A circuit for detecting live wire adhesion and grounding in AC charging piles

Abstract

This utility model discloses a live wire adhesion detection and grounding detection circuit for AC charging piles, comprising a first diode, a first resistor, an operational amplifier, and an MCU unit connected in series from left to right. The input terminal of the diode is connected to either the live wire output terminal or the live wire input terminal. The operational amplifier compares a preset reference voltage with the voltage to be measured after passing through the first resistor and outputs a level signal to the MCU unit. The output terminal of the MCU unit is connected to a preset main control CPU and sends a status signal indicating the level signal detection to the preset main control CPU. The technical solution provided by this utility model is not only small in size and saves hardware costs, allowing for a smaller AC charging pile control board, but also conforms to the current trend of miniaturization in AC charging piles.

Description

Technical Field

[0001] This utility model relates to the detection technology of live wire adhesion and grounding detection in AC charging piles, and in particular to a live wire adhesion and grounding detection circuit applied to AC charging piles. Background Technology

[0002] Live wire adhesion detection and grounding detection are crucial electrical safety features in AC charging stations. Live wire adhesion detection primarily verifies whether the DC contactor inside the charging interface is stuck, ensuring the reliability of the electrical connection. Grounding detection ensures a reliable connection between the charging station's metal casing or internal circuitry and the earth, guaranteeing the safety of the equipment's grounding.

[0003] Existing 7kW AC charging piles typically use voltage transformers and comparators for live wire adhesion and grounding detection. However, this approach suffers from large hardware size and high cost. As AC charging piles trend towards miniaturization, this existing solution has become a bottleneck in product iteration and optimization. Utility Model Content

[0004] To overcome the shortcomings of the prior art, this utility model provides a circuit for detecting live wire adhesion and grounding in AC charging piles.

[0005] A live wire adhesion detection and grounding detection circuit for AC charging piles includes a first diode, a first resistor, an operational amplifier, and an MCU unit connected in series from left to right; wherein, the input terminal of the diode is used to connect to the live wire output terminal or the live wire input terminal; the operational amplifier is used to compare a preset reference voltage with the voltage to be measured after passing through the first resistor, and outputs a level signal to the MCU unit; the output terminal of the MCU unit is connected to a preset main control CPU, and is used to send a status signal of the level signal detection to the preset main control CPU.

[0006] Optionally, the preset reference voltage is provided by a reference voltage input circuit; the reference voltage input circuit includes a second resistor and a third resistor connected in series between the input operating voltage and ground, and a first capacitor connected in parallel with the third resistor; the input operating voltage is divided by the second resistor and the third resistor, and then filtered by the first capacitor to obtain the preset reference voltage; the preset reference voltage is connected to the fourth pin of the operational amplifier.

[0007] Optionally, a fourth, fifth, sixth, seventh, and eighth resistor are connected in series between the output terminal of the first resistor and the third pin of the operational amplifier; a ninth resistor and a second capacitor are also connected in parallel between the seventh and eighth resistors.

[0008] Optionally, the operational amplifier includes an output pin, which is connected in series with a ninth resistor and then connected to the MCU unit.

[0009] Optionally, the operational amplifier further includes a working voltage input pin, which is used to connect to a preset working voltage, and a tenth resistor is connected between the working voltage input pin and the output pin.

[0010] Optionally, the MCU unit is a 32-bit microcontroller.

[0011] The live wire adhesion detection and grounding detection circuit provided by this utility model for AC charging piles uses an operational amplifier and MCU unit combination as the core. It can be connected to the live wire output terminal and the live wire input terminal respectively to realize live wire adhesion detection and grounding detection. At the same time, compared with the prior art, the components of this live wire adhesion detection and grounding detection circuit are more streamlined, achieving dual-purpose functionality. It is not only small in size and saves hardware costs, but also allows the AC charging pile control board to be made smaller, and is also suitable for the current trend of miniaturization of AC charging piles. Attached Figure Description

[0012] Figure 1 This is a framework diagram of the live wire adhesion detection method applied to AC charging piles in this embodiment of the present invention;

[0013] Figure 2 This is a circuit diagram of the live wire adhesion detection applied to AC charging piles in this embodiment of the present invention;

[0014] Figure 3 This is a framework diagram of grounding detection applied to AC charging piles in an embodiment of this utility model;

[0015] Figure 4 This is a circuit diagram of a grounding detection circuit applied to an AC charging pile in an embodiment of this utility model. Detailed Implementation

[0016] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0017] A circuit for detecting live wire adhesion and grounding in AC charging piles is provided, comprising a first diode, a first resistor, an operational amplifier, and an MCU unit connected in series from left to right. The input terminal of the diode is connected to either the live wire output terminal or the live wire input terminal; that is, it is connected to the live wire output terminal when live wire adhesion detection is required, and to the live wire input terminal when grounding detection is required. The operational amplifier compares a preset reference voltage with the voltage to be measured after passing through the first resistor and outputs a level signal to the MCU unit. The MCU unit is a microcontroller, and its output terminal is connected to a preset main control CPU, which sends a status signal indicating the level signal detection to the preset main control CPU. The preset main control CPU performs the final detection of live wire adhesion and grounding.

[0018] like Figure 1 , 2 As shown, when performing live wire adhesion detection, the operational amplifier U653 uses the GS8591 as a comparator. The MCU unit uses a 32-bit CMS32L051 microcontroller. The input operating voltage is 4.37V. The first diode is D22, the first resistor is R148, and the second to tenth resistors are R188, R195, R149, R105, R104, R388, R146, R158, R154, and R143, respectively; the first capacitor and the second capacitor are C152 and C137, respectively. Among them, the parameters of R148, R149, R105, R104, and R388 are all 2.4MΩ, ±1%; the parameter of R188 is 10KΩ, ±1%; the parameter of R195 is 1KΩ, ±1%; the parameters of R146 and R154 are 1kΩ, ±1%; the parameter of R143 is 4.7kΩ, ±1%; the parameter of R158 is 100kΩ, ±1%; and the parameters of C152 and C137 are 100nF, ±10%, 50V.

[0019] Specifically, when the AC power relay closes, the live wire to ground (PGND) at the control board output terminal has a 220V AC voltage. This voltage passes through L1_OUT, connected to diode D22, and then in series with resistors R148, R149, R105, R104, R388, and R158 for voltage division. After being filtered by capacitor C137, it is connected in series with resistor R146 and then connected to pin 3 of U653. Simultaneously, 4.37V is divided by resistors R188 and R195, filtered by C152, and used as a reference voltage, which is then input to pin 4 of U653. Because the AC voltage changes alternately, when the voltage at pin 3 of U653 is higher than the voltage at pin 4, pin 1 of U653 outputs a high level. When the voltage at pin 3 of U653 is lower than the voltage at pin 4, pin 1 of U653 outputs a low level. The first pin of U653 is connected in series with resistor R154 to the I / O port of the CMS32L051 microcontroller. This means that the I / O port of the CMS32L051 microcontroller will receive a constantly changing voltage level. When the relay trips, the I / O port of the CMS32L051 microcontroller will receive a low voltage level, and the CMS32L051 will send the detected status signal to the preset main control CPU. The preset main control CPU will then implement the live wire adhesion detection function.

[0020] like Figure 3 , 4 As shown, during grounding detection, the operational amplifier U651 uses the GS8591 as a comparator. The MCU unit uses a 32-bit CMS32L051 microcontroller. The input operating voltage is 4.37V. The first diode is D24, the first resistor is R150, and the second to tenth resistors are R200, R196, R151, R153, R106, R389, R165, R173, R160, and R173, respectively; the first capacitor and the second capacitor are C158 and C142, respectively. Among them, the parameters of R150, R151, R153, R106, and R389 are all 2.4MΩ, ±1%; the parameter of R200 is 10KΩ, ±1%; the parameter of R196 is 1KΩ, ±1%; the parameters of R165 and R160 are 1kΩ, ±1%; the parameter of R172 is 4.7kΩ, ±1%; the parameter of R173 is 100kΩ, ±1%; and the parameters of C158 and C142 are 100nF, ±10%, 50V.

[0021] Specifically, when the AC terminal is powered on, the live wire ground (PGND) of the control board input terminal has a 220V AC voltage. This voltage passes through L1_IN1, connects to diode D24, and is then divided by resistors R150, R151, R153, R106, R389, and R173. After being filtered by capacitor C173, it is connected in series with resistor R165 and then connected to pin 3 of U651. Simultaneously, 4.37V is divided by resistors R200 and R196, filtered by C158, and used as a reference voltage, which is then input to pin 4 of U651. Because the AC voltage changes alternately, when the voltage at pin 3 of U653 is higher than the voltage at pin 4 of U651, pin 1 of U651 outputs a high level. When the voltage at pin 3 of U651 is lower than the voltage at pin 4 of U651, pin 1 of U651 outputs a low level. The first pin of U651 is connected in series with resistor R160 to the I / O port of the CMS32L051 microcontroller. This means that the I / O port of the CMS32L051 microcontroller will receive a constantly changing voltage level. When the relay trips, the I / O port of the CMS32L051 microcontroller will receive a low voltage level, and the CMS32L051 will send the detected status signal to the preset master control CPU, which will then perform the grounding detection function.

[0022] The above is a description of the present utility model, which is used to help understand the present utility model. However, the implementation of the present utility model is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the principle of the present utility model shall be considered as equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. A circuit for detecting live wire adhesion and grounding in AC charging piles, characterized in that, The device comprises a first diode, a first resistor, an operational amplifier, and an MCU unit connected in series from left to right. The input terminal of the diode is used to connect to a live wire output terminal or a live wire input terminal. The operational amplifier is used to compare a preset reference voltage with the voltage to be measured after passing through the first resistor and output a level signal to the MCU unit. The output terminal of the MCU unit is connected to a preset main control CPU and is used to send a status signal of the level signal detection to the preset main control CPU.

2. The live wire adhesion detection and grounding detection circuit for AC charging piles as described in claim 1, characterized in that, The preset reference voltage is provided by a reference voltage input circuit; the reference voltage input circuit includes a second resistor and a third resistor connected in series between the input working voltage and ground, and a first capacitor connected in parallel with the third resistor; the input working voltage is divided by the second resistor and the third resistor, and then filtered by the first capacitor to obtain the preset reference voltage; The preset reference voltage is connected to the fourth pin of the operational amplifier.

3. The live wire adhesion detection and grounding detection circuit for AC charging piles as described in claim 1, characterized in that, A fourth, fifth, sixth, seventh, and eighth resistor are connected in series between the output terminal of the first resistor and the third pin of the operational amplifier; a ninth resistor and a second capacitor are also connected in parallel between the seventh and eighth resistors.

4. The live wire adhesion detection and grounding detection circuit for AC charging piles as described in claim 1, characterized in that, The operational amplifier includes an output pin, which is connected in series with a ninth resistor and then connected to the MCU unit.

5. The live wire adhesion detection and grounding detection circuit for AC charging piles as described in claim 4, characterized in that, The operational amplifier also includes a working voltage input pin, which is used to connect to a preset working voltage, and a tenth resistor is connected between the working voltage input pin and the output pin.

6. The live wire adhesion detection and grounding detection circuit for AC charging piles as described in any one of claims 1 to 5, characterized in that, The MCU unit is a 32-bit microcontroller.

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