Relay adhesion detection circuit, detection method and electric vehicle charging method

Abstract

The invention discloses a relay adhesion detection circuit and method and an electric vehicle charging method, and belongs to the technical field of electronic circuits. The detection circuit comprises a live wire connected with the L end of the charging gun and a zero wire connected with the N end of the charging gun; the live wire is connected in series with a relay K1; the zero line is connected in series with a relay K2; a first detection circuit is connected between the live wire and the zero wire, and the first detection circuit is provided with a detection point M; the live wire is connected with a second detection circuit, the output end of the second detection circuit is connected with an operational amplifier detection circuit, and the operational amplifier detection circuit is provided with a detection point R. By only controlling the opening and closing of the relay K1 and combining the first detection circuit and the second detection circuit, whether the relay K1 and the relay K2 are adhered or not can be efficiently detected.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic circuits and relates to a relay adhesion detection circuit, a detection method and an electric vehicle charging method. Background Art

[0002] With the continuous innovation of electric vehicle technology and the improvement of global environmental awareness, the electric vehicle industry is booming at an unprecedented rate. This trend has directly led to the rapid expansion of electric vehicle charging infrastructure. Among them, charging piles, as a bridge connecting electric vehicles and the power grid, are of self-evident importance. Charging piles are not only related to the charging convenience of electric vehicle users, but also directly affect the popularity of electric vehicles and the sustainable development of the entire industry. In the complex system of charging piles, relays, as an important electrical control component, play a vital role. They accurately control the opening and closing of the charging circuit to ensure the safe and efficient charging process. However, the working environment of relays is often harsh. They are subjected to high current and high voltage shocks for a long time. In addition, frequent operation makes the relay contacts prone to adhesion due to wear, arc erosion or material aging. Once the relay contacts are adhered, the charging circuit cannot be disconnected as expected. This not only means that the electric vehicle cannot automatically stop charging after being fully charged, causing unnecessary power loss, but also may cause extreme situations such as overheating, expansion and even explosion due to long-term overcharging of the battery, directly threatening the safety of users' lives and property. At the same time, it may also cause electrical fires, bringing huge risks to the surrounding environment and facilities.

[0003] Faced with the rapid growth of electric vehicle ownership, the demand for charging has shown an explosive growth trend, which has put forward higher requirements on the performance of charging equipment, especially in terms of safety and reliability. Therefore, how to integrate efficient and accurate relay adhesion detection technology into the design of charging piles has become a key issue that the industry needs to solve urgently. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of low detection efficiency, low safety and low accuracy of relay detection technology in the prior art, avoid the technical problem of false detection when drawing a gun, and provide a relay adhesion detection circuit, detection method and electric vehicle charging method.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention discloses a relay adhesion detection circuit, comprising a live wire connected to the L end of a charging gun, and a neutral wire connected to the N end of the charging gun; a relay K1 is connected in series to the live wire; a relay K2 is connected in series to the neutral wire; a first detection circuit is connected between the live wire and the neutral wire, and a detection point M is provided in the first detection circuit; a second detection circuit is connected to the live wire, and an output end of the second detection circuit is connected to an operational amplifier detection circuit, and the operational amplifier detection circuit is provided with a detection point R.

[0006] Further improvements are: The first detection circuit includes a rectifier module D1 whose positive electrode is connected to the L end of the charging gun. The rectifier module D1 is connected to a first diode D2 and an optocoupler U1 in parallel through a current limiting module R1. The optocoupler U1 is connected to the N end of the charging gun. A control module A is arranged between the relay K1 and the relay K2.

[0007] The optocoupler U1 includes a light emitting diode and a transistor; the cathode of the light emitting diode is connected to the N terminal of the charging gun and is also connected to the anode of the first diode D2; the anode of the light emitting diode is connected to the cathode of the rectifier module D1 through a current limiting resistor R1; the emitter of the transistor is grounded, and the collector is connected to a high level through a pull-up resistor R2; a detection point M is set between the transistor and the pull-up resistor R2, if the M detection point is a square wave signal, the K2 relay is adhered, if it is a high level signal, the K2 relay is not adhered.

[0008] The second detection circuit includes an inductor L1 connected to the L end of the charging gun, the inductor L1 is connected in series with a resistor R6, one end of the resistor R6 is connected in series with a first RC parallel circuit and grounded; the first RC parallel circuit includes a parallel resistor R7 and a capacitor C1; the inductor L1 is connected in series with a parallel diode D4 and a diode D5, the positive electrode of the diode D4 is connected to the negative electrode of the diode D5, and the negative electrode of the diode D4 is connected to the positive electrode of the diode D5; the intersection of the resistor R6 and the RC parallel circuit is the P-terminal output; the D4 diode is connected in series with a second RC parallel circuit and grounded, and the intersection is the N-terminal output; the second RC parallel circuit includes a parallel resistor R8 and a capacitor C2.

[0009] The operational amplifier detection circuit includes an operational amplifier, one end of which is provided with a P input terminal, an N input terminal and a REF reference voltage terminal, and the other end is provided with an output terminal, which is a detection point R; if the R detection point is a sine wave, the K1 relay is adhered, and if the level signal is a reference voltage, the K1 relay is not adhered.

[0010] The charging pile also includes a PE grounding terminal and a CP terminal; the relay adhesion detection circuit also includes a power supply control module B, the voltage output terminal and the PWM signal terminal of the power supply control module B are connected with a switching switch, and the switching switch is connected to the CP terminal through the current limiting resistor R5; a detection point Q is set between the switching switch and the current limiting resistor R5, the CP terminal is connected to the first end of the resistors R3 and R4 through the diode D3, the other end of the resistor R3 is connected to the PE grounding terminal, and the other end of the resistor R4 is connected to the PE grounding terminal through the switch S2.

[0011] In a second aspect, the present invention discloses a relay adhesion detection method based on the above circuit, comprising: Keep the K2 relay disconnected at all times; When the relay to be detected is K2, the K1 relay is controlled to close, and the calculation detection circuit collects the K1 relay closing signal. A sine wave signal is obtained at the detection point R to ensure that the K1 relay is in a closed state. At the same time, the collector voltage signal of the transistor in the optocoupler U1 in the first detection circuit is obtained. If the M detection point is a square wave signal, the K2 relay is stuck. If the M detection point is a high level signal, the K2 relay is not stuck.

[0012] When the relay to be detected is K1, the K1 relay is controlled to be disconnected, and the operational amplifier detection circuit collects the signal of the K1 relay. According to the signal at the detection point R, it is determined whether the current K1 relay is stuck. If the R detection point is a sinusoidal wave signal, it means that the K1 relay is stuck. If the level signal at the R detection point is the reference voltage, it means that the K1 relay is not stuck.

[0013] In a third aspect, the present invention discloses an electric vehicle charging method based on the above detection method, comprising: Determine whether the charging gun is inserted into the electric vehicle; When the charging gun is inserted into the electric vehicle, the relay is subjected to adhesion detection based on the detection method; first, the K1 relay is closed to detect the adhesion of the K2 relay, and if it is adhered, an alarm signal is output; if it is not adhered, the K1 relay is disconnected to detect the adhesion of the K2 relay, and if it is adhered, an alarm signal is output; if it is not adhered, charging is started and the charging state is entered; After charging is finished, the relay is disconnected, and a sticking detection is performed on the relay based on the detection method; first, the K1 relay is closed to perform a sticking detection on the K2 relay, and if there is sticking, an alarm signal is output; if there is no sticking, the K1 relay is disconnected to perform a sticking detection on the K2 relay, and if there is sticking, an alarm signal is output; if there is no sticking, the system is normal.

[0014] The specific method of determining whether the charging gun is inserted into the electric vehicle is as follows: Switch the switch to the 12V voltage output terminal of the power supply control module. After the charging gun is inserted into the electric vehicle, if the voltage at the detection point Q is the first voltage, it indicates that the charging gun is successfully inserted. If the voltage at the detection point Q is 12v, it indicates that the charging gun has failed to be inserted.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a relay adhesion detection circuit, which can efficiently detect whether the K1 relay and the K2 relay are adhered by only controlling the opening and closing of the K1 relay and combining the first detection circuit and the second detection circuit. This design simplifies the detection process and improves the detection efficiency. This circuit does not require additional complex equipment or sensors, and can achieve adhesion detection only through the live wire and the neutral wire and the relay in series, thereby reducing the overall cost. Relay adhesion may cause circuit abnormality or failure. Through this detection circuit, the adhesion problem can be discovered and handled in time, potential safety hazards can be avoided, and the stability and safety of the system can be improved. The circuit structure is simple and clear, and it is easy to implement and maintain. Once a problem is found, it can be quickly located and repaired, reducing the difficulty and cost of maintenance. This detection circuit is not only suitable for specific application scenarios such as charging guns, but can also be widely used in other circuits that need to detect the adhesion state of relays, and has high versatility and practicality.

[0016] The present invention discloses a relay adhesion detection method, which can accurately judge the adhesion state of K1 and K2 relays by accurately controlling the closing and opening of K1 relay and combining the acquisition and analysis of signals by the operation detection circuit. In particular, the accuracy of detection is ensured by comparing the sine wave signal of detection point R with the reference voltage, and distinguishing the square wave signal of detection point M from the high-level signal. The detection method is concise and clear. By controlling the state of a single relay and detecting related signals, the detection of the adhesion state of two relays can be realized, which greatly improves the detection efficiency. The method is not only suitable for detecting the adhesion state of a single relay, but also can detect multiple relays at the same time, showing its good flexibility and scalability. By continuously monitoring the relay state and signal changes, the method can promptly discover and deal with relay adhesion problems, avoid circuit anomalies or safety accidents caused by relay failures, and improve the reliability of the system.

[0017] The present invention discloses a method for charging an electric vehicle. Before and after charging, a relay is subjected to adhesion detection to ensure that the relay is in a normal state, thereby avoiding charging anomalies or safety accidents caused by relay adhesion and improving the safety of the charging process. By accurately judging whether a charging gun is inserted into an electric vehicle, invalid charging attempts are avoided and charging efficiency is improved. At the same time, charging is started after confirming that the relay is not adhered, thereby ensuring the smooth progress of the charging process. The method combines automated detection and judgment technology to achieve intelligent management of the charging process. By detecting the voltage change at point Q, it is possible to accurately judge whether the charging gun is successfully inserted, thereby automatically entering the next step of operation. When relay adhesion is detected, an alarm signal is output in time to remind the user or maintenance personnel to handle it, thereby avoiding the expansion of the fault or causing more serious consequences. By regularly performing adhesion detection on the relay, potential faults can be discovered and handled in time, thereby enhancing the stability and reliability of the charging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A circuit diagram of a relay adhesion detection circuit in the present invention; Figure 2 It is an operational amplifier detection circuit diagram of a relay adhesion detection circuit in the present invention; Figure 3 A flow chart of a relay adhesion detection method in the present invention; Figure 4 The present invention is a flow chart of an electric vehicle charging method.

[0020] Among them: 1-charging device end; 2-electric vehicle end; 3-on-board charger. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1The embodiment of the present invention discloses a relay adhesion detection circuit, including a live wire connected to the L end of a charging gun, and a neutral wire connected to the N end of the charging gun; a relay K1 is connected in series to the live wire; a relay K2 is connected in series to the neutral wire; a first detection circuit is connected between the live wire and the neutral wire, and the first detection circuit is provided with a detection point M; a second detection circuit is connected to the live wire, and an operational amplifier detection circuit is connected to the output end of the second detection circuit, and the operational amplifier detection circuit is provided with a detection point R. The first detection circuit includes a rectifier module D1 whose positive electrode is connected to the L end of the charging gun, and the rectifier module D1 is connected to a first diode D2 and an optical coupler U1 in parallel through a current limiting module R1, and the optical coupler U1 is connected to the N end of the charging gun; a control module A is provided between the relay K1 and the relay K2. The optocoupler U1 includes a light emitting diode and a transistor; the cathode of the light emitting diode is connected to the N terminal of the charging gun and is also connected to the anode of the first diode D2; the anode of the light emitting diode is connected to the cathode of the rectifier module D1 through a current limiting resistor R1; the emitter of the transistor is grounded, and the collector is connected to a high level through a pull-up resistor R2; a detection point M is set between the transistor and the pull-up resistor R2, if the M detection point is a square wave signal, the K2 relay is adhered, if it is a high level signal, the K2 relay is not adhered. The second detection circuit includes an inductor L1 connected to the L end of the charging gun, the inductor L1 is connected in series with a resistor R6, one end of the resistor R6 is connected in series with a first RC parallel circuit and grounded; the first RC parallel circuit includes a parallel resistor R7 and a capacitor C1; the inductor L1 is connected in series with a parallel diode D4 and a diode D5, the positive electrode of the diode D4 is connected to the negative electrode of the diode D5, and the negative electrode of the diode D4 is connected to the positive electrode of the diode D5; the intersection of the resistor R6 and the RC parallel circuit is the P-terminal output; the D4 diode is connected in series with a second RC parallel circuit and grounded, and the intersection is the N-terminal output; the second RC parallel circuit includes a parallel resistor R8 and a capacitor C2. The charging pile also includes a PE grounding terminal and a CP terminal; the relay adhesion detection circuit also includes a power supply control module B, the voltage output terminal and the PWM signal terminal of the power supply control module B are connected with a switching switch, and the switching switch is connected to the CP terminal through the current limiting resistor R5; a detection point Q is set between the switching switch and the current limiting resistor R5, the CP terminal is connected to the first end of the resistors R3 and R4 through the diode D3, the other end of the resistor R3 is connected to the PE grounding terminal, and the other end of the resistor R4 is connected to the PE grounding terminal through the switch S2.

[0025] See also Figure 2 The operational amplifier detection circuit includes an operational amplifier, one end of the operational amplifier is provided with a P input terminal, an N input terminal and a REF reference voltage terminal, and the other end is provided with an output terminal, which is a detection point R; if the R detection point is a sine wave, the K1 relay is adhered, and if the level signal is a reference voltage, the K1 relay is not adhered.

[0026] The present invention discloses a relay adhesion detection circuit, which can efficiently detect whether the K1 relay and the K2 relay are adhered by only controlling the opening and closing of the K1 relay and combining the first detection circuit and the second detection circuit. This design simplifies the detection process and improves the detection efficiency. This circuit does not require additional complex equipment or sensors, and can achieve adhesion detection only through the live wire and the neutral wire and the relay in series, thereby reducing the overall cost. Relay adhesion may cause circuit abnormality or failure. Through this detection circuit, the adhesion problem can be discovered and handled in time, potential safety hazards can be avoided, and the stability and safety of the system can be improved. The circuit structure is simple and clear, and it is easy to implement and maintain. Once a problem is found, it can be quickly located and repaired, reducing the difficulty and cost of maintenance. This detection circuit is not only suitable for specific application scenarios such as charging guns, but can also be widely used in other circuits that need to detect the adhesion state of relays, and has high versatility and practicality.

[0027] join Figure 3 The embodiment of the present invention discloses a relay adhesion detection method based on the above circuit, comprising: Keep the K2 relay disconnected at all times; When the relay to be detected is K2, the K1 relay is controlled to close, and the calculation detection circuit collects the K1 relay closing signal. A sine wave signal is obtained at the detection point R to ensure that the K1 relay is in a closed state. At the same time, the collector voltage signal of the transistor in the optocoupler U1 in the first detection circuit is obtained. If the M detection point is a square wave signal, the K2 relay is stuck. If the M detection point is a high level signal, the K2 relay is not stuck.

[0028] When the relay to be detected is K1, the K1 relay is controlled to be disconnected, and the operational amplifier detection circuit collects the signal of the K1 relay. According to the signal at the detection point R, it is determined whether the current K1 relay is stuck. If the R detection point is a sinusoidal wave signal, it means that the K1 relay is stuck. If the level signal at the R detection point is the reference voltage, it means that the K1 relay is not stuck.

[0029] See also Figure 4 The present invention discloses an electric vehicle charging method based on the above relay adhesion detection method, comprising: Determine whether the charging gun is inserted into the electric vehicle; When the charging gun is inserted into the electric vehicle, the relay is subjected to adhesion detection based on the detection method; first, the K1 relay is closed to detect the adhesion of the K2 relay, and if it is adhered, an alarm signal is output; if it is not adhered, the K1 relay is disconnected to detect the adhesion of the K2 relay, and if it is adhered, an alarm signal is output; if it is not adhered, charging is started and the charging state is entered; After charging is finished, the relay is disconnected, and a sticking detection is performed on the relay based on the detection method; first, the K1 relay is closed to perform a sticking detection on the K2 relay, and if there is sticking, an alarm signal is output; if there is no sticking, the K1 relay is disconnected to perform a sticking detection on the K2 relay, and if there is sticking, an alarm signal is output; if there is no sticking, the system is normal.

[0030] The specific method of determining whether the charging gun is inserted into the electric vehicle is as follows: Switch the switch to the 12V voltage output terminal of the power supply control module. After the charging gun is inserted into the electric vehicle, if the voltage at the detection point Q is the first voltage, it indicates that the charging gun is successfully inserted. If the voltage at the detection point Q is 12v, it indicates that the charging gun has failed to be inserted.

[0031] The working principle of the present invention is as follows: Figure 1 The schematic diagram of a charging device consisting of an electric vehicle and a charging circuit of the present invention is specifically a charging pile for an electric vehicle. As shown in the left frame of the figure, the charging device end of the charging pile is shown, and the right frame is shown as the electric vehicle end. The charging device includes a charging gun, a charging circuit connected to the charging gun, and a detection circuit connected to the live wire end of the AC power supply. The L end and the N end of the charging gun are respectively connected to the live wire and the neutral wire of the AC power supply, and a relay K1 and K2 are respectively connected in series on the live wire and the neutral wire. The detection circuit at the rear end of the relays K1 and K2 includes a rectifier module D1, a current limiting module R1, a control module A, an optocoupler U1, a first diode D2, and a pull-up resistor R2, wherein the diode D1 is a half-wave rectifier module, and the resistor R1 is a current limiting module.

[0032] The optocoupler U1 includes a light emitting diode and a transistor. The cathode of the light emitting diode in the optocoupler U1 is connected to the N terminal of the charging gun and is also connected to the anode of the first diode D2. The anode of the light emitting diode is connected to the cathode of the diode D1 through a current limiting resistor R1. The anode of the diode D1 is connected to the L terminal of the charging gun. The emitter of the transistor in the optocoupler U1 is grounded, and the collector is connected to a high level through a pull-up resistor R2.

[0033] Point M is the detection point, and the voltage at point M can be used to determine whether the relay is stuck. If the M detection point is a square wave signal, it means that the K2 relay is stuck. If it is a high-level signal, it means that the K2 relay is not stuck.

[0034] The second detection circuit connected to the live wire end of the AC power supply includes an inductor L1, resistors R6, R7, R8, diodes D4, D5, capacitors C1, C2, wherein one end of the inductor L1 is connected to the L end of the charging gun, and the other end is connected in series with a resistor R6, one end of R6 is connected to an RC parallel circuit and grounded, the RC parallel circuit includes a resistor R7 and a capacitor C1, diodes D4 and D5 are connected in parallel, the positive electrode of the diode D4 is connected to the negative electrode of the diode D5, the negative electrode of the diode D4 is connected to the positive electrode of the diode D5, the intersection of the resistor R6 and the left RC parallel circuit is the P-terminal output, the D4 diode is connected to the right RC parallel circuit and grounded, and the intersection is the N-terminal output.

[0035] like Figure 2 There is an operational amplifier detection circuit at the output back end of the P terminal and the N terminal, and the operational amplifier detection circuit includes an operational amplifier inside. The left side of the operational amplifier detection circuit is the P input terminal, the N input terminal, and the reference voltage, and the right output terminal is the detection point R. Whether the relay is stuck can be judged by the voltage at the point R. When the R detection point is a sine wave, it means that the current relay is stuck. If the level signal is the reference voltage, the current relay is not stuck.

[0036] It should be noted that in the relay adhesion circuit of the present invention, the K2 relay remains disconnected, and it is only necessary to control the K1 relay to be disconnected and closed to determine whether the K1 relay and the K2 relay are adhered. If the relay to be detected is K2, only the K1 relay is controlled to be closed, and the operational amplifier detection circuit collects the K1 relay closing signal, and a sine wave signal can be obtained at the detection point R to ensure that the K1 relay is in a closed state. At the same time, the collector voltage signal of the transistor in the optocoupler U1 is obtained. If the M detection point is a square wave signal, it means that the K2 relay is adhered, and if the M detection point is a high level signal, it means that the K2 relay is not adhered; if the relay to be detected is K1, the K1 relay is controlled to be disconnected, and the operational amplifier detection circuit collects the signal of the K1 relay. According to the signal at the detection point R, it is determined whether the current K1 relay is adhered. If the R detection point is a sine wave signal, it means that the K1 relay is adhered, and if the level signal at the R detection point is a reference voltage, it means that the K1 relay is not adhered.

[0037] Combination Figure 1 It can be seen that the charging pile includes an L terminal, an N terminal, a PE terminal, and a CP terminal, wherein the PE terminal is grounded, the voltage output terminal and the PWM signal terminal of the power supply control module are connected to the switching switch, and the switching switch is connected to the CP terminal through the current limiting resistor R5, wherein there is a detection point Q between the switching switch and the current limiting resistor R5, the CP terminal is connected to the first ends of the resistors R3 and R4 through the diode D3, the other end of the resistor R3 is connected to the PE terminal, and the other end of the resistor R4 is connected to the PE terminal through the switch S2.

[0038] The switch is switched to the PWM signal output terminal, and switch S2 is closed at the same time. If the voltage at the detection point Q is the second voltage, relays K1 and K2 are closed, and the electric vehicle starts charging. If the charging gun is detected to be pulled out during the relay adhesion detection process, the two relays should be disconnected immediately and the detection should be stopped.

[0039] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A relay adhesion detection circuit, characterized in that: It includes a live wire connected to the L end of the charging gun and a neutral wire connected to the N end of the charging gun; a relay K1 is connected in series to the live wire; a relay K2 is connected in series to the neutral wire; a first detection circuit is connected between the live wire and the neutral wire, and a detection point M is provided in the first detection circuit; a second detection circuit is connected to the live wire, and an output end of the second detection circuit is connected to an operational amplifier detection circuit, and a detection point R is provided in the operational amplifier detection circuit.

2. The relay adhesion detection circuit according to claim 1, characterized in that: The first detection circuit includes a rectifier module D1 whose positive electrode is connected to the L end of the charging gun. The rectifier module D1 is connected to a first diode D2 and an optocoupler U1 in parallel through a current limiting module R1. The optocoupler U1 is connected to the N end of the charging gun. A control module A is arranged between the relay K1 and the relay K2.

3. The relay adhesion detection circuit according to claim 2, characterized in that: The optocoupler U1 includes a light emitting diode and a transistor; the cathode of the light emitting diode is connected to the N terminal of the charging gun and is also connected to the anode of the first diode D2; the anode of the light emitting diode is connected to the cathode of the rectifier module D1 through a current limiting resistor R1; the emitter of the transistor is grounded, and the collector is connected to a high level through a pull-up resistor R2; a detection point M is set between the transistor and the pull-up resistor R2, if the M detection point is a square wave signal, the K2 relay is adhered, if it is a high level signal, the K2 relay is not adhered.

4. The relay adhesion detection circuit according to claim 1, characterized in that: The second detection circuit includes an inductor L1 connected to the L end of the charging gun, the inductor L1 is connected in series with a resistor R6, one end of the resistor R6 is connected in series with a first RC parallel circuit and grounded; the first RC parallel circuit includes a parallel resistor R7 and a capacitor C1; the inductor L1 is connected in series with a parallel diode D4 and a diode D5, the positive electrode of the diode D4 is connected to the negative electrode of the diode D5, and the negative electrode of the diode D4 is connected to the positive electrode of the diode D5; the intersection of the resistor R6 and the RC parallel circuit is the P-terminal output; the D4 diode is connected in series with a second RC parallel circuit and grounded, and the intersection is the N-terminal output; the second RC parallel circuit includes a parallel resistor R8 and a capacitor C2.

5. The relay adhesion detection circuit according to claim 1, characterized in that: The operational amplifier detection circuit includes an operational amplifier, one end of which is provided with a P input terminal, an N input terminal and a REF reference voltage terminal, and the other end is provided with an output terminal, which is a detection point R; if the R detection point is a sine wave, the K1 relay is adhered, and if the level signal is a reference voltage, the K1 relay is not adhered.

6. The relay adhesion detection circuit according to claim 1, characterized in that: The charging pile also includes a PE grounding terminal and a CP terminal; the relay adhesion detection circuit also includes a power supply control module B, the voltage output terminal and the PWM signal terminal of the power supply control module B are connected with a switching switch, and the switching switch is connected to the CP terminal through the current limiting resistor R5; a detection point Q is set between the switching switch and the current limiting resistor R5, the CP terminal is connected to the first end of the resistors R3 and R4 through the diode D3, the other end of the resistor R3 is connected to the PE grounding terminal, and the other end of the resistor R4 is connected to the PE grounding terminal through the switch S2.

7. A relay adhesion detection method based on the circuit according to any one of claims 1 to 6, characterized in that: include: Keep the K2 relay disconnected at all times; When the relay to be detected is K2, the K1 relay is controlled to close, and the calculation detection circuit collects the K1 relay closing signal. A sine wave signal is obtained at the detection point R to ensure that the K1 relay is in a closed state. At the same time, the collector voltage signal of the transistor in the optocoupler U1 in the first detection circuit is obtained. If the M detection point is a square wave signal, the K2 relay is stuck. If the M detection point is a high level signal, the K2 relay is not stuck.

8. The relay adhesion detection method according to claim 7, characterized in that: include: When the relay to be detected is K1, the K1 relay is controlled to be disconnected, and the operational amplifier detection circuit collects the signal of the K1 relay. According to the signal at the detection point R, it is determined whether the current K1 relay is stuck. If the R detection point is a sinusoidal wave signal, it means that the K1 relay is stuck. If the level signal at the R detection point is the reference voltage, it means that the K1 relay is not stuck.

9. An electric vehicle charging method based on the detection method of claim 8, characterized in that: include: Determine whether the charging gun is inserted into the electric vehicle; When the charging gun is inserted into the electric vehicle, the relay is subjected to adhesion detection based on the detection method; first, the K1 relay is closed to perform adhesion detection on the K2 relay, and an alarm signal is output if adhesion occurs; If it is not sticky, disconnect the K1 relay to perform a sticky test on the K1 relay, and if it is sticky, output an alarm signal; If it is not sticky, then start charging and enter the charging state; After charging is finished, the relay is disconnected, and a sticking detection is performed on the relay based on the detection method; first, the K1 relay is closed to perform a sticking detection on the K2 relay, and if sticking occurs, an alarm signal is output; If it is not sticky, disconnect the K1 relay to perform a sticky test on the K1 relay, and if it is sticky, output an alarm signal; If there is no sticking, the system is normal.

10. The electric vehicle charging method according to claim 9, characterized in that: The specific method of determining whether the charging gun is inserted into the electric vehicle is as follows: Switch the switch to the 12V voltage output terminal of the power supply control module. After the charging gun is inserted into the electric vehicle, if the voltage at the detection point Q is the first voltage, it indicates that the charging gun is successfully inserted. If the voltage at the detection point Q is 12v, it indicates that the charging gun has failed to be inserted.

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