the buck averaging component is connected to another input end of the voltage comparison circuit. The output end of the voltage comparison circuit is connected to the input end of the optocoupler isolation transmission circuit. The output end of the transmission circuit is connected to the MCU sampling circuit, and the MCU sampling circuit is connected to the control unit.

4. A charger, characterized in that: A 380VAC protection circuit, an AC / DC conversion circuit and a control unit as described in any one of claims 1 to 3 are provided, wherein the rear end of the input rectifier and filter circuit in the 380VAC protection circuit is connected to the AC / DC conversion circuit, and the control unit is respectively connected to the AC / DC conversion circuit and the high-voltage auxiliary power supply circuit and the high-voltage voltage sampling circuit in the 380VAC protection circuit.

5. A charger according to claim 4, characterized in that The AC / DC conversion circuit includes: a PFC active power factor conversion circuit, which is used to convert the externally provided AC mains power into high-voltage bus DC power and improve the power factor of the whole machine; a DC / DC conversion circuit, which is used to realize the conversion of DC voltage and convert the high-voltage bus DC power into the level voltage required for battery charging.

6. A charger according to claim 4, characterized in that The control unit includes: a main control MCU unit, which is used to implement the whole machine control algorithm, control the whole machine working timing logic and respond to the protection action; an internal indicator light driving circuit, which is used to receive the control signal output by the main control MCU unit and drive the indicator light on the charger body to display; an external indicator light driving circuit, which is used to receive the control signal output by the main control MCU unit and drive the indicator light outside the charger to display; The first temperature sampling circuit is used to sample the internal temperature of the charger product; The second temperature sampling circuit is used for sampling the external environment temperature of the charger product; A first driving circuit, used for driving a first relay in the input power supply interlocking circuit; A second driving circuit, used for driving a second relay in the input power supply interlocking circuit; The third driving circuit is used to drive the output relay in the AC / DC conversion circuit.

7. A method for using a charger as claimed in any one of claims 4 to 6, characterized in that The following steps are involved: Step 1: The control unit is powered by a high-voltage auxiliary power circuit to ensure that it works normally under any supply voltage conditions; Step 2: The control unit samples the supply voltage through the high voltage sampling circuit. In order to ensure the accuracy of the sampled AC supply voltage, the least squares linear fitting algorithm is used to calibrate the internal curve. The implementation method of this algorithm is as follows: The formula to be calibrated is: U samp =U0(1+aU ac ) Actual N tests U samp and U ac , respectively denoted as U sampi and U aci , i = 1, 2, ..., N, Let U0=a, cU0=b be two parameters to be estimated, then the error formula can be written as: v i =U sampi -(a+U aci b)(i=1,2,···,N) According to the error equation, the normal equation is listed: Substitute the AC voltage value to be calibrated to obtain the coefficients a, b, c and U0; After detecting the input AC power supply voltage, when the input power supply voltage Uac is within the normal operating voltage range of the charger product, that is, Uac<280V, the control unit issues a control instruction to drive the second relay K2 in the input power supply interlocking circuit to operate and close, and the soft start charging of the PFC active power factor conversion circuit in the AC-DC conversion circuit is performed through the input filter rectifier circuit; after a delay of 1 second, the control unit issues a control instruction to drive the first relay K1 in the input power supply interlocking circuit to operate and close, and provide energy to the AC-DC conversion circuit through the input filter rectifier circuit; when the input power supply voltage is not within the normal operating voltage range of the charger product, the control unit issues a control instruction not to drive the first relay K1 and the second relay K2 in the input power supply interlocking circuit to operate, and at this time, the external risk voltage is isolated from the AC-DC conversion circuit, which plays an absolute protective role for the AC-DC conversion circuit, and at the same time outputs an alarm prompt signal to the outside, and waits for the AC input voltage to be normal.

8. A method for using a charger according to claim 7, characterized in that Also includes: When the charger is in use, the control unit collects the internal ambient temperature of the charger and the external ambient temperature of the charger product through the first temperature sampling circuit and the second temperature sampling circuit; the control unit calibrates the charging curve according to the collected ambient temperature; the calibration algorithm is: taking 20°C as a reference, the output voltage of the charger is normalized to a decrease or increase of 4mV or 3mV for each 1°C increase / decrease in ambient temperature; the control unit controls the DC output of the AC / DC conversion circuit according to the calibrated charging curve to reach the voltage and current points required by the charged battery.

Images