An alternating current charging pile output short circuit detection circuit

Abstract

The utility model relates to an alternating current charging pile output short circuit detection's circuit, and this circuit includes relay circuit, voltage input circuit, signal detection circuit. Relay circuit includes relay, first triode and fourth diode, and first triode accepts the signal of control chip to start or close detection. Voltage input circuit includes input resistance and first diode, and the positive and negative pole of first diode is connected to input resistance, relay one contact. Signal detection circuit includes MOS tube, second diode and pull -up resistance, and the drain of MOS tube is connected pull -up resistance R5 and the signal sampling end of control chip U1 respectively, and the gate of MOS tube is connected to input voltage circuit node through second diode, and relay circuit controls signal detection circuit and the conduction of alternating current charging pile's output two ends, through low -voltage signal injection and resistance voltage division network, realizes the linearization processing of voltage signal, promotes detection sensitivity, and circuit simplifies, and the cost is reduced and the space is saved.

Description

Technical Field

[0001] This utility model relates to the field of new energy charging technology, specifically to a circuit for detecting short circuits in the output of an AC charging pile. Background Technology

[0002] With the rapid development of the electric vehicle industry, the demand for charging piles, as a core supporting facility, has surged. However, the quality of charging piles on the market varies greatly, and many products do not meet safety requirements. To address this, relevant departments issued mandatory national standards for charging piles GB39752-2024 and GB44263-2024 in 2024. The new national standards require that AC charging piles should not charge when a short circuit occurs in the AC output circuit before energy transmission.

[0003] Traditional detection methods are complex. Early short-circuit detection relied on air switches and residual current devices (RCDs), requiring manual troubleshooting and making it impossible to predict short-circuit risks before charging. Existing technologies use complex relay switching logic (such as multiple relays connected in series), resulting in high circuit costs and difficult maintenance. Utility Model Content

[0004] In view of this, a circuit for short circuit detection of AC charging pile output is provided, which has a simplified circuit structure, low cost, and separate low-voltage circuit.

[0005] A circuit for detecting short circuits at the output of an AC charging pile, wherein the AC charging pile has a first output terminal LO and a second output terminal NO, and the circuit includes a relay circuit, a voltage input circuit, and a signal detection circuit. The relay circuit includes a relay K1, a first transistor Q1, and a fourth diode D4. The relay K1 has a winding and a switching switch. The base of the first transistor Q1 is connected to the control chip U1, and the collector of the first transistor Q1 is connected to the anode of the fourth diode D4. The fourth diode D4 is connected in parallel with the two ends of the winding of the relay K1, and the cathode of the fourth diode D4 and the anode of the winding of the relay K1 are connected in parallel to the first power supply voltage terminal. The third contact pin of the switching switch is connected to the first output line terminal LO, the fourth contact pin of the switching switch is connected to the second output line terminal NO, and the fifth contact pin of the switching switch is grounded. The voltage input circuit includes at least one input resistor and a first diode D1 connected in series. The first end of the input resistor is connected to the third power supply voltage terminal, the second end of the input resistor is connected to the positive terminal of the first diode D1, and the negative terminal of the first diode D1 is connected to the second contact pin of the switch. The second contact pin and the third contact pin switch between on and off, and the fourth contact pin and the fifth contact pin switch between on and off. The signal detection circuit includes a second MOSFET Q2, a second diode D2, and a pull-up resistor R5; the gate of the second MOSFET Q2 is connected to the cathode of the second diode D2; the anode of the second diode D2 is connected between the anode of the first diode D1 and the second terminal of the input resistor; the drain of the second MOSFET Q2 is connected to the pull-up resistor R5 and the signal sampling terminal of the control chip U1; the pull-up resistor R5 is connected to the second power supply voltage terminal; and the source of the second MOSFET Q2 is grounded.

[0006] Preferably, there are multiple input resistors; the multiple input resistors are connected in series.

[0007] Specifically, the source of the second MOSFET Q2 is connected to ground via a fourth resistor R4 and a third diode D3; the first terminal of the fourth resistor R4 is connected to the cathode of the second diode D2 and the gate of the second MOSFET Q2; the second terminal of the fourth resistor R4 is grounded; the third diode D3 is connected in parallel with the fourth resistor R4; the cathode of the third diode D3 is connected to the cathode of the second diode D2 and the gate of the second MOSFET Q2; and the anode of the third diode D3 is grounded.

[0008] Preferably, the pull-up resistor R5 is connected to a positive voltage input; the second power supply voltage terminal provides a +3.3V voltage.

[0009] Furthermore, the drain of the second MOS transistor Q2 is connected in series with a sampling resistor R6 and then connected to the signal sampling terminal of the control chip U1.

[0010] Preferably, the switching switch is a double-pole double-throw switch so that the switching on and off between the second contact pin and the third contact pin is synchronized with the switching on and off between the fourth contact pin and the fifth contact pin.

[0011] Furthermore, when the relay K1 is powered on during charging, the winding synchronously controls the second contact pin and the third contact pin to be energized and the fourth contact pin and the fifth contact pin to be energized and the fifth contact pin to be energized and the second contact pin and the third contact pin to be energized and the fourth contact pin and the fifth contact pin to be energized and the fourth contact pin to be energized ... fifth contact pin to be energized and the second contact pin to be energized and the third contact pin to be energized and the fifth contact pin to be energized and the fifth contact pin to be energized and the third contact pin to be energized and the fifth contact pin to be ener

[0012] Preferably, the third power supply voltage terminal provides a +12V voltage.

[0013] Preferably, the first power supply voltage terminal provides a +5V voltage.

[0014] Furthermore, when the second MOSFET Q2 is not turned on, the short-circuit detection signal MCU_ADC is pulled high to +3.3V, and the second power supply voltage terminal can provide a continuous pull-up voltage for at least 400ms, so that the control chip U1 can determine that the AC charging pile output port is short-circuited and terminate the charging process.

[0015] In the aforementioned AC charging pile output short-circuit detection circuit, a relay voltage is first provided through the first power supply voltage terminal. During operation, under the control of the control chip U1, the first transistor Q1 conducts, and the relay actuates. When the AC charging pile output Lo-No is not short-circuited, the MCU_ADC signal remains at a low level, and the MCU determines that the output is in a normal open-circuit state. When a short circuit occurs, the MCU_ADC signal becomes high, and the control chip U1 determines that a short circuit has occurred, thus terminating the charging process. Therefore, this circuit achieves linearization of the voltage signal through low-voltage signal injection and a resistor divider network, improving detection sensitivity. The use of a signal relay for detection separates the high and low voltage circuits, ensuring the system's anti-interference capability. By utilizing a simplified circuit system to detect output short circuits, it significantly reduces costs and saves space. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the circuit principle for short circuit detection of AC charging pile output according to an embodiment of this utility model.

[0017] Figure 2 This is a schematic diagram of the control chip used in the AC charging pile output short circuit detection circuit of this utility model embodiment. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0019] Please see Figure 1 and Figure 2This illustration shows the basic principle of a short-circuit detection circuit for an AC charging pile according to an embodiment of the present invention. The AC charging pile has a first output terminal LO and a second output terminal NO. The circuit includes a relay circuit, a voltage input circuit, and a signal detection circuit. The relay circuit includes a relay K1, a first transistor Q1, and a fourth diode D4. The relay K1 has a winding and a switching switch. The base of the first transistor Q1 is connected to a control chip U1, and the collector of the first transistor Q1 is connected to the positive terminal of the fourth diode D4. The fourth diode D4 is connected in parallel with the two ends of the winding of the relay K1, and the negative terminal of the fourth diode D4 is connected in parallel with the positive terminal of the winding of the relay K1 to a first power supply voltage terminal. The third contact pin of the switching switch is connected to the first output terminal LO, the fourth contact pin of the switching switch is connected to the second output terminal NO, and the fifth contact pin of the switching switch is grounded.

[0020] The voltage input circuit includes at least one input resistor and a first diode D1 connected in series. The first end of the input resistor is connected to the third power supply voltage terminal, the second end of the input resistor is connected to the positive terminal of the first diode D1, and the negative terminal of the first diode D1 is connected to the second contact pin of the switch. The second contact pin and the third contact pin switch between on and off, and the fourth contact pin and the fifth contact pin switch between on and off.

[0021] The signal detection circuit includes a second MOSFET Q2, a second diode D2, and a pull-up resistor R5; the gate of the second MOSFET Q2 is connected to the cathode of the second diode D2; the anode of the second diode D2 is connected between the anode of the first diode D1 and the second terminal of the input resistor; the drain of the second MOSFET Q2 is connected to the pull-up resistor R5 and the signal sampling terminal of the control chip U1; the pull-up resistor R5 is connected to the second power supply voltage terminal; and the source of the second MOSFET Q2 is grounded.

[0022] In a specific embodiment, preferably, there are multiple input resistors; the multiple input resistors are connected in series. The example shown in the figure has three input resistors, namely the first input resistor R1, the second input resistor R2, and the third input resistor R3, which are connected in series between the third power supply voltage terminal and the first diode D1.

[0023] Specifically, the source of the second MOSFET Q2 is connected to ground via a fourth resistor R4 and a third diode D3; the first terminal of the fourth resistor R4 is connected to the cathode of the second diode D2 and the gate of the second MOSFET Q2; the second terminal of the fourth resistor R4 is grounded; the third diode D3 is connected in parallel with the fourth resistor R4; the cathode of the third diode D3 is connected to the cathode of the second diode D2 and the gate of the second MOSFET Q2; and the anode of the third diode D3 is grounded.

[0024] Preferably, the pull-up resistor R5 is connected to a positive voltage input, preferably +3.3V; that is, the second power supply voltage terminal provides a +3.3V voltage. Further, the drain of the second MOSFET Q2 is connected in series with a sampling resistor R6 and then connected to the signal sampling terminal of the control chip U1.

[0025] Preferably, the switching switch is a double-pole double-throw switch so that the switching on and off of the second contact pin and the third contact pin is synchronized with the switching on and off of the fourth contact pin and the fifth contact pin. The synchronous switching on and off of these four contact pins enables the switching between whether charging is started and whether the detection circuit is activated.

[0026] Furthermore, when charging is started, the winding of relay K1 synchronously controls the second contact pin and the third contact pin to be energized and conducting, as well as the fourth contact pin and the fifth contact pin to be energized and conducting. When the short circuit detection signal obtained by the control chip U1 is low level and there is no short circuit signal, the winding of relay K1 synchronously controls the second contact pin and the third contact pin to be disconnected, as well as the fourth contact pin and the fifth contact pin to be disconnected, and enters the normal charging process.

[0027] Preferably, the third power supply voltage terminal provides a +12V voltage. Preferably, the first power supply voltage terminal provides a +5V voltage.

[0028] Furthermore, when the second MOSFET Q2 is not conducting, the short-circuit detection signal MCU_ADC is pulled high to +3.3V. The second power supply voltage terminal can provide a continuous pull-up voltage for at least 400ms, so that the control chip U1 can determine that the AC charging pile output port is short-circuited and terminate the charging process. Therefore, when the output Lo-No is short-circuited, the MCU starts to perform short-circuit detection on the AC charging pile output, controls the K1 relay contact to close, pin 2 of K1 is pulled low to GND, the anode voltage of diode D2 is pulled low to GND, the Q2 MOSFET is not conducting, the short-circuit detection signal MCU_ADC is pulled high to 3.3V, and the MCU monitors this level as 3.3V for 400ms, then determines that the AC charging pile output port is short-circuited, the MCU reports a fault, and terminates the charging process.

[0029] In the aforementioned AC charging pile output short-circuit detection circuit, a relay voltage is first provided through the first power supply voltage terminal. During operation, under the control of the control chip U1, the first transistor Q1 conducts, and the relay actuates. When the AC charging pile output Lo-No is not short-circuited, the MCU_ADC signal remains at a low level, and the MCU determines that the output is in a normal open-circuit state. When a short circuit occurs, the MCU_ADC signal becomes high, and the control chip U1 determines that a short circuit has occurred, thus terminating the charging process. Therefore, this circuit achieves linearization of the voltage signal through low-voltage signal injection and a resistor divider network, improving detection sensitivity. The use of a signal relay for detection separates the high and low voltage circuits, ensuring the system's anti-interference capability. By utilizing a simplified circuit system to detect output short circuits, it significantly reduces costs and saves space.

[0030] It should be noted that this utility model is not limited to the above-described embodiments. Based on the inventive spirit of this utility model, those skilled in the art can make other changes, and these changes made based on the inventive spirit of this utility model should be included within the scope of protection claimed by this utility model.

Claims

1. A circuit for detecting short circuits at the output of an AC charging pile, wherein the AC charging pile has a first output terminal LO and a second output terminal NO, characterized in that, The circuit includes a relay circuit, a voltage input circuit, and a signal detection circuit; The relay circuit includes a relay K1, a first transistor Q1, and a fourth diode D4. The relay K1 has a winding and a switching switch. The base of the first transistor Q1 is connected to the control chip U1, and the collector of the first transistor Q1 is connected to the anode of the fourth diode D4. The fourth diode D4 is connected in parallel with the two ends of the winding of the relay K1, and the cathode of the fourth diode D4 and the anode of the winding of the relay K1 are connected in parallel to the first power supply voltage terminal. The third contact pin of the switching switch is connected to the first output line terminal LO, the fourth contact pin of the switching switch is connected to the second output line terminal NO, and the fifth contact pin of the switching switch is grounded. The voltage input circuit includes at least one input resistor and a first diode D1 connected in series. The first end of the input resistor is connected to the third power supply voltage terminal, the second end of the input resistor is connected to the positive terminal of the first diode D1, and the negative terminal of the first diode D1 is connected to the second contact pin of the switch. The second contact pin and the third contact pin switch between on and off, and the fourth contact pin and the fifth contact pin switch between on and off. The signal detection circuit includes a second MOSFET Q2, a second diode D2, and a pull-up resistor R5; the gate of the second MOSFET Q2 is connected to the cathode of the second diode D2; the anode of the second diode D2 is connected between the anode of the first diode D1 and the second terminal of the input resistor; the drain of the second MOSFET Q2 is connected to the pull-up resistor R5 and the signal sampling terminal of the control chip U1; the pull-up resistor R5 is connected to the second power supply voltage terminal; and the source of the second MOSFET Q2 is grounded.

2. The circuit for detecting short circuits at the output of an AC charging pile as described in claim 1, characterized in that, There are multiple input resistors; the multiple input resistors are connected in series.

3. The circuit for detecting short circuits at the output of an AC charging pile as described in claim 1, characterized in that, The source of the second MOSFET Q2 is connected to ground via a fourth resistor R4 and a third diode D3; the first terminal of the fourth resistor R4 is connected to the cathode of the second diode D2 and the gate of the second MOSFET Q2; the second terminal of the fourth resistor R4 is grounded; the third diode D3 is connected in parallel with the fourth resistor R4; the cathode of the third diode D3 is connected to the cathode of the second diode D2 and the gate of the second MOSFET Q2; the anode of the third diode D3 is grounded.

4. The circuit for detecting short circuits at the output of an AC charging pile as described in claim 1, characterized in that, The pull-up resistor R5 is connected to a positive voltage input; the second power supply voltage terminal provides a +3.3V voltage.

5. The circuit for detecting short circuits at the output of an AC charging pile as described in claim 1, characterized in that, The drain of the second MOS transistor Q2 is connected in series with a sampling resistor R6 and then connected to the signal sampling terminal of the control chip U1.

6. The circuit for detecting short circuits at the output of an AC charging pile as described in claim 1, characterized in that, The switching switch is a double-pole double-throw switch so that the switching on and off between the second contact pin and the third contact pin is synchronized with the switching on and off between the fourth contact pin and the fifth contact pin.

7. The circuit for detecting short circuits at the output of an AC charging pile as described in claim 1, characterized in that, When the relay K1 is charging and powered on, the winding synchronously controls the second contact pin and the third contact pin to be energized and the fourth contact pin and the fifth contact pin to be energized and powered on. When the short circuit detection signal obtained by the control chip U1 is low level and there is no short circuit signal, the winding of the relay K1 synchronously controls the second contact pin and the third contact pin to be disconnected and the fourth contact pin and the fifth contact pin to be disconnected.

8. The circuit for detecting short circuits at the output of an AC charging pile as described in claim 1, characterized in that, The third power supply voltage terminal provides a +12V voltage.

9. The circuit for detecting short circuits at the output of an AC charging pile as described in claim 1, characterized in that, The first power supply voltage terminal provides a +5V voltage.

10. The circuit for detecting short circuits at the output of an AC charging pile as described in claim 1, characterized in that, When the second MOSFET Q2 is not turned on, the short-circuit detection signal MCU_ADC is pulled high to +3.3V. The second power supply voltage terminal can provide a continuous pull-up voltage for at least 400ms so that the control chip U1 can determine that the AC charging pile output port is short-circuited and terminate the charging process.

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