A Current Sampling Circuit for New Energy Vehicles Based on a Current Sensor

Abstract

This utility model discloses a current sampling circuit for new energy vehicles based on a current sensor, within the field of current sensor technology. The current sensor P1 is connected to a negative feedback differential amplifier circuit via a filter circuit. The negative feedback differential amplifier circuit is connected to an emitter follower circuit, which outputs a current sampling value. Using a current sensor, bidirectional current is collected. The collected voltage is input to the negative feedback differential amplifier circuit, and after passing through the negative feedback differential amplifier circuit, it is input to the emitter follower circuit, ultimately outputting a stable current sampling value. The circuit features a simple structure, is easy to install, achieves high-voltage interference control without external isolation, exhibits good dynamic characteristics, and has a fast conversion speed.

Description

Technical Field

[0001] This utility model relates to a current sampling circuit for new energy vehicles in the field of current sensor technology. Background Technology

[0002] Electric vehicles use ternary lithium or lithium iron phosphate batteries. Lithium batteries are susceptible to overcharging, over-discharging, and temperature runaway during use, which can easily lead to spontaneous combustion or even explosion. Current battery management systems (BMS) use shunts to measure current, which requires direct contact with high-voltage circuitry. This allows interference from the battery terminal to enter the control circuit. Therefore, to improve sampling accuracy, an additional isolation circuit is needed to separate the main control unit from the shunt. This results in a complex circuit and makes installation difficult. Utility Model Content

[0003] The purpose of this invention is to provide a current sampling circuit for new energy vehicles based on a current sensor. It has a simple structure, is easy to install, can achieve high voltage interference without external isolation, has good dynamic characteristics, and a fast conversion speed.

[0004] To achieve the above objectives, this utility model provides a current sampling circuit for new energy vehicles based on a current sensor. The current sensor P1 is connected to a negative feedback differential amplifier circuit via a filter circuit. The negative feedback differential amplifier circuit is connected to an emitter follower circuit, which outputs the current sampling value.

[0005] Compared with existing technologies, the advantages of this invention lie in its use of a current sensor to collect bidirectional current. The collected voltage is then input to a negative feedback differential amplifier circuit, and after passing through the negative feedback differential amplifier circuit, the voltage is input to an emitter follower circuit, ultimately outputting a stable current sampling value. The structure is simple, easy to install, and can achieve high-voltage interference without external isolation. It also exhibits good dynamic characteristics and fast switching speed.

[0006] As a further improvement of this utility model, the filter circuit includes a resistor R1. One end of the resistor R1 is connected to pin 2 of the current sensor P1, pin 1 of the current sensor P1 is grounded, the other end of the resistor R1 is connected to one end of the capacitor C1, the other end of the capacitor C1 is connected to one end of the resistor R2 and grounded, and the other end of the resistor R2 is connected to one end of the capacitor C1 and the negative feedback differential amplifier circuit.

[0007] In this way, R13 and C1 form a low-pass filter circuit to filter out high-frequency noise in the output voltage of the current sensor. R2 is a pull-down resistor to stabilize the DC bias of the filtered voltage and avoid zero drift.

[0008] As a further improvement of this utility model, the negative feedback differential amplifier circuit includes an operational amplifier U1A. Pin 2 of the operational amplifier U1A is connected to the other end of resistor R2. Pin 3 of the operational amplifier U1A is connected to one end of resistor R3. The other end of resistor R3 is connected to pin 1 of the operational amplifier U1A and the emitter follower circuit, respectively. A capacitor C2 is connected in parallel across the two ends of resistor R3. Pin 4 of the operational amplifier U1A is grounded, and pin 8 of the operational amplifier U1A is grounded through capacitor C3.

[0009] This achieves voltage amplification through operational amplifier U1A, where resistor R3 is the feedback resistor and capacitor is the compensation capacitor. The two are connected in parallel to prevent high-frequency self-oscillation and stabilize the amplifier circuit. In addition, capacitor C3 provides high-frequency decoupling for the amplified signal, further filtering out noise.

[0010] As a further improvement of this utility model, the emitter follower circuit includes an operational amplifier U1B, pin 5 of the operational amplifier U1B is connected to pin 1 of the operational amplifier U1A, pin 6 of the operational amplifier U1B is connected to pin 7, and pin 7 of the operational amplifier U1B outputs a sampling current.

[0011] This high impedance matching improves the output load capacity and prevents load changes from affecting amplification accuracy. Attached Figure Description

[0012] Figure 1 This is the circuit diagram of this utility model. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings: like Figure 1 The diagram shows a current sampling circuit for a new energy vehicle based on a current sensor. The current sensor P1 is connected to a negative feedback differential amplifier circuit via a filter circuit. The negative feedback differential amplifier circuit is connected to an emitter follower circuit, which outputs the current sampling value.

[0014] The filter circuit includes a resistor R1. One end of the resistor R1 is connected to pin 2 of the current sensor P1, and pin 1 of the current sensor P1 is grounded. The other end of the resistor R1 is connected to one end of the capacitor C1. The other end of the capacitor C1 is connected to one end of the resistor R2 and grounded. The other end of the resistor R2 is connected to one end of the capacitor C1 and the negative feedback differential amplifier circuit.

[0015] The negative feedback differential amplifier circuit includes an operational amplifier U1A. Pin 2 of the operational amplifier U1A is connected to the other end of resistor R2. Pin 3 of the operational amplifier U1A is connected to one end of resistor R3. The other end of resistor R3 is connected to pin 1 of the operational amplifier U1A and the emitter follower circuit. A capacitor C2 is connected in parallel across the two ends of resistor R3. Pin 4 of the operational amplifier U1A is grounded, and pin 8 of the operational amplifier U1A is grounded through capacitor C3.

[0016] The emitter follower circuit includes operational amplifier U1B. Pin 5 of operational amplifier U1B is connected to pin 1 of operational amplifier U1A. Pins 6 and 7 of operational amplifier U1B are connected. Pin 7 of operational amplifier U1B outputs the sampling current.

[0017] In this invention, the current sensor P1 collects the bidirectional current of the battery pack and outputs a voltage signal that is proportional to the current; when the current direction changes, the polarity of the output voltage reverses accordingly, thus realizing bidirectional current detection.

[0018] Resistor R1 is connected in series with the sensor output to protect the op-amp input and also performs impedance matching with the sensor output impedance. Resistor R2 and capacitor C1 are connected in parallel between the op-amp's non-inverting input and ground to filter out high-frequency noise in the sensor output signal, making the signal input to the op-amp more stable.

[0019] In the negative feedback differential amplifier circuit, operational amplifier U1A amplifies the weak voltage signal output from the current sensor, converting the signal into a voltage suitable for subsequent circuit processing. Resistor R3 is the feedback resistor, which determines the amplification factor; capacitor C2 is the phase compensation capacitor, preventing the op-amp from self-oscillating and ensuring stable circuit operation.

[0020] Capacitor C3 is a DC blocking capacitor, connected in series between the output terminal of U1A and the input terminal of U1B. It blocks the DC component and only allows the AC signal to pass through, preventing the DC bias of the previous stage from affecting the subsequent circuit. It provides high-frequency decoupling for the amplified signal and further filters out noise.

[0021] An emitter follower achieves impedance transformation, improving load-driving capability. The output voltage is equal to the input voltage, but the output current capability is enhanced, enabling the circuit to drive subsequent loads (such as AD converters). The non-inverting input (pin 5) of operational amplifier U1B is connected to the input signal, and the inverting input (pin 6) is directly connected to the output (pin 7), forming a voltage follower. Its high input impedance and low output impedance act as a buffer, isolating the preceding amplifier stage from the subsequent load and preventing load changes from affecting the preceding stage's amplification factor.

[0022] This invention employs dual operational amplifiers, features low power consumption and single power supply, making it suitable for battery-powered systems and meeting the low power consumption requirements of current sampling circuits. Multiple grounding points (such as sensor ground and operational amplifier ground) ensure a common ground for the circuit, preventing interference introduced by ground potential differences.

[0023] The overall working process of this utility model is as follows: The current sensor P1 converts the measured current into a voltage signal. After being filtered by R2 and C1, the signal is input to the non-inverting input of operational amplifier U1A. It is amplified through the negative feedback network R3 and C2, and then output to operational amplifier U1B after DC blocking by capacitor C3. Operational amplifier U1B forms a voltage follower, outputting a stable current sampling signal for use by subsequent AD acquisition or control circuits.

[0024] Through the coordination of the above circuits, this invention achieves accurate acquisition, filtering, amplification and stable output of bidirectional current of the battery pack, providing reliable current sampling values ​​for the battery management system (BMS).

[0025] This utility model is not limited to the above embodiments. Based on the technical solutions disclosed herein, those skilled in the art can make some substitutions and modifications to some of the technical features without creative labor, and these substitutions and modifications are all within the protection scope of this utility model.

Claims

1. A current sampling circuit for new energy vehicles based on a current sensor, characterized in that: The current sensor P1 is connected to the negative feedback differential amplifier circuit via a filter circuit. The negative feedback differential amplifier circuit is connected to the emitter follower circuit, which outputs the current sampling value.

2. The current sampling circuit for new energy vehicles based on a current sensor according to claim 1, characterized in that: The filter circuit includes a resistor R1. One end of the resistor R1 is connected to pin 2 of the current sensor P1, and pin 1 of the current sensor P1 is grounded. The other end of the resistor R1 is connected to one end of the capacitor C1. The other end of the capacitor C1 is connected to one end of the resistor R2 and grounded. The other end of the resistor R2 is connected to one end of the capacitor C1 and the negative feedback differential amplifier circuit.

3. The current sampling circuit for new energy vehicles based on a current sensor according to claim 2, characterized in that: The negative feedback differential amplifier circuit includes an operational amplifier U1A. Pin 2 of the operational amplifier U1A is connected to the other end of resistor R2. Pin 3 of the operational amplifier U1A is connected to one end of resistor R3. The other end of resistor R3 is connected to pin 1 of the operational amplifier U1A and the emitter follower circuit. A capacitor C2 is connected in parallel across the two ends of resistor R3. Pin 4 of the operational amplifier U1A is grounded, and pin 8 of the operational amplifier U1A is grounded through capacitor C3.

4. The current sampling circuit for new energy vehicles based on a current sensor according to claim 3, characterized in that: The emitter follower circuit includes operational amplifier U1B. Pin 5 of operational amplifier U1B is connected to pin 1 of operational amplifier U1A. Pins 6 and 7 of operational amplifier U1B are connected. Pin 7 of operational amplifier U1B outputs the sampling current.

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