CP negative voltage detection circuit of charging gun

By designing a CP negative voltage detection circuit in the charging gun, using the combination of anti-reverse unit, reverse reduction unit and judgment unit, the misjudgment problem of charging equipment when detecting the ready-to-be-electric vehicle is solved, improving detection accuracy and reducing high-voltage safety risks.

CN119716284APending Publication Date: 2025-03-28SAIC MOTOR
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Patent Information

Application Number
CN202311258626.8
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2023-09-26
Publication Date
2025-03-28

AI Technical Summary

Technical Problem

When existing charging equipment detects whether the electric vehicle is ready, the level of the control guide signal jumps due to the resistance introduced by environmental factors, and misjudgment of the vehicle being connected, resulting in the high-voltage relay being erroneously operated, and there are problems of inaccurate detection and high-voltage safety risks.

Method used

A charging gun CP negative voltage detection circuit is designed, including an anti-reverse unit, a reverse reduction unit and a judgment unit. The anti-reverse unit screens the CP voltage, the reverse reduction unit reverses the detection voltage, and the judgment unit identifies whether there is a diode in the electric vehicle based on the reduction voltage, thereby determining whether the vehicle is ready.

Benefits of technology

Through the combination of diodes and reverse proportional op amp circuits, it is possible to accurately identify whether the vehicle has a CP detection diode, which improves detection accuracy and reduces the high-voltage safety risks and detection costs during the use of charging equipment.

✦ Generated by Eureka AI based on patent content.

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Abstract

The invention discloses a charging gun CP negative voltage detection circuit. The charging gun CP negative voltage detection circuit comprises an anti-reverse unit, a reverse reduction unit and a judgment unit, one end of the anti-reverse unit is connected with the output end of the control guide CP signal, and the other end of the anti-reverse unit is connected with the input end of the reverse reduction unit; the anti-reverse unit is used for acquiring CP voltages and screening the CP voltages to obtain voltages to be detected; the output end of the reverse reduction unit is connected with the input end of the judgment unit; the reverse reduction unit is used for acquiring the to-be-detected voltage and performing reverse reduction on the to-be-detected voltage to obtain reduced voltage; and the judging unit is used for acquiring the reduced voltage and identifying and judging whether a diode exists in the electric automobile or not based on the reduced voltage. Therefore, the CP negative voltage amplitude is detected through the combined use of the diode and the reverse proportion operational amplifier circuit, and whether the vehicle is provided with the CP detection diode or not is accurately identified by using the least devices, so that the detection accuracy is improved.
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Description

Technical Field

[0001] The present application relates to the technical field of electric vehicle charging, and in particular to a charging gun CP negative pressure detection circuit. Background Art

[0002] With the vigorous development of the new energy vehicle industry and the vigorous promotion of charging infrastructure construction, the safety of electric vehicle charging is becoming more and more important. The signal interaction between charging equipment and electric vehicles is a very important key link.

[0003] Mode 2 on-board charging gun is a charging device with a cable control box, which has the function of sending control guide PC signal and controlling relay closing / opening. The existing detection circuit generally uses the charging device to judge whether the vehicle is ready based on the control guide CP voltage. However, due to environmental factors such as rain / sewage, the charging gun head introduces resistance between the control guide signal pin and the ground, causing the control guide signal level to jump. The charging device mistakenly believes that the vehicle is connected, causing the high-voltage relay to malfunction, causing the risk of electric shock to personnel, and causing inaccurate detection.

[0004] Therefore, how to improve detection accuracy is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] Based on the above problems, the present application provides a charging gun CP negative pressure detection circuit, including:

[0006] Anti-reverse unit, reverse reduction unit and judgment unit;

[0007] One end of the anti-reverse unit is connected to the output end of the control guidance CP signal, and the other end is connected to the input end of the reverse reduction unit;

[0008] The anti-reverse unit is used to obtain the CP voltage and screen the CP voltage to obtain a voltage to be detected;

[0009] The output end of the reverse reduction unit is connected to the input end of the judgment unit;

[0010] The reverse reduction unit is used to obtain the voltage to be detected, and reversely reduce the voltage to be detected to obtain a reduced voltage;

[0011] The determination unit is used to obtain the reduced voltage and identify and determine whether a diode exists in the electric vehicle based on the reduced voltage.

[0012] Optionally, the anti-reverse unit includes: an anti-reverse diode;

[0013] The cathode terminal of the anti-reverse diode is connected to the output terminal of the CP signal, and the anode terminal is connected to the input terminal of the reverse reduction unit.

[0014] Optionally, the reverse reduction unit includes: a reverse operational amplifier;

[0015] The reverse input terminal of the reverse operational amplifier is connected to the positive terminal of the anti-reverse diode;

[0016] The non-inverting terminal of the inverting operational amplifier is grounded;

[0017] The output end of the inverting operational amplifier is connected to the input end of the judging unit.

[0018] Optionally, the inverting operational amplifier comprises: a first feedback resistor, a second feedback resistor and an operational amplifier;

[0019] One end of the first feedback resistor is connected to the positive terminal of the anti-reverse diode, and the other end is connected to the reverse input terminal of the operational amplifier;

[0020] The non-inverting terminal of the operational amplifier is grounded;

[0021] One end of the second feedback resistor is connected to the inverting input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier;

[0022] The output terminal of the operational amplifier is connected to the input terminal of the judging unit.

[0023] Optionally, the resistance of the first feedback resistor is 10k.

[0024] Optionally, the resistance of the second feedback resistor is 51k.

[0025] Optionally, the inverting operational amplifier further includes: a grounding resistor;

[0026] One end of the grounding resistor is connected to the non-inverting end of the operational amplifier, and the other end is grounded;

[0027] The grounding resistor is used to slow down the discharge speed.

[0028] Optionally, the resistance of the grounding resistor is 10k.

[0029] Optionally, the judgment unit includes: a single-chip microcomputer MCU;

[0030] The A / D conversion interface of the MCU is connected to the output end of the inverting operational amplifier;

[0031] The MCU is used to detect the reduced voltage.

[0032] Optionally, the judgment unit further includes: a control unit;

[0033] The control unit is connected to the MCU;

[0034] The control unit is used to determine whether there is a diode in the electric vehicle according to the reduced voltage detected by the MCU, and obtain a determination result;

[0035] When the judgment result is that there is a diode in the electric vehicle, controlling the high-voltage relay to close;

[0036] When the judgment result is that there is no diode in the electric vehicle, the high-voltage relay is controlled to be disconnected.

[0037] It can be seen from the above technical solutions that compared with the prior art, the present application has the following advantages:

[0038] A charging gun CP negative voltage detection circuit provided in the present application includes: an anti-reverse unit, a reverse reduction unit and a judgment unit. Among them, one end of the anti-reverse unit is connected to the output end of the control guide CP signal, and the other end is connected to the input end of the reverse reduction unit. The anti-reverse unit is used to obtain the CP voltage and screen the CP voltage to obtain the voltage to be detected. In addition, the output end of the reverse reduction unit is connected to the input end of the judgment unit. The reverse reduction unit is used to obtain the voltage to be detected, and reversely reduce the voltage to be detected to obtain the reduced voltage. Finally, the judgment unit is used to obtain the reduced voltage, and identify and judge whether there is a diode in the electric vehicle based on the reduced voltage. In this way, the CP negative voltage amplitude is detected by combining the diode and the reverse proportional op amp circuit, and the vehicle is accurately identified using the least number of devices to identify whether it has a CP detection diode, thereby improving the accuracy of the detection and greatly reducing the high-voltage safety risks and detection costs during the use of the charging equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the structure of a charging gun CP negative pressure detection circuit disclosed in an embodiment of the present application;

[0040] Figure 2 A schematic diagram of the structure of an anti-reverse unit disclosed in an embodiment of the present application;

[0041] Figure 3 A schematic diagram of the structure of an inverting operational amplifier disclosed in an embodiment of the present application;

[0042] Figure 4 A schematic diagram of the structure of another inverting operational amplifier disclosed in an embodiment of the present application;

[0043] Figure 5 A structural schematic diagram of a judgment unit disclosed in this application;

[0044] Figure 6 This is a schematic diagram of the structure of another judgment unit disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0045] As mentioned above, the existing technology has the problem of inaccurate detection. Specifically, with the vigorous development of the new energy vehicle industry and the vigorous promotion of charging infrastructure construction, the safety of electric vehicle charging is becoming more and more important. The signal interaction between the charging equipment and the electric vehicle is a very important key link. The mode 2 on-board charging gun is a charging device with an on-cable control box, which has the function of sending a control guide PC signal and controlling the relay to close / disconnect. The existing detection circuit generally uses the charging device to determine whether the vehicle is ready based on the control guide CP voltage, but the charging gun head introduces resistance between the control guide signal pin and the ground due to environmental factors such as rainwater / sewage, resulting in a jump in the control guide signal level. The charging device mistakenly believes that the vehicle is connected, causing the high-voltage relay to malfunction, causing the risk of electric shock to personnel, and causing inaccurate detection.

[0046] To solve the above problems, the present application provides a charging gun CP negative pressure detection circuit, which includes: an anti-reverse unit, a reverse reduction unit and a judgment unit; one end of the anti-reverse unit is connected to the output end of the control guide CP signal, and the other end is connected to the input end of the reverse reduction unit; the anti-reverse unit is used to obtain the CP voltage, and screen the CP voltage to obtain a voltage to be detected; the output end of the reverse reduction unit is connected to the input end of the judgment unit; the reverse reduction unit is used to obtain the voltage to be detected, and reversely reduce the voltage to be detected to obtain a reduced voltage; the judgment unit is used to obtain the reduced voltage, and identify and judge whether there is a diode in the electric vehicle based on the reduced voltage.

[0047] In this way, the CP negative voltage amplitude is detected by combining a diode with an inverse proportional op amp circuit, and the vehicle is accurately identified as having a CP detection diode using a minimum of components, thereby improving the accuracy of detection and greatly reducing the high-voltage safety risks and detection costs during the use of charging equipment.

[0048] It should be noted that the charging gun CP negative pressure detection circuit provided in the present application can be applied to the field of electric vehicle charging technology. The above is only an example and does not limit the application field of the charging gun CP negative pressure detection circuit provided in the present application.

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0050] Figure 1 This is a schematic diagram of the structure of a charging gun CP negative pressure detection circuit disclosed in an embodiment of the present application. Figure 1 As shown, a charging gun CP negative pressure detection circuit provided in the present application includes: an anti-reverse unit 101, a reverse reduction unit 102 and a judgment unit 103;

[0051] One end of the anti-reverse unit 101 is connected to the output end of the control guidance CP signal, and the other end is connected to the input end of the reverse reduction unit 102;

[0052] The anti-reverse unit 101 is used to obtain the CP voltage and screen the CP voltage to obtain a voltage to be detected;

[0053] The output end of the reverse reduction unit 102 is connected to the input end of the judgment unit 103;

[0054] The reverse reduction unit 102 is used to obtain the voltage to be detected, and reversely reduce the voltage to be detected to obtain a reduced voltage;

[0055] The determination unit 103 is used to obtain the reduced voltage and identify and determine whether there is a diode in the electric vehicle based on the reduced voltage.

[0056] In practical applications, combined with Figure 1As shown, the traditional charging device sends a CP signal to the vehicle, and the vehicle determines the charging current based on the identified CP signal duty cycle. The charging device determines whether the vehicle is ready based on the CP voltage. If the vehicle is connected to the charging device and the S2 switch is controlled to be closed, the charging device thinks that the vehicle is ready, and then closes the AC relay to transmit the AC power to the vehicle, and the vehicle battery is charged by the on-board charger. However, this method may have misjudgments, so this application accurately identifies whether the vehicle diode is connected by detecting the negative 12V level of the charging gun control guide signal, and then identifies the connection between the electric vehicle and the on-board charging gun, so as to prevent the on-board charging gun from being affected by environmental factors such as rainwater and sludge when it is not connected to the vehicle. The high-voltage AC relay malfunctions and generates high-voltage safety risks. Specifically, in this application, the anti-reverse unit 101, the reverse reduction unit 102 and the judgment unit 103 are sequentially connected to form a charging gun CP negative pressure detection circuit. Among them, one end of the anti-reverse unit 101 is connected to the output end of the control guide CP signal to obtain the CP voltage, and the CP voltage is screened to obtain the voltage to be detected. Then, the input end of the reverse reduction unit 102 is connected to the other end of the anti-reverse unit 101 to obtain the voltage to be detected, and reversely reduce the voltage to be detected to obtain the reduced voltage. Finally, the input end of the judgment unit 103 is connected to the output end of the reverse reduction unit 102 to obtain the reduced voltage, and identify and judge whether there is a diode in the electric vehicle based on the reduced voltage.

[0057] Figure 2 Schematic diagram of the structure of an anti-reverse unit disclosed in an embodiment of the present application. Figure 2 As shown, how to implement waveform filtering. The anti-reverse unit includes: an anti-reverse diode 201;

[0058] The cathode terminal of the anti-reverse diode 201 is connected to the output terminal of the CP signal, and the anode terminal is connected to the input terminal of the reverse reduction unit 102 .

[0059] In practical applications, the cathode of the anti-reverse diode 201 is connected to the output of the CP signal, and the anode is connected to the input of the reverse reduction unit 102. Specifically, the anti-reverse diode 201 cuts off the +12V waveform in the CP waveform, and does not affect the operation and sampling of other circuits for +12V. The waveform of the -12V part will be sampled and enter the reverse reduction unit 102 for conditioning, thereby achieving the effect of waveform filtering.

[0060] As an implementation method, regarding how to achieve reverse amplification of a signal, the reverse reduction unit 102 includes: a reverse operational amplifier 202;

[0061] The reverse input terminal of the reverse operational amplifier 202 is connected to the positive terminal of the anti-reverse diode 201;

[0062] The non-inverting terminal of the inverting operational amplifier 202 is grounded;

[0063] The output terminal of the inverting operational amplifier 202 is connected to the input terminal of the determination unit 103 .

[0064] In practical applications, the reverse reduction unit 102 is composed of a reverse operational amplifier 202. The reverse input terminal of the reverse operational amplifier 202 is connected to the positive terminal of the anti-reverse diode 201, and is used to obtain the -12V voltage to be detected filtered by the anti-reverse diode 201, and the non-reverse terminal is grounded. In addition, the output terminal of the reverse operational amplifier 202 is connected to the input terminal of the judgment unit 103, and is used to output the -12V voltage after reverse reduction.

[0065] Figure 3 Schematic diagram of the structure of an inverting operational amplifier disclosed in an embodiment of the present application. Figure 3 As shown, regarding how to achieve reverse amplification of a signal, the reverse operational amplifier includes: a first feedback resistor 301, a second feedback resistor 302 and an operational amplifier 303;

[0066] One end of the first feedback resistor 301 is connected to the positive terminal of the anti-reverse diode 201, and the other end is connected to the reverse input terminal of the operational amplifier 303;

[0067] The non-inverting terminal of the operational amplifier 303 is grounded;

[0068] One end of the second feedback resistor 302 is connected to the inverting input end of the operational amplifier 303, and the other end is connected to the output end of the operational amplifier 303;

[0069] The output terminal of the operational amplifier 303 is connected to the input terminal of the determination unit 103 .

[0070] In practical applications, the reverse operational amplifier 202 specifically includes a first feedback resistor 301, a second feedback resistor 302, and an operational amplifier 303. One end of the first feedback resistor 301 is connected to the positive terminal of the anti-reverse diode 201, and the other end is connected to the output end of the operational amplifier 303, and is used to determine the reduction factor of the reverse operational amplifier together with the second feedback resistor 302. Then, the non-reverse end of the operational amplifier 303 is grounded, one end of the second feedback resistor 302 is connected to the reverse input end of the operational amplifier 303, and the other end is connected to the output end of the operational amplifier 303. Finally, the output end of the operational amplifier 303 is connected to the input end of the judgment unit 103, and is used to output the conditioned voltage signal.

[0071] As an implementation method, how to set the resistance value of the first feedback resistor 301. Accordingly, the resistance value of the first feedback resistor 301 is 10k.

[0072] In practical applications, the resistance of the first feedback resistor 301 may be set to 10k, ie, 10000 ohms.

[0073] As an implementation method, how to set the resistance value of the second feedback resistor 302. Accordingly, the resistance value of the second feedback resistor 302 is 51k.

[0074] In practical applications, the resistance of the second feedback resistor 302 can be set to 51k, that is, 51000 ohms.

[0075] Figure 4 FIG. 2 is a schematic diagram of the structure of another inverting operational amplifier 202 disclosed in an embodiment of the present application. Figure 4 As shown, in order to slow down the discharge speed, the above-mentioned inverting operational amplifier 202 further includes: a grounding resistor 304;

[0076] One end of the grounding resistor 304 is connected to the non-inverting end of the operational amplifier 303, and the other end is grounded;

[0077] The grounding resistor 304 is used to slow down the discharge speed.

[0078] In practical applications, the grounded discharge device can slow down the discharge speed by connecting a series resistor. Therefore, the present application can add a grounding resistor 304 to the reverse operational amplifier 202. Specifically, one end of the grounding resistor 304 is connected to the non-reverse end of the operational amplifier 303, and the other end is grounded to slow down the discharge speed.

[0079] As an implementation method, how to set the resistance value of the grounding resistor 304. Accordingly, the resistance value of the grounding resistor 304 is 10k.

[0080] In practical applications, the resistance of the grounding resistor 304 may be set to 10k, ie, 10000 ohms.

[0081] Figure 5 FIG. 1 is a schematic diagram of the structure of a judgment unit 103 disclosed in this application. Figure 5 As shown, regarding how to determine whether a vehicle has a diode, the determination unit 103 includes: a single-chip microcomputer MCU203;

[0082] The A / D conversion interface of the MCU is connected to the output end of the reverse operational amplifier 202;

[0083] The MCU is used to detect the reduced voltage.

[0084] In practical applications, the A / D conversion interface of the single-chip microcomputer MCU is connected to the output end of the reverse operational amplifier 202 for detecting the reduced voltage. Specifically, the anti-reverse diode 201 cuts off the +12V waveform in the CP waveform ±12V, and does not affect the operation and sampling of other circuits for +12V. The waveform part of -12V will be sent to the single-chip microcomputer MCU for voltage detection after conditioning by the reverse operational amplifier 202 composed of the operational amplifier 303, the first feedback resistor 301, the second feedback resistor 302 and the grounding resistor 304. For example, when the vehicle has a diode D1, the CP-12V voltage is cut off by the D1 diode, and its amplitude is -12V. After passing through the anti-reverse diode 201 (assuming that its voltage drop is 0.6V), the voltage drops to -11.4V, and after passing through the reverse operational amplifier 202, the voltage is 2.24V. In addition, when the vehicle does not have a diode D1 (i.e., it is regarded as D1 short-circuited), the vehicle resistor divides the CP-12V into -6V. After the voltage passes through the anti-reverse diode 201, the voltage will be -5.4V, and after passing through the reverse operational amplifier 202, the voltage will be 1.06V. That is to say, when the vehicle has a diode, the CP negative voltage is -12V, and the reduced voltage detected by the MCU is 2.24V; when the vehicle has no diode, the CP negative voltage is -6V, and the reduced voltage detected by the MCU is 1.06V.

[0085] Figure 6 FIG. 1 is a schematic diagram of another structure of a judgment unit 103 disclosed in an embodiment of the present application. Figure 6 As shown, regarding how to control the high voltage relay, the above-mentioned determination unit 103 further includes: a control unit 204;

[0086] The control unit 204 is connected to the MCU;

[0087] The control unit 204 is used to determine whether there is a diode in the electric vehicle according to the reduced voltage detected by the MCU, and obtain a determination result;

[0088] When the judgment result is that there is a diode in the electric vehicle, controlling the high-voltage relay to close;

[0089] When the judgment result is that there is no diode in the electric vehicle, the high-voltage relay is controlled to be disconnected.

[0090] In practical applications, a control function can be added to the judgment unit 103. Specifically, a control unit 204 is added to the judgment unit 103 to connect with the MCU. The MCU is used to detect the reduced voltage, and the control unit 204 is used to determine whether there is a diode in the electric vehicle according to the reduced voltage detected by the MCU to obtain a judgment result. And the closing and disconnection of the high-voltage relay are controlled based on the judgment result. Correspondingly, when the judgment result is that there is a diode in the electric vehicle, the high-voltage relay is controlled to close; when the judgment result is that there is no diode in the electric vehicle, the high-voltage relay is controlled to disconnect. Combined with the above example, when there is a diode in the vehicle, the CP negative voltage is -12V, the voltage value detected by the MCU is 2.24V, and the control unit 204 controls the high-voltage relay to close; when there is no diode in the vehicle, the CP negative voltage is -6V, the voltage value detected by the MCU is 1.06V, and the control unit 204 controls the high-voltage relay to disconnect.

[0091] In summary, the present application provides a charging gun CP negative pressure detection circuit including: an anti-reverse unit, a reverse reduction unit and a judgment unit. Among them, one end of the anti-reverse unit is connected to the output end of the control guide CP signal, and the other end is connected to the input end of the reverse reduction unit. The anti-reverse unit is used to obtain the CP voltage and screen the CP voltage to obtain the voltage to be detected. In addition, the output end of the reverse reduction unit is connected to the input end of the judgment unit. The reverse reduction unit is used to obtain the voltage to be detected and reversely reduce the voltage to be detected to obtain the reduced voltage. Finally, the judgment unit is used to obtain the reduced voltage and identify and judge whether there is a diode in the electric vehicle based on the reduced voltage. In this way, the CP negative voltage amplitude is detected by combining the diode and the reverse proportional op amp circuit, and the vehicle is accurately identified using the least number of devices to identify whether it has a CP detection diode, thereby improving the accuracy of the detection and greatly reducing the high-voltage safety risks and detection costs during the use of the charging equipment.

[0092] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A charging gun CP negative pressure detection circuit, characterized in that: include: Anti-reverse unit, reverse reduction unit and judgment unit; One end of the anti-reverse unit is connected to the output end of the control guidance CP signal, and the other end is connected to the input end of the reverse reduction unit; The anti-reverse unit is used to obtain the CP voltage and screen the CP voltage to obtain a voltage to be detected; The output end of the reverse reduction unit is connected to the input end of the judgment unit; The reverse reduction unit is used to obtain the voltage to be detected, and reversely reduce the voltage to be detected to obtain a reduced voltage; The determination unit is used to obtain the reduced voltage and identify and determine whether a diode exists in the electric vehicle based on the reduced voltage.

2. A charging gun CP negative pressure detection circuit according to claim 1, characterized in that: The anti-reverse unit comprises: an anti-reverse diode; The cathode terminal of the anti-reverse diode is connected to the output terminal of the CP signal, and the anode terminal is connected to the input terminal of the reverse reduction unit.

3. A charging gun CP negative pressure detection circuit according to claim 2, characterized in that: The reverse reduction unit includes: a reverse operational amplifier; The reverse input terminal of the reverse operational amplifier is connected to the positive terminal of the anti-reverse diode; The non-inverting terminal of the inverting operational amplifier is grounded; The output end of the inverting operational amplifier is connected to the input end of the judging unit.

4. A charging gun CP negative pressure detection circuit according to claim 3, characterized in that: The inverse operational amplifier comprises: a first feedback resistor, a second feedback resistor and an operational amplifier; One end of the first feedback resistor is connected to the positive terminal of the anti-reverse diode, and the other end is connected to the reverse input terminal of the operational amplifier; The non-inverting terminal of the operational amplifier is grounded; One end of the second feedback resistor is connected to the inverting input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier; The output terminal of the operational amplifier is connected to the input terminal of the judging unit.

5. A charging gun CP negative pressure detection circuit according to claim 4, characterized in that: The resistance of the first feedback resistor is 10k.

6. A charging gun CP negative pressure detection circuit according to claim 4, characterized in that: The resistance of the second feedback resistor is 51k.

7. A charging gun CP negative pressure detection circuit according to claim 4, characterized in that: The inverting operational amplifier further includes: a grounding resistor; One end of the grounding resistor is connected to the non-inverting end of the operational amplifier, and the other end is grounded; The grounding resistor is used to slow down the discharge speed.

8. A charging gun CP negative pressure detection circuit according to claim 7, characterized in that: The resistance of the grounding resistor is 10k.

9. A charging gun CP negative pressure detection circuit according to claim 3, characterized in that: The judging unit comprises: a single chip microcomputer MCU; The A / D conversion interface of the MCU is connected to the output end of the inverting operational amplifier; The MCU is used to detect the reduced voltage.

10. A charging gun CP negative pressure detection circuit according to claim 9, characterized in that: The determination unit further includes: a control unit; The control unit is connected to the MCU; The control unit is used to determine whether there is a diode in the electric vehicle according to the reduced voltage detected by the MCU, and obtain a determination result; When the judgment result is that there is a diode in the electric vehicle, controlling the high-voltage relay to close; When the judgment result is that there is no diode in the electric vehicle, the high-voltage relay is controlled to be disconnected.