A battery charging current control device

Abstract

The application provides a battery charging current control device, belonging to the field of battery charging, which comprises an H-bridge circuit connected with an external power supply and a battery respectively, used for transmitting the current of the external power supply to the battery to supply power for the battery; a sampling circuit connected with the H-bridge circuit, used for collecting the output current and output voltage of the H-bridge circuit to obtain current analog signals and voltage analog signals; a control circuit connected with the sampling circuit, used for generating a control signal according to the current analog signals, the voltage analog signals and the capacity of the battery; and a pulse width modulation circuit connected with the control circuit and the H-bridge circuit respectively, used for pulse width modulating the H-bridge circuit according to the control signal to control the output current of the H-bridge circuit. The size of the output current can be freely set through the pulse width modulation circuit and the H-bridge circuit, which is suitable for various batteries requiring large current charging and improves the charging efficiency of the battery.

Description

Technical Field

[0001] This invention relates to the field of battery charging, and in particular to a battery charging current control device. Background Technology

[0002] Battery range and charging speed are important considerations for most users when choosing electric vehicles. Battery range is closely related to battery capacity, and at the same charging speed, a larger battery capacity requires a control circuit that can support a higher charging current.

[0003] Therefore, there is an urgent need for a control device to control the battery charging current. Summary of the Invention

[0004] The purpose of this invention is to provide a battery charging current control device that can control the charging current of the battery and improve charging efficiency.

[0005] To achieve the above objectives, the present invention provides the following solution: A battery charging current control device, comprising: The H-bridge circuit is connected to an external power source and a battery, respectively, and is used to transmit the current from the external power source to the battery to power the battery. A sampling circuit, connected to the H-bridge circuit, is used to acquire the output current and output voltage of the H-bridge circuit to obtain analog current signals and analog voltage signals. A control circuit, connected to the sampling circuit, is used to generate a control signal based on the current analog signal, the voltage analog signal, and the battery capacity. A pulse width modulation circuit is connected to both the control circuit and the H-bridge circuit, and is used to perform pulse width modulation on the H-bridge circuit according to the control signal to control the output current of the H-bridge circuit.

[0006] Optionally, the control circuit is further configured to convert the current analog signal into a current value and the voltage analog signal into a voltage value; The battery charging current control device further includes: A communication circuit, connected to the control circuit, is used to send the current and voltage values ​​to a host computer for display.

[0007] Optionally, the communication circuit is a MAX13487 chip.

[0008] Optionally, the battery charging current control device further includes: The power supply circuit is connected to the external power supply, the sampling circuit, the control circuit, and the pulse width modulation circuit, respectively, and is used to supply power to the sampling circuit, the control circuit, and the pulse width modulation circuit.

[0009] Optionally, the power supply circuit includes: The rectifier and filter sub-circuit is connected to an external power supply and is used to rectify and filter the DC voltage of the external power supply to obtain the filtered current. A square wave oscillator sub-circuit, connected to the rectifier filter sub-circuit, is used to output a square wave signal according to the filter current; The transformer voltage conversion sub-circuit is connected to the square wave oscillation sub-circuit, the sampling circuit, the control circuit, and the pulse width modulation circuit, respectively, and is used to supply power to the sampling circuit, the control circuit, and the pulse width modulation circuit based on the square wave signal.

[0010] Optionally, the control circuit is also used to provide a reference voltage; The sampling circuit includes: A current sampling sub-circuit is connected to the negative terminal of the output of the H-bridge circuit and the control circuit, respectively, for acquiring the output current of the H-bridge circuit and determining the current analog signal based on the reference voltage and the output current; A voltage sampling sub-circuit is connected to the positive terminal of the output of the H-bridge circuit and the control circuit, respectively, to acquire the output voltage of the H-bridge circuit and obtain a voltage analog signal.

[0011] Optionally, the current sampling sub-circuit includes: The sampling resistor has one end connected to the negative terminal of the output of the H-bridge circuit and the other end grounded, and is used to collect the output current of the H-bridge circuit. An inverting amplifier has its inverting input connected between the sampling resistor and the negative terminal of the output of the H-bridge circuit, and its non-inverting input and output connected to the control circuit. It is used to amplify the voltage across the sampling resistor based on the reference voltage to obtain a current analog signal.

[0012] Optionally, the H-bridge circuit includes: a first power transistor, a second power transistor, a third power transistor, a fourth power transistor, and an inductor; The inductor is connected to the source of the first power transistor, the source of the second power transistor, the drain of the third power transistor, and the drain of the fourth power transistor, respectively. The drain of the first power transistor, the drain of the second power transistor, the source of the third power transistor, and the drain of the fourth power transistor are all connected to an external power supply. The gates of the first power transistor, the second power transistor, the third power transistor, and the fourth power transistor are all connected to the pulse width modulation circuit.

[0013] Optionally, the inductor has a size of 30uH.

[0014] Optionally, the pulse width modulation circuit includes: The first PWM driving circuit is connected to the gate of the first power transistor and the gate of the second power transistor respectively, and is used to perform pulse width modulation on the first power transistor and the second power transistor according to the control signal to control the connection state of the first power transistor and the second power transistor. The second PWM drive circuit is connected to the gate of the third power transistor and the gate of the fourth power transistor respectively, and is used to perform pulse width modulation on the third power transistor and the fourth power transistor according to the control signal to control the connection state of the third power transistor and the fourth power transistor. The first power transistor and the fourth power transistor are in the same connected state at the same time; The second power transistor and the third power transistor are in the same connected state at the same time; The first power transistor and the third power transistor are in different connected states at the same time.

[0015] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: the output current and output voltage of the H-bridge circuit are collected by the sampling circuit to obtain the current analog signal and voltage analog signal; the control circuit generates a control signal according to the current analog signal, the voltage analog signal and the battery capacity; the pulse width modulation circuit modulates the H-bridge circuit according to the control signal to control the output current of the H-bridge circuit, thereby realizing the adjustment of the charging current according to the battery capacity and improving the charging efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the battery charging current control device of the present invention; Figure 2 This is the schematic diagram of an H-bridge circuit; Figure 3 This is the schematic diagram of the current sampling sub-circuit; Figure 4This is the schematic diagram of the voltage sampling sub-circuit; Figure 5 This is a schematic diagram of a communication circuit. Figure 6 This is the schematic diagram of the rectifier filter sub-circuit; Figure 7 This is a schematic diagram of a square wave oscillator circuit and a transformer voltage conversion circuit.

[0018] Symbol explanation: Power supply circuit-1, rectifier filter sub-circuit-11, square wave oscillator sub-circuit-12, transformer voltage conversion sub-circuit-13, sampling circuit-2, current sampling sub-circuit-21, voltage sampling sub-circuit-22, pulse width modulation circuit-3, first PWM drive circuit-31, second PWM drive circuit-32, H-bridge circuit-4, communication circuit-5, control circuit-6. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The purpose of this invention is to provide a battery charging current control device that supports high-current battery charging and also has communication functions. The output current can be freely set through a pulse width modulation circuit and an H-bridge circuit to achieve a current output of 0-20A, which is suitable for various batteries that require high-current charging and improves the applicability of the charging current control device.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, the battery charging current control device of the present invention includes: an H-bridge circuit 4, a sampling circuit 2, a control circuit 6, and a pulse width modulation circuit 3.

[0023] The H-bridge circuit 4 is connected to both an external power source and a battery. The H-bridge circuit 4 is used to transmit the current from the external power source to the battery to supply power to the battery.

[0024] Specifically, such as Figure 2As shown, the H-bridge circuit 4 includes: a first power transistor M1, a second power transistor M2, a third power transistor M3, a fourth power transistor M4, and an inductor L1. In this embodiment, the inductor has a specification of 30uH / 60A. The first power transistor M1, the second power transistor M2, the third power transistor M3, and the fourth power transistor M4 are all N-channel MOSFETs.

[0025] The inductor L1 is connected to the source of the first power transistor M1, the source of the second power transistor M2, the drain of the third power transistor M3, and the drain of the fourth power transistor M4, respectively.

[0026] The drain of the first power transistor M1, the drain of the second power transistor M2, the source of the third power transistor M3, and the drain of the fourth power transistor M4 are all connected to an external power supply.

[0027] The gates of the first power transistor M1, the second power transistor M2, the third power transistor M3, and the fourth power transistor M4 are all connected to the pulse width modulation circuit 3.

[0028] The H-bridge circuit 4 also includes multiple capacitors (C1, C2, C3, C4, C35, C36), multiple resistors (R9, R10, R11, R12), and multiple electrolytic capacitors (E2, E3, E7, E15, E16, E17). Resistor R9 and capacitor C1 are connected in series and then in parallel with the first power transistor M1; resistor R11 and capacitor C3 are connected in series and then in parallel with the second power transistor M2; resistor R10 and capacitor C2 are connected in series and then in parallel with the third power transistor M3; and resistor R12 and capacitor C4 are connected in series and then in parallel with the fourth power transistor C4. The connection relationship of each component is as follows: Figure 2 As shown.

[0029] In the H-bridge circuit 4, the two NMOS transistors diagonally opposite each other are grouped together: the first power transistor M1 and the fourth power transistor M4 form one group, and the second power transistor M2 and the third power transistor M3 form another group. The gate voltages of the two groups of power transistors are controlled by two pulse width modulation circuits 3 respectively. The power transistors within each group are turned on and off simultaneously during circuit operation, while the power transistors between groups are never simultaneously connected during circuit operation.

[0030] The sampling circuit 2 is connected to the H-bridge circuit 4. The sampling circuit 2 is used to collect the output current and output voltage of the H-bridge circuit 4 to obtain the current analog signal and voltage analog signal.

[0031] Specifically, the control circuit 6 is used to provide a reference voltage. The sampling circuit 2 includes a current sampling sub-circuit 21 and a voltage sampling sub-circuit 22.

[0032] The current sampling sub-circuit 21 is connected to the negative terminal VOUT- of the output terminal of the H-bridge circuit 4 and the control circuit 6, respectively. The current sampling sub-circuit 21 is used to collect the output current of the H-bridge circuit 4 and determine the current analog signal based on the reference voltage and the output current.

[0033] In this embodiment, the current sampling sub-circuit 21 includes a sampling resistor RS1 and an inverting amplifier U7.

[0034] One end of the sampling resistor RS1 is connected to the negative terminal VOUT- of the output terminal of the H-bridge circuit 4, and the other end of the sampling resistor RS1 is grounded. The sampling resistor RS1 is used to collect the output current of the H-bridge circuit 4.

[0035] The inverting input terminal of the inverting amplifier U7 is connected between the sampling resistor and the negative terminal of the output terminal of the H-bridge circuit 4. The non-inverting input terminal and the output terminal of the inverting amplifier U7 are both connected to the control circuit 6. The inverting amplifier U7 is used to amplify the voltage on the sampling resistor RS1 based on the reference voltage to obtain a current analog signal.

[0036] Furthermore, such as Figure 3 As shown, the current sampling sub-circuit 21 also includes multiple resistors (R49, R50, R51, R52) and a capacitor C25.

[0037] The current sampling is implemented as follows: The sampling resistor RS1 is connected between the negative terminal VOUT- of the circuit output and MGND. The voltage across the sampling resistor RS1 is amplified 22 times by the inverting amplifier U7 and then connected to the MCU. After analog-to-digital conversion by the MCU, the voltage across the sampling resistor RS1 can be obtained, and the magnitude of the current flowing through the sampling resistor RS1 can be calculated, thus completing the current sampling. The two input terminals of the inverting amplifier U7 are connected to one end of the sampling resistor RS1 and the reference voltage Vref output from the MCU's digital-to-analog converter, respectively.

[0038] The voltage sampling sub-circuit 22 is connected to the positive terminal of the output of the H-bridge circuit 4 and the control circuit 6, respectively. The voltage sampling sub-circuit 22 is used to collect the output voltage of the H-bridge circuit 4 to obtain a voltage analog signal.

[0039] Furthermore, such as Figure 4As shown, the voltage sampling sub-circuit 22 includes three resistors (R45, R54, R55) and two capacitors (C27 and C38). One end of capacitor R54 is connected to VOUT+, and the other end is connected to the MCU. Capacitor C38 is connected in series with resistor R45 and then in parallel with capacitor R54. One end of resistor R55 is grounded, and the other end is connected between resistor R54 and the MCU. One end of capacitor C27 is connected between resistor R55 and ground, and the other end is connected to the MCU. The voltage sampling method is based on resistor voltage divider sampling. Resistors R54 and R55 are connected to the output of the circuit to perform voltage division, and the result of the voltage division is input to the MCU for analog-to-digital conversion, thereby completing the voltage sampling.

[0040] Control circuit 6 is connected to sampling circuit 2, and is used to generate control signals based on the current analog signal, the voltage analog signal, and the battery capacity. In this embodiment, control circuit 6 is an MCU (Microcontroller Unit).

[0041] The pulse width modulation circuit 3 is connected to the control circuit 6 and the H-bridge circuit 4 respectively. The pulse width modulation circuit 3 is used to perform pulse width modulation on the H-bridge circuit 4 according to the control signal to control the output current of the H-bridge circuit 4.

[0042] Specifically, the pulse width modulation circuit 3 includes a first PWM driving circuit 31 and a second PWM driving circuit 32.

[0043] The first PWM driving circuit 31 is connected to the gate of the first power transistor and the gate of the second power transistor respectively. The first PWM driving circuit 31 is used to perform pulse width modulation on the first power transistor and the second power transistor according to the control signal to control the connection state of the first power transistor and the second power transistor.

[0044] The second PWM driving circuit 32 is connected to the gate of the third power transistor and the gate of the fourth power transistor respectively. The second PWM driving circuit 32 is used to perform pulse width modulation on the third power transistor and the fourth power transistor according to the control signal to control the connection state of the third power transistor and the fourth power transistor.

[0045] The first power transistor and the fourth power transistor are in the same connected state at the same time.

[0046] The second power transistor and the third power transistor are in the same connected state at the same time.

[0047] The first power transistor and the third power transistor are in different connected states at the same time.

[0048] Furthermore, the control circuit 6 is also used to convert the current analog signal into a current value and the voltage analog signal into a voltage value.

[0049] In this embodiment, both the first PWM drive circuit 31 and the second PWM drive circuit 32 are UCC21222 chips.

[0050] In the H-bridge circuit 4, the first power transistor M1 and the fourth power transistor M4 are controlled by the first PWM drive circuit 31, while the second power transistor M2 and the third power transistor M3 are controlled by the second PWM drive circuit 32. The two control circuits 6 must not be switched on and off simultaneously. When the first PWM drive circuit 31 outputs a high PWM signal, the first power transistor M1 and the fourth power transistor M4 are turned on, and the current in inductor L1 flows from left to right. Conversely, when the second PWM drive circuit 32 outputs a high PWM signal, the second power transistor M2 and the third power transistor M3 are turned on, and the current in inductor L1 reverses direction, generating a large induced electromotive force, which in turn causes the voltage of VOUT- to drop. In this embodiment, the positive input terminal VIN+ and the positive output terminal VOUT+ of the H-bridge circuit 4 share the same voltage. The circuit achieves a high voltage output mainly by reducing the voltage of the negative output terminal VOUT-. This method allows for flexible adjustment of the circuit's output current and voltage, and enables the use of a large inductor (30uH / 60A) to achieve a large current output.

[0051] Intelligent charging services are essential for ensuring electric mobility. However, due to insufficient intelligence in battery charging, users cannot monitor the charging progress in real time, posing certain safety hazards. Therefore, the battery charging current control device provided by this invention also includes a communication circuit 5. The communication circuit 5 is connected to the control circuit 6 and is used to send the current and voltage values ​​to a host computer for display. In this embodiment, the communication circuit 5 is a MAX13487 chip. It communicates with the host computer in real time via RS-485 communication technology, thereby providing real-time feedback on the voltage and current of the charging battery.

[0052] Specifically, such as Figure 5 As shown, communication circuit 5 adopts RS-485 two-wire communication to achieve multi-point bidirectional communication. The input of communication circuit 5 is connected to the serial port output of the MCU. The MCU processes the collected voltage and current data and sends it to communication circuit 5. The output of communication circuit 5 is connected to the host computer to achieve communication. The host computer can monitor the communication status between the two in real time and obtain real-time voltage and current.

[0053] Furthermore, the battery charging current control device provided by the present invention also includes a power supply circuit 1. The power supply circuit 1 is connected to an external power source, the sampling circuit 2, the control circuit 6, the pulse width modulation circuit 3, and the communication circuit 5, respectively. The power supply circuit 1 is used to supply power to the sampling circuit 2, the control circuit 6, the pulse width modulation circuit 3, and the communication circuit 5.

[0054] In this embodiment, the power supply circuit 1 receives 48V DC as input and outputs a first control power supply VCC1, a second control power supply VCC2, and a third control power supply VCC3. The first control power supply VCC1 and the third control power supply VCC3 provide the internal operating voltage for the chips in the subsequent pulse width modulation circuit 3. The first control power supply VCC1 is also regulated to VCC3.3V by a voltage regulator chip LM1117, providing power to various subsequent chips (MCU, operational amplifiers, etc.). The second control power supply VCC2 provides the power supply voltage for the communication circuit 5.

[0055] Specifically, the power supply circuit 1 includes: a rectifier filter sub-circuit 11, a square wave oscillator sub-circuit 12, and a transformer voltage conversion sub-circuit 13.

[0056] The rectifier and filter sub-circuit 11 is connected to an external power supply. The rectifier and filter sub-circuit 11 is used to rectify and filter the DC voltage of the external power supply to obtain the filtered current.

[0057] The square wave oscillator sub-circuit 12 is connected to the rectifier filter sub-circuit 11, and the square wave oscillator sub-circuit 12 is used to output a square wave signal according to the filter current.

[0058] The transformer voltage conversion sub-circuit 13 is connected to the square wave oscillation sub-circuit 12, the sampling circuit 2, the control circuit 6, the pulse width modulation circuit 3, and the communication circuit 5, respectively. The transformer voltage conversion sub-circuit 13 supplies power to the sampling circuit 2, the control circuit 6, the pulse width modulation circuit 3, and the communication circuit 5 based on the square wave signal. The transformer voltage conversion sub-circuit 13 includes a transformer and multiple diodes.

[0059] The input to power supply circuit 1 is an external DC voltage, which, after rectification and filtering, powers the square wave oscillator circuit 12. The output of the square wave oscillator circuit 12 is connected to the primary coil of the transformer. The transformer converts the voltage into the required supply voltage for other circuits through electromagnetic induction.

[0060] like Figure 6As shown, the input of power supply circuit 1 is connected to safety capacitors CY3 and CY4 to suppress common-mode interference. After rectification and filtering, the voltage VCC_555 of the NE555 chip is supplied through transistor N1 and Zener diode Z1. In addition, power supply circuit 1 also includes a capacitor C51, three electrolytic capacitors (E5, E6, E8), two resistors (R61 and R62), and a diode D20.

[0061] like Figure 7 As shown, resistors R71 and R72 divide the voltage, causing pins 2 and 6 of the NE555 chip to be at 1 / 3 VCC_555. At this point, the NE555 output is low, and VCC_555 charges capacitor C34 through resistor R67. When capacitor C34 is charged to 1 / 3 VCC_555, the output is high and power transistor M9 is turned on. Immediately afterwards, capacitor C37 is charged through resistor R75 until it reaches 1 / 3 VCC_555, at which point transistor N2 is turned on, and capacitor C34 discharges through transistor N2. At this point, the NE555 output is low, power transistor M9 is turned off, and VCC_555 continues to charge capacitor C34 through resistor R67. This cycle generates a square wave oscillation. This square wave oscillation is connected to the primary coil of a transformer. The transformer, through electromagnetic induction, converts the voltage into three control power supplies: VCC1 (first control power supply), VCC2 (second control power supply), and VCC3 (third control power supply). MGND in the diagram represents the MCU's GND.

[0062] This invention achieves real-time monitoring of battery charging current and voltage through voltage and current sampling and communication circuits. Utilizing pulse width modulation and H-bridge circuits with DC drive, the output current can be freely set, achieving a range of 0-20A. This makes it suitable for various batteries requiring high-current charging, improving the applicability of the battery charging current control device. Furthermore, the circuit structure of this invention is simple, easy to debug, and can be implemented using conventional components, facilitating complete domestic production.

[0063] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the device and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, 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 the present invention.

Claims

1. A battery charging current control device, characterized in that, The battery charging current control device includes: The H-bridge circuit is connected to an external power source and a battery, respectively, and is used to transmit the current from the external power source to the battery to power the battery. The H-bridge circuit includes: a first power transistor, a second power transistor, a third power transistor, a fourth power transistor, and an inductor; the inductor is connected to the source of the first power transistor, the source of the second power transistor, the drain of the third power transistor, and the drain of the fourth power transistor, respectively; the drains of the first power transistor, the second power transistor, the source of the third power transistor, and the fourth power transistor are all connected to an external power supply; the gates of the first power transistor, the second power transistor, the third power transistor, and the fourth power transistor are all connected to a pulse width modulation circuit; the inductor has a value of 30uH; A sampling circuit, connected to the H-bridge circuit, is used to acquire the output current and output voltage of the H-bridge circuit to obtain analog current signals and analog voltage signals. A control circuit, connected to the sampling circuit, is used to generate a control signal based on the current analog signal, the voltage analog signal, and the battery capacity. A pulse width modulation circuit is connected to both the control circuit and the H-bridge circuit, and is used to perform pulse width modulation on the H-bridge circuit according to the control signal to control the output current of the H-bridge circuit. The pulse width modulation circuit includes: The first PWM driving circuit is connected to the gate of the first power transistor and the gate of the second power transistor respectively, and is used to perform pulse width modulation on the first power transistor and the second power transistor according to the control signal to control the connection state of the first power transistor and the second power transistor. The second PWM drive circuit is connected to the gate of the third power transistor and the gate of the fourth power transistor respectively, and is used to perform pulse width modulation on the third power transistor and the fourth power transistor according to the control signal to control the connection state of the third power transistor and the fourth power transistor. The first power transistor and the fourth power transistor are in the same connected state at the same time; The second power transistor and the third power transistor are in the same connected state at the same time; The first power transistor and the third power transistor are in different connected states at the same time; When the first PWM drive circuit outputs a high PWM signal, the first and fourth power transistors are turned on, and the current in the inductor flows from left to right. When the second PWM drive circuit outputs a high PWM signal, the second and third power transistors are turned on, and the current in the inductor flows in the opposite direction, generating a large induced electromotive force. This causes the voltage at the negative terminal VOUT- of the H-bridge circuit's output to drop. The positive terminal VIN+ of the H-bridge circuit's input and the positive terminal VOUT+ of its output are at the same voltage. The circuit achieves a high voltage output mainly by reducing the voltage at the negative terminal VOUT- of the output.

2. The battery charging current control device according to claim 1, characterized in that, The control circuit is also used to convert the current analog signal into a current value and the voltage analog signal into a voltage value. The battery charging current control device further includes: A communication circuit, connected to the control circuit, is used to send the current and voltage values ​​to a host computer for display.

3. The battery charging current control device according to claim 2, characterized in that, The communication circuit uses the MAX13487 chip.

4. The battery charging current control device according to claim 1, characterized in that, The battery charging current control device further includes: The power supply circuit is connected to the external power supply, the sampling circuit, the control circuit, and the pulse width modulation circuit, respectively, and is used to supply power to the sampling circuit, the control circuit, and the pulse width modulation circuit.

5. The battery charging current control device according to claim 4, characterized in that, The power supply circuit includes: The rectifier and filter sub-circuit is connected to an external power supply and is used to rectify and filter the DC voltage of the external power supply to obtain the filtered current. A square wave oscillator sub-circuit, connected to the rectifier filter sub-circuit, is used to output a square wave signal according to the filter current; The transformer voltage conversion sub-circuit is connected to the square wave oscillation sub-circuit, the sampling circuit, the control circuit, and the pulse width modulation circuit, respectively, and is used to supply power to the sampling circuit, the control circuit, and the pulse width modulation circuit based on the square wave signal.

6. The battery charging current control device according to claim 1, characterized in that, The control circuit is also used to provide a reference voltage; The sampling circuit includes: A current sampling sub-circuit is connected to the negative terminal of the output of the H-bridge circuit and the control circuit, respectively, for acquiring the output current of the H-bridge circuit and determining the current analog signal based on the reference voltage and the output current; A voltage sampling sub-circuit is connected to the positive terminal of the output of the H-bridge circuit and the control circuit, respectively, to acquire the output voltage of the H-bridge circuit and obtain a voltage analog signal.

7. The battery charging current control device according to claim 6, characterized in that, The current sampling sub-circuit includes: The sampling resistor has one end connected to the negative terminal of the output of the H-bridge circuit and the other end grounded, and is used to collect the output current of the H-bridge circuit. An inverting amplifier has its inverting input connected between the sampling resistor and the negative terminal of the output of the H-bridge circuit, and its non-inverting input and output connected to the control circuit. It is used to amplify the voltage across the sampling resistor based on the reference voltage to obtain a current analog signal.

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