An electric vehicle charging pile anti-creeping control circuit

Abstract

The utility model discloses an electric vehicle charging pile anti -electric leakage control circuit relates to charging pile field, and this electric vehicle charging pile anti -electric leakage control circuit includes: DC power supply, electric leakage monitoring device, controller, electric leakage alarm cut -off circuit, main control switch, switch power supply circuit and power supply control circuit, electric leakage alarm cut -off circuit includes: electric leakage cut -off switch, electric leakage prompt drive circuit and alarm, commercial power is connected to electric leakage cut -off switch input end, and electric leakage cut -off switch output end is connected to main control switch input end, and main control switch output end is the power supply output end of electric vehicle charging pile, and the first output end of DC power supply is powered for alarm and electric leakage cut -off switch through electric leakage prompt drive circuit, and controller first output end is connected to electric leakage prompt drive circuit control end. This electric vehicle charging pile anti -electric leakage control circuit solves the problem that cannot realize electric leakage detection in the prior art.

Description

Technical Field

[0001] This utility model relates to the field of charging piles, specifically to a leakage protection control circuit for electric vehicle charging piles. Background Technology

[0002] In existing technology, electric vehicle charging piles include: a DC power supply, a relay RL1, a controller, and a coil drive circuit. The relay RL1 has its input terminals connected to the AC power lines L and N, and its output terminals L1 and N1 connected to the charging gun of the electric vehicle charging pile. The DC power supply powers the relay RL1 through the coil drive circuit. The control terminal of the coil drive circuit is connected to the output terminal of the controller. When the controller detects an external power demand through a switch or other means, it controls the coil in the relay RL1 to operate, thereby achieving the opening and closing action and preventing arbitrary power supply.

[0003] Although the above-mentioned electric vehicle charging pile has the function of controlling power supply, there is still a problem: when there is no power supply demand, there is still voltage output near the output terminal of relay RL1, resulting in leakage. Therefore, how to detect leakage is an urgent problem to be solved in this application. Utility Model Content

[0004] This utility model aims to provide a leakage current prevention control circuit for electric vehicle charging piles, solving the problem that leakage current detection cannot be achieved in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This utility model discloses a leakage current prevention control circuit for electric vehicle charging piles, including: a DC power supply, a leakage current monitoring device, a controller, a leakage current alarm cut-off circuit, a main control switch, a switch power supply circuit, and a power supply control circuit; the leakage current alarm cut-off circuit includes: a leakage current cut-off switch, a leakage current indication drive circuit, and an alarm. Mains power is connected to the input terminal of the leakage current cut-off switch, and the output terminal of the leakage current cut-off switch is connected to the input terminal of the main control switch. The output terminal of the main control switch is the power supply output terminal of the electric vehicle charging pile. The first output terminal of the DC power supply supplies power to the alarm and the leakage current cut-off switch through the leakage current indication drive circuit. The first output terminal of the controller is connected to the control terminal of the leakage current indication drive circuit. The first output terminal of the DC power supply is powered through the switch power supply circuit, and the second output terminal of the controller is connected to the control terminal of the switch power supply circuit through the power supply control circuit. The leakage current monitoring device includes: a current sensing coil, a Hall sensor, and a signal processing circuit. The current sensing coil is installed at the power supply output terminal of the electric vehicle charging pile, and a Hall sensor is installed at the current sensing coil. The output terminal of the Hall sensor is connected to the input terminal of the signal processing circuit, and the output terminal of the signal processing circuit is connected to the input terminal of the controller.

[0007] Preferably, the signal processing circuit includes an amplification module and a comparison module. The input terminal of the amplification module is connected to the output terminal of the Hall sensor, the output terminal of the amplification module is connected to the input terminal of the comparison module, and the output terminal of the comparison module is the output terminal of the signal processing circuit.

[0008] Preferably, the power supply control circuit includes: resistors R1, R3, and R4, transistor Q1, capacitor C1, and optocoupler U1. The first end of resistor R4 is connected to the second output terminal of the controller, the second end of resistor R4 is connected to the base of transistor Q1, the emitter of transistor Q1 is grounded, the collector of transistor Q1 is connected to the cathode of the light-emitting diode in optocoupler U1, the anode of the diode in optocoupler U1 is connected to the first end of resistor R3, the second output terminal of the DC power supply is connected to the second end of resistor R3, the collector of the receiving transistor in optocoupler U1 is connected to the first output terminal of the DC power supply, the emitter of the transistor in optocoupler U1 is connected to one end of resistor R1, the other end of resistor R1 is connected to the anode of capacitor C1, and the cathode of capacitor C1 is grounded.

[0009] Preferably, the leakage current indication driving circuit includes: diode D2 and transistor Q3. The base of transistor Q3 is the control terminal of the leakage current indication driving circuit and is connected to the emitter of transistor Q3 to ground. The collector of transistor Q3 is connected to the cathode of diode D2. The anode of diode D2 is connected to the negative terminal of the alarm. The positive terminal of the alarm is connected to the first output terminal of the DC power supply.

[0010] Preferably, the leakage current cut-off switch is a relay RL2 and the main control switch is a relay RL1.

[0011] Preferably, the switching power supply circuit includes: resistor R2, resistor R5, capacitor C2, transistor Q2, and common anode diode D1. The base of transistor Q2 is connected to the first terminal of resistor R2, which is the control terminal of the switching power supply circuit. The emitter of transistor Q2 is grounded. The collector of transistor Q2 is connected to the anode of common anode diode D1 and the negative terminal of the main control switch. The anode of the main control switch is connected to the cathode of common anode diode D1. The cathode of common anode diode D1 is connected to the first terminal of resistor R5 and the positive terminal of capacitor C2. The negative terminal of capacitor C2 is grounded. The second terminal of resistor R5 is connected to the first output terminal of the DC power supply.

[0012] Preferably, the amplification module includes: an operational amplifier U2 and a resistor R6. The non-inverting input terminal of the operational amplifier U2 is the input terminal of the amplification module. One end of the non-inverting input terminal of the operational amplifier U2 is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the output terminal of the operational amplifier U2. The output terminal of the operational amplifier U2 is the output terminal of the amplification module.

[0013] Preferably, the comparison module includes: comparator U3, resistor R7 and resistor R8. The non-inverting input terminal of comparator U3 is the input terminal of the comparison module. The inverting input terminal of comparator U3 is connected to the first terminal of resistor R7. The second terminal of resistor R7 is connected to the second output terminal of DC power supply. The first terminal of resistor R7 is connected to one terminal of resistor R8, and the other terminal of resistor R8 is grounded.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] In this application, by installing a current sensing coil at the power output terminal of the electric vehicle charging pile, a power-off state is achieved when the main control switch is not supplying power. At this point, the power output terminal of the electric vehicle charging pile has no voltage, as there is a distance between the current sensing coil and the input terminal of the main control switch. Under normal circumstances, in the power-off state, no induced current is generated at the current sensing coil because it is far from the input terminal of the main control switch. If leakage occurs, current flows at the power output terminal of the electric vehicle charging pile in the power-off state, thus detecting the leakage. After the current sensing coil induces current, it generates a magnetic field. The Hall sensor senses the magnetic field, and the change in the magnetic field causes a change in the output voltage of the Hall sensor. The signal processing circuit processes this voltage change and sends it to the controller for identification. The controller then controls the leakage current cut-off switch (a normally closed switch that opens when energized; it closes under normal use, but when the alarm sounds, it simultaneously drives the leakage current cut-off switch to open, thus preventing leakage from the leakage current cut-off switch to the main control switch) to cut off the leakage, and the leakage current indication circuit drives the alarm to sound an alarm to indicate leakage.

[0016] Other advantages, objectives and features of this invention will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of this invention. Attached Figure Description

[0017] Figure 1 This is a circuit diagram of the leakage current alarm cut-off circuit, main control switch, switch power supply circuit, and power supply control circuit.

[0018] Figure 2 This is the circuit diagram for the signal processing circuit.

[0019] Figure 3 This is a structural diagram of a current sensing coil and a Hall sensor at the power output terminal of an electric vehicle charging station. Detailed Implementation

[0020] To make the technical means, creative features, achieved objectives and functions of this utility model clearer and easier to understand, the utility model will be further described below with reference to the accompanying drawings and specific embodiments:

[0021] like Figures 1 to 3 As shown, this utility model discloses a leakage current prevention control circuit for electric vehicle charging piles, including: a DC power supply, a leakage current monitoring device, a controller, a leakage current alarm cut-off circuit, a main control switch, a switch power supply circuit, and a power supply control circuit; the leakage current alarm cut-off circuit includes: a leakage current cut-off switch, a leakage current indication drive circuit, and an alarm. The mains power (L, N) is connected to the input terminal of the leakage current cut-off switch, and the output terminal of the leakage current cut-off switch is connected to the input terminal of the main control switch. The output terminal of the main control switch is the power supply output terminal (L1, N1) of the electric vehicle charging pile. The first output terminal V2 of the DC power supply (output voltage of 12V to meet the power supply requirements of the coils in the main control switch and the leakage current cut-off switch) supplies power to the alarm and the leakage current cut-off switch through the leakage current indication drive circuit. The first output terminal of the controller is connected to the control terminal of the leakage current indication drive circuit; the first output terminal V2 of the DC power supply is powered through the switch power supply circuit, and the second output terminal of the controller is connected to the control terminal of the switch power supply circuit through the power supply control circuit. The leakage current monitoring device includes: a current sensing coil 1, a Hall sensor 2, and a signal processing circuit. The current sensing coil 1 is installed at the power output terminal of the electric vehicle charging pile. The Hall sensor 2 is installed at the current sensing coil 1. The output terminal of the Hall sensor 2 is connected to the input terminal of the signal processing circuit. The output terminal of the signal processing circuit is connected to the input terminal of the controller.

[0022] like Figure 3 As shown, the current sensing coil 1 is wound in a superior arc structure, generating a magnetic field when current flows through the power supply output terminal of the electric vehicle charging pile. This enables the detection of whether the power supply output terminal of the electric vehicle charging pile is at the current sensing coil 1 when the entire electric vehicle charging pile's leakage protection control circuit is not supplying power.

[0023] In this application, the controller can be a control chip such as the STM32 series.

[0024] In this application, the leakage current cut-off switch is a normally closed switch, meaning it is closed when not energized. When power is supplied to the alarm, power is simultaneously supplied to the leakage current cut-off switch, thereby cutting off the power output terminal between the leakage current cut-off switch and the electric vehicle charging pile, ensuring immediate disconnection upon leakage in this section of the line. The main control switch is a normally open switch, meaning it is open when not energized. Under the control of the controller, the main control switch is closed to supply power only when charging is required, controlled by the switch power supply circuit and the power supply control circuit.

[0025] In this application, the signal processing circuit includes an amplification module and a comparison module. The input terminal of the amplification module is connected to the output terminal of the Hall sensor 2, the output terminal of the amplification module is connected to the input terminal of the comparison module, and the output terminal of the comparison module is the output terminal of the signal processing circuit.

[0026] When Hall sensor 2 senses the magnetic field generated by current sensing coil 1, the output voltage of Hall sensor 2 changes. The amplification module amplifies the voltage change, and then the voltage change is input to the comparison module. The comparison module compares whether the voltage change is greater than a specified value. Because the current sensing coil 1 may generate a certain current when connected to the mains power, the current induced by the current sensing coil 1 will increase after leakage. The comparison module will compare whether the voltage change is greater than the specified value, thereby realizing the detection of leakage when no power is supplied. If leakage is detected, an alarm will be triggered immediately through the leakage cut-off switch, the leakage indication drive circuit, and the alarm.

[0027] In this application, the power supply control circuit includes: resistors R1, R3, and R4, transistor Q1, capacitor C1, and optocoupler U1. The first terminal of resistor R4 is connected to the second output terminal of the controller, and the second terminal of resistor R4 is connected to the base of transistor Q1. The emitter of transistor Q1 is grounded, and the collector of transistor Q1 is connected to the cathode of the light-emitting diode in optocoupler U1. The anode of the diode in optocoupler U1 is connected to the first terminal of resistor R3. The second output terminal V1 of the DC power supply (output voltage of 3.3V) is connected to the second terminal of resistor R3. The collector of the receiving transistor in optocoupler U1 is connected to the first output terminal V2 of the DC power supply, and the emitter of the transistor in optocoupler U1 is connected to one end of resistor R1. The other end of resistor R1 is connected to the anode of capacitor C1, and the cathode of capacitor C1 is grounded. The positive terminal of capacitor C1 is the output terminal of the power supply control circuit, and the output terminal of the power supply control circuit is connected to the control terminal of the switching power supply circuit.

[0028] Resistors R1 and R3, the LED in optocoupler U1, and the collector-emitter junction of transistor Q1 form a branch. When the base of transistor Q1 is connected to a high level under the control of the controller, the LED in optocoupler U1 emits light, and the transistor in optocoupler U1 closes. This enables the output of the power supply control circuit to provide a high level to the control terminal of the switching power supply circuit, providing isolated drive and making the drive voltage more stable. It also prevents mutual interference due to the high voltage connected to the transistor in optocoupler U1.

[0029] In this application, the leakage current warning drive circuit includes: diode D2 and transistor Q3. The base of transistor Q3 is the control terminal of the leakage current warning drive circuit, and the emitter of transistor Q3 is connected to ground. The collector of transistor Q3 is connected to the cathode of diode D2. The anode of diode D2 is connected to the negative terminal of alarm BUZ1. The positive terminal of alarm BUZ1 is connected to the first output terminal V2 of DC power supply. Diode D2 limits the current direction. When the base of transistor Q3 is connected to a high level under the control of the controller, the collector and emitter of transistor Q3 are connected, the cathode of diode D2 is grounded, alarm BUZ1 is turned on, alarm BUZ1 sounds, and at the same time, the coil of the leakage current cut-off switch connected in parallel with alarm BUZ1 and diode D2 is energized, and the leakage current cut-off switch is switched from closed to open to prevent leakage current in the line between the leakage current cut-off switch and the power supply output terminal of the electric vehicle charging pile.

[0030] In this application, the leakage current cut-off switch is relay RL2, and the main control switch is relay RL1.

[0031] In this application, the switching power supply circuit includes: resistor R2, resistor R5, capacitor C2, transistor Q2, and common-anode diode D1. The base of transistor Q2 is connected to the first terminal of resistor R2, which is the control terminal of the switching power supply circuit. The emitter of transistor Q2 is grounded, and the collector of transistor Q2 is connected to the anode of common-anode diode D1 and the negative terminal of the main control switch. The anode of the main control switch is connected to the cathode of common-anode diode D1. The cathode of common-anode diode D1 is connected to the first terminal of resistor R5 and the positive terminal of capacitor C2. The negative terminal of capacitor C2 is grounded. The second terminal of resistor R5 is connected to the first output terminal V2 of the DC power supply. Resistor R2 stabilizes the base voltage of transistor Q2. When the power supply control circuit outputs a high level, transistor Q2 closes, and the coil in the main control switch is energized, thus controlling the main control switch to change from open to closed, thereby achieving normal external power supply. Common-anode diode D1 and capacitor C2 both serve to stabilize the voltage.

[0032] In this application, the amplification module includes an operational amplifier U2 and a resistor R6. The non-inverting input of the operational amplifier U2 is the input terminal of the amplification module. One end of the resistor R6 is connected to the non-inverting input of the operational amplifier U2, and the other end of the resistor R6 is connected to the output terminal of the operational amplifier U2. The output terminal of the operational amplifier U2 is the output terminal of the amplification module. The operational amplifier U2 can be an OP1P type amplification chip.

[0033] In this application, the comparison module includes: comparator U3, resistors R7 and R8. The non-inverting input of comparator U3 is the input terminal of the comparison module. The inverting input of comparator U3 is connected to the first terminal of resistor R7. The second terminal of resistor R7 is connected to the second output terminal V1 of the DC power supply. The first terminal of resistor R7 is connected to one end of resistor R8, and the other end of resistor R8 is grounded. Comparator U3 can use a comparator chip such as LM358. Resistors R7 and R8 function as a voltage divider, providing a reference voltage for comparator U3.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A leakage protection control circuit for electric vehicle charging stations, characterized in that, include: DC power supply, leakage current monitoring device, controller, leakage current alarm cut-off circuit, main control switch, switch power supply circuit and power supply control circuit; The leakage current alarm and cut-off circuit includes: a leakage current cut-off switch, a leakage current indication drive circuit, and an alarm. Mains power is connected to the input terminal of the leakage current cut-off switch, and the output terminal of the leakage current cut-off switch is connected to the input terminal of the main control switch. The output terminal of the main control switch is the power supply output terminal of the electric vehicle charging station. The first output terminal of the DC power supply powers the alarm and the leakage current cut-off switch through the leakage current indication drive circuit. The first output terminal of the controller is connected to the control terminal of the leakage current indication drive circuit. The first output terminal of the DC power supply is powered through a switch power supply circuit, and the second output terminal of the controller is connected to the control terminal of the switch power supply circuit through a power supply control circuit. The leakage current monitoring device includes: a current sensing coil, a Hall sensor, and a signal processing circuit. The current sensing coil is installed at the power supply output terminal of the electric vehicle charging station, and a Hall sensor is installed at the current sensing coil. The output terminal of the Hall sensor is connected to the input terminal of the signal processing circuit, and the output terminal of the signal processing circuit is connected to the input terminal of the controller.

2. The electric vehicle charging pile anti-leakage control circuit according to claim 1, characterized in that, The signal processing circuit includes an amplification module and a comparison module. The input terminal of the amplification module is connected to the output terminal of the Hall sensor, the output terminal of the amplification module is connected to the input terminal of the comparison module, and the output terminal of the comparison module is the output terminal of the signal processing circuit.

3. The electric vehicle charging pile leakage prevention control circuit according to claim 1 or 2, characterized in that, The power supply control circuit includes: resistors R1, R3, and R4, transistor Q1, capacitor C1, and optocoupler U1. The first end of resistor R4 is connected to the second output terminal of the controller, the second end of resistor R4 is connected to the base of transistor Q1, the emitter of transistor Q1 is grounded, the collector of transistor Q1 is connected to the cathode of the light-emitting diode in optocoupler U1, the anode of the diode in optocoupler U1 is connected to the first end of resistor R3, the second output terminal of the DC power supply is connected to the second end of resistor R3, the collector of the receiving transistor in optocoupler U1 is connected to the first output terminal of the DC power supply, the emitter of the transistor in optocoupler U1 is connected to one end of resistor R1, the other end of resistor R1 is connected to the anode of capacitor C1, and the cathode of capacitor C1 is grounded.

4. The electric vehicle charging pile anti-leakage control circuit according to claim 3, characterized in that, The leakage current indication drive circuit includes: diode D2 and transistor Q3. The base of transistor Q3 is the control terminal of the leakage current indication drive circuit and is connected to the emitter of transistor Q3 to ground. The collector of transistor Q3 is connected to the cathode of diode D2. The anode of diode D2 is connected to the negative terminal of the alarm. The positive terminal of the alarm is connected to the first output terminal of the DC power supply.

5. The electric vehicle charging pile leakage prevention control circuit according to claim 4, characterized in that, The leakage current cut-off switch is relay RL2, and the main control switch is relay RL1.

6. The electric vehicle charging pile anti-leakage control circuit according to claim 5, characterized in that, The amplification module includes: operational amplifier U2 and resistor R6. The non-inverting input terminal of operational amplifier U2 is the input terminal of the amplification module. One end of resistor R6 is connected to the non-inverting input terminal of operational amplifier U2, and the other end of resistor R6 is connected to the output terminal of operational amplifier U2. The output terminal of operational amplifier U2 is the output terminal of the amplification module.

7. The electric vehicle charging pile anti-leakage control circuit according to claim 6, characterized in that, The comparison module includes: comparator U3, resistor R7 and resistor R8. The non-inverting input of comparator U3 is the input of the comparison module. The inverting input of comparator U3 is connected to the first end of resistor R7. The second end of resistor R7 is connected to the second output of the DC power supply. The first end of resistor R7 is connected to one end of resistor R8, and the other end of resistor R8 is grounded.

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