AC charging pile protection grounding detection circuit

Abstract

The utility model discloses a protection grounding detection circuit for an AC charging pile, and the circuit collects the voltage of a live wire through the AC voltage dividing characteristics of safety capacitors CY1 and CY2 connected between a live wire L and a protection grounding (PE) and between a null line N and the protection grounding (PE) and through the condition that the voltage of the live wire is different when the protection grounding (PE) is connected to the ground and the contact is good or not. The sampling voltage is sent to the master control CPU through the metering chip, the state of charging pile protection grounding (PE) is judged, good safety is achieved, in addition, the situation that a live wire and a null line are reversely connected can be detected, the safety of the alternating current charging pile is further improved, implementation is easy, and cost is low. The AC charging pile protection grounding detection circuit provided by the utility model realizes AC charging pile protection grounding (PE) detection, and is simple in circuit structure, low in cost and high in reliability.

Description

Technical Field

[0001] The utility model relates to an AC charging pile protection grounding detection circuit, belonging to the technical field of charging pile grounding detection. Background Art

[0002] Energy and environment have become the focus of the world. Environmentally friendly new energy electric vehicles have been vigorously developed and entered a period of rapid development. Charging piles are an important basic support for electric vehicles. The charging safety and reliability of charging piles are also of great concern. In particular, the outdoor installation conditions of AC charging piles determine that they must have good safety to avoid accidental electric shock accidents. Therefore, ensuring that the protective grounding (PE) of the AC charging pile is correctly connected and in good contact is crucial to ensure safety.

[0003] However, the existing AC charging pile grounding detection circuit has problems such as low grounding detection reliability, complex implementation, high cost, and low safety. Utility Model Content

[0004] Purpose: In order to overcome the deficiencies in the prior art, the utility model provides an AC charging pile protection grounding detection circuit.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the utility model is:

[0006] An AC charging pile protection grounding detection circuit includes: a sampling resistor is connected to one end of a resistor R6, one end of a TVS diode V1, one end of a capacitor C1 and a positive input end of an operational amplifier D1A; the other end of the resistor R6 is connected to the other end of the TVS diode V1 and the other end of the capacitor C1, and then connected to the AC charging pile main control ground GND.

[0007] The positive power supply of the operational amplifier D1A is connected to one end of the capacitor C3 and the positive power supply of the working power supply, and the other end of the capacitor C3 is connected to the main control ground GND of the AC charging pile. The negative power supply of the operational amplifier D1A is connected to one end of the capacitor C2 and the negative power supply of the working power supply, and the other end of the capacitor C2 is connected to the main control ground GND of the AC charging pile.

[0008] One end of the resistor R7 is connected to the negative input end of the operational amplifier D1A, the other end of the resistor R7 is connected to the output end of the operational amplifier D1A and then to one end of the resistor R8, the other end of the resistor R8 is connected to one end of the resistor R9 and the positive input end of the operational amplifier D1B, and the other end of the resistor R9 is connected to the main control ground GND of the AC charging pile.

[0009] One end of the resistor R10 is connected to the negative input end of the operational amplifier D1B, the other end of the resistor R10 is connected to the output end of the operational amplifier D1B and then connected to one end of the resistor R11, the other end of the resistor R11 is connected to one end of the capacitor C4, the other end of the capacitor C4 is connected to the main control ground GND of the AC charging pile, and the common point between the resistor R11 and the capacitor C4 outputs the live line L voltage sampling signal Vout.

[0010] The safety capacitor CY1 is connected in series with the safety capacitor CY2, and the common point of the safety capacitor CY1 and the safety capacitor CY2 is connected to the protective grounding PE of the AC charging pile.

[0011] Furthermore, the sampling resistor is composed of a resistor R1, a resistor R2, a resistor R3, a resistor R4, and a resistor R5 connected in series.

[0012] Furthermore, the input end of the resistor R1 is connected to the live wire L, the live wire L is connected to one end of the safety capacitor CY1, the other end of the safety capacitor CY1 is connected to the AC charging pile protective ground PE, the neutral wire N is connected to one end of the safety capacitor CY2, and the other end of the safety capacitor CY2 is connected to the AC charging pile protective ground PE.

[0013] Furthermore, the main control ground GND of the AC charging pile is connected to one end of the magnetic bead L1, and the other end of the magnetic bead L1 is connected to the protective ground PE of the AC charging pile.

[0014] Furthermore, the safety capacitor CY1 and the safety capacitor CY2 are both Y-type safety capacitors.

[0015] Furthermore, the positive pole of the working power supply is set to +12V.

[0016] Furthermore, the negative pole of the working power supply is set to -12V.

[0017] Furthermore, the capacity of the safety capacitor CY1 is equal to the capacity of the safety capacitor CY2.

[0018] Furthermore, the operational amplifier D1A and the operational amplifier D1B are provided by a dual operational amplifier integrated chip.

[0019] Furthermore, it also includes: a metering chip, which is connected to a common point between the resistor R11 and the capacitor C4 and is used to convert the input Vout analog signal into a digital signal.

[0020] Furthermore, it also includes: a main control CPU, the input end of the metering chip is connected to the main control CPU, when the sampling voltage signal Vout of the live wire L received by the main control CPU is only half of the original, the main control CPU outputs an alarm that the AC charging pile protective ground PE is not connected to the ground or has a poor contact. When the sampling voltage signal Vout of the live wire L received by the main control CPU is around 0V, the main control CPU outputs an alarm that the live wire and neutral wire are connected in reverse.

[0021] As a preferred option,

[0022] Beneficial effect: The utility model provides an AC charging pile protective grounding detection circuit, which collects the voltage of the live wire through the AC voltage-dividing characteristics of the safety capacitors CY1 and CY2 connected between the live wire L and the neutral wire N and the protective grounding (PE), and sends the sampled voltage to the main control CPU through a metering chip to judge the state of the charging pile protective grounding (PE). In addition, the reverse connection of the live wire and the neutral wire can also be detected, further increasing the safety of the AC charging pile, and the implementation is simple and the cost is low.

[0023] The utility model realizes protection grounding (PE) detection of an AC charging pile, has a simple circuit structure, low cost and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the working structure of the utility model. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the examples of the utility model in conjunction with the drawings in the examples of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the utility model.

[0026] The present invention will be further described below in conjunction with specific embodiments.

[0027] like Figure 1 As shown, an AC charging pile protection grounding detection circuit includes: an operational amplifier, a TVS diode V1, a magnetic bead L1, a safety capacitor CY1, a safety capacitor CY2, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, and a resistor R11.

[0028] One end of the resistor R1 is connected to the live wire L, the other end of the resistor R1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R3, the other end of the resistor R3 is connected to one end of the resistor R4, the other end of the resistor R4 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, one end of the TVS diode V1, one end of the capacitor C1 and the positive input pin 3 of the operational amplifier D1A, the other end of the resistor R6 is connected to the other end of the TVS diode V1 and the other end of the capacitor C1, and then connected to the main control ground GND of the AC charging pile.

[0029] The positive power pin 8 of the operational amplifier D1A is connected to one end of the capacitor C3 and the positive electrode of the working power supply, and the other end of the capacitor C3 is connected to the main control ground GND of the AC charging pile. The negative power pin 4 of the operational amplifier D1A is connected to one end of the capacitor C2 and the negative electrode of the working power supply, and the other end of the capacitor C2 is connected to the main control ground GND of the AC charging pile.

[0030] One end of the resistor R7 is connected to the negative input pin 2 of the operational amplifier D1A, the other end of the resistor R7 is connected to the output pin 1 of the operational amplifier D1A and then to one end of the resistor R8, the other end of the resistor R8 is connected to one end of the resistor R9 and the positive input pin 6 of the operational amplifier D1B, and the other end of the resistor R9 is connected to the main control ground GND of the AC charging pile.

[0031] One end of the resistor R10 is connected to the negative input pin 5 of the operational amplifier D1B, the other end of the resistor R10 is connected to the output pin 7 of the operational amplifier D1B and then connected to one end of the resistor R11, the other end of the resistor R11 is connected to one end of the capacitor C4, the other end of the capacitor C4 is connected to the main control ground GND of the AC charging pile, and the common point between the resistor R11 and the capacitor C4 outputs the live line L voltage sampling signal Vout.

[0032] The main control ground GND of the AC charging pile is connected to one end of the magnetic bead L1, and the other end of the magnetic bead L1 is connected to the protective ground PE of the AC charging pile.

[0033] The live wire L is connected to one end of the safety capacitor CY1, the other end of the safety capacitor CY1 is connected to the protective ground PE of the AC charging pile, the neutral wire N is connected to one end of the safety capacitor CY2, the other end of the safety capacitor CY2 is connected to the protective ground PE of the AC charging pile.

[0034] Furthermore, the safety capacitor CY1 and the safety capacitor CY2 are both Y-type safety capacitors.

[0035] Furthermore, the positive pole of the working power supply is set to +12V.

[0036] Furthermore, the negative pole of the working power supply is set to -12V.

[0037] Furthermore, the capacity of the safety capacitor CY1 is equal to the capacity of the safety capacitor CY2.

[0038] Furthermore, the operational amplifier D1A and the operational amplifier D1B are provided by a dual operational amplifier integrated chip.

[0039] Furthermore, it also includes: a metering chip, which is connected to a common point between the resistor R11 and the capacitor C4 and is used to convert the input Vout analog signal into a digital signal.

[0040] Furthermore, it also includes: a main control CPU, the input end of the metering chip is connected to the main control CPU, when the sampling voltage signal Vout of the live wire L received by the main control CPU is only half of the original, the main control CPU outputs an alarm that the AC charging pile protective ground PE is not connected to the ground or has a poor contact. When the sampling voltage signal Vout of the live wire L received by the main control CPU is around 0V, the main control CPU outputs an alarm that the live wire and neutral wire are connected in reverse.

[0041] Example:

[0042] The working principle of the utility model is as follows: the 220VAC input of the AC charging pile has three lines, one live line L (live wire), one neutral line N (neutral line), and one protective grounding (PE).

[0043] The live wire L is input from one end of the resistor R1, and after being connected in series with the resistor R1, the resistor R2, the resistor R3, the resistor R4 and the resistor R5, it is connected to one end of the resistor R6 to divide the voltage and output the sampled voltage of the live wire L. The other end of the resistor R6 is connected to the main control ground GND of the AC charging pile. The sampled voltage of the live wire L output by the resistor R6 divides the voltage and suppresses the interference pulse through the transient voltage suppression diode TVS tube, and then is filtered by the capacitor C1 and input to the positive input end of the operational amplifier D1A. The negative input end of the operational amplifier D1A receives the feedback voltage from the output end of the operational amplifier D1A through the resistor R7 to form a voltage follower with a large input resistance and a small output resistance, which can truly convert the positive The sampling voltage signal of the live wire L at the input end is transmitted to the load with very small current. The resistor R7 improves the stability and accuracy of the voltage follower. The sampling voltage signal of the live wire L is buffered and isolated by the voltage follower, and then divided by resistors R8 and R9 and output to the next voltage follower composed of an operational amplifier D1B and a resistor R10. This can further reduce interference misjudgment, and then the sampling voltage signal Vout of the live wire L is transmitted to the metering chip through resistor R3 and capacitor C4. The resistor R3 and capacitor C4 will further eliminate the pulse interference signal in the output signal of the operational amplifier, adjust the output impedance, and make the analog signal output to the metering chip more accurate.

[0044] The metering chip converts the input Vout analog signal into a digital signal and sends it to the main control CPU. When the voltage value of Vout is the output sampling value designed by this circuit, the main control CPU outputs that the AC charging protection grounding is normal, and the live wire and neutral wire are connected normally. The main control CPU issues an instruction to close the relay switch, and the AC charging pile is powered and works.

[0045] The AC charging pile protection ground PE is connected to the AC charging pile main control ground GND through the magnetic bead L1. The magnetic bead L1 can prevent external high-frequency interference from accessing the AC charging pile main control ground GND.

[0046] The live wire L is connected to one end of the safety capacitor CY1, and the other end of the safety capacitor CY1 is connected to one end of the safety capacitor CY2 and then connected to the AC charging pile protective grounding PE. The other end of the safety capacitor CY2 is connected to the neutral wire N. Because the power supply is TN-S mode (three-phase five-wire system), the neutral wire N is connected to the earth at the power supply end. The potential of the neutral wire N to the earth is about 0V. If the charging pile protective grounding PE is not connected to the earth or has poor contact, and the live wire L and the neutral wire N have AC power, and there are safety capacitors CY1 and CY2, and the capacitance of safety capacitors CY1 and CY2 is equal, a voltage division is formed, so that the voltage of L (live wire) to the AC charging pile main control ground GND is only half of the original, and the sampling voltage signal Vout of the live wire L is only half of the voltage transmitted to the metering chip. Based on this, the main control CPU can determine that the AC charging pile protective grounding PE is not connected to the earth or has poor contact. In this way, it can ensure that the AC charging pile protective grounding PE is connected to the earth and has good contact, effectively avoiding the occurrence of accidental electric shock accidents and ensuring the safety of the AC charging pile.

[0047] If the live wire L and the neutral wire N are connected in reverse, that is, the neutral wire N is connected to the live wire L position, and the neutral wire L is connected to the live wire N position, since the potential of the neutral wire N to the ground is about 0V, then the voltage of the live wire sample input to the operational amplifier D1A pin 3 is about 0V, and the sampled voltage signal Vout is about 0, and the voltage transmitted to the metering chip is also about 0, based on which it can be determined that the live wire and the neutral wire are connected in reverse. This can prevent the live wire and the neutral wire from being charged due to the reverse connection of the live wire and the neutral wire, and further increase the safety of the AC charging pile.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An AC charging pile protection grounding detection circuit, characterized in that: include: The sampling resistor is connected to one end of the resistor R6, one end of the TVS diode V1, one end of the capacitor C1 and the positive input end of the operational amplifier D1A. The other end of the resistor R6 is connected to the other end of the TVS diode V1 and the other end of the capacitor C1 and then connected to the main control ground GND of the AC charging pile. The positive electrode of the power supply of the operational amplifier D1A is connected to one end of the capacitor C3 and the positive electrode of the working power supply, and the other end of the capacitor C3 is connected to the main control ground GND of the AC charging pile. The negative electrode of the power supply of the operational amplifier D1A is connected to one end of the capacitor C2 and the negative electrode of the working power supply, and the other end of the capacitor C2 is connected to the main control ground GND of the AC charging pile; One end of the resistor R7 is connected to the negative input end of the operational amplifier D1A, the other end of the resistor R7 is connected to the output end of the operational amplifier D1A and then connected to one end of the resistor R8, the other end of the resistor R8 is connected to one end of the resistor R9 and the positive input end of the operational amplifier D1B, and the other end of the resistor R9 is connected to the main control ground GND of the AC charging pile; One end of the resistor R10 is connected to the negative input end of the operational amplifier D1B, the other end of the resistor R10 is connected to the output end of the operational amplifier D1B and then connected to one end of the resistor R11, the other end of the resistor R11 is connected to one end of the capacitor C4, the other end of the capacitor C4 is connected to the main control ground GND of the AC charging pile, and the common point between the resistor R11 and the capacitor C4 outputs the live line L voltage sampling signal Vout; The safety capacitor CY1 is connected in series with the safety capacitor CY2, and the common point of the safety capacitor CY1 and the safety capacitor CY2 is connected to the protective grounding PE of the AC charging pile.

2. An AC charging pile protective grounding detection circuit according to claim 1, characterized in that: Also includes: The main control ground GND of the AC charging pile is connected to one end of the magnetic bead L1, and the other end of the magnetic bead L1 is connected to the protective ground PE of the AC charging pile.

3. An AC charging pile protective grounding detection circuit according to claim 1 or 2, characterized in that: The safety capacitor CY1 and the safety capacitor CY2 are both Y-type safety capacitors.

4. An AC charging pile protective grounding detection circuit according to claim 1 or 2, characterized in that: The positive pole of the working power supply is set to +12V, and the negative pole of the working power supply is set to -12V.

5. An AC charging pile protective grounding detection circuit according to claim 1 or 2, characterized in that: The capacity of the safety capacitor CY1 is equal to the capacity of the safety capacitor CY2.

6. An AC charging pile protective grounding detection circuit according to claim 1 or 2, characterized in that: The operational amplifier D1A and the operational amplifier D1B are provided by a dual operational amplifier integrated chip.

7. An AC charging pile protective grounding detection circuit according to claim 1 or 2, characterized in that: Also includes: A metering chip is connected to a common point between the resistor R11 and the capacitor C4 and is used to convert an input Vout analog signal into a digital signal.

8. An AC charging pile protective grounding detection circuit according to claim 7, characterized in that: Also includes: The main control CPU, the input end of the metering chip is connected to the main control CPU. When the sampling voltage signal Vout of the live wire L received by the main control CPU is only half of the original, the main control CPU outputs an alarm that the protective grounding PE of the AC charging pile is not connected to the ground or has poor contact; when the sampling voltage signal Vout of the live wire L received by the main control CPU is around 0V, the main control CPU outputs an alarm that the live wire and the neutral wire are connected reversely.

9. An AC charging pile protective grounding detection circuit according to claim 1 or 2, characterized in that: The sampling resistor is composed of a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R5 connected in series.

10. An AC charging pile protective grounding detection circuit according to claim 9, characterized in that: The input end of the resistor R1 is connected to the live wire L, the live wire L is connected to one end of the safety capacitor CY1, the other end of the safety capacitor CY1 is connected to the AC charging pile protective ground PE, the neutral wire N is connected to one end of the safety capacitor CY2, and the other end of the safety capacitor CY2 is connected to the AC charging pile protective ground PE.

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