Device for protecting ground wire of three-phase vehicle-mounted charger from being misconnected with power supply live wire

Abstract

The embodiment of the utility model provides a protection device for protecting a ground wire of a three-phase vehicle-mounted charger from being misconnected with a power supply live wire, and belongs to the technical field of charging safety. The protection device for misconnection of the protection ground wire of the three-phase vehicle-mounted charger with the power supply live wire comprises an input protection ground wire, a casing protection ground, a three-phase live wire input and normally open relay and a control circuit thereof, and the normally open relay is connected in series between the input protection ground wire and the casing protection ground and is used for keeping an off state when detecting that the input protection ground wire is mistakenly connected to the power supply live wire. According to the scheme of the utility model, the normally open relay is connected in series to the protection ground wire in the charger and the relay is effectively controlled, so that the protection when the input protection ground wire of the vehicle-mounted charger is misconnected with the power supply live wire is realized, and the isolation and safety of the metal shell of the vehicle-mounted charger and the power supply live wire are ensured; the safety of other low-voltage power supply control equipment on the vehicle is also ensured; the number of added elements is small, control is easy, and the increased cost is little.

Description

TECHNICAL FIELD

[0001] The utility model relates to charging safety technical field, specifically relates to a three -phase vehicle charger protection ground wire mistake supplies power live wire's protection device. BACKGROUND

[0002] At present, the three -phase alternating current input vehicle charger, when the charger casing is metal shell, the gold plastic shell is usually directly connected input protection ground, and the more common is like various engineering vehicle's vehicle charger, and the charger casing is fixed on the metal frame of engineering vehicle through screw, but when the input protection ground wire of vehicle charger is connected to the power supply live wire due to non - standard wiring or improper operation in engineering site, it can lead to the charger casing to be connected to the live wire and be brought high - voltage electricity, this condition is because the metal frame of engineering vehicle is directly connected to the live wire and brings the hidden danger to personal safety, and the second is because the gold plastic frame is connected to the live wire and can lead to the damage or damage of other low - voltage power supply control equipment on the vehicle. SUMMARY

[0003] In view of the above problem, the utility model embodiment aims at providing a three -phase vehicle charger protection ground wire mistake supplies power live wire's protection device.

[0004] In order to realize the above -mentioned purpose, the utility model embodiment provides a three -phase vehicle charger protection ground wire mistake supplies power live wire's protection device, the three -phase vehicle charger protection ground wire mistake supplies power live wire's protection device includes: input protection ground wire, casing protection ground, three -phase live wire input and normally open relay and its control circuit, the normally open relay is connected in series between the input protection ground wire and the casing protection ground, and is used for detecting the input protection ground wire mistake supplies power live wire and keeping the open state.

[0005] Optionally, the three -phase vehicle charger protection ground wire mistake supplies power live wire's protection device further includes: a main control unit circuit, for receiving the input voltage signal from the voltage detection circuit between the three -phase live wire input, and judging the state of three -phase input voltage based on the signal, to control the communication or disconnection of the relay.

[0006] Optionally, the voltage detection circuit generates the line -to -line voltage signal between the three -phase live wire input, and transmits the line -to -line voltage signal to the main control unit circuit, so that the main control unit circuit judges the connectivity of three -phase voltage based on the effective value of the line -to -line voltage signal.

[0007] Optionally, the control circuit of normally open relay includes: NPN triode, a plurality of resistors and a plurality of capacitors, for realizing the time delay attraction or disconnection of the relay through the control signal of the main control unit circuit.

[0008] Optionally, the three-phase live wire inputs are connected to other functional modules of the charger through filtering modules, rectifying modules, PFC modules, DCDC power conversion modules and auxiliary power supply circuits respectively.

[0009] Optionally, each of the phase inputs of the three-phase live wire is connected with a safety Y capacitor.

[0010] Optionally, the capacitance values of the safety Y capacitors are equal, so as to ensure that the potentials between the charger housing and the power supply protection ground are equal, thereby maintaining the charger housing at zero potential.

[0011] Optionally, the main control unit circuit is used to determine the effective value of the three-phase input voltage, and when it is detected that the input protection ground is misconnected to the power supply live wire, an instruction is sent to disconnect the relay, so as to isolate the metal housing of the charger from the power supply live wire.

[0012] Optionally, the relay can be a normally open AC relay, an AC contactor, a magnetic latching relay or a semiconductor element switch, which is used to realize safe communication between the housing protection ground and the input protection ground.

[0013] Optionally, when the input protection ground is correctly connected and the three-phase voltage is normal, the main control unit circuit controls the relay to be attracted, so that the charger enters a normal working mode and returns to normal after a fault is removed.

[0014] Through the above technical solution, by connecting a normally open relay to the internal protection ground wire of the charger and effectively controlling the relay, protection is realized when the input protection ground wire of the vehicle-mounted charger is misconnected to the power supply live wire, the metal housing of the vehicle-mounted charger is isolated from the power supply live wire and safe, and the safety of other low-voltage power supply control devices on the vehicle is also ensured; the added elements are few, the control is simple, and the cost increase is little.

[0015] Other features and advantages of the embodiments of the present application will be described in detail in the following specific implementation manner. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used together with the following specific implementation to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the drawings:

[0017] Figure 1 is a principle schematic diagram of a protection device for misconnection of a three-phase vehicle-mounted charger protection ground to a power supply live wire provided by an embodiment of the present application;

[0018] Figure 2 is a principle schematic diagram of a protection device for misconnection of a three-phase vehicle-mounted charger protection ground to a power supply live wire provided by an embodiment of the present application; Figure 1A circuit diagram of a protection device for protecting ground wire misconnection of live wire power supply of a three-phase AC input vehicle-mounted charger

[0019] Figure 3 A principle block diagram of another protection device for protecting ground wire misconnection of live wire power supply of a three-phase AC input vehicle-mounted charger is provided in an embodiment of the utility model,

[0020] Figure 4 A circuit diagram of another protection device for protecting ground wire misconnection of live wire power supply of a three-phase AC input vehicle-mounted charger is provided in an embodiment of the utility model, Figure 3

[0021] Figure 5 A circuit diagram of another protection device for protecting ground wire misconnection of live wire power supply of a three-phase AC input vehicle-mounted charger is provided in an embodiment of the utility model, DETAILED DESCRIPTION

[0022] The specific embodiments of the utility model embodiments will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the utility model embodiments, and are not used to limit the utility model embodiments.

[0023] In the embodiments of the utility model, unless otherwise stated, the orientation words such as "up, down, left and right" generally refer to the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the utility model product is used.

[0024] The terms "first", "second", "third" and the like are only used for distinction and description, and cannot be understood as indicating or implying relative importance.

[0025] The terms "horizontal", "vertical", "suspension" and the like do not mean that the components must be absolutely horizontal, vertical or suspended, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0026] In addition, the terms "approximately", "substantially" and the like are intended to describe the relevant content and not to require absolute accuracy, but there can be some deviation. For example, "approximately equal" does not mean only absolute equality, because in the actual production and operation process, it is difficult to achieve absolute "equality", and generally there is a certain deviation. Therefore, in addition to absolute equality, "approximately equal" also includes the above-mentioned case of a certain deviation. For example, in other cases, unless otherwise specified, the terms "approximately", "substantially" and the like have the same meaning as above.

[0027] ​In the description of the utility model, still need explaining, unless another explicit provision and limitation, term '' set '', '' install '', '' link '', '' connect '' should do broad sense understanding, for example, can be fixed connection, also can be detachable connection, or integrally connected, can be direct connection, also can indirectly connect through intermediate medium, can be two element inside intercommunication. For ordinary skilled person in the art, can understand the concrete meaning of above-mentioned term in the utility model with specific circumstances.

[0028] Please refer to Figure 1 The embodiment provides a three-phase vehicle-mounted charger protection ground wire misconnection live wire power supply protection device, which comprises an input protection ground wire, a case protection ground, three-phase live wire input and a normally open relay and a control circuit thereof; the normally open relay is connected in series between the input protection ground wire and the case protection ground, and is used for keeping a disconnected state when the input protection ground wire is misconnected to the live wire for power supply.

[0029] In a possible implementation, the three-phase vehicle-mounted charger protection ground wire misconnection live wire power supply protection device comprises a relay, a relay control circuit, an auxiliary power supply output power supply, a main control unit circuit, an approval Y capacitor between input three live wires and a protection ground, a charger metal shell, other filtering, rectification, PFC, DCDC power conversion, auxiliary power supply and detection control processing circuits and the like;

[0030] The Vin_U signal, the Vin_V signal and the Vin_W signal are all live wire inputs, the Vin_PE signal is an input protection ground, and the CASE_PE signal is a charger metal shell ground; the protection ground CASE_PE signal is connected with the charger shell;

[0031] Further, the relay is connected in series between the input protection ground Vin_PE of the vehicle-mounted power supply and the case ground CASE_PE, and is used for realizing the connection and disconnection of the input protection ground wire;

[0032] Further, the charger shell ground CASE_PE is connected with the live wire input Vin_U through a total equivalent approval Y capacitor C1, the charger shell ground CASE_PE is connected with the live wire input Vin_V through a total equivalent approval Y capacitor C2, and the charger shell ground CASE_PE is connected with the live wire input Vin_W through a total equivalent approval Y capacitor C3;

[0033] Further, the three live wire inputs Vin_U, Vin_V and Vin_W of the three-phase input are subjected to power conversion processing through other filtering, rectification, PFC, DCDC power conversion, auxiliary power supply and detection control processing circuits and the like, so that the related functions of the charger are realized;

[0034] Furthermore, the line-to-line voltage between the live wire inputs Vin_U and Vin_V is used by the input voltage detection circuit 1 to generate a sampling signal Use_UV, which is then sent to the main control unit circuit for calculation and processing; the line-to-line voltage between the live wire inputs Vin_U and Vin_W is used by the input voltage detection circuit 1 to generate a sampling signal Use_UW, which is then sent to the main control unit circuit for calculation and processing; the line-to-line voltage between the live wire inputs Vin_V and Vin_W is used by the input voltage detection circuit 1 to generate a sampling signal Use_VW, which is then sent to the main control unit circuit for calculation and processing.

[0035] Furthermore, the main control unit circuit calculates and compares the effective values ​​of the three-phase input voltage detection signals Use_UV, Use_UW, and Use_VW. When it is determined that all three-phase input voltages are normal, it sends a command to the relay control circuit to activate the relay, and the chassis protective ground CASE_PE is connected to the input protective ground Vin_PE. When it is determined that the chassis protective ground is connected to a certain input live wire, it continues to send a command to the relay control circuit to deactivate the relay, maintaining the relay in the deactivated state, effectively preventing the charger chassis from being connected to the high voltage of the input live wire.

[0036] Furthermore, the relay control circuit controls the activation or deactivation of the relay connected in series with the input protective ground wire of the vehicle power supply. The relay control can be analog or digital, and the relay is controlled according to the specific activation or deactivation command given by the main control unit circuit.

[0037] Furthermore, the protective grounding wire is not a fixed connection. To better isolate faults and improve safety performance, the safety capacitance of the AC input section to the protective grounding wire must be ensured. Figure 2 The safety Y capacitors C1, C2, and C3 shown in the diagram represent the total equivalent capacitance of the charger's input Vin_U, Vin_V, and Vin_W lines to CASE_PE. The total capacitance should not be too large to meet the charger's leakage current requirements. The key is to ensure that the values ​​of the safety Y capacitors C1, C2, and C3 are as equal as possible to ensure the safety of personnel from leakage current.

[0038] Furthermore, the control and protection principle of this utility model is explained as follows:

[0039] When the input protection ground of the on-board charger is connected correctly, and the AC input voltage is normal, the main control unit circuit calculates the effective value of the three line-to-line input voltage detection signals Use_UV, Use_UW and Use_VW, the effective values of the three sampling signals should be substantially equal, the main control unit circuit sends a relay attraction instruction to the relay control circuit, the relay control circuit attracts the relay, thereby connecting the protection ground CASE_PE of the on-board charger to the power supply protection ground Vin_PE normally, and entering a normal working mode.

[0040] When the input protection ground of the on-board charger is connected to a power supply live wire, and at the same time, an input live wire is connected to the power supply protection ground, in this case, the effective values of the three line-to-line input voltage detection signals Use_UV, Use_UW and Use_VW will no longer be substantially equal, and the effective value voltage of one of the three lines is about 1.73 times the effective value voltage of the other two lines, the main control unit circuit determines that the input connection is incorrect, and determines that the protection ground is connected to a power supply live wire, the main control unit circuit continues to give a relay disconnection instruction to the relay control circuit, and maintains the relay in a disconnected state, and the protection ground CASE_PE inside the charger is disconnected from the power supply live wire. In this case, the on-board charger shell is not electrified, and the internal circuit of the charger is not damaged.

[0041] Further, since the protection ground is not fixedly connected, in order to better realize fault isolation and improve safety performance, it is necessary to ensure that the safety capacitance capacity of the AC input part to the protection ground cannot be too large to meet the charger leakage current requirement, and the key is to require the safety Y capacitors C1, C2 and C3 to be as equal as possible, and the equivalent safety Y capacitors C1, C2 and C3 are connected in a star type in the charger, when the C1, C2 and C3 capacitor values are equal, the shell protection ground CASE_PE is equal to the potential of the power supply protection ground without being connected to the power supply protection ground, and the potential of the shell protection ground CASE_PE is zero, which can ensure the safety of the charger shell electrification.

[0042] Further, the three live wire inputs Vin_U, Vin_V and Vin_W of the three-phase input are subjected to power conversion processing through other filtering, rectification, PFC, DCDC power conversion, auxiliary power supply and detection control processing circuits, to realize the related functions of the charger.

[0043] In view of the above problems, the utility model also provides another optimization solution Figure 3As shown: a normally open relay is connected in series on the input protection ground of the vehicle power supply. The relay is used to disconnect or connect only the charger shell to the input protection ground Vin_PE. When the protection ground line is misconnected to the power supply live line, the relay maintains the normally open state to confirm that the protection ground line is connected correctly after the normally open relay is attracted.

[0044] Embodiment one:

[0045] Reference Figure 2 As a specific embodiment, it is applicable to normal three-phase 380VAC / 50HZ AC input.

[0046] The entire circuit includes a relay, a relay control circuit, an auxiliary power supply output, a main control unit circuit, an input three live wire to protection ground safety Y capacitor, a charger metal shell, other filtering, rectification, PFC, DCDC power conversion, auxiliary power supply and detection control processing circuit.

[0047] Specifically, the Vin_U signal, the Vin_V signal and the Vin_W signal are live wire inputs, the Vin_PE signal is an input protection ground, the CASE_PE signal is a charger metal shell ground, and the protection ground CASE_PE signal is connected to the charger shell;

[0048] Specifically, the charger shell ground CASE_PE is connected to the live wire input Vin_U through a total equivalent safety Y capacitor C1, the charger shell ground CASE_PE is connected to the live wire input Vin_V through a total equivalent safety Y capacitor C2, and the charger shell ground CASE_PE is connected to the live wire input Vin_W through a total equivalent safety Y capacitor C3.

[0049] Further, the three live wire inputs Vin_U, Vin_V and Vin_W of the three-phase input are processed by other filtering, rectification, PFC, DCDC power conversion, auxiliary power supply and detection control processing circuit to realize the related functions of the charger.

[0050] Specifically, one end of the normally open relay K1 is connected to the input protection ground Vin_PE, and the other end of the normally open relay K1 is connected to the input charger shell protection ground CASE_PE.

[0051] Specifically, one end of the control line package of the normally open relay K1 is connected to the anode of the diode VD1 and the collector of the NPN triode VT1, the other end of the control line package of the normally open relay K1 is connected to the cathode of the diode VD1 and the positive terminal VCC of the power supply, the base of the NPN triode VT1 is connected to one end of the resistor R1, one end of the resistor R2 and one end of the capacitor C4, the other end of the resistor R2, the other end of the capacitor C4 and the emitter of the NPN triode VT1 are connected to the working digital ground GND_D, the other end of the resistor R1 is connected to the relay control signal K1_CTL;

[0052] Specifically, one end of the control line package of the normally open relay K1 is connected to the anode of the diode VD1 and the collector of the NPN triode VT1, the other end of the control line package of the normally open relay K1 is connected to the cathode of the diode VD1 and the positive terminal VCC of the power supply, the base of the NPN triode VT1 is connected to one end of the resistor R1, one end of the resistor R2 and one end of the capacitor C4, the other end of the resistor R2, the other end of the capacitor C4 and the emitter of the NPN triode VT1 are connected to the working digital ground GND_D, the other end of the resistor R1 is connected to the relay control signal K1_CTL;

[0053] Specifically, the hot input Vin_U signal is connected to one end of resistor R19, the other end of resistor R19 is connected to one end of resistor R20, the other end of resistor R20 is connected to one end of resistor R21, the other end of resistor R21 is connected to one end of resistor R22, the other end of resistor R22 is connected to one end of resistor R18, one end of capacitor C12, one end of resistor R28, the 3rd pin of diode VD6 and the 3rd pin of the same direction input terminal of operational amplifier D2A, the other end of resistor R18 is connected to the power supply VCC+3.3VA_PFC, the other end of resistor R28, the other end of capacitor C12, the 1st pin of diode VD6, the 4th pin of operational amplifier D2A and one end of capacitor C9 are connected to working analog ground GND_A, the 2nd pin of diode VD6 and the other end of capacitor C9 are connected to the power supply VCC+5VA_PFC, the hot input Vin_W signal is connected to one end of resistor R23, the other end of resistor R23 is connected to one end of resistor R24, the other end of resistor R24 is connected to one end of resistor R25, the other end of resistor R25 is connected to one end of resistor R26, the other end of resistor R26 is connected to one end of resistor R27, one end of capacitor C10, one end of resistor R17, the 3rd pin of diode VD7 and the 2nd pin of the reverse input terminal of operational amplifier D2A, the other end of resistor R27 and the 1st pin of diode VD7 are connected to working analog ground GND_A, the 2nd pin of diode VD7 is connected to the power supply VCC+5VA_PFC, the other end of capacitor C10, the other end of resistor R17, one end of resistor R16 and the 1st pin of the output terminal of operational amplifier D2A are connected, the other end of resistor R16, one end of capacitor C11 and the 3rd pin of diode VD5 are connected to generate an input voltage sampling signal Use_UW, the other end of capacitor C11 and the 1st pin of diode VD5 are connected to working analog ground GND_A, the 2nd pin of diode VD5 is connected to the power supply VCC+3.3VA_PFC;

[0054] Specifically, the hot input Vin_V signal is connected to one end of resistor R32, the other end of resistor R32 is connected to one end of resistor R33, the other end of resistor R33 is connected to one end of resistor R34, the other end of resistor R34 is connected to one end of resistor R35, the other end of resistor R35 is connected to one end of resistor R31, one end of capacitor C16, one end of resistor R41, the third pin of diode VD9 and the third pin of the same direction input of operational amplifier D3A, the other end of resistor R31 is connected to the power supply VCC+3.3VA_PFC, the other end of resistor R41, the other end of capacitor C16, the first pin of diode VD9, the fourth pin of operational amplifier D3A and one end of capacitor C13 are connected to working analog ground GND_A, the second pin of diode VD9 and the other end of capacitor C13 are connected to the power supply VCC+5VA_PFC, the hot input Vin_W signal is connected to one end of resistor R36, the other end of resistor R36 is connected to one end of resistor R37, the other end of resistor R37 is connected to one end of resistor R38, the other end of resistor R38 is connected to one end of resistor R39, the other end of resistor R39 is connected to one end of resistor R40, one end of capacitor C14, one end of resistor R30, the third pin of diode VD10 and the second pin of the reverse input of operational amplifier D3A, the other end of resistor R40 and the first pin of diode VD10 are connected to working analog ground GND_A, the second pin of diode VD10 is connected to the power supply VCC+5VA_PFC, the other end of capacitor C14, the other end of resistor R30, one end of resistor R29 and the first pin of the output of operational amplifier D3A are connected, the other end of resistor R29, one end of capacitor C15 and the third pin of diode VD8 are connected to generate the input voltage sampling signal Use_VW, the other end of capacitor C15 and the first pin of diode VD8 are connected to working analog ground GND_A, the second pin of diode VD8 is connected to the power supply VCC+3.3VA_PFC;

[0055] Specifically, the input voltage sampling signal Use_UV, the input voltage sampling signal Use_UW, the input voltage sampling signal Use_VW and working analog ground are sent to the main control unit circuit, and after the three input voltage signals are operated and processed by the main control unit circuit, the relay control signal K1_CTL and working digital ground GND_D are output.

[0056] The principle of this embodiment is specifically described as follows:

[0057] When the input protection ground of the on-board charger is connected correctly, and the AC input voltage is normal, the main control unit circuit calculates the effective value of the three line-to-line input voltage detection signals Use_UV, Use_UW and Use_VW. The effective values of the three sampling signals should be substantially equal. The main control unit circuit sends a high-level relay control signal K1_CTL to the relay control circuit. The high-level signal K1_CTL is delayed by the resistor R1, the resistor R2 and the capacitor C4, and then drives the triode VT1 to turn on, thereby attracting the relay K1, connecting the protection ground CASE_PE of the on-board charger to the protection ground Vin_PE of the power supply, and entering the normal working mode. Thereafter, the relay is not actively disconnected when the charger has other faults or alarm conditions.

[0058] When the input protection ground of the on-board charger is connected to a power supply live wire, and at the same time one of the input live wires is connected to the protection ground of the power supply, the effective values of the three line-to-line input voltage detection signals Use_UV, Use_UW and Use_VW will no longer be substantially equal. The effective value voltage of one of the lines is about 1.73 times the effective value voltage of the other two lines. The main control unit circuit determines that the input connection is incorrect, and that the input protection ground is mistakenly connected to a power supply live wire. The main control unit circuit continues to give a low-level relay command K1_CTL to the relay control circuit, and the triode VT1 remains off. The relay K1 remains in the open state, and the protection ground CASE_PE inside the charger is disconnected from the power supply live wire. In this case, the on-board charger shell is not electrified, and the internal circuit of the charger is not damaged. After the input line of the on-board power supply is correctly connected, the charger can work normally.

[0059] Embodiment Two

[0060] As Figure 3 , the technical solution of this embodiment is basically the same as the control circuit and principle of the technical solution Figure 1 . The specific solution is not repeated. The difference is that in the solution Figure 1 , the relay is only used to control the connection or disconnection between the shell and the input protection ground. Since the shell itself is not directly connected to the input part of the equivalent total capacitance C1, C2 and C3, there is no special requirement for the input Y capacitor of the on-board charger. However, it needs to meet the requirements of the on-board power supply input Y capacitor leakage current to the ground, or the requirements of the specific customer for this index.

[0061] Specifically, as Figure 4The embodiment is applicable to normal AC input of three-phase 380VAC / 50HZ. The overall circuit includes a normally open relay, a relay control circuit, an auxiliary power supply, a main control unit circuit, an approval Y capacitor between the three-phase live line input Vin_U, Vin_V and Vin_W and the protection ground, and a charger metal shell. The remaining circuit also includes filtering, rectification, PFC (power factor correction), DCDC power conversion, an auxiliary power supply, and a detection control processing circuit.

[0062] 1) The signal connection Vin_U, Vin_V and Vin_W signal is a three-phase live line input, Vin_PE is an input protection ground, and CASE_PE is a charger metal shell ground. The protection ground CASE_PE is connected to the charger shell through a relay.

[0063] 2) Approval Y capacitor: The approval Y capacitors C1, C2 and C3 are respectively connected between the charger shell protection ground CASE_PE and the live line input Vin_U, Vin_V and Vin_W, for ensuring that the leakage current meets the safety standards.

[0064] 3) Power supply circuit and conversion: After the three-phase live line Vin_U, Vin_V and Vin_W pass through filtering, rectification, PFC, DCDC power conversion, etc., the charger can work normally.

[0065] 4) Relay control: The normally open relay K1 is used for the connection and disconnection of the protection ground. One side of the control end of the relay K1 is connected to the anode of the diode VD1 and the collector of the NPN triode VT1, and the other side is connected to the cathode of the diode VD1 and the positive end VCC of the power supply. The base of the NPN triode VT1 is connected to the relay control signal K1_CTL through the resistor R1, the resistor R2 and the capacitor C4. The emitter of VT1 is connected to the working digital ground GND_D.

[0066] 5) Voltage sampling and main control: The line voltage between each live line is sampled by the detection circuit to generate signals Use_UV, Use_UW and Use_VW, which are transmitted to the main control unit for effective value calculation. If the calculation result shows that the voltage is abnormal, the main control unit issues a relay disconnection instruction to ensure that the protection ground CASE_PE is disconnected from the input live line.

[0067] 6) Control protection logic: When the input protection ground is connected to a certain live line and a certain live line is connected to the power supply protection ground, the detection signal effective value will not be equal, and the voltage effective value of a certain line is 1.73 times that of the other two lines. At this time, the main control unit issues a relay disconnection instruction to keep CASE_PE and the live line isolated.

[0068] 7) Restore to normal mode: After detecting that the three-phase input voltage is normal and the input protection is properly connected, the main control unit circuit sends a command to the latching relay, the relay is attracted, CASE_PE is connected with Vin_PE, and the charger enters the normal working mode.

[0069] As Figure 5 , to correspond Figure 2 , Figure 3 The circuit schematic diagram of the input voltage detection circuit 1, the input voltage detection circuit 2 and the input voltage detection circuit 3 is shown in the following figure. The specific description is as follows:

[0070] 1) Hot wire input and sampling resistance: The hot wire inputs Vin_U, Vin_V and Vin_W are connected through a series of resistors (such as R6 to R9, R10 to R14, etc.) to form a voltage dividing network, thereby reducing the voltage and providing corresponding sampling signals.

[0071] 2) Filtering and rectification: A filtering capacitor (such as C5, C6, etc.) and a rectifier diode (such as VD2, VD3, etc.) are arranged on each sampling line to ensure the stability of the sampling signal and avoid the influence of voltage fluctuations on the sampling accuracy.

[0072] 3) Operational amplifier configuration: The sampling signals are processed by operational amplifiers (such as D1A, D2A, D3A), and the amplified and filtered signals are used to generate input voltage detection signals Use_UV, Use_UW and Use_VW, which correspond to the voltages between Vin_U and Vin_V, Vin_U and Vin_W, and Vin_V and Vin_W, respectively.

[0073] 4) Output and main control unit connection: The generated signals Use_UV, Use_UW, Use_VW are transmitted to the main control unit circuit, and the main control unit calculates the effective value based on these signals to determine whether the three-phase input voltage is normal, so as to decide whether to attract or disconnect the relay and realize the protection function.

[0074] The above describes the optional implementation of the embodiments of the present application in detail in combination with the drawings, but the embodiments of the present application are not limited to the specific details in the above implementation. Within the technical concept of the embodiments of the present application, the technical solution of the embodiments of the present application can be variously modified, and these simple modifications all belong to the protection scope of the embodiments of the present application.

[0075] In addition, it should be noted that each specific technical feature described in the above specific implementation can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the embodiments of the present application do not further describe various possible combinations.

[0076] Those skilled in the art can understand that all or part of the steps of the methods in the above embodiments can be completed by a program instructing relevant hardware, the program is stored in a storage medium, and the program includes a plurality of instructions for enabling a single-chip microcomputer, a chip or a processor to execute all or part of the steps of the methods described in various embodiments of the present application. The foregoing storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk and various storage medium capable of storing program codes.

[0077] In addition, various different embodiments of the present application can be combined arbitrarily, as long as they do not deviate from the spirit of the present application, and should be considered as disclosed by the present application.

Claims

1. A protection device for protecting the ground wire of a three-phase on-board charger from being mistakenly supplied with live current, characterized in that The three-phase vehicle-mounted charger protection device for protecting the ground wire from being connected to the live wire for power supply includes: an input protection ground wire, a chassis protection ground, three-phase live wire inputs, and a normally open relay and its control circuit; the normally open relay is connected in series between the input protection ground wire and the chassis protection ground, and is used to keep the state of disconnection when the input protection ground wire is connected to the live wire for power supply by mistake.

2. The protection device for protecting ground line of three-phase on-board charger from being connected to live line of power supply according to claim 1, characterized in that, The three-phase vehicle-mounted charger protection device for protecting the ground wire from being connected to the live wire for power supply further includes: a main control unit circuit, which is used to receive an input voltage signal from a voltage detection circuit between the three-phase live wire inputs, and determine the state of the three-phase input voltage based on the signal to control the connection or disconnection of the relay.

3. The protection device for protecting ground fault of three-phase on-board charger according to claim 2, characterized in that, The voltage detection circuit generates a line-to-line voltage signal between the three-phase live wire inputs, and transmits the line-to-line voltage signal to the main control unit circuit, so that the main control unit circuit determines the connectivity of the three-phase voltage based on the effective value of the line-to-line voltage signal.

4. The protection device for protecting ground fault of three-phase on-board charger according to claim 1, characterized in that, The control circuit of the normally open relay includes: an NPN triode, multiple resistors, and multiple capacitors, which are used to realize the time-delay closing or opening of the relay through the control signal of the main control unit circuit.

5. The protection device for protecting ground fault of three-phase on-board charger according to claim 4, characterized in that, The three-phase live wire inputs are connected to other functional modules of the charger through a filtering module, a rectifying module, a PFC module, a DC / DC power conversion module, and an auxiliary power supply circuit, respectively.

6. The three-phase on-board charger protection device that protects ground miswiring with hot in accordance with claim 1, wherein, An approval Y capacitor is connected between the chassis protection ground and each phase of the three-phase live wire input.

7. The protection device for protecting ground fault of three-phase on-board charger according to claim 6, characterized in that, The capacitance values of the approval Y capacitors are equal to ensure that the potential between the charger chassis protection ground and the power supply protection ground is equal, thereby maintaining the chassis in a zero potential state.

8. The protection device for protecting ground fault of three-phase on-board charger according to claim 4, characterized in that, The main control unit circuit is used to determine the effective value of the three-phase input voltage, and when it detects that the input protection ground is connected to the live wire for power supply by mistake, it issues an instruction to disconnect the relay to isolate the metal chassis of the charger and the live wire for power supply.

9. The three-phase on-board charger protection device of claim 8, wherein, The relay can be a normally open AC relay, an AC contactor, a magnetic latching relay, or a semiconductor element switch, which is used to realize the safe connection between the chassis protection ground and the input protection ground.

10. The protection device for a three-phase on-board charger that protects the ground wire from being mistakenly supplied with power from the hot line according to claim 1, characterized by, When the input protection ground is connected correctly and the three-phase voltage is normal, the main control unit circuit controls the relay to be closed, so that the charger enters a normal working mode, and returns to normal after the fault is removed.

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