Ground fault and contact adhesion two-in-one detection circuit

By designing a two-in-one detection circuit for grounding fault and contact adhesion, using components such as resistor-capacitance buck circuit and voltage comparator, the voltage signal of the relay output contact is collected for feedback detection, which solves the problem of failure to effectively detect relay contact adhesion and grounding faults in the prior art, and achieves fast and accurate fault judgment and fault early warning detection, improving the safety of charging piles.

CN222784566UActive Publication Date: 2025-04-22HENGDIAN GRP TOSPO LIGHTING
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Patent Information

Application Number
CN202421124632.4
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2024-05-22
Publication Date
2025-04-22
Estimated Expiration
2034-05-22

AI Technical Summary

Technical Problem

Existing AC charging pile products fail to effectively detect the adhesion state and grounding fault of the relay contacts, resulting in failure of fault detection and affecting the safety of the charging pile use.

Method used

A two-in-one detection circuit for grounding fault and contact adhesion is designed. Through the combination of relay K1, output terminal P1 and feedback detection circuit, the resistor-capacitance buck circuit, voltage comparator U1A, reference voltage circuit and voltage divider circuit, the voltage signal of the relay output contact is collected for feedback detection, so as to achieve fast and accurate fault judgment of grounding fault and contact adhesion.

Benefits of technology

It realizes rapid and accurate fault judgments for grounding faults and relay contact adhesions, and timely failure warning and detection are made, effectively improving the safety of AC charging pile products, and has the characteristics of simple structure, low cost, high accuracy and flexible application.

✦ Generated by Eureka AI based on patent content.

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Abstract

The utility model discloses a ground fault and contact adhesion two-in-one detection circuit, which comprises a feedback detection circuit, the feedback detection circuit comprises a voltage comparator U1A, a second pin of the voltage comparator U1A is connected with a resistance-capacitance step-down circuit, the resistance-capacitance step-down circuit is connected with a first pin of an output terminal P1, a third pin of the voltage comparator U1A is connected with a reference voltage circuit, and a fourth pin of the voltage comparator U1A is connected with a fourth pin of the output terminal P1. The first pin of the voltage comparator U1A is connected with a voltage division circuit, and the voltage division circuit outputs a CHECK signal to a post-stage MCU microprocessor. According to the utility model, the voltage signal of the output contact of the relay K1 is collected for feedback detection, so that rapid and accurate fault judgment of grounding faults or adhesion of the contact of the relay K1 is realized, a timely fault early warning detection function is realized, and the application safety of an AC charging pile product is effectively improved.
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Description

Technical Field

[0001] The utility model belongs to the technical field of AC charging piles, and specifically relates to a two-in-one detection circuit for ground fault and contact adhesion. Background Art

[0002] With the rapid development of new energy vehicles, the market for AC charging piles has gradually expanded. As an important supporting facility for new energy vehicles, the safety and reliability of the product design of charging piles have attracted much attention from consumers. In the charging control application of AC charging piles, the charging piles should monitor ground faults and relay contact faults in real time, so as to make fault warnings and danger warnings in time and improve the safety of daily use of charging piles.

[0003] As one of the core components of charging pile products, the reliability of the contact actuator of the relay is related to the safe use of the charging pile products. During use, the relay may have contact burning and adhesion phenomena, which may cause the contacts to fail to disconnect normally, resulting in the inability to control the output of power supply cut off, and the charging pile grounding circuit breaker, all of which affect the safety of the charging pile.

[0004] How to quickly and accurately detect the sticking state of relay contacts plays a key role in the fault warning and safe use of charging pile products. Most AC charging pile products on the market do not detect ground faults and the sticking state of relay contacts, or directly detect them through the auxiliary contact feedback of the relay. When the relay auxiliary contact fails, there is a risk of detection failure. Utility Model Content

[0005] The purpose of the utility model is to provide a two-in-one detection circuit for ground fault and contact adhesion to solve the problems raised in the above background technology. The utility model provides a two-in-one detection circuit for ground fault and contact adhesion, which has the characteristics of realizing fast and ready fault judgment of ground fault and relay contact adhesion, achieving timely fault warning detection function, and effectively improving the safety of AC charging pile product application.

[0006] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a two-in-one detection circuit for ground fault and contact adhesion, comprising a relay K1, an output terminal P1 and a feedback detection circuit, wherein pin 1 of the output terminal P1 is respectively connected to the feedback detection circuit and the output end of the relay K1, the input end of the relay K1 is connected to the mains input L_IN, the feedback detection circuit comprises a RC step-down circuit, a voltage comparator U1A, a reference voltage circuit and a voltage divider circuit, wherein pin 2 of the voltage comparator U1A is connected to the RC step-down circuit, the RC step-down circuit is connected to pin 1 of the output terminal P1, pin 3 of the voltage comparator U1A is connected to the reference voltage circuit, pin 8 of the voltage comparator U1A is connected to +12V, pin 4 of the voltage comparator U1A is connected to -12V, pin 1 of the voltage comparator U1A is connected to the voltage divider circuit, and the voltage divider circuit outputs a CHECK signal to a subsequent MCU microprocessor.

[0007] In order to convert the AC 220V AC voltage of the mains into a pulsating voltage signal of a low voltage of about 0.7V, further, the RC step-down circuit includes a capacitor C1, a capacitor C2, a resistor R1 and a resistor R2, wherein one end of the capacitor C1 is connected to pin 1 of the output terminal P1, the other end of the capacitor C1 is connected to one end of the capacitor C2, the other end of the capacitor C2 is connected to the resistor R1, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and pin 2 of the voltage comparator U1A, and the other end of the resistor R2 is connected to the ground terminal.

[0008] In order to play the role of overvoltage protection, a diode D1 is further included, the cathode end of the diode D1 is connected between the capacitor C2 and the resistor R1, and the anode end of the diode D1 is connected to the ground end.

[0009] In order to perform filtering, a capacitor C3 is further included, one end of the capacitor C3 is connected between the resistor R2 and the pin 2 of the voltage comparator U1A, and the other end of the capacitor C3 is connected to the ground.

[0010] In order to divide the 12V voltage and provide a reference comparison voltage of 0.39V, the reference voltage circuit further includes a resistor R3 and a resistor R4, wherein one end of the resistor R3 is connected to +12V, the other end of the resistor R3 is respectively connected to one end of the resistor R4 and pin 3 of the voltage comparator U1A, and the other end of the resistor R4 is connected to the ground terminal.

[0011] Furthermore, a capacitor C4 is included, one end of the capacitor C4 is connected between the resistor R3 and the resistor R4, and the other end of the capacitor C4 is connected to the ground.

[0012] In order to divide the pulse signal output from pin 1 of the voltage comparator U1A to obtain a pulse signal with an amplitude of 3V, the voltage divider circuit further includes a resistor R6 and a resistor R7, wherein one end of the resistor R6 is connected to pin 1 of the voltage comparator U1A, the other end of the resistor R6 outputs a CHECK signal and is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the ground.

[0013] In order to serve as a pull-up resistor of the voltage comparator U1A, further, pin 1 of the voltage comparator U1A is connected to one end of a resistor R5, and the other end of the resistor R5 is connected to +12V.

[0014] In order to play the role of overvoltage protection, a diode D2 is further included, the cathode end of the diode D2 is connected between the resistor R6 and the resistor R7, and the other end of the diode D2 is connected to the ground end.

[0015] In the present invention, the method for implementing the two-in-one detection circuit of ground fault and contact adhesion comprises the following steps:

[0016] (i) When the contact of relay K1 is closed, the AC input L_IN is converted into a pulsating voltage signal after passing through the RC step-down circuit and output to pin 2 of the voltage comparator U1A;

[0017] (ii) Resistors R3 and R4 divide the 12V voltage to provide a reference comparison voltage for the voltage comparator U1A;

[0018] (iii) The voltage comparator U1A compares the received pulsating voltage signal with the reference comparison voltage, and outputs a pulse signal through pin 1 of the voltage comparator U1A;

[0019] (iv) The output pulse signal is divided by resistors R6 and R7 to obtain a pulse signal with an amplitude of 3V, and the subsequent MCU microprocessor performs state judgment on the pulse signal;

[0020] The logic of state judgment is:

[0021] When the control relay K1 is closed, a pulse signal is detected, and the control of the relay K1 is judged to be effective; when no pulse signal is detected, the control of the relay K1 is judged to be invalid or the charging pile is grounded.

[0022] When the control relay K1 is disconnected and no pulse signal output is detected, it is judged that the relay K1 has no contact adhesion fault; when continuous pulse signal output is detected, it is judged that the relay K1 has a contact adhesion fault.

[0023] Compared with the prior art, the beneficial effects of the utility model are:

[0024] 1. The utility model collects the voltage signal of the output contact of relay K1 for feedback detection, thereby realizing rapid and accurate fault judgment of ground fault or contact adhesion of relay K1, achieving timely fault warning detection function, effectively improving the safety of AC charging pile product application, and having the characteristics of simple structure, low cost, high accuracy and flexible application;

[0025] 2. The utility model also includes a diode D1 and a diode D2. Both the diode D1 and the diode D2 are transient suppression diodes that play a role in overvoltage protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a circuit diagram of the utility model; DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments 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 in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] Example 1

[0029] See also Figure 1 The utility model provides the following technical solutions: a two-in-one detection circuit for ground fault and contact adhesion, including a relay K1, an output terminal P1 and a feedback detection circuit, wherein the 1st pin of the output terminal P1 is respectively connected to the feedback detection circuit and the output end of the relay K1, the input end of the relay K1 is connected to the mains input L_IN, the feedback detection circuit includes a resistor-capacitor voltage-drop circuit, a voltage comparator U1A, a reference voltage circuit and a voltage divider circuit, wherein the 2nd pin of the voltage comparator U1A is connected to the resistor-capacitor voltage-drop circuit, the resistor-capacitor voltage-drop circuit is connected to the output terminal P1, and the feedback detection circuit includes a resistor-capacitor voltage-drop circuit, a voltage comparator U1A, a reference voltage circuit and a voltage divider circuit, wherein the 2nd pin of the voltage comparator U1A is connected to the resistor-capacitor voltage-drop circuit, and the resistor-capacitor voltage-drop circuit is connected to the output terminal P1. Pin 1 of the output terminal P1 is connected, pin 3 of the voltage comparator U1A is connected to the reference voltage circuit, pin 8 of the voltage comparator U1A is connected to +12V, pin 4 of the voltage comparator U1A is connected to -12V, pin 1 of the voltage comparator U1A is connected to the voltage divider circuit, the voltage divider circuit outputs a CHECK signal to the subsequent MCU microprocessor (not shown in the drawings), pin 2 of the output terminal P1 is connected to the ground terminal, and the charging pile internally connects pin 2 of the output terminal P1 to the power ground inside the board, and the model of the voltage comparator U1A is LM293.

[0030] By adopting the above technical solution, the utility model collects the voltage signal of the output contact of relay K1 for feedback detection, thereby realizing fast and accurate fault judgment of ground fault or contact adhesion of relay K1, achieving timely fault warning detection function, effectively improving the safety of AC charging pile product application, and having the characteristics of simple structure, low cost, high accuracy and flexible application.

[0031] Specifically, the RC step-down circuit includes a capacitor C1, a capacitor C2, a resistor R1 and a resistor R2, wherein one end of the capacitor C1 is connected to pin 1 of the output terminal P1, the other end of the capacitor C1 is connected to one end of the capacitor C2, the other end of the capacitor C2 is connected to the resistor R1, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and pin 2 of the voltage comparator U1A, the other end of the resistor R2 is connected to the ground terminal, the capacity of the capacitor C1 and the capacitor C2 is 33nF, the withstand voltage is 3KV, and the resistance values ​​of the resistor R1 and the resistor R2 are both 1K.

[0032] By adopting the above technical solution, the AC 220V AC voltage of the mains is converted into a pulsating voltage signal of a low voltage of about 0.7V.

[0033] Specifically, it also includes a capacitor C3, one end of the capacitor C3 is connected between the resistor R2 and the 2nd pin of the voltage comparator U1A, the other end of the capacitor C3 is connected to the ground, and the capacitance of the capacitor C3 is 100nF.

[0034] By adopting the above technical solution, capacitor C3 is used as a filter capacitor to perform filtering.

[0035] Specifically, the reference voltage circuit includes a resistor R3 and a resistor R4, wherein one end of the resistor R3 is connected to +12V, the other end of the resistor R3 is respectively connected to one end of the resistor R4 and pin 3 of the voltage comparator U1A, the other end of the resistor R4 is connected to the ground terminal, the resistance value of the resistor R3 is 2K, and the resistance value of the resistor R4 is 68 ohms.

[0036] By adopting the above technical solution, the 12V voltage is divided to provide a reference comparison voltage of 0.39V.

[0037] Specifically, the voltage divider circuit includes a resistor R6 and a resistor R7, wherein one end of the resistor R6 is connected to pin 1 of the voltage comparator U1A, the other end of the resistor R6 outputs a CHECK signal and is connected to one end of the resistor R7, the other end of the resistor R7 is connected to the ground, the resistance value of the resistor R6 is 3K, and the resistance value of the resistor R7 is 2K.

[0038] By adopting the above technical solution, the pulse signal output from pin 1 of the voltage comparator U1A is divided to obtain a pulse signal with an amplitude of 3V.

[0039] Specifically, pin 1 of the voltage comparator U1A is also connected to one end of the resistor R5, the other end of the resistor R5 is connected to +12V, and the resistance value of the resistor R5 is 3K.

[0040] By adopting the above technical solution, the resistor R5 is used as a pull-up resistor of the voltage comparator U1A.

[0041] Example 2

[0042] This embodiment is different from Embodiment 1 in that: specifically, it further includes a diode D1 and a diode D2, the cathode end of the diode D1 is connected between the capacitor C2 and the resistor R1, and the anode end of the diode D1 is connected to the ground end; the cathode end of the diode D2 is connected between the resistor R6 and the resistor R7, and the other end of the diode D2 is connected to the ground end, the model of the diode D1 is TVS6.5VAC; the model of the diode D2 is TVS5VAC.

[0043] By adopting the above technical solution, both the diode D1 and the diode D2 are transient suppression diodes, which play a role in overvoltage protection.

[0044] Example 3

[0045] The present embodiment is different from the first embodiment in that: specifically, a capacitor C4 is further included, one end of the capacitor C4 is connected between the resistor R3 and the resistor R4, and the other end of the capacitor C4 is connected to the ground.

[0046] By adopting the above technical solution, the capacitor C4 filters the divided voltage of the resistor R3 and the resistor R4 to provide a stable voltage reference signal.

[0047] Example 4

[0048] Furthermore, the implementation method of the two-in-one detection circuit of ground fault and contact adhesion described in the utility model comprises the following steps:

[0049] (i) When the contact of relay K1 is closed, the AC input L_IN is converted into a pulsating voltage signal after passing through the RC step-down circuit and output to pin 2 of the voltage comparator U1A;

[0050] (ii) Resistors R3 and R4 divide the 12V voltage to provide a reference comparison voltage for the voltage comparator U1A;

[0051] (iii) The voltage comparator U1A compares the received pulsating voltage signal with the reference comparison voltage, and outputs a pulse signal through pin 1 of the voltage comparator U1A;

[0052] (iv) The output pulse signal is divided by resistors R6 and R7 to obtain a pulse signal with an amplitude of 3V, and the subsequent MCU microprocessor performs state judgment on the pulse signal;

[0053] The logic of state judgment is:

[0054] When the control relay K1 is closed, a pulse signal is detected, and the control of the relay K1 is judged to be effective; when no pulse signal is detected, the control of the relay K1 is judged to be invalid or the charging pile is grounded.

[0055] When the control relay K1 is disconnected and no pulse signal output is detected, it is judged that the relay K1 has no contact adhesion fault; when continuous pulse signal output is detected, it is judged that the relay K1 has a contact adhesion fault.

[0056] In summary, the utility model collects the voltage signal of the output contact of the relay K1 for feedback detection, thereby realizing rapid and accurate fault judgment of ground fault or contact adhesion of the relay K1, achieving timely fault warning detection function, and effectively improving the safety of the application of AC charging pile products. It has the characteristics of simple structure, low cost, high accuracy and flexible application; the utility model also includes a diode D1 and a diode D2, both of which are transient suppression diodes, which play a role in overvoltage protection.

[0057] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A two-in-one detection circuit for ground fault and contact adhesion, characterized in that: It includes a relay K1, an output terminal P1 and a feedback detection circuit, wherein pin 1 of the output terminal P1 is respectively connected to the feedback detection circuit and the output end of the relay K1, the input end of the relay K1 is connected to the mains input L_IN, the feedback detection circuit includes a resistor-capacitor voltage-step-down circuit, a voltage comparator U1A, a reference voltage circuit and a voltage divider circuit, wherein pin 2 of the voltage comparator U1A is connected to the resistor-capacitor voltage-step-down circuit, the resistor-capacitor voltage-step-down circuit is connected to pin 1 of the output terminal P1, pin 3 of the voltage comparator U1A is connected to the reference voltage circuit, pin 8 of the voltage comparator U1A is connected to +12V, pin 4 of the voltage comparator U1A is connected to -12V, pin 1 of the voltage comparator U1A is connected to the voltage divider circuit, and the voltage divider circuit outputs a CHECK signal to a subsequent MCU microprocessor.

2. A two-in-one ground fault and contact adhesion detection circuit according to claim 1, characterized in that: The RC step-down circuit includes a capacitor C1, a capacitor C2, a resistor R1 and a resistor R2, wherein one end of the capacitor C1 is connected to pin 1 of the output terminal P1, the other end of the capacitor C1 is connected to one end of the capacitor C2, the other end of the capacitor C2 is connected to the resistor R1, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and pin 2 of the voltage comparator U1A, and the other end of the resistor R2 is connected to the ground terminal.

3. A two-in-one ground fault and contact adhesion detection circuit according to claim 2, characterized in that: The diode D1 is also included. The cathode terminal of the diode D1 is connected between the capacitor C2 and the resistor R1 , and the anode terminal of the diode D1 is connected to the ground terminal.

4. A two-in-one ground fault and contact adhesion detection circuit according to claim 2, characterized in that: The device further includes a capacitor C3, one end of which is connected between the resistor R2 and the pin 2 of the voltage comparator U1A, and the other end of the capacitor C3 is connected to the ground.

5. A two-in-one ground fault and contact adhesion detection circuit according to claim 1, characterized in that: The reference voltage circuit includes a resistor R3 and a resistor R4, wherein one end of the resistor R3 is connected to +12V, the other end of the resistor R3 is respectively connected to one end of the resistor R4 and pin 3 of the voltage comparator U1A, and the other end of the resistor R4 is connected to the ground.

6. A two-in-one ground fault and contact adhesion detection circuit according to claim 5, characterized in that: The device further includes a capacitor C4 , one end of which is connected between the resistor R3 and the resistor R4 , and the other end of which is connected to the ground.

7. A two-in-one ground fault and contact adhesion detection circuit according to claim 1, characterized in that: The voltage divider circuit includes a resistor R6 and a resistor R7, wherein one end of the resistor R6 is connected to pin 1 of the voltage comparator U1A, the other end of the resistor R6 outputs a CHECK signal and is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the ground.

8. A two-in-one ground fault and contact adhesion detection circuit according to claim 1, characterized in that: Pin 1 of the voltage comparator U1A is also connected to one end of the resistor R5, and the other end of the resistor R5 is connected to +12V.

9. A two-in-one ground fault and contact adhesion detection circuit according to claim 7, characterized in that: A diode D2 is also included. The cathode end of the diode D2 is connected between the resistor R6 and the resistor R7, and the other end of the diode D2 is connected to the ground.