An electric vehicle alternating current power supply device control panel grounding detection circuit
By designing a differential amplification detection circuit composed of operational amplifiers, combined with voltage divider and filter circuits, the problem of AC charging piles being unable to detect different grounding voltages was solved, achieving accurate detection of grounding voltage and reducing false alarm rate and after-sales costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI XUNDAO NEW ENERGY TECH CO LTD
- Filing Date
- 2025-08-08
- Publication Date
- 2026-08-04
AI Technical Summary
Existing AC charging pile control boards can only detect whether the grounding status is present or absent, but cannot detect different grounding voltages. This leads to false grounding fault reports in rural areas where the grounding network is incomplete, causing trouble for users.
Design a grounding detection circuit for the control board of an electric vehicle AC power supply equipment. The circuit uses a differential amplifier detection circuit composed of operational amplifiers U2A, U2B, and U3A, combined with a voltage divider circuit for the neutral and protective ground wires. The signal is amplified and filtered by the operational amplifiers, and then output to the ADC interface of the microcontroller for grounding voltage detection.
It enables the detection of different grounding voltages, reduces false alarms during after-sales service, and lowers after-sales costs.
Smart Images
Figure CN224594815U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of detection circuit technology, and in particular to a grounding detection circuit for the control board of an electric vehicle AC power supply equipment. Background Technology
[0002] With the increasing popularity of electric passenger vehicles globally and the continuous improvement of standards, electric vehicle charging stations are becoming more and more common. AC charging stations need to have safety detection circuits such as grounding detection.
[0003] The current AC charging pile control board grounding detection circuit determines whether the grounding status is present or absent. However, in most rural areas, the grounding network is imperfect and affected by the environment. Different users may have different grounding voltages, and the same user may have different grounding voltages at different times. This may lead to false alarms and cause the charging pile to stop charging due to grounding faults, causing a lot of trouble for users.
[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this utility model, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content
[0005] The purpose of this invention is to solve the technical problem in the prior art that it can only detect the presence or absence of grounding status but cannot detect different grounding voltages. To this end, a grounding detection circuit for the control board of an electric vehicle AC power supply equipment is provided.
[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A grounding detection circuit for an AC power supply control board of an electric vehicle includes an operational amplifier U2A; The non-inverting input terminal of the operational amplifier U2A is electrically connected to the output terminal of the neutral line voltage divider circuit, and the input terminal of the neutral line voltage divider circuit is connected to the neutral line of the power grid. The inverting input terminal of the operational amplifier U2A is electrically connected to the output terminal of the protective ground voltage divider circuit, and the input terminal of the protective ground voltage divider circuit is connected to the protective ground wire of the power grid. The output terminal of the operational amplifier U2A is electrically connected to the input terminal of the rectifier circuit through resistor R27. The output terminal of the rectifier circuit is electrically connected to the input terminal of the first low-pass filter circuit. The output terminal of the first low-pass filter circuit is electrically connected to the input terminal of the follower circuit. The output terminal of the follower circuit is electrically connected to the second low-pass filter circuit.
[0007] The following is a further defined technical solution of this utility model: the neutral line voltage divider circuit includes resistors R21, R22, and R23 connected in series. The other end of resistor R21 is connected to the neutral line of the power grid, and the other end of resistor R23 is electrically connected to the non-inverting input terminal of operational amplifier U2A.
[0008] The following is a further defined technical solution of this utility model: the protective ground voltage divider circuit includes resistors R30, R31 and R32 connected in series. The other end of resistor R30 is connected to the protective ground of the power grid, and the other end of resistor R32 is electrically connected to the inverting input terminal of operational amplifier U2A.
[0009] The following is a further defined technical solution of this utility model: the non-inverting input terminal of the operational amplifier U2A is connected to the GND terminal through a parallel resistor R25 and a capacitor C18, and a parallel resistor R35 and a capacitor C22 are connected between the inverting input terminal and the output terminal of the operational amplifier U2A.
[0010] The following is a further defined technical solution of this utility model: the positive input terminal of the operational amplifier U2A is connected to a +12V voltage and then connected to the GND terminal through a capacitor C17, and the negative input terminal of the operational amplifier U2A is connected to a -12V voltage and then connected to the GND terminal through a capacitor C21.
[0011] The following is a further defined technical solution of this utility model, wherein the rectifier circuit includes an operational amplifier U2B; The non-inverting input terminal of the operational amplifier U2B is electrically connected to one end of the resistor R24, and the other end of the resistor R24 is connected to the GND terminal. The inverting input terminal of the operational amplifier U2B is electrically connected to one end of resistor R28, and the other end of resistor R28 is connected to one end of resistor R27. The inverting input terminal and the output terminal of the operational amplifier U2B are electrically connected to a rectifier diode D4, the output terminal of the operational amplifier U2B is electrically connected to the positive terminal of a rectifier diode D3, and the negative terminal of the rectifier diode D3 is connected to the input terminal of the first low-pass filter circuit. One end of resistor R27 is connected to the input terminal of the first low-pass filter circuit through resistor R36.
[0012] The following is a further defined technical solution of this utility model: the first low-pass filter circuit includes resistors R26 and R34 and capacitor C20. One end of resistor R26 is connected to the output terminal of the rectifier circuit, and the other end of resistor R26 is connected to the input terminal of the follower circuit. The other end of resistor R26 is connected to the GND terminal through resistor R34 and capacitor C20 in parallel.
[0013] The following is a further defined technical solution of this utility model: the follower circuit includes an operational amplifier U3A, the non-inverting input terminal of the operational amplifier U3A is connected to the output terminal of the first low-pass filter circuit, the inverting input terminal and the output terminal of the operational amplifier U3A are connected, the positive power input terminal of the operational amplifier U3A is connected to +12V, and the negative power input terminal of the operational amplifier U3A is connected to -12V.
[0014] The following is a further defined technical solution of this utility model: the second low-pass filter circuit includes resistors R29 and R33 and capacitor C19. One end of resistor R29 is connected to the output terminal of the follower circuit, and the other end of resistor R29 serves as the output terminal of the detection circuit. The other end of resistor R29 is connected to the GND terminal through resistor R33 and capacitor C19 in parallel.
[0015] Compared with the prior art, the present invention has the following technical effects: This invention utilizes three operational amplifiers (U2A, U2B, and U3A) in conjunction with a neutral voltage divider circuit, a protective ground voltage divider circuit, a first low-pass filter circuit, and a second low-pass filter circuit. It can detect different grounding voltages and output a continuous analog signal from the ADC1_IN9 terminal to the microcontroller. The actual grounding voltage at the input terminal is calculated from the signal value, reducing false alarms and effectively lowering after-sales costs.
[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a circuit connection diagram of this utility model. Detailed Implementation
[0019] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.
[0020] like Figure 1 As shown, a grounding detection circuit for the control board of an electric vehicle AC power supply equipment is provided. It is a differential amplifier detection circuit composed of three operational amplifiers, namely U2A, U2B, and U3A. It also includes a neutral line voltage divider circuit, a protective ground line voltage divider circuit, a first low-pass filter circuit, and a second low-pass filter circuit.
[0021] Specifically: The neutral voltage divider circuit includes resistors R21, R22, and R23 connected in series. One end of resistor R21 is connected to the neutral line of the power grid, and the other end of resistor R23 is electrically connected to the non-inverting input of operational amplifier U2A. The protective ground voltage divider circuit includes resistors R30, R31, and R32 connected in series. One end of resistor R30 is connected to the protective ground of the power grid, and the other end of resistor R32 is electrically connected to the inverting input of operational amplifier U2A. The non-inverting input of operational amplifier U2A is connected to GND via a parallel resistor R25 and capacitor C18. A parallel resistor R35 and capacitor C22 are connected between the inverting input and output of operational amplifier U2A. The positive power input of operational amplifier U2A is connected to +12V and then to GND via capacitor C17. The negative power input of operational amplifier U2A is connected to -12V and then to GND via capacitor C21. The non-inverting input of operational amplifier U2B is electrically connected to one end of resistor R24, and the other end of resistor R24 is connected to GND. The inverting input of operational amplifier U2B is electrically connected to one end of resistor R28, and the other end of resistor R28 is connected to one end of resistor R27. The other end of resistor R27 is electrically connected to the output of operational amplifier U2A. A rectifier diode D4 is electrically connected between the inverting input and output of operational amplifier U2B. The output of operational amplifier U2B is electrically connected to the positive terminal of rectifier diode D3, and the negative terminal of rectifier diode D3 is connected to the input of the first low-pass filter circuit. One end of resistor R27 is connected to the input of the first low-pass filter circuit through resistor R36. The first low-pass filter circuit includes resistors R26 and R34 and capacitor C20. One end of resistor R26 is connected to the cathode of rectifier diode D3, and the other end of resistor R26 is connected to the non-inverting input of operational amplifier U3A. The other end of resistor R26 is connected to GND via parallel resistor R34 and capacitor C20. The inverting input and output of operational amplifier U3A are connected together. The positive input of operational amplifier U3A is connected to +12V, and the negative input is connected to -12V. The second low-pass filter circuit includes resistors R29 and R33 and capacitor C19. One end of resistor R29 is connected to the output of operational amplifier U3A, and the other end of resistor R29 serves as the output of the detection circuit ADC1_IN9. The other end of resistor R29 is connected to GND via parallel resistor R33 and capacitor C19.
[0022] exist Figure 1 In the circuit, the mains signal is introduced through the left-side N (neutral) and PE (protective ground) terminals. This signal is then sampled via a voltage divider network consisting of resistors R21, R22, and R23 (voltage divider on the N side) and resistors R30, R31, and R32 (voltage divider on the PE side). This resistor-based voltage divider limits the current, adjusts the signal amplitude to meet the detection requirements of subsequent circuits, and also provides some current-limiting protection.
[0023] Capacitors C18 (connected to the relevant branch of TP1), C17, C21, and C22 are filter capacitors. Among them, capacitors C17 and C21 can filter out high-frequency interference introduced by the +12V and -12V power supplies; capacitor C18 filters the signal after voltage division on the N side; capacitor C22, together with resistor R35, forms a filter in the feedback loop, making the signal input to the op-amp purer and avoiding high-frequency noise from affecting the detection accuracy.
[0024] Op-amp U2A is the core detection device, forming a comparator amplifier circuit (depending on specific parameter configuration). Figure 1 The middle section is a typical op-amp feedback structure. The voltage divider signal on the PE side is input to the inverting input terminal (pin 2) of op-amp U2A. The inverting input terminal (pin 2) may be determined by the circuit's own feedback or the reference voltage (combined with resistor R35 and capacitor C22, etc., to form negative feedback and stabilize the op-amp's operation).
[0025] When the PE grounding is normal, the PE potential is stable. The signal input to operational amplifier U2A after voltage division causes operational amplifier U2A to output a specific level. If the PE grounding is abnormal (such as grounding disconnection or excessive grounding resistance), the PE potential changes. The signal input to operational amplifier U2A after voltage division changes, and the output level of operational amplifier U2A flips. Therefore, the circuit monitors the PE grounding status through voltage division sampling, compares and judges the status through operational amplifier U2A, and outputs a signal to the system when an abnormality occurs, realizing grounding fault detection and protection, which meets the grounding monitoring requirements in the safety specifications for AC charging piles.
[0026] The voltage on the N side is divided by resistors R21, R22, R23, and R25, and then amplified by a differential sampling circuit composed of operational amplifier U2A. The output is then filtered by a rectifier circuit composed of operational amplifier U2B, diodes D3 and D4, and resistors R24, R36, and R28, and a first low-pass filter circuit composed of resistors R26, R34, and capacitor C20. Impedance matching is achieved by a follower circuit composed of operational amplifier U3A, and then the output is sent to the ADC interface detection pin (ADC1_IN9) of the MCU by a second low-pass filter circuit composed of resistors R29, R33, and capacitor C19. The ADC1_IN9 pin outputs a continuous analog signal to the microcontroller, and the actual value of the input ground voltage is calculated from the signal value.
[0027] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any way. Any person skilled in the art can make many possible variations and modifications to the technical solution of this utility model using the disclosed methods and techniques, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of this utility model. Therefore, all equivalent changes made based on the shape, structure, and principle of this utility model without departing from its technical solution should be covered within the protection scope of this utility model.
Claims
1. A grounding detection circuit for an AC power supply control board of an electric vehicle, characterized in that, Including operational amplifier U2A; The non-inverting input terminal of the operational amplifier U2A is electrically connected to the output terminal of the neutral line voltage divider circuit, and the input terminal of the neutral line voltage divider circuit is connected to the neutral line of the power grid. The inverting input terminal of the operational amplifier U2A is electrically connected to the output terminal of the protective ground voltage divider circuit, and the input terminal of the protective ground voltage divider circuit is connected to the protective ground wire of the power grid. The output terminal of the operational amplifier U2A is electrically connected to the input terminal of the rectifier circuit through resistor R27. The output terminal of the rectifier circuit is electrically connected to the input terminal of the first low-pass filter circuit. The output terminal of the first low-pass filter circuit is electrically connected to the input terminal of the follower circuit. The output terminal of the follower circuit is electrically connected to the second low-pass filter circuit.
2. An electric vehicle alternating current supply apparatus control panel ground detection circuit as defined in claim 1, wherein, The neutral line voltage divider circuit includes resistors R21, R22, and R23 connected in series. The other end of resistor R21 is connected to the neutral line of the power grid, and the other end of resistor R23 is electrically connected to the non-inverting input terminal of operational amplifier U2A.
3. An electric vehicle alternating current supply apparatus control panel ground detection circuit as defined in claim 1, wherein, The protective ground voltage divider circuit includes resistors R30, R31, and R32 connected in series. The other end of resistor R30 is connected to the protective ground of the power grid, and the other end of resistor R32 is electrically connected to the inverting input terminal of operational amplifier U2A.
4. An electric vehicle alternating current supply apparatus control panel ground detection circuit as defined in claim 1, wherein, The non-inverting input terminal of the operational amplifier U2A is connected to the GND terminal through a parallel resistor R25 and a capacitor C18, and the inverting input terminal and the output terminal of the operational amplifier U2A are connected in parallel with a resistor R35 and a capacitor C22.
5. An electric vehicle alternating current supply apparatus control panel ground detection circuit as defined in Claim 4, wherein, The positive input terminal of the operational amplifier U2A is connected to a +12V voltage and then to the GND terminal via capacitor C17. The negative input terminal of the operational amplifier U2A is connected to a -12V voltage and then to the GND terminal via capacitor C21.
6. An electric vehicle alternating current supply apparatus control panel ground detection circuit as defined in Claim 1, wherein, The rectifier circuit includes an operational amplifier U2B; The non-inverting input terminal of the operational amplifier U2B is electrically connected to one end of the resistor R24, and the other end of the resistor R24 is connected to the GND terminal. The inverting input terminal of the operational amplifier U2B is electrically connected to one end of resistor R28, and the other end of resistor R28 is connected to one end of resistor R27. The inverting input terminal and the output terminal of the operational amplifier U2B are electrically connected to a rectifier diode D4, the output terminal of the operational amplifier U2B is electrically connected to the positive terminal of a rectifier diode D3, and the negative terminal of the rectifier diode D3 is connected to the input terminal of the first low-pass filter circuit. One end of resistor R27 is connected to the input terminal of the first low-pass filter circuit through resistor R36.
7. An electric vehicle alternating current supply apparatus control panel ground detection circuit as defined in Claim 1, wherein, The first low-pass filter circuit includes resistors R26 and R34 and capacitor C20. One end of resistor R26 is connected to the output terminal of the rectifier circuit, and the other end of resistor R26 is connected to the input terminal of the follower circuit. The other end of resistor R26 is connected to the GND terminal through resistor R34 and capacitor C20 in parallel.
8. An electric vehicle alternating current supply apparatus control panel ground detection circuit as defined in Claim 1, wherein, The follower circuit includes an operational amplifier U3A. The non-inverting input of the operational amplifier U3A is connected to the output of the first low-pass filter circuit. The inverting input and output of the operational amplifier U3A are connected. The positive power input of the operational amplifier U3A is connected to +12V, and the negative power input of the operational amplifier U3A is connected to -12V.
9. An electric vehicle alternating current supply apparatus control panel ground detection circuit as defined in Claim 1, wherein, The second low-pass filter circuit includes resistors R29 and R33 and capacitor C19. One end of resistor R29 is connected to the output of the follower circuit, and the other end of resistor R29 serves as the output of the detection circuit. The other end of resistor R29 is connected to the GND terminal through resistor R33 and capacitor C19 in parallel.