Signal acquisition circuit for alternating current charging pile of electric vehicle

Abstract

The utility model provides an electric automobile AC charging pile signal acquisition circuit, and relates to the technical field of electric automobile AC charging equipment, the electric automobile AC charging pile signal acquisition circuit comprises a CP pulse circuit and a voltage sampling circuit, the CP pulse circuit is provided with a second inductor and a second capacitor, the second inductor is electrically connected with the second capacitor, the second capacitor is grounded, and the voltage sampling circuit is electrically connected with the CP pulse circuit. The CP pulse circuit comprises a fifth resistor, a sixth resistor, a third capacitor and a first operational amplifier; one end of the fifth resistor is connected between the second inductor and the second capacitor, the other end of the fifth resistor is connected with the sixth resistor and the first operational amplifier, the sixth resistor is grounded, the sixth resistor and the first operational amplifier are connected in parallel, and the negative electrode input end and the negative electrode output end of the first operational amplifier are communicated. The device can accurately measure the peak value of the CP signal.

Description

Technical Field

[0001] The utility model relates to the technical field of electric vehicle AC charging equipment, in particular to an electric vehicle AC charging pile signal acquisition circuit. Background Art

[0002] According to the provisions of the electric vehicle charging pile standard GB / T-18487.1-2023, the control circuit of the AC charging pile needs to generate a CP pulse signal for control guidance, and collect and measure the peak voltage of this signal. The CP signal is a 1KHz bipolar square wave signal. The charging pile notifies the vehicle end of the current information that the charging pile can output through the duty cycle of the positive pulse of the CP signal. The vehicle end notifies the charging pile of the vehicle end's plug-in and charging commands through the diode, resistor and S2 switch on the CP signal line. Due to the high frequency of the CP signal and the need for the AC charging pile to collect other analog quantities, it is a difficult problem to quickly and accurately sample the peak voltage of the CP signal. Most AC charging pile products on the market have poor performance in measuring the peak value of the CP signal, and it often takes dozens of milliseconds to obtain a more accurate measurement voltage. This measurement delay directly affects the charging pile's handling performance for violent gun pulling during charging: when the charging pile detects gun pulling during charging, the relay should be disconnected immediately for protection according to the national standard to avoid the charging gun from burning the contact pin when disconnecting under load. If the CP voltage detection delay is too large, the relay will not be disconnected in time, which will burn the charging gun head. In addition, the latest 2023 version of GB / T-18487.1, Article A.2.6, requires the presence of the diode on the CP line to be detected. Currently, no products on the market support this function.

[0003] Therefore, there is an urgent need for an electric vehicle AC charging pile signal acquisition circuit to solve the problem of poor performance of existing AC charging pile products in peak measurement of CP signals. Utility Model Content

[0004] The utility model provides an electric vehicle AC charging pile signal acquisition circuit, which solves the problem that the existing AC charging pile products have poor performance in peak value measurement of CP signals.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] An electric vehicle AC charging pile signal acquisition circuit, comprising:

[0007] A CP pulse circuit, the CP pulse circuit comprising a first resistor, a second resistor, a third resistor, a fourth resistor, a comparator, a first capacitor, a second capacitor, a first inductor, a second inductor and a first diode; the first resistor, the second resistor and the third resistor are all electrically connected to the input end of the comparator, the first resistor, the second resistor and the third resistor are arranged in parallel, and the other end of the third resistor is grounded; the first capacitor is arranged in parallel with the third resistor; one end of the fourth resistor is connected to the comparator, and the other end is connected to the first inductor, the second inductor and the first diode, the first inductor, the second inductor and the first diode are arranged in parallel, the other end of the first diode is grounded, the second inductor is electrically connected to the second capacitor, and the second capacitor is grounded;

[0008] A voltage sampling circuit, the voltage sampling circuit comprising a fifth resistor, a sixth resistor, a third capacitor and a first operational amplifier; one end of the fifth resistor is connected between the second inductor and the second capacitor, and the other end is connected to the sixth resistor and the first operational amplifier, the sixth resistor is grounded, the sixth resistor and the first operational amplifier are connected in parallel, and the negative input terminal of the first operational amplifier is connected to the output terminal.

[0009] Furthermore, it also includes a seventh resistor, an eighth resistor, a ninth resistor, a second diode, a third diode, a fourth capacitor and a second operational amplifier;

[0010] One end of the seventh resistor is connected between the second inductor and the second capacitor, and the other end is connected to the negative input terminal of the second operational amplifier. One end of the seventh resistor is connected to the second diode, and the second diode is grounded. The output end of the second operational amplifier is sequentially connected to the third diode, the eighth resistor and the fourth capacitor, and the fourth capacitor is grounded. One end of the ninth resistor is connected to the negative input terminal of the second operational amplifier, and the other end is connected between the eighth resistor and the fourth capacitor.

[0011] In summary, due to the adoption of the above technical solution, the beneficial effects of the utility model are:

[0012] In actual operation, the first operational amplifier is used for positive peak voltage sampling, the CP signal is attenuated by the fifth resistor and the sixth resistor, and is filtered by the third capacitor before entering the first operational amplifier for buffering, and the buffered low impedance signal is sent to the AD port of the single chip computer through CP_VOL for sampling. The utility model can accurately measure the peak value of the CP signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0014] The utility model is described in detail below in conjunction with the accompanying drawings.

[0015] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0016] This embodiment provides an electric vehicle AC charging pile signal acquisition circuit, such as Figure 1 As shown, including:

[0017] A CP pulse circuit, the CP pulse circuit comprising a first resistor R50, a second resistor R51, a third resistor R52, a fourth resistor R53, a comparator U7, a first capacitor C27, a second capacitor C30, a first inductor L4, a second inductor L3 and a first diode; the first resistor R50, the second resistor R51 and the third resistor R52 are all electrically connected to the input end of the comparator U7, the first resistor R50, the second resistor R51 and the third resistor R52 are arranged in parallel, and the other end of the third resistor R52 is grounded; the first capacitor C27 is arranged in parallel with the third resistor R52; one end of the fourth resistor R53 is connected to the comparator U7, and the other end is connected to the first inductor L4, the second inductor L3 and the first diode VD1, the first inductor L4, the second inductor L3 and the first diode VD1 are arranged in parallel, the other end of the first diode VD1 is grounded, the second inductor L3 is electrically connected to the second capacitor C30, and the second capacitor C30 is grounded;

[0018] A voltage sampling circuit, the voltage sampling circuit includes a fifth resistor R54, a sixth resistor R55, a third capacitor C31 and a first operational amplifier U9A; one end of the fifth resistor R54 is connected between the second inductor L3 and the second capacitor C30, and the other end is connected to the sixth resistor R55 and the first operational amplifier U9A, the sixth resistor R55 is grounded, the sixth resistor R55 and the first operational amplifier U9A are connected in parallel, and the negative input terminal of the first operational amplifier U9A is connected to the output terminal.

[0019] like Figure 1 As shown, the PWM signal in the figure comes from the single-chip microcomputer, which is a variable duty cycle 3.3V TTL signal waveform with a frequency of 1KHz. U7 is an operational amplifier with high output capability. It is used as a comparator in the circuit of the utility model to convert the 3.3V TTL level output by the single-chip microcomputer into a positive and negative 12V bipolar signal required by the national standard. The signal generated by U7 passes through the 1K resistor R53 required by the national standard and then is sent to the AC charging port of the electric vehicle through CP.

[0020] U9A is used for positive peak voltage sampling. The CP signal is attenuated by R54 and R55, filtered by C31 and then enters U9A for buffering. The buffered low-impedance signal is sent to the AD port of the microcontroller through CP_VOL for sampling.

[0021] The above implementation is further optimized, further comprising a seventh resistor R87, an eighth resistor R88, a ninth resistor R89, a second diode VD2, a third diode VD3, a fourth capacitor C35 and a second operational amplifier U9C;

[0022] One end of the seventh resistor R87 is connected between the second inductor L3 and the second capacitor C30, and the other end is connected to the negative input terminal of the second operational amplifier U9C. One end of the seventh resistor R87 is connected to the second diode VD2, and the second diode VD2 is grounded. The output end of the second operational amplifier U9C is sequentially connected to the third diode VD3, the eighth resistor R88 and the fourth capacitor C35, and the fourth capacitor C35 is grounded. One end of the ninth resistor R89 ​​is connected to the negative input terminal of the second operational amplifier U9C, and the other end is connected between the eighth resistor R88 and the fourth capacitor C35.

[0023] U9C is used for negative peak voltage measurement. Unlike positive peak sampling, negative peak voltage is only used for diode presence detection, and there is no requirement for fast measurement. Therefore, peak detection is completed by operational amplifier U9C, and the microcontroller only needs to collect the DC voltage after peak detection, and it can be used for diode presence detection after simple averaging. U9C adopts an inverting amplifier structure to convert -12V into positive voltage, which can simplify the power supply circuit.

[0024] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A signal acquisition circuit for an electric vehicle AC charging pile, characterized in that: include: A CP pulse circuit, the CP pulse circuit comprising a first resistor, a second resistor, a third resistor, a fourth resistor, a comparator, a first capacitor, a second capacitor, a first inductor, a second inductor and a first diode; the first resistor, the second resistor and the third resistor are all electrically connected to the input end of the comparator, the first resistor, the second resistor and the third resistor are arranged in parallel, and the other end of the third resistor is grounded; the first capacitor is arranged in parallel with the third resistor; one end of the fourth resistor is connected to the comparator, and the other end is connected to the first inductor, the second inductor and the first diode, the first inductor, the second inductor and the first diode are arranged in parallel, the other end of the first diode is grounded, the second inductor is electrically connected to the second capacitor, and the second capacitor is grounded; A voltage sampling circuit, the voltage sampling circuit comprising a fifth resistor, a sixth resistor, a third capacitor and a first operational amplifier; one end of the fifth resistor is connected between the second inductor and the second capacitor, and the other end is connected to the sixth resistor and the first operational amplifier, the sixth resistor is grounded, the sixth resistor and the first operational amplifier are connected in parallel, and the negative input terminal of the first operational amplifier is connected to the output terminal.

2. The electric vehicle AC charging pile signal acquisition circuit according to claim 1, characterized in that: Also includes a seventh resistor, an eighth resistor, a ninth resistor, a second diode, a third diode, a fourth capacitor, and a second operational amplifier; One end of the seventh resistor is connected between the second inductor and the second capacitor, and the other end is connected to the negative input terminal of the second operational amplifier. One end of the seventh resistor is connected to the second diode, and the second diode is grounded. The output end of the second operational amplifier is sequentially connected to the third diode, the eighth resistor and the fourth capacitor, and the fourth capacitor is grounded. One end of the ninth resistor is connected to the negative input terminal of the second operational amplifier, and the other end is connected between the eighth resistor and the fourth capacitor.

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