Low voltage series charging circuit

Abstract

This application discloses a low-voltage series charging circuit, relating to the field of lithium battery production. The low-voltage series charging circuit includes a BUCK circuit, a battery switching circuit, a battery voltage acquisition circuit, and an MCU main circuit. One BUCK circuit can charge up to four individual batteries. The voltage of each individual battery is transmitted to the MCU main circuit through the battery voltage acquisition circuit. The MCU main circuit determines the state of each individual battery based on the voltage signal and then outputs a corresponding control signal to the battery switching circuit. Simultaneously, it outputs a current adjustment signal to the BUCK circuit to control the magnitude of the charging current. This application employs a series formation method to charge and power multiple individual batteries using one BUCK circuit, improving the efficiency and utilization rate of the BUCK circuit.

Description

Technical Field

[0001] This application relates to the field of lithium battery production, and in particular to a low-voltage series charging circuit. Background Technology

[0002] In existing lithium-ion battery production processes, each battery typically corresponds to a single BUCK circuit, which charges and powers the battery to complete the formation process. Because the battery voltage and required current are both relatively low during formation, the efficiency and utilization of the BUCK circuit are low, further reducing the utilization rate of the formation equipment. Therefore, it is necessary to improve the efficiency and utilization rate of the BUCK circuit to reduce the cost of battery formation equipment, thereby lowering the overall cost of battery production. Summary of the Invention

[0003] The purpose of this application is to provide a low-voltage series charging circuit that uses a series formation method to charge and power multiple individual batteries using a set of BUCK circuits, thereby improving the efficiency and utilization of the BUCK circuit.

[0004] To achieve the above objectives, this application provides a low-voltage series charging circuit, including: a BUCK circuit, a battery switching circuit, a battery voltage acquisition circuit, and an MCU main circuit; The output terminal of the BUCK circuit is connected to the input terminal of the battery switching circuit. The BUCK circuit is used to generate charging current to power and charge the series battery pack. The number of individual cells in the series battery pack does not exceed 4. The output terminal of the battery switching circuit is connected to the series battery pack, and the control terminal of the battery switching circuit is connected to the first control signal output terminal of the MCU main circuit. The battery switching circuit is used to switch the state of each individual battery in the series battery pack according to the control signal output by the MCU main circuit. The input terminal of the battery voltage acquisition circuit is connected to each individual battery in the series battery pack, and the output terminal of the battery voltage acquisition circuit is connected to the first signal input terminal of the MCU main circuit. The battery voltage acquisition circuit is used to acquire the real-time voltage of each individual battery, and transmit it to the MCU main circuit after signal conditioning. The MCU main circuit is used to receive the voltage signal transmitted by the battery voltage acquisition circuit, determine the state of each individual battery cell based on the voltage signal, and then output the corresponding control signal to the battery switching circuit. At the same time, it outputs the current adjustment signal to the BUCK circuit to control the magnitude of the charging current.

[0005] According to the specific embodiments provided in this application, this application has the following technical effects: This application significantly improves the workload and conversion efficiency of the BUCK circuit by connecting no more than four individual cells in series and charging them uniformly through the same BUCK circuit. This solves the problems of low BUCK efficiency and poor equipment utilization caused by low voltage and low current of individual cells in the prior art. At the same time, by combining the MCU main circuit, battery voltage acquisition circuit and battery switching circuit to form a closed-loop control system, it not only realizes real-time monitoring of the voltage and intelligent judgment of the status of each individual cell, but also dynamically switches the battery access status and adjusts the charging current. While ensuring the safety and consistency of formation, it greatly reduces the number of BUCK circuits, reduces the hardware cost and system complexity of the formation equipment, and thus effectively reduces the production cost of lithium batteries while improving efficiency and optimizing the process. Attached Figure Description

[0006] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0007] Figure 1 A circuit diagram of a low-voltage series charging circuit provided in an embodiment of this application; Figure 2 for Figure 1 Circuit diagram of the BUCK circuit; Figure 3 The circuit diagram for the sub-switching circuit; Figure 4 The circuit diagram for the sub-acquisition circuit; Figure 5 This is a circuit diagram of the charging current acquisition circuit. Detailed Implementation

[0008] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0009] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0010] In one exemplary embodiment, such as Figure 1As shown, a low-voltage series charging circuit is provided, including: a BUCK circuit, a battery switching circuit, a battery voltage acquisition circuit, and an MCU main circuit.

[0011] The output of the BUCK circuit is connected to the input of the battery switching circuit. The BUCK circuit generates a charging current to power and charge the series-connected battery pack. The number of individual cells in the series-connected battery pack does not exceed four. Figure 1 Battery 1-Battery 4.

[0012] The output terminal of the battery switching circuit is connected to the series battery pack, and the control terminal of the battery switching circuit is connected to the first control signal output terminal of the MCU main circuit. The battery switching circuit is used to switch the state of each individual battery in the series battery pack according to the control signal output by the MCU main circuit.

[0013] The input terminal of the battery voltage acquisition circuit is connected to each individual battery cell in the series battery pack, and the output terminal of the battery voltage acquisition circuit is connected to the first signal input terminal of the MCU main circuit. The battery voltage acquisition circuit is used to acquire the real-time voltage of each individual battery cell, perform signal conditioning, and then transmit the signal to the MCU main circuit.

[0014] The MCU main circuit is used to receive the voltage signal transmitted by the battery voltage acquisition circuit, determine the state of each individual battery cell based on the voltage signal, and then output the corresponding control signal to the battery switching circuit. At the same time, it outputs the current adjustment signal to the BUCK circuit to control the magnitude of the charging current.

[0015] In one specific embodiment, such as Figure 2 As shown, the BUCK circuit includes: MOSFET Q1, MOSFET Q2, inductor L1 and capacitor C1.

[0016] The drain of the MOSFET Q1 is connected to a 24V power supply; The source of the MOS transistor Q1 is connected to the drain of the MOS transistor Q2 and one end of the inductor L1, respectively. The source of the MOS transistor Q2 is connected to the power supply ground; The other end of the inductor L1 is connected to one end of the capacitor C1 and the input terminal of the battery switching circuit; the other end of the inductor L1 is the output terminal of the BUCK circuit. The other end of capacitor C1 is connected to power ground; The gates of both MOSFET Q1 and MOSFET Q2 are connected to the second control signal output terminal of the MCU main circuit to receive the current adjustment signal.

[0017] The BUCK circuit provides a constant charging current to the entire low-voltage series charging circuit via an external 24V AC / DC power supply. This design, with one BUCK circuit supporting four batteries, significantly reduces equipment costs.

[0018] In one specific embodiment, the battery switching circuit includes sub-switching circuits corresponding one-to-one with each individual battery cell, such as... Figure 3 As shown, each sub-switching circuit includes: MOSFET Q3, MOSFET Q4, resistor R1, resistor R2, resistor R3 and resistor R4.

[0019] The drain of the MOSFET Q3 is connected to the output terminal of the BUCK circuit, the source terminal of the MOSFET Q4, and one end of the resistor R4; the drain of the MOSFET Q3 is the input terminal of the sub-switching circuit. The gate of the MOS transistor Q3 is connected to one end of the resistor R1 and one end of the resistor R2, respectively. The other end of the resistor R1 is connected to the first control signal output terminal of the MCU main circuit; it receives the control signal EN1.

[0020] The source of the MOS transistor Q3 is connected to the other end of the resistor R2 and the negative terminal of the corresponding single cell; and the source of the MOS transistor Q3 in the preceding sub-switching circuit is connected in series with the input terminal of the following sub-switching circuit. The gate of the MOS transistor Q4 is connected to one end of the resistor R3 and the other end of the resistor R4, respectively. The other end of the resistor R3 is connected to the first control signal output terminal of the MCU main circuit; it receives the control signal EN2.

[0021] The drain of the MOS transistor Q4 is connected to the positive terminal of the corresponding single cell. The positive and negative terminals of the individual battery are also connected to the input terminal of the battery voltage acquisition circuit.

[0022] The input terminal of the battery switching circuit (i.e., the drain of MOSFET Q3 in the first sub-switching circuit of multiple series-connected sub-switching circuits) is connected to the output terminal IA+ of the BUCK circuit, and the output terminal IA- of the preceding sub-switching circuit is connected to the input terminal of the following sub-switching circuit. The battery switching circuit can independently control any single cell in the series-connected battery pack to bypass or connect in series with the battery pack, and it achieves contactless operation, continuous current flow, and no impact on the overall series circuit.

[0023] The states of a single battery cell include resting, charging, and bypassing. The states of MOSFETs Q3 and Q4 are controlled by the control signal output from the first control signal output terminal of the MCU main circuit, thereby achieving state switching of the single battery cell. When both MOSFETs Q3 and Q4 are off, the single battery cell is in the resting state; when MOSFET Q3 is off and MOSFET Q4 is on, the single battery cell is in the bypass state; when both MOSFETs Q3 and Q4 are on, the single battery cell is in the charging state.

[0024] The battery switching circuit adopts single-stage control. By controlling the corresponding MOSFETs Q3 and Q4 through control signals EN1 and EN2, it can control the individual battery to switch between three states: resting (Q3 and Q4 are both off), charging (Q3 is off, Q4 is on), and bypass (Q3 is on, Q4 is off).

[0025] In one specific embodiment, the battery voltage acquisition circuit includes sub-acquisition circuits corresponding one-to-one with each individual battery cell, such as... Figure 4 As shown, each sub-acquisition circuit includes: operational amplifier U1, resistor R5, resistor R6, resistor R7, resistor R8 and resistor R9.

[0026] Both pin 1 and pin 8 of the operational amplifier U1 are floating. Pin 4 of the operational amplifier U1 is connected to the negative power supply VEE, and pin 7 of the operational amplifier U1 is connected to the positive power supply VDD. Pin 2 of the operational amplifier U1 is connected to one end of resistor R5 and one end of resistor R7, respectively. Pin 3 of the operational amplifier U1 is connected to one end of resistor R8 and one end of resistor R9, respectively. The other end of the resistor R7 is connected to the negative terminal of the corresponding single cell. The other end of the resistor R8 is connected to the positive terminal of the corresponding single battery cell; The other end of the resistor R9 is grounded; The operational amplifier pin 6 is connected to the other end of resistor R5 and one end of resistor R6, respectively. The other end of the resistor R6 is connected to the first signal input terminal of the MCU main circuit as the output terminal of the sub-acquisition circuit.

[0027] The operational amplifier U1 is a low-temperature drift operational amplifier; resistors R5, R7, R8, and R9 are all low-temperature drift, high-precision resistors. This allows for more precise acquisition of the voltage of individual battery cells. The operational amplifier U1 and the surrounding feedback resistors form a proportional operational circuit, which proportionally reduces the acquired battery voltage to a reasonable voltage range so that it can be acquired by the analog-to-digital converter in the MCU main circuit for judgment.

[0028] The battery voltage acquisition circuit enables high-precision real-time acquisition of the voltage of each individual battery cell, and transmits the real-time voltage to the MCU main circuit to complete the status judgment and fault judgment of the individual battery cells, as well as the logic processing and interlocking of control signals.

[0029] In one specific embodiment, such as Figure 1 As shown, the low-voltage series charging circuit further includes: a charging current acquisition circuit; the current sampling terminal of the charging current acquisition circuit is connected to the total output terminal of the battery switching circuit, and is used to acquire the charging current flowing through the series battery pack; the signal output terminal of the charging current acquisition circuit is connected to the second signal input terminal of the MCU main circuit, and is used to transmit the charging current to the MCU main circuit; the MCU main circuit is used to output a current adjustment signal to the BUCK circuit based on the charging current.

[0030] like Figure 5 As shown, the charging current acquisition circuit includes: operational amplifier U2, sampling resistor R10, resistor R11 and resistor R12.

[0031] Both pin 1 and pin 8 of the operational amplifier U2 are floating. Pin 4 of the operational amplifier U2 is connected to the negative power supply VEE, and pin 7 of the operational amplifier U1 is connected to the positive power supply VDD. Pin 5 of the operational amplifier U2 is grounded as the REF terminal; Pin 2 of the operational amplifier U2 is connected to one end of the resistor R12; Pin 3 of the operational amplifier U2 is connected to one end of the resistor R11; One end of the sampling resistor R10 is connected to the other end of the resistor R11 and the total output terminal of the battery switching circuit; one end of the sampling resistor R10 is the current sampling terminal of the charging current acquisition circuit. The other end of the sampling resistor R10 is connected to the other end of the resistor R12 and grounded; Pin 6 of the operational amplifier U2 is connected to the second signal input terminal of the MCU main circuit, and is used to transmit the collected charging current signal to the MCU main circuit; pin 6 of the operational amplifier U2 is the signal output terminal of the charging current acquisition circuit.

[0032] The sampling resistor R10 is a milliohm-level low-temperature drift precision resistor, mainly used to convert the current signal into a voltage signal for acquisition by operational amplifier U2. Operational amplifier U2 is an operational amplifier with a built-in feedback resistor. The built-in feedback resistor can reduce resistor aging during long-term use and ensure the accuracy of current acquisition after long-term use. The charging acquisition circuit proportionally amplifies the acquired charging current to a reasonable current range for acquisition by the analog-to-digital converter and for judgment by the MCU main circuit.

[0033] In one specific embodiment, the MCU main circuit implements three core control functions: (1) Single cell state switching control.

[0034] The MCU main circuit compares the real-time voltage of each individual battery cell (the digital signals corresponding to BV1~BV4) with the preset upper voltage limit: If the real-time voltage of a single cell does not reach the upper limit: maintain the "charging" state of the single cell in the sub-switching circuit (EN1=low, EN2=high, Q3 off, Q4 on). If the real-time voltage of a single battery cell reaches the upper limit: the MCU main circuit outputs a control signal to switch the single battery cell to the "bypass" state (EN1=high, EN2=low, Q3 is on, Q4 is off), the single battery cell is removed from the series circuit, and the current flows through Q3 bypass, without affecting the continued charging of other single batteries cell; If a single battery cell is detected to be not installed (voltage signal is abnormally 0): directly control the single battery cell to switch to "bypass" state to avoid circuit break.

[0035] (2) Constant charging current control.

[0036] The MCU main circuit compares the real-time collected charging current (the digital signal corresponding to VO) with the preset target current value: If the charging current is less than the target value: the MCU main circuit outputs a current adjustment signal to the BUCK circuit, increasing the conduction time of MOSFET Q1 and decreasing the conduction time of MOSFET Q2, thereby increasing the output current of the BUCK circuit; If the charging current is greater than the target value: the MCU main circuit outputs a current adjustment signal to reduce the on-time of MOSFET Q1 and increase the on-time of MOSFET Q2, thereby reducing the output current; By using high-frequency dynamic adjustment, the charging current is kept stable within the preset range, thus achieving constant current charging.

[0037] (3) Overcurrent fault protection control.

[0038] If the MCU main circuit detects that the charging current exceeds the preset overcurrent protection threshold (e.g., due to a short circuit or battery malfunction causing a sudden increase in current): Immediately output a signal to the BUCK circuit to turn off MOSFETs Q1 and Q2 and cut off the charging current; At the same time, a signal is output to the battery switching circuit to switch all individual batteries to the "resting" state (EN1=low, EN2=low, Q3 and Q4 are both cut off) to avoid circuit damage or battery safety accidents.

[0039] After charging is complete, when the MCU main circuit detects that all individual batteries have reached their voltage limit (or have been bypassed) and the charging current remains weak (indicating that the battery is fully charged): the MCU main circuit outputs a signal to the BUCK circuit to turn off MOSFETs Q1 and Q2 and stop the constant current output; it also outputs a signal to the battery switching circuit to switch all individual batteries to the "resting" state; the battery voltage acquisition circuit and the charging current acquisition circuit stop outputting signals, and the entire charging process ends.

[0040] After receiving the voltage signal, the MCU main circuit performs fault diagnosis and control on the battery status. After logic processing and interlocking of the signal, it drives the battery switching circuit to switch between two states, ensuring reliable triggering of battery charging and bypassing charging. The switching process is determined by the timing logic of the control signals, preventing interruption of charging current and short circuits between the positive and negative terminals of the battery. This enables the connection and bypassing of individual series-connected cells. During the series-connected charging process, the connection or disconnection of one battery will not affect the normal operation of other batteries, provided that the current is not interrupted.

[0041] This application provides a low-voltage series charging circuit. A single BUCK circuit can charge up to four individual batteries. The voltage of each individual battery is transmitted to the MCU main circuit via a battery voltage acquisition circuit. By comparing the individual battery voltage with a set upper limit for battery voltage charging, the on / off state of the MOSFET in each sub-switching circuit is controlled to control the charging or bypassing of the individual battery. When the voltage of an individual battery reaches the set voltage, or when there is no battery in the battery position, the corresponding sub-switching circuit can be put into bypass mode, without affecting the charging of individual batteries in other circuits. At the same time, the charging current acquired by the charging current acquisition circuit is also transmitted back to the MCU main circuit. The magnitude of the transmitted charging current can be used to adjust the drive of the MOSFET in the BUCK circuit, thereby controlling the magnitude of the charging current.

[0042] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A low-voltage series charging circuit, characterized in that, include: BUCK circuit, battery switching circuit, battery voltage acquisition circuit and MCU main circuit; The output terminal of the BUCK circuit is connected to the input terminal of the battery switching circuit. The BUCK circuit is used to generate charging current to power and charge the series battery pack. The number of individual cells in the series battery pack does not exceed 4. The output terminal of the battery switching circuit is connected to the series battery pack, and the control terminal of the battery switching circuit is connected to the first control signal output terminal of the MCU main circuit. The battery switching circuit is used to switch the state of each individual battery in the series battery pack according to the control signal output by the MCU main circuit. The input terminal of the battery voltage acquisition circuit is connected to each individual battery in the series battery pack, and the output terminal of the battery voltage acquisition circuit is connected to the first signal input terminal of the MCU main circuit. The battery voltage acquisition circuit is used to acquire the real-time voltage of each individual battery, and transmit it to the MCU main circuit after signal conditioning. The MCU main circuit is used to receive the voltage signal transmitted by the battery voltage acquisition circuit, determine the state of each individual battery cell based on the voltage signal, and then output the corresponding control signal to the battery switching circuit. At the same time, it outputs the current adjustment signal to the BUCK circuit to control the magnitude of the charging current.

2. The low-voltage series charging circuit according to claim 1, characterized in that, The BUCK circuit includes: MOSFET Q1, MOSFET Q2, inductor L1 and capacitor C1; The drain of the MOSFET Q1 is connected to a 24V power supply; The source of the MOS transistor Q1 is connected to the drain of the MOS transistor Q2 and one end of the inductor L1, respectively. The source of the MOS transistor Q2 is connected to the power supply ground; The other end of the inductor L1 is connected to one end of the capacitor C1 and the input terminal of the battery switching circuit; the other end of the inductor L1 is the output terminal of the BUCK circuit. The other end of capacitor C1 is connected to power ground; The gates of both MOSFET Q1 and MOSFET Q2 are connected to the second control signal output terminal of the MCU main circuit to receive the current adjustment signal.

3. The low-voltage series charging circuit according to claim 2, characterized in that, Both MOS transistors Q1 and Q2 are N-type MOS transistors.

4. The low-voltage series charging circuit according to claim 1, characterized in that, The battery switching circuit includes sub-switching circuits corresponding to each individual battery cell. Each sub-switching circuit includes: MOSFET Q3, MOSFET Q4, resistor R1, resistor R2, resistor R3 and resistor R4. The drain of the MOSFET Q3 is connected to the output terminal of the BUCK circuit, the source of the MOSFET Q4, and one end of the resistor R4, respectively. The gate of the MOS transistor Q3 is connected to one end of the resistor R1 and one end of the resistor R2, respectively. The other end of the resistor R1 is connected to the first control signal output terminal of the MCU main circuit. The source of the MOS transistor Q3 is connected to the other end of the resistor R2 and the negative terminal of the corresponding single cell; and the source of the MOS transistor Q3 in the preceding sub-switching circuit is connected in series with the input terminal of the following sub-switching circuit. The gate of the MOS transistor Q4 is connected to one end of the resistor R3 and the other end of the resistor R4, respectively. The other end of the resistor R3 is connected to the first control signal output terminal of the MCU main circuit. The drain of the MOS transistor Q4 is connected to the positive terminal of the corresponding single cell. The positive and negative terminals of the individual battery are also connected to the input terminal of the battery voltage acquisition circuit.

5. The low-voltage series charging circuit according to claim 4, characterized in that, The states of the individual battery include static storage, charging, and bypass; the states of MOSFETs Q3 and Q4 are controlled by the control signal output from the first control signal output terminal of the MCU main circuit, thereby realizing the state switching of the individual battery.

6. The low-voltage series charging circuit according to claim 5, characterized in that, When both MOSFETs Q3 and Q4 are off, the single cell is in a resting state; when MOSFET Q3 is off and MOSFET Q4 is on, the single cell is in a bypass state; when both MOSFETs Q3 and Q4 are on, the single cell is in a charging state.

7. The low-voltage series charging circuit according to claim 1, characterized in that, The battery voltage acquisition circuit includes sub-acquisition circuits corresponding to each individual battery cell. Each sub-acquisition circuit includes: operational amplifier U1, resistor R5, resistor R6, resistor R7, resistor R8 and resistor R9. Both pin 1 and pin 8 of the operational amplifier U1 are floating. Pin 4 of the operational amplifier U1 is connected to the negative power supply VEE, and pin 7 of the operational amplifier U1 is connected to the positive power supply VDD. Pin 2 of the operational amplifier U1 is connected to one end of resistor R5 and one end of resistor R7, respectively. Pin 3 of the operational amplifier U1 is connected to one end of resistor R8 and one end of resistor R9, respectively. The other end of the resistor R7 is connected to the negative terminal of the corresponding single cell. The other end of the resistor R8 is connected to the positive terminal of the corresponding single battery cell; The other end of the resistor R9 is grounded; The operational amplifier pin 6 is connected to the other end of resistor R5 and one end of resistor R6, respectively. The other end of the resistor R6 is connected to the first signal input terminal of the MCU main circuit as the output terminal of the sub-acquisition circuit.

8. The low-voltage series charging circuit according to claim 7, characterized in that, The operational amplifier U1 is a low-temperature drift operational amplifier; resistors R5, R7, R8, and R9 are all low-temperature drift resistors.

9. The low-voltage series charging circuit according to claim 1, characterized in that, The low-voltage series charging circuit further includes: a charging current acquisition circuit; the current sampling terminal of the charging current acquisition circuit is connected to the total output terminal of the battery switching circuit, and is used to acquire the charging current flowing through the series battery pack; the signal output terminal of the charging current acquisition circuit is connected to the second signal input terminal of the MCU main circuit, and is used to transmit the charging current to the MCU main circuit; the MCU main circuit is used to output a current adjustment signal to the BUCK circuit based on the charging current.

10. The low-voltage series charging circuit according to claim 9, characterized in that, The charging current acquisition circuit includes: operational amplifier U2, sampling resistor R10, resistor R11 and resistor R12; Both pin 1 and pin 8 of the operational amplifier U2 are floating. Pin 4 of the operational amplifier U2 is connected to the negative power supply VEE, and pin 7 of the operational amplifier U1 is connected to the positive power supply VDD. Pin 5 of the operational amplifier U2 is grounded as the REF terminal; Pin 2 of the operational amplifier U2 is connected to one end of the resistor R12; Pin 3 of the operational amplifier U2 is connected to one end of the resistor R11; One end of the sampling resistor R10 is connected to the other end of the resistor R11 and the total output terminal of the battery switching circuit; one end of the sampling resistor R10 is the current sampling terminal of the charging current acquisition circuit. The other end of the sampling resistor R10 is connected to the other end of the resistor R12 and grounded; Pin 6 of the operational amplifier U2 is connected to the second signal input terminal of the MCU main circuit, and is used to transmit the collected charging current signal to the MCU main circuit; pin 6 of the operational amplifier U2 is the signal output terminal of the charging current acquisition circuit.

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