A-type electric leakage detection circuit and charging pile

Abstract

The utility model provides an A-type electric leakage detection circuit and a charging pile. The detection circuit comprises a current transformer; a filtering module; a leakage current detection chip; a divider resistor; a main control chip; wherein the current transformer is installed near a zero line and a live line of an output terminal of a charging pile, two ends of the current transformer are connected with an input end of the filtering module, an output end of the filtering module is connected with an input pin of the leakage current detection chip, an output pin of the leakage current detection chip is connected with the divider resistor, and the divider resistor is connected with the charging pile. The divider resistor is connected with the main control chip, the leakage current detection chip detects that leakage current exists in an input pin and outputs driving current at an output pin of the leakage current detection chip, level data is generated on the divider resistor, and the main control chip performs leakage detection according to the level data.

Description

Technical Field

[0001] The utility model relates to a leakage detection circuit, in particular to an A-type leakage detection circuit and a charging pile. Background Art

[0002] At present, with the popularization of electric vehicles, there are more and more electric vehicle-related charging piles. The charging safety of existing charging piles needs to be paid attention to. At present, there is leakage in existing charging piles. For the leakage of charging piles, the traditional technical solution mainly adopts AC leakage detection circuit. However, the above AC leakage detection circuit cannot meet the national standard GB / T 18487.1-2015, and the above traditional AC leakage detection circuit has poor action reliability for suddenly applied or slowly rising leakage sinusoidal alternating current and pulsating direct current. Utility Model Content

[0003] One of the purposes of the utility model is to provide a type A leakage detection circuit and a charging pile. The type A leakage detection circuit can detect the leakage current signal and convert it into a voltage signal through a leakage detection chip and a voltage divider resistor, and input the voltage signal into a main control chip for leakage analysis and execution of corresponding leakage protection operations, thereby improving the reliability of leakage protection.

[0004] Another object of the utility model is to provide a type A leakage detection circuit and a charging pile. The type A leakage detection circuit is provided with a filtering module, and the filtering module can filter and differentially filter the leakage current signal, thereby improving the accuracy of leakage current signal detection and reducing the interference of impurity signals on the leakage current signal.

[0005] Another object of the utility model is to provide an A-type leakage detection circuit and a charging pile. The leakage current signal input end of the A-type leakage detection circuit is configured with a magnetic bead. The magnetic bead can effectively prevent the interference of the environmental magnetic field on the detection signal, thereby improving the accuracy of leakage current signal detection.

[0006] In order to achieve at least one of the above-mentioned utility model purposes, the utility model provides an A-type leakage detection circuit, the detection circuit comprising:

[0007] Current transformer;

[0008] Filter module;

[0009] Leakage current detection chip;

[0010] Voltage divider resistor;

[0011] Main control chip;

[0012] The current transformer is installed near the neutral line and the live line of the output terminal of the charging pile, the two ends of the current transformer are connected to the input end of the filter module, the output end of the filter module is connected to the input pin of the leakage current detection chip, the output pin of the leakage current detection chip is connected to the voltage dividing resistor, the voltage dividing resistor is connected to the main control chip, the leakage current detection chip detects the presence of leakage current at the input pin, and outputs a driving current at the output pin of the leakage current detection chip, generates level data on the voltage dividing resistor, and the main control chip performs leakage detection according to the level data.

[0013] According to one preferred embodiment of the present invention, two input ends of the filter module are respectively configured with magnetic beads, and a third resistor is connected between the two input ends of the filter module.

[0014] According to another preferred embodiment of the utility model, the filtering module includes a second resistor, a fourth resistor, a second capacitor, a fourth capacitor and a seventh capacitor; wherein the leakage current detection chip includes a first input pin and a second input pin, the second resistor is connected to the first input pin, and the fourth resistor is connected to the second input pin.

[0015] According to another preferred embodiment of the utility model, the second capacitor includes a first end and a second end, and the seventh capacitor includes a first end and a second end, wherein the first end of the second capacitor is respectively connected to the second resistor and the first input pin of the leakage current detection chip, and the second end of the second capacitor is grounded; wherein the first end of the seventh capacitor is respectively connected to the fourth resistor and the second input pin, and the second end of the second capacitor is grounded.

[0016] According to another preferred embodiment of the present invention, two ends of the fourth capacitor of the filtering module are respectively connected to the first end of the second capacitor and the second end of the seventh capacitor.

[0017] According to another preferred embodiment of the utility model, a limiting protector is arranged between the two input ends of the filtering module, and the limiting protector is composed of a first diode and a second diode with positive and negative electrodes connected in series end to end, the positive electrode of the first diode and the negative electrode of the second diode are connected to an input terminal of the filtering module, and the negative electrode of the first diode is also connected to another input terminal of the filtering module.

[0018] According to another preferred embodiment of the utility model, the voltage-dividing resistor includes a sixth resistor and a seventh resistor, wherein one end of the seventh resistor is connected to the output pin of the leakage current detection chip, and the other end of the seventh resistor is connected to one end of the sixth resistor, the other end of the sixth resistor is grounded, an eighth capacitor is connected in parallel to the seventh resistor, and the input pin of the main control chip is connected between the seventh resistor and the sixth resistor, and the driving current of the output pin of the leakage current detection chip generates level data on the sixth resistor of the voltage-dividing resistor and transmits it to the main control chip.

[0019] According to another preferred embodiment of the utility model, the output end of the main control chip is connected to the charging pile relay control circuit, wherein the charging pile relay control circuit includes a fifth resistor, an eighth resistor, a ninth capacitor, a transistor and a third diode; wherein the eighth resistor and the ninth capacitor are connected in parallel to the base and emitter of the transistor.

[0020] According to another preferred embodiment of the utility model, the anode of the third diode of the charging pile relay control circuit is connected to the collector of the transistor, and the cathode of the third diode is connected to one terminal of the charging pile relay.

[0021] In order to achieve at least one of the above-mentioned purposes of the utility model, the utility model provides a charging pile, and the charging pile is equipped with the type A leakage detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shown is a structural schematic diagram of an A-type leakage detection circuit of the utility model. DETAILED DESCRIPTION

[0023] The following description is used to disclose the utility model so that those skilled in the art can implement the utility model. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the utility model defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the utility model.

[0024] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0025] Please combine Figure 1The utility model discloses an A-type leakage detection circuit and a charging pile, wherein the A-type leakage detection circuit mainly includes the following parts: a current transformer, a filter module, a leakage current detection chip, a voltage dividing resistor and a main control chip; wherein the current transformer is Figure 1 CT1 in the figure, wherein the current transformer CT1 is installed near the live wire L and the neutral wire N of the charging pile, the two ends of the current transformer CT1 are respectively connected to the input ends corresponding to the filter module, and the output end corresponding to the filter module is connected to the input pin corresponding to the leakage current detection chip U1, the output pin of the leakage current detection chip is connected to the voltage-dividing resistor, and the voltage-dividing resistor is used to generate level data, the voltage-dividing resistor is connected to the input pin I of the main control chip MCU, and the output pin I of the main control chip MCU is connected to a charging pile relay control circuit for controlling the switch of the charging pile relay K1. The leakage current detection chip U1 is preferably an FM2147B chip.

[0026] For more details, please refer to Figure 1 , the filter module includes: a second resistor R2, a fourth resistor R4, a second capacitor C2, a fourth capacitor C4 and a seventh capacitor C7; wherein the leakage current detection chip U1 includes a first input pin IN1 and a second input pin IN2, the second resistor R2 is connected to the first input pin IN1, and the fourth resistor is connected to the second input pin IN2. Wherein a magnetic bead FB1 and FB2 are respectively configured at the two input ends of the filter module, the current transformer CT1 samples the leakage current of the charging pile, and the magnetic beads FB1 and FB2 are used to shield the influence of the magnetic field environment around the charging pile on the leakage current detection signal. A third resistor R3 for sampling the leakage current signal is also configured at the two input ends of the filter module, and a limit protector is also connected at the two input ends of the filter module. The limit protector D1 is composed of a first diode and a second diode connected in series, wherein the positive pole of the first diode and the negative pole of the second diode are connected to an input terminal of the filter module, and the first diode negative pole is also connected to another input terminal of the filter module. Wherein the limit protector is installed after the third resistor R3 and connected to the input terminal of the filter module.

[0027] It is worth mentioning that the second capacitor C2 of the filtering module described in the utility model includes a first end and a second end, and the seventh capacitor C7 includes a first end and a second end, wherein the first end of the second capacitor C2 is respectively connected to the second resistor R2 and the first input pin IN1 of the leakage current detection chip U1, and the second end of the second capacitor C2 is grounded; wherein the first end of the seventh capacitor C7 is respectively connected to the fourth resistor R4 and the second input pin IN2, and the second end of the second capacitor C2 is grounded. The first end of the second capacitor C2 and the second end of the seventh capacitor C7 are respectively connected to the two ends of the fourth capacitor C4, and the fourth capacitor C4 can realize differential mode filtering of the leakage current signal.

[0028] In this utility model, please refer to Figure 1 The voltage-dividing resistor includes a sixth resistor R6 and a seventh resistor R7, wherein one end of the seventh resistor R7 is connected to the output pin OS of the leakage current detection chip U1, and the other end of the seventh resistor R7 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is grounded GND, an eighth capacitor C8 is connected in parallel to the seventh resistor R7, and the input pin I of the main control chip MCU is connected between the seventh resistor R7 and the sixth resistor R6, and the driving current of the output pin OS of the leakage current detection chip U1 generates level data on the sixth resistor R6 of the voltage-dividing resistor and transmits it to the main control chip MCU.

[0029] The output end of the main control chip is connected to the charging pile relay control circuit, wherein the charging pile relay control circuit includes a fifth resistor R5, an eighth resistor R8, a ninth capacitor R9, a transistor T1 and a third diode; wherein the eighth resistor and the ninth capacitor are connected in parallel to the base and emitter of the transistor.

[0030] In the above embodiment of the utility model, the magnetic beads FB1 and FB2 are 300R / 1.7A, R3 is 120R, R2 and R4 are 2.4KΩ, R5 is 1KΩ, R6 is 15KΩ, R7 is 3KΩ, R8 is 10KΩ, R1 is 75KΩ, C1 is 1uF, C2 and C7 are 2.2nF, C3 is 10nF, C4 and C6 are 330nF, C8 and C9 are 0.1uF, the diode of the limit protector D1 is LBAV99LT1G, and the diode of D2 is M7.

[0031] Furthermore, the above circuit structure of the utility model can achieve the following technical effects:

[0032] When the leakage voltage signal between the first input pin IN1 and the second input pin IN2 of the leakage current detection chip FM2147B is between 4mV RMS and 4.4mV RMS, the output pin OS of the leakage current detection chip outputs an intermittent drive current of about 220uA, generating a high level with a pulse width greater than 20ms on the resistor R6, which is sent to the input port I of the main control chip MCU for collection.

[0033] When the leakage voltage signal between the first input pin IN1 and the second input pin IN2 of the leakage current detection chip FM2147B is greater than 4.4mV, the output pin OS of the leakage current detection chip outputs a continuous driving current of about 220uA, generates a 3.3V high level on the resistor R6, and sends it to the input port I of the MCU for collection. The main control chip MCU can accurately determine whether the charging pile is leaking by detecting the pulse waveform or high level waveform of the LEAK_IN of the output pin OS of the leakage protection chip U1, with a simple structure and high system reliability.

[0034] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments. Without departing from the principles, the implementation methods of the present invention may be deformed or modified in any way.

Claims

1. A type A leakage detection circuit, characterized in that: The detection circuit comprises: Current transformer; Filter module; Leakage current detection chip; Voltage divider resistor; Main control chip; The current transformer is installed near the neutral line and the live line of the output terminal of the charging pile, the two ends of the current transformer are connected to the input end of the filter module, the output end of the filter module is connected to the input pin of the leakage current detection chip, the output pin of the leakage current detection chip is connected to the voltage dividing resistor, the voltage dividing resistor is connected to the main control chip, the leakage current detection chip detects the presence of leakage current at the input pin, and outputs a driving current at the output pin of the leakage current detection chip, generates level data on the voltage dividing resistor, and the main control chip performs leakage detection according to the level data.

2. A type A leakage detection circuit according to claim 1, characterized in that: The two input ends of the filter module are respectively configured with magnetic beads, and a third resistor is connected between the two input ends of the filter module.

3. A type A leakage detection circuit according to claim 1, characterized in that: The filtering module includes a second resistor, a fourth resistor, a second capacitor, a fourth capacitor and a seventh capacitor; wherein the leakage current detection chip includes a first input pin and a second input pin, the second resistor is connected to the first input pin, and the fourth resistor is connected to the second input pin.

4. A type A leakage detection circuit according to claim 3, characterized in that: The second capacitor includes a first end and a second end, and the seventh capacitor includes a first end and a second end, wherein the first end of the second capacitor is respectively connected to the second resistor and the first input pin of the leakage current detection chip, and the second end of the second capacitor is grounded; wherein the first end of the seventh capacitor is respectively connected to the fourth resistor and the second input pin, and the second end of the second capacitor is grounded.

5. A type A leakage detection circuit according to claim 4, characterized in that: Two ends of the fourth capacitor of the filter module are respectively connected to the first end of the second capacitor and the second end of the seventh capacitor.

6. The A-type leakage detection circuit according to claim 1, characterized in that: A limiting protector is configured between the two input ends of the filter module. The limiting protector is composed of a first diode and a second diode connected in series with positive and negative electrodes. The positive electrode of the first diode and the negative electrode of the second diode are connected to one input terminal of the filter module, and the negative electrode of the first diode is also connected to another input terminal of the filter module.

7. The A-type leakage detection circuit according to claim 1, characterized in that: The voltage-dividing resistor includes a sixth resistor and a seventh resistor, wherein one end of the seventh resistor is connected to the output pin of the leakage current detection chip, and the other end of the seventh resistor is connected to one end of the sixth resistor, the other end of the sixth resistor is grounded, an eighth capacitor is connected in parallel to the seventh resistor, and the input pin of the main control chip is connected between the seventh resistor and the sixth resistor, and the driving current of the output pin of the leakage current detection chip generates level data on the sixth resistor of the voltage-dividing resistor and transmits it to the main control chip.

8. The A-type leakage detection circuit according to claim 1, characterized in that: The output end of the main control chip is connected to the charging pile relay control circuit, wherein the charging pile relay control circuit includes a fifth resistor, an eighth resistor, a ninth capacitor, a transistor and a third diode; wherein the eighth resistor and the ninth capacitor are connected in parallel to the base and emitter of the transistor.

9. The A-type leakage detection circuit according to claim 8, characterized in that: The anode of the third diode of the charging pile relay control circuit is connected to the collector of the transistor, and the cathode of the third diode is connected to one terminal of the charging pile relay.

10. A charging pile, characterized in that: The charging pile is equipped with a type A leakage detection circuit as described in any one of claims 1-8.

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