A circuit for detecting negative level of CP signal

Abstract

This utility model discloses a circuit for detecting the negative level of a CP signal, relating to the field of new energy vehicle charging technology. It includes a Zener diode ZD1, with its positive terminal grounded and its negative terminal connected to the CP signal input terminal and a filter unit. The filter unit is connected to the first terminal of a resistor R1. The second terminal of resistor R1 is connected to the positive terminal of a diode D1, the first terminal of a resistor R2, and the inverting input terminal of an operational amplifier. The non-inverting input terminal of the operational amplifier is grounded. The output terminal of the operational amplifier is connected in sequence to a diode D2 and a voltage-to-current conversion unit, and then connected to the second terminal of resistor R2, serving as the detection signal output terminal. This utility model has a simple circuit that can be implemented using conventional components. It detects the negative level of the CP signal by judging whether there is voltage in the detection signal CP_DET, eliminating false positives. The use of an operational amplifier for voltage inversion offers advantages such as reduced cost, fewer components, simplified circuitry, and high detection accuracy, making it highly practical.

Description

Technical Field

[0001] This utility model relates to the field of new energy vehicle charging technology, specifically, a circuit for detecting the negative level of the CP signal. Background Technology

[0002] The CP (Control Pilot function) signal is mainly used to monitor the interaction between electric vehicles and their power supply equipment (such as charging piles). It plays a controlling and guiding role in the charging process of new energy vehicles, and its accurate detection is crucial for the charging process. GB / T18487.1-2023 requires that power supply equipment should be able to detect the presence of diode D1 in the control pilot circuit, which essentially requires detecting the negative level of the CP signal. Existing detection methods often require a level conversion chip to convert the negative voltage to a positive voltage, followed by signal processing through a passive filtering circuit. This results in complex detection circuits, low reliability, and high cost; or the detection accuracy may not meet expectations, leading to misjudgments during the charging process of new energy vehicles. Utility Model Content

[0003] The purpose of this invention is to provide a circuit for detecting the negative level of the CP signal, which solves the problems of complex circuits, low reliability, high cost, low detection accuracy, and misjudgment in the existing methods for detecting the negative level of the CP signal.

[0004] The present invention solves the above problems through the following technical solution:

[0005] A circuit for detecting a negative level of a CP signal includes a Zener diode ZD1, the positive terminal of which is grounded, the negative terminal of which is connected to the CP signal input terminal and a filter unit, the filter unit being connected to the first terminal of a resistor R1, the second terminal of which is connected to the positive terminal of a diode D1, the first terminal of a resistor R2, and the inverting input terminal of an operational amplifier, the non-inverting input terminal of which is grounded, and the output terminal of the operational amplifier being connected in sequence to a diode D2 and a voltage-to-current conversion unit, and then connected to the second terminal of the resistor R2, serving as the detection signal output terminal.

[0006] Furthermore, the filtering unit is an LC filter circuit.

[0007] Furthermore, the voltage-current conversion unit includes a resistor R3 and a capacitor C2. The first end of the resistor R3 is connected to the negative terminal of the diode D2, the second end of the resistor R3 is connected to the first end of the capacitor C2 and the second end of the resistor R3, and the second end of the capacitor C2 is grounded.

[0008] Furthermore, resistors R1 and R2 form a voltage divider network.

[0009] Furthermore, diodes D1 and D2 are rectifier diodes.

[0010] Furthermore, the clamping voltage of the Zener diode ZD1 is +12V.

[0011] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0012] This invention features a simple circuit that can be implemented using conventional components. It detects the negative level of the CP signal by judging whether there is voltage in the detection signal CP_DET, eliminating the possibility of false judgments. This invention uses an operational amplifier to achieve voltage inversion, resulting in a simple circuit. It has the advantages of reduced cost, fewer components, simplified circuit, and high detection accuracy, making it highly practical. Attached Figure Description

[0013] Figure 1 This is the circuit schematic diagram of this utility model;

[0014] U1 is an operational amplifier. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0016] Example:

[0017] Combined with appendix Figure 1 As shown, a circuit for detecting the negative level of a CP signal includes a Zener diode ZD1. The positive terminal of the Zener diode ZD1 is grounded, and the negative terminal of the Zener diode ZD1 is connected to the CP signal input terminal and a filter unit. The filter unit is connected to the first terminal of a resistor R1. The second terminal of the resistor R1 is connected to the positive terminal of a diode D1, the first terminal of a resistor R2, and the inverting input terminal of an operational amplifier U1. The non-inverting input terminal of the operational amplifier U1 is grounded. The output terminal of the operational amplifier U1 is connected in sequence to a diode D2 and a voltage-to-current conversion unit, and then connected to the second terminal of the resistor R2, serving as the output terminal of the detection signal CP_DET.

[0018] Furthermore, the filtering unit is an LC filter circuit.

[0019] Furthermore, the voltage-current conversion unit includes a resistor R3 and a capacitor C2. The first end of the resistor R3 is connected to the negative terminal of the diode D2, the second end of the resistor R3 is connected to the first end of the capacitor C2 and the second end of the resistor R3, and the second end of the capacitor C2 is grounded.

[0020] Furthermore, resistors R1 and R2 form a voltage divider network.

[0021] Furthermore, diodes D1 and D2 are rectifier diodes.

[0022] Furthermore, the clamping voltage of the Zener diode ZD1 is +12V.

[0023] Working principle:

[0024] When the CP signal voltage is +12V, it flows to ground after passing through LC (inductor L1 and capacitor C1), resistor R1, and diode D1. Since the voltage at the inverting input terminal of operational amplifier U1 is higher than that at the non-inverting input terminal at this time, the output terminal of operational amplifier U1 is negative and cannot pass through rectifier diode D2, so there is no voltage at the detection signal CP_DET.

[0025] When the CP signal voltage is -12V, it flows into the inverting input terminal of the operational amplifier U1 after LC filtering and resistor R1 (diode D1 blocks the negative voltage). Since the voltage at the inverting input terminal of the operational amplifier U1 is lower than that at the non-inverting input terminal, the output terminal of the operational amplifier U1 is positive. After passing through rectifier diode D2 and resistor R3, the detection signal CP_DET has voltage.

[0026] Therefore, the negative level of the CP signal can be detected based on the presence or absence of voltage in the detection signal CP_DET. This invention requires fewer electronic components and can be implemented using conventional electronic parts. By judging whether there is voltage in the detection signal CP_DET, the negative level of the CP signal is detected, eliminating false judgments and achieving high detection accuracy. It has the advantages of reducing costs, reducing components, simplifying circuitry, and improving detection accuracy.

[0027] Although the present invention has been described herein with reference to illustrative embodiments, the above embodiments are merely preferred embodiments of the present invention, and the implementation of the present invention is not limited to the above embodiments. It should be understood that those skilled in the art can design many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in this application.

Claims

1. A circuit for detecting a negative level of a CP signal, characterized by The voltage stabilizer ZD1 is connected to ground at the positive electrode, and the negative electrode of the voltage stabilizer ZD1 is connected to the CP signal input end and a filter unit, the first end of the resistor R1 is connected to the filter unit, the second end of the resistor R1 is connected to the positive electrode of the diode D1, the first end of the resistor R2 and the inverting input end of the operational amplifier, the non-inverting input end of the operational amplifier is connected to ground, the output end of the operational amplifier is connected to the second end of the resistor R2 through the diode D2 and a current-voltage conversion unit in sequence, and the output end is used as a detection signal output end.

2. The circuit for detecting negative level of CP signal according to claim 1, wherein, The filter unit is an LC filter circuit.

3. The circuit for detecting negative level of CP signal according to claim 1, wherein, The current-voltage conversion unit comprises a resistor R3 and a capacitor C2, the first end of the resistor R3 is connected to the negative electrode of the diode D2, the second end of the resistor R3 is connected to the first end of the capacitor C2 and the second end of the resistor R3, and the second end of the capacitor C2 is connected to ground.

4. The circuit for detecting negative level of CP signal according to claim 3, wherein, The resistor R1 and the resistor R2 constitute a voltage division network.

5. The circuit for detecting negative level of CP signal according to claim 1, wherein, The diode D1 and the diode D2 are rectifier diodes.

6. The circuit for detecting negative level of CP signal according to claim 1, wherein, The clamping voltage of the voltage stabilizer ZD1 is +12V.

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