An AC charging pile connector contact adhesion fault detection circuit and method

Abstract

The present invention discloses a contact adhesion fault detection circuit for an AC charging pile connector. The circuit includes a on-off control circuit, an L-phase adhesion detection circuit, and an N-phase adhesion detection circuit. The L-phase adhesion detection circuit is arranged on the output side L line side of its on-off control circuit and is used to detect whether the L line is adhered when the connector is disconnected. The N-phase adhesion detection circuit is arranged on the output side N line side of its on-off control circuit and is used to detect whether the N line is adhered when the connector is disconnected. The L phase of the connector generates a digital signal indicating whether there is adhesion through electromagnetic induction and signal amplification, and the N phase of the connector generates an analog signal indicating whether there is adhesion through relay startup and transformer isolation sampling. The present invention can detect the adhesion faults of the L phase and N phase of the charging pile connector without contact, and the detection circuit has low power consumption, high measurement instantaneity, and high stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric vehicle charging piles, and particularly relates to a detection circuit and method for the adhesion fault of the contacts of an AC charging pile connector. Background Art

[0002] More and more electric vehicles are entering thousands of households. As one of the energy replenishment devices for electric vehicles, AC charging piles for electric vehicles are widely installed in private parking spaces and operation stations. When the AC charging pile for electric vehicles is not starting to charge or after charging is completed, the connector inside it should be in a disconnected state, and the charging gun that the user touches is in a state without high voltage, which is relatively safe. During the use of the AC charging pile, due to accidental start / stop or internal component failures, the phenomenon of contact adhesion of the connector may occur. When the connector is in an adhered state, the charging gun should originally be in a state where the circuit is disconnected and there is no high voltage, but actually carries a voltage of 220Vac / 380Vac, which will pose an electric shock risk to the users, and the charging pile cannot charge and replenish energy for the electric vehicle. Summary of the Invention

[0003] To achieve the above object, the present invention provides a detection circuit for the adhesion fault of the contacts of an AC charging pile connector. Through the detection circuit for the adhesion fault of the contacts of the connector, adhesion faults such as single-contact adhesion and double-contact adhesion can be effectively and timely detected, an alarm can be given in time, and the charging service can be stopped. It can effectively avoid damage to the users or electric vehicles, and remind the user to repair or replace the AC charging pile in time. Specifically, the circuit includes a on-off control circuit, an L-phase adhesion detection circuit, and an N-phase adhesion detection circuit.

[0004] The L-phase adhesion detection circuit is arranged on the output side L line side of its on-off control circuit, and is used to detect whether there is adhesion on the L line when the connector is disconnected; the N-phase adhesion detection circuit is arranged on the output side N line side of its on-off control circuit, and is used to detect whether there is adhesion on the N line when the connector is disconnected.

[0005] The L-phase of the connector generates a digital signal indicating whether there is adhesion through electromagnetic induction and signal amplification, and the N-phase of the connector generates an analog signal indicating whether there is adhesion through relay startup and transformer isolation sampling.

[0006] Based on the above technical solution, the L-phase detection circuit and the N-phase detection circuit are electrically completely isolated and will not reduce the insulation level between the two phases.

[0007] As an improvement of the present invention, the on-off control circuit includes a freewheeling diode VD1, a power relay K1, a resistor R1, and an NPN transistor V1. One end of the resistor R1 is connected to the control signal Sw1, and the other end is connected to the base of the NPN transistor V1. The collector of the NPN transistor V1 is connected to one end of the power relay K1 and the anode of the freewheeling diode VD1, and its emitter is grounded. The other end of the power relay K1 is connected to the cathode of the freewheeling diode VD1.

[0008] As an improvement of the present invention, the N-phase electromagnetic induction detection circuit includes a relay K3, a freewheeling diode VD3, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C2, an NPN transistor V7, a voltage transformer PT1, and an induction coil L1.

[0009] One end of the resistor R3 and one end of the capacitor C2 are connected to the control signal Sw2. The other end of the capacitor C2 is connected to the emitter of the NPN transistor V7. The base of the NPN transistor V7 is connected to the other end of the resistor R3. The collector of the NPN transistor V7 is connected to the second port of the relay K3 and the anode of the freewheeling diode VD3. The cathode of the freewheeling diode VD3 is connected to the first port of the relay K3. The fourth port of the relay K3 is connected to the first port of the voltage transformer PT1. One end of the resistor R4 is connected, and the other end is connected to one end of the resistor R5. The other end of the resistor R5 is connected to one end of the resistor R6. The other end of the resistor R6 is connected to the second port of the voltage transformer PT1. One end of the resistor R7 is connected to the third port of the voltage transformer PT1 and the induction coil L1, and the other end is connected to the fourth port of the voltage transformer PT1.

[0010] As an improvement of the present invention, the L-phase electromagnetic induction detection circuit includes an induction coil L2, NPN transistors V3, V4, V5, and V6.

[0011] One end of the induction coil L2 is connected to the base of the NPN transistor V3. The emitter of the NPN transistor V3 is connected to the base of the NPN transistor V4. The emitter of the NPN transistor V5 is connected to one end of the resistor R8. The emitter of the NPN transistor V5 is grounded and the emitters of the NPN transistors V6. The base of the NPN transistor V6 is connected to the other end of the resistor R8. The collector of the NPN transistor V6 is connected to one end of the resistor R9 and one end of the capacitor C3. The other end of the capacitor C3 is connected to the emitters of the NPN transistors V5 and V6.

[0012] As an improvement of the present invention, the on-off control circuit further includes a capacitor C1. One end of the capacitor C1 is connected to one end of the resistor R1, and the other end is connected to the ground and the emitter of the NPN transistor V1.

[0013] As an improvement of the present invention, a method for detecting the contact adhesion fault of the AC charging pile connector based on the detection circuit, the method includes the following steps:

[0014] Step 1) Determine whether the relay control is disconnected or not.

[0015] Step 2) After the relay control is disconnected, determine the relay disconnection delay.

[0016] Step 3) After the relay disconnection delay for a certain time, the main processing chip performs signal acquisition and detection, and then outputs a judgment result.

[0017] As an improvement of the present invention, in step 3), after the relay K1 moves from being attracted to being disconnected, the main processing chip makes a judgment according to the control signal Sw1 and the input signal VL_ki. When the control signal Sw1 is set low and the input signal VL_ki is set low, it is judged that the L phase is adhered, otherwise it is in a non-adhered state.

[0018] As an improvement of the present invention, in step 3), after the relay K2 moves from being attracted to being disconnected, the control signal Sw2 is high. When the main processing chip acquires a non-zero power frequency signal of the signal Vn_adc, it is determined that the N phase is adhered, otherwise it is in a non-adhered state.

[0019] As an improvement of the present invention, when the relay K1 is disconnected and the contact is in an adhered state, a power frequency electromagnetic signal appears at the terminal block, and an induced voltage is generated in the L2 coil. The induced voltage is amplified by the NPN transistors V3, V4 and V5. The NPN transistor V6 is in a conducting state, and the voltage of the input signal VL_ki is low. The main processing chip makes a judgment according to the control signal Sw1 and the input signal VL_ki. When the control signal Sw1 is set low and the input signal VL_ki is set low, it is judged that the L phase is adhered.

[0020] As an improvement of the present invention, when the relay K2 is disconnected and the contact has an adhesion fault, the main processor control signal Sw2 is high, the NPN transistor V7 is conducting, the relay K3 is attracted, the circuit works, and the secondary side Vn_adc signal of the current transformer PT1 is a non-zero power frequency signal. When the K2 relay is disconnected, the control signal Sw2 signal is high, and when the main processing chip acquires the Vn_adc signal as a non-zero power frequency signal, it is determined that the N phase is adhered.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1) The innovation of the present invention is that through electromagnetic induction technology, weak power frequency electromagnetic signals can be amplified, and the adhesion fault of the L phase of the charging pile connector can be detected without contact. The detection circuit has low power consumption, high measurement instantaneity and high stability;

[0023] 2) Through electromagnetic induction sampling technology, the N-phase adhesion fault of the charging pile connector can be detected in an isolated manner. The detection circuit is controllable, with high instantaneity and accurate precision.

[0024] 3) The two sets of detection circuits are isolated from each other and from the primary power supply side, and will not have any impact on the phase insulation and the insulation performance at both ends of the break point. Description of the Drawings

[0025] Figure 1 It is the system architecture diagram of the detection circuit described in the present invention.

[0026] Figure 2 It is the circuit diagram of the N-phase on-off control described in the present invention.

[0027] Figure 3 It is the circuit diagram of the L-phase on-off control described in the present invention.

[0028] Figure 4 It is the circuit diagram of the N-phase adhesion detection described in the present invention.

[0029] Figure 5 It is the circuit diagram of the L-phase adhesion detection described in the present invention.

[0030] Figure 6 It is the schematic diagram of the detection method process described in the present invention. Detailed Embodiments

[0031] The following further clarifies the present invention in conjunction with the drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0032] Embodiment: An AC charging pile connector contact adhesion fault detection circuit, the circuit includes an on-off control circuit, an L-phase adhesion detection circuit and an N-phase adhesion detection circuit. The L-phase adhesion detection circuit is arranged on the output side L line side of its on-off control circuit, and is used to detect whether there is adhesion on the L line when the connector is disconnected; the N-phase adhesion detection circuit is arranged on the output side N line side of its on-off control circuit, and is used to detect whether there is adhesion on the N line when the connector is disconnected; the L-phase of the connector generates a digital signal indicating adhesion or not through electromagnetic induction and signal amplification, and the N-phase of the connector generates an analog signal indicating adhesion or not through relay activation and transformer isolation sampling. The L-phase detection circuit and the N-phase detection circuit are electrically completely isolated and will not reduce the insulation level between the two phases.

[0033] As Figure 1As shown in the figure, the main processing chip controls the relay K1 and K2 to conduct by setting the Sw1 signal high. When conducting, the L outgoing terminal is connected to the L incoming terminal, and the N outgoing terminal is connected to the N incoming terminal. The LN two phases on the output side have an AC220V voltage. When the main processing chip sets the Sw1 signal low to control the relay K1 and K2 to disconnect, the L outgoing terminal is completely electrically disconnected from the L outgoing terminal, and the N outgoing terminal is completely electrically disconnected from the N incoming terminal. There is no voltage on the LN two phases on the output side. On the L line side of the output side, an electromagnetic induction coil and its detection circuit are arranged. When the connector (contactor or relay) is disconnected, it can detect whether there is an adhesion phenomenon on the L line and output a digital signal VL_ki. On the N line side of the output side, a relay and an AC electromagnetic sampling circuit are arranged. When the connector (contactor or relay) is disconnected, it can detect whether there is an adhesion phenomenon on the N line and output an analog signal VN_adc. The main processing chip determines whether L-phase adhesion, N-phase adhesion, or LN adhesion occurs by discriminating the VL_ki and VN_adc signals.

[0034] As Figure 2 shown, the N-phase on-off control circuit includes a freewheeling diode VD2, a power relay K2, a resistor R2, and an NPN transistor V2. One end of the resistor R2 is connected to the signal Sw2, and the other end is connected to the base of the NPN transistor V2. The collector of the NPN transistor V2 is connected to one end of the power relay K2 and the anode of the freewheeling diode VD2. Its emitter is grounded, and the other end of the power relay K2 is connected to the cathode of the freewheeling diode VD2.

[0035] As Figure 3 shown, the L-phase on-off control circuit includes a freewheeling diode VD1, a power relay K1, a resistor R1, and an NPN transistor V1. One end of the resistor R1 is connected to the signal Sw1, and the other end is connected to the base of the NPN transistor V1. The collector of the NPN transistor V1 is connected to one end of the power relay K1 and the anode of the freewheeling diode VD1. Its emitter is grounded, and the other end of the power relay K1 is connected to the cathode of the freewheeling diode VD1. A capacitor C1 is also included. One end of the capacitor C1 is connected to one end of the resistor R1, and the other end is connected to the ground and the emitter of the NPN transistor V1.

[0036] The on-off control circuit of the charging pile connector works as follows:

[0037] 1) Sw1 is the main control signal, R1 / R2 are current-limiting resistors, V1 / V2 are NPN switching transistors, K1 / K2 are power relays with a contact capacity of 40A, and VD1 / VD2 are freewheeling diodes;

[0038] 2) When the Sw1 signal is set low, the V1 / V2 triodes are not conducting, the K1 / K2 relay coils do not operate, the contacts are open, there is no connection between UL_in and UL_out, no connection between UN_in and UN_out, and there is no voltage between UL_out and UN_out;

[0039] 3) When the Sw1 signal is set high, the V1 / V2 triodes conduct, the K1 / K2 relay coils operate, the contacts close, UL_in and UL_out are conducting, UN_in and UN_out are conducting, and there is AC220V voltage between UL_out and UN_out;

[0040] 4) When the phenomenon of relay contact adhesion occurs, the main control signal Sw1 is set low, the relay coil does not operate, but the relay contacts are in a connected state.

[0041] As Figure 4 shown, the N-phase electromagnetic induction detection circuit includes relay K3, freewheeling diode VD3, resistor R3, resistor R4, resistor R5, resistor R6, resistor R7, capacitor C2, NPN transistor V7, voltage transformer PT1 and induction coil L1,

[0042] One end of the resistor R3 and one end of the capacitor C2 are connected to the signal Sw2. The other end of the capacitor C2 is connected to the emitter of the NPN transistor V7. The base of the NPN transistor V7 is connected to the other end of the resistor R3. The collector of the NPN transistor V7 is connected to the second port of the relay K3 and the anode of the freewheeling diode VD3. The cathode of the freewheeling diode VD3 is connected to the first port of the relay K3. The fourth port of the relay K3 is connected to the first port of the voltage transformer PT1. One end of the resistor R4 is connected, and its other end is connected to one end of the resistor R5. The other end of the resistor R5 is connected to one end of the resistor R6. The other end of the resistor R6 is connected to the second port of the voltage transformer PT1. One end of the resistor R7 is connected to the third port of the voltage transformer PT1 and the induction coil L1, and its other end is connected to the fourth port of the voltage transformer PT1.

[0043] The working principle of the N-phase detection circuit is as follows:

[0044] 1) The Sw2 of the circuit is the control signal of the main processor. When the signal is set low, the transistor V7 does not conduct, the K3 relay does not pull in, the circuit does not work, there is no voltage on the primary side of the transformer PT1, and the secondary side Vn_adc signal is 0V;

[0045] 2) When the relay K2 is open, the circuit is disconnected, there is no voltage between UL_in and UN_out. The main processor controls Sw2 to be high, the transistor V7 conducts, the K3 relay pulls in, the circuit works, there is no voltage on the primary side of the transformer PT1, so the secondary side Vn_adc signal is 0V;

[0046] 3) When the relay K2 is disconnected and the contacts have an adhesion fault, there is an AC220V voltage between UL_in and UN_out. The main processor controls Sw2 to be high, the triode V7 conducts, the K3 relay is energized, the circuit works, and there is an AC220V voltage on the primary side of the current transformer PT1. Therefore, the Vn_adc signal on the secondary side is a power frequency signal of 733mV;

[0047] 4) When the K2 relay is disconnected, the Sw2 signal is high. The main processor collects that the Vn_adc signal is a non-zero power frequency signal and determines that the N phase is adhered;

[0048] As Figure 5 shown, the L-phase electromagnetic induction detection circuit includes an induction coil L2, NPN transistors V3, V4, V5, and V6.

[0049] One end of the induction coil L2 is connected to the base of the NPN transistor V3. The emitter of the NPN transistor V3 is connected to the base of the NPN transistor V4. The emitter of the NPN transistor V5 is connected to one end of the resistor R8. The emitter of the NPN transistor V5 is grounded and connected to the emitters of the NPN transistor V6. The base of the NPN transistor V6 is connected to the other end of the resistor R8. The collector of the NPN transistor V6 is connected to one end of the resistor R9 and one end of the capacitor C3. The other end of the capacitor C3 is connected to the emitters of the NPN transistor V5 and the NPN transistor V6.

[0050] The working principle of the L-phase detection circuit is as follows:

[0051] 1) The L2 induction coil of the circuit is arranged close to the UL_out terminal block;

[0052] 2) When the relay K1 is disconnected, the circuit is disconnected, there is no voltage at UL_out, no power frequency electromagnetic signal, the induced voltage of the L2 coil is 0, the NPN transistors V3 / NPN transistor V4 / NPN transistor V5 are all in the off state, and the NPN transistor V6 is in the off state. The voltage of VL_ki is high;

[0053] 3) When the relay K1 is energized, the circuit is conducting, there will be an AC220V power frequency voltage at UL_out, there is a power frequency electromagnetic signal at the terminal block, the L2 coil generates an induced voltage, the induced voltage is amplified by the V3 / V4 / V5 transistors, and the NPN transistor V6 is in the on state. The voltage of VL_ki is low;

[0054] 4) When the relay K1 is disconnected, but the contacts are in a stuck state, UL_out will have an AC220V power frequency voltage, and a power frequency electromagnetic signal will appear at the terminal block. An induced voltage will be generated in the L2 coil. The induced voltage is amplified by the NPN transistors V3 / NPN transistor V4 / NPN transistor V5, and the NPN transistor V6 is in a conducting state, and the voltage of VL_ki is low;

[0055] 5) The main processing chip makes a judgment based on the control signal Sw1 and the input signal VL_ki. When the control signal Sw1 is set low and the input signal VL_ki is set low, it is judged that the L phase is stuck.

[0056] As Figure 6 shown, after the relay K1 moves from being pulled in to being disconnected, the main processing chip makes a judgment based on the control signal Sw1 and the input signal VL_ki. When the control signal Sw1 is set low and the input signal VL_ki is set low, it is judged that the L phase is stuck, otherwise it is in a non-stuck state. After the K2 relay moves from being pulled in to being disconnected, the main processor controls the Sw2 signal to be high. When the main processor collects that the Vn_adc signal is a non-zero power frequency signal, it is determined that the N phase is stuck, otherwise it is in a non-stuck state.

[0057] It should be noted that the above content only illustrates the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches all fall within the protection scope of the claims of the present invention.

Claims

1. An AC charging pile connector contact adhesion fault detection circuit, characterized in that The circuit includes an on-off control circuit, an L-phase adhesion detection circuit, and an N-phase adhesion detection circuit. The L-phase adhesion detection circuit is arranged on the output side L line side of its on-off control circuit and is used to detect whether the L line is adhered when the connector is disconnected; the N-phase adhesion detection circuit is arranged on the output side N line side of its on-off control circuit and is used to detect whether the N line is adhered when the connector is disconnected; The L phase of the connector generates a digital signal indicating whether there is adhesion through electromagnetic induction and signal amplification, and the N phase of the connector generates an analog signal indicating whether there is adhesion through relay startup and transformer isolation sampling. The N-phase adhesion detection circuit includes a relay K3, a freewheeling diode VD3, resistors R3, R4, R5, R6, R7, a capacitor C2, an NPN transistor V7, a voltage transformer PT1, and an induction coil L1. One end of the resistor R3 and one end of the capacitor C2 are connected to the control signal Sw2. The other end of the capacitor C2 is connected to the emitter of the NPN transistor V7. The base of the NPN transistor V7 is connected to the other end of the resistor R3. The collector of the NPN transistor V7 is connected to the second port of the relay K3 and the anode of the freewheeling diode VD3. The cathode of the freewheeling diode VD3 is connected to the first port of the relay K3. The fourth port of the relay K3 is connected to the first port of the voltage transformer PT1. One end of the resistor R4 is connected to the output terminal block, and its other end is connected to one end of the resistor R5. The other end of the resistor R5 is connected to one end of the resistor R6. The other end of the resistor R6 is connected to the second port of the voltage transformer PT1. One end of the resistor R7 is connected to the third port of the voltage transformer PT1 and the induction coil L1, and its other end is connected to the fourth port of the voltage transformer PT1. The L-phase adhesion detection circuit includes an induction coil L2, NPN transistors V3, V4, V5, and V6. One end of the induction coil L2 is connected to the base of the NPN transistor V3. The emitter of the NPN transistor V3 is connected to the base of the NPN transistor V4. The collector of the NPN transistor V3 is connected to the +12V voltage. The emitter of the NPN transistor V4 is connected to the base of the NPN transistor V5. The collector of the NPN transistor V4 is connected to the +12V voltage. The collector of the NPN transistor V5 is connected to one end of the resistor R8 and the +12V voltage. The emitter of the NPN transistor V5 is grounded, the emitter of the NPN transistor V6, and one end of the capacitor C3. The base of the NPN transistor V6 is connected to the other end of the resistor R8. The collector of the NPN transistor V6 is connected to one end of the resistor R9 and the other end of the capacitor C3.

2. The contact adhesion fault detection circuit of an AC charging pile connector according to claim 1, wherein The on-off control circuit includes a freewheeling diode VD1, a power relay K1, a resistor R1, and an NPN transistor V1. One end of the resistor R1 is connected to the control signal Sw1, and its other end is connected to the base of the NPN transistor V1. The collector of the NPN transistor V1 is connected to one end of the power relay K1 and the anode of the freewheeling diode VD1, and its emitter is grounded. The other end of the power relay K1 is connected to the cathode of the freewheeling diode VD1.

3. The contact adhesion fault detection circuit of an AC charging pile connector according to claim 2, characterized in that, The on-off control circuit further includes a capacitor C1. One end of the capacitor C1 is connected to one end of the resistor R1, and the other end is connected to the ground and the emitter of the NPN transistor V1.

4. A method for detecting the contact adhesion fault of the AC charging pile connector based on the detection circuit according to any one of claims 1 to 3, characterized in that, The method includes the following steps: Step 1) Determine whether the relay control is off or not. Step 2) After the relay control is off, determine the relay off delay. Step 3) After the relay off delay for a certain time, the main processing chip performs signal acquisition and judgment, and outputs the judgment result.

5. The method for detecting the contact adhesion fault of the AC charging pile connector according to claim 4, wherein, In Step 3), after the relay K1 moves from being attracted to being off, the main processing chip makes a judgment according to the control signal Sw1 and the input signal VL_ki. When the control signal Sw1 is set low and the input signal VL_ki is set low, it is judged that the L phase is stuck, otherwise it is in a non-stuck state.

6. The method for detecting the adhesion fault of the AC charging pile connector contacts according to claim 5, characterized in that In Step 3), after the relay K2 moves from being attracted to being off, the control signal Sw2 is high. When the main processing chip acquires that the signal Vn_adc is a non-zero power frequency signal, it is determined that the N phase is stuck, otherwise it is in a non-stuck state.

7. The method for detecting the adhesion fault of the AC charging pile connector contacts according to claim 6, wherein When the relay K1 is off and the contact is in a stuck state, a power frequency electromagnetic signal appears at the terminal block, and an induced voltage is generated in the L2 coil. After being amplified by the NPN transistors V3, V4, and V5, the NPN transistor V6 is in a conducting state, and the voltage of the input signal VL_ki is low. The main processing chip makes a judgment according to the control signal Sw1 and the input signal VL_ki. When the control signal Sw1 is set low and the input signal VL_ki is set low, it is judged that the L phase is stuck.

8. The method for detecting the contact adhesion fault of the AC charging pile connector according to claim 7, wherein, When the relay K2 is off and the contact has a sticking fault, the main processor control signal Sw2 is high, the NPN transistor V7 is conducting, the relay K3 is attracted, the circuit works, and the secondary side signal Vn_adc of the transformer PT1 is a non-zero power frequency signal. When the K2 relay is off, the control signal Sw2 is high, and when the main processing chip acquires that the signal Vn_adc is a non-zero power frequency signal, it is determined that the N phase is stuck.

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