Battery charging method and battery charging control circuit

Abstract

The application provides a battery charging method and a battery charging control circuit, and relates to the field of battery control. The method comprises the following steps: determining an initial charging current value of a battery pack according to a pre-identified cell string number of the battery pack and a preset cell type; controlling a current adjusting switch to be turned on and outputting a pulse width modulation signal, wherein the pulse width modulation signal is used for adjusting the charging current of the battery pack on the basis of the initial charging current value to obtain a constant-output charging current; and detecting voltage values of single batteries of the battery pack during the constant-output process of the charging current, adjusting the pulse width modulation signal according to a comparison result between the voltage values and cut-off voltage thresholds of different step voltage ranges, and adjusting the battery pack current to a current value corresponding to the cell capacity, so as to solve the technical problems of poor cell string number compatibility and single charging mode of the battery charging mode in the related art.

Description

Technical Field

[0001] This invention relates to the field of battery control technology, and more specifically, to a battery charging method and a battery charging control circuit. Background Technology

[0002] With the rapid development of new energy vehicles, energy storage systems, and portable electronic devices, lithium batteries have become the mainstream energy storage device due to their high energy density and long cycle life. To ensure the safe and efficient charging of lithium batteries, a constant current-constant voltage charging mode is commonly used in related technologies: initially, the battery pack is charged with a constant current; when the total voltage of the battery pack reaches the set cutoff voltage, it switches to a constant voltage mode, and the charging current naturally decreases as the battery's state of charge increases until it drops to a proportion of the rated capacity, at which point it is considered fully charged. However, this lithium battery charging method has obvious drawbacks: 1. Poor compatibility of charging cell series. The constant voltage output value of traditional chargers is fixed and only adapts to battery packs with a specific number of series (such as only supporting 12 or 24 series). If used for low-number series batteries (such as 6 series), it is easy to cause overcharging of individual cells due to voltage exceeding the limit, leading to the risk of thermal runaway; if used for high-number series batteries (such as 32 series), insufficient voltage will result in incomplete charging and low capacity utilization. 2. The charging mode is limited and lacks dynamic adjustment capability. It usually only supports a single constant current value and a single constant voltage value, which makes it difficult to meet the application requirements of high-rate and high-safety charging. Summary of the Invention

[0003] The main objective of this invention is to provide a battery charging method and a battery charging control circuit to solve the technical problems of poor compatibility of cell series and single charging mode in related technologies.

[0004] To achieve the above objectives, according to one aspect of the present invention, a battery charging method is provided, comprising: determining an initial charging current value of the battery pack based on a pre-identified number of battery cells in series and a preset cell type; controlling a current regulation switch to be turned on and outputting a pulse width modulation signal, wherein the pulse width modulation signal is used to adjust the charging current of the battery pack based on the initial charging current value to obtain a constant output charging current; during the constant output charging current process, detecting the voltage value of each individual cell in the battery pack, and adjusting the pulse width modulation signal based on a comparison result between the voltage value and a cutoff voltage threshold of different step voltage ranges to adjust the battery pack current to a current value corresponding to the cell capacity.

[0005] Optionally, before determining the initial charging current value of the battery pack based on the pre-identified cell string count and preset cell type, the method further includes: performing a cell string count identification operation when the battery pack does not contain a battery management system; controlling a high-voltage multiplexer to sequentially conduct and measuring the voltage of each individual cell, wherein the high-voltage multiplexer includes n analog switches, the input terminal of each analog switch is connected to the voltage interface of the individual cell, the output terminal of the analog switch is connected to an analog-to-digital converter through a voltage divider resistor, and the analog-to-digital converter is connected to a controller; and identifying the cell string count of the battery pack based on the voltage measurement results.

[0006] Optionally, before determining the initial charging current value of the battery pack based on the pre-identified number of battery cells and the preset cell type, the method further includes: if the battery pack includes a battery management system, performing a cell number identification operation; sending a battery status parameter reading instruction to the battery management system to obtain the battery status and charging configuration parameters, wherein the charging configuration parameters include at least the number of battery cells in the battery pack.

[0007] Optionally, determining the initial charging current value of the battery pack based on the pre-identified number of battery cells and the preset cell type includes: when the battery pack does not include a battery management system, receiving a setting command issued by the user terminal via a status button, parsing the setting command to obtain the preset cell type and battery capacity, and determining the initial charging current value of the battery pack based on the number of battery cells, the preset cell type, and the battery capacity; when the battery pack includes a battery management system, obtaining the preset cell type and battery capacity through the battery management system, and determining the initial charging current value of the battery pack based on the number of battery cells, the preset cell type, and the battery capacity.

[0008] Optionally, detecting the voltage value of each individual cell in the battery pack and adjusting the pulse width modulation signal based on the comparison between the voltage value and the cutoff voltage threshold of different voltage steps includes: detecting the voltage value of each individual cell in the battery pack using a sensor; when the voltage value of any individual cell in the battery pack is greater than the cutoff voltage threshold of a preset first voltage step range, adjusting the pulse width modulation signal and outputting a first duty cycle adjustment signal, wherein the first duty cycle adjustment signal is used to adjust the battery pack current to 0.1C of the cell capacity, and to charge the battery pack at a constant current of 0.1C until the battery pack voltage reaches the cutoff voltage threshold; when the voltage value of any individual cell in the battery pack is greater than the cutoff voltage threshold of a preset second voltage step range, adjusting the pulse width modulation signal and outputting a second duty cycle adjustment signal, wherein the second duty cycle adjustment signal is used to adjust the battery pack current to 0.05C of the cell capacity, and to charge the battery pack at a constant current of 0.05C until the battery pack voltage reaches the cutoff voltage threshold; and to charge the battery pack at a constant current of 0.05C.

[0009] Optionally, after charging the battery pack at a constant current of 0.05C, the method further includes: if the voltage of any single cell in the battery pack is detected to be greater than the cutoff voltage threshold, controlling the charging switch to close, and the charging is completed.

[0010] According to another aspect of the present invention, a battery charging control circuit is provided, comprising: a constant current source circuit for generating a constant current source current; and a charging current adjustment circuit connected to the constant current source circuit, comprising: a current sensor, a current adjustment switch, a controller, and a plurality of voltage divider resistors, wherein the current sensor is connected to the constant current source circuit, the current adjustment switch is connected to the current sensor, and the controller is used to execute the battery charging method described in any one of the preceding embodiments.

[0011] Optionally, the charging current regulation circuit includes: a first charging current regulation circuit, comprising: a high-voltage multiplexer analog switch, a first linear regulator, a first current sensor, a first current regulation switch, a first controller, and a first analog-to-digital converter group, wherein the high-voltage multiplexer analog switch is used to detect the number of cells in series in the battery pack, the first current sensor is connected to the constant current source circuit, the first current regulation switch is connected to the first current sensor, and the first controller is connected to the first analog-to-digital converter group; and a second charging current regulation circuit, comprising: a battery management system, a second linear regulator, a second current sensor, a second current regulation switch, a second controller, and a second analog-to-digital converter group, wherein the battery management system detects the number of cells in series in the battery pack, the second current sensor is connected to the constant current source circuit, the second current regulation switch is connected to the second current sensor, and the second controller is connected to the second analog-to-digital converter group.

[0012] Optionally, the high-voltage multiplex analog switch includes n analog switches, wherein the input terminal of each analog switch is connected to the voltage interface of a single battery cell, the output terminal of each analog switch is connected to an analog-to-digital converter through a voltage divider resistor, the analog-to-digital converter is connected to a controller, and n is a positive integer.

[0013] Optionally, the constant current source circuit includes: an AC / DC converter, or a DC / DC converter, for generating a constant current source current.

[0014] By applying the technical solution of this invention, the initial charging current value of the battery pack can be determined based on the pre-identified number of battery cells and the preset cell type. Then, the pulse width modulation signal is adjusted to regulate the charging current of the battery pack. In this embodiment, the number of battery cells can be automatically identified, enabling the charger to adapt to battery pack structures with different numbers of battery cells, improving the versatility of the device. Furthermore, through a stepped cross-current charging method, adaptive charging control of the battery pack under different numbers of cells and different chemical systems is achieved, improving the battery charging adaptability to various scenarios. This solves the technical problems of poor compatibility of battery cells and a single charging mode in related technologies. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0016] Figure 1 This is a flowchart of an optional battery charging method according to an embodiment of the present invention; and

[0017] Figure 2 This is a schematic diagram of an optional battery charging control circuit according to an embodiment of the present invention. Detailed Implementation

[0018] 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. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0021] To facilitate understanding of the present invention by those skilled in the art, some terms or nouns involved in the various embodiments of the present invention are explained below:

[0022] A Battery Management System (BMS) is used to monitor, protect, and balance the operating status of individual cells in a battery pack, ensuring system safety and stable performance.

[0023] An analog-to-digital converter (ADC) converts analog voltage signals into digital signals for the controller to recognize and process, and is used to acquire the voltage of individual lithium battery cells.

[0024] A microcontroller unit (MCU) is a central control unit responsible for identifying the number of battery cells in a series, determining the cell type, generating pulse width modulation signals, adjusting current feedback, and controlling charging logic.

[0025] Pulse Width Modulation (PWM) controls the on-time of switching devices by adjusting the duty cycle of a square wave signal, thereby precisely regulating the average output charging current.

[0026] An AC / DC converter converts AC mains power into DC power, which is then used as the input of a constant current source in the charging circuit.

[0027] A DC / DC converter converts one DC voltage to another DC voltage or current, serving as a constant current source input to a charging circuit.

[0028] The current regulating switch, SW2 / SW3, is controlled by the MCU to turn on and off via PWM signals, thereby enabling graded adjustment of the output current of the preceding constant current source.

[0029] A Hall effect sensor is used to monitor the actual current value in the charging circuit in real time and feed the current signal back to the control to adjust the PWM duty cycle in a closed loop to ensure stable charging current.

[0030] This invention is applicable to lithium battery charging scenarios, such as new energy vehicle power battery packs, portable energy storage devices, and home energy storage systems.

[0031] This invention dynamically adjusts the charging current by adjusting the duty cycle of the pulse width modulation signal, and combines automatic identification of the number of battery strings with real-time compensation for line loss to achieve high-precision segmented constant current charging for lithium battery packs with different chemical systems and different numbers of strings. It does not rely on constant voltage control and effectively improves charging safety, compatibility and efficiency.

[0032] Figure 1 This is a flowchart of an optional battery charging method according to an embodiment of the present invention, such as... Figure 1 As shown, the battery charging method includes steps S101 to S103. The present invention will be described in detail below with reference to each implementation step.

[0033] Step S101: Determine the initial charging current value of the battery pack based on the pre-identified number of battery cells in series and the preset cell type.

[0034] In this embodiment, it is necessary to identify the number of battery cells in the battery pack in advance based on whether the battery pack includes a battery management system (BMS). Optionally, before determining the initial charging current value of the battery pack based on the pre-identified number of battery cells and the preset cell type, the method further includes: performing a cell number identification operation when the battery pack does not include a BMS; controlling a high-voltage multiplexer to sequentially turn on and measure the voltage of each individual battery cell, wherein the high-voltage multiplexer includes n analog switches, the input terminal of each analog switch is connected to the voltage interface of the individual battery cell, and the output terminal of the analog switch is connected to an analog-to-digital converter through a voltage divider resistor, and the analog-to-digital converter is connected to a controller; and identifying the number of battery cells in the battery pack based on the voltage measurement results.

[0035] For battery packs without a battery management system, this embodiment uses a high-voltage multiplexer to sample the voltage of individual cells in series. The high-voltage multiplexer may include n independent analog switches. The input of each analog switch is directly connected to the positive and negative voltage interfaces of the corresponding individual cell, and the output is attenuated to the input voltage range of the analog-to-digital converter (ADC) via a voltage divider resistor, thus preventing high-voltage signals from damaging the analog front-end circuitry. The ADC converts the analog voltage signals of each individual cell into digital signals and transmits them to the controller. The controller sequentially triggers the high-voltage multiplexer switches according to a preset timing sequence, completing the sequential acquisition of the voltage of each cell. By analyzing whether each channel voltage has a valid value and considering the continuity of the voltage distribution, the number of currently connected battery strings can be determined. For example, if the voltage of the k-th channel is zero or close to zero, while the voltage of the (k-1)-th channel is a normal individual cell voltage, the number of battery strings is determined to be k-1. This process requires no external configuration and is suitable for battery packs without communication interfaces, enabling the charger to have autonomous identification capabilities.

[0036] It should be noted that the resistance ratio of the voltage divider network in this embodiment has been calibrated to ensure that the sampled voltage is within the linear operating range of the analog-to-digital converter, thereby improving voltage measurement accuracy and enhancing the reliability of cell string count identification. Under conditions where voltage fluctuations across multiple cells are small, the controller can eliminate interference from abnormal cells or open-circuit faults based on the step-like differences in voltage amplitude and the location of missing channels, assisting in string count determination. This approach is independent of communication protocols and is suitable for low-cost battery applications without a BMS.

[0037] Additionally, it should be noted that the high-voltage multiplexer in this embodiment must meet the insulation withstand voltage requirements at the highest voltage level of the battery pack, and its on-resistance should be sufficiently low to reduce the impact of voltage drop along the sampling path. The resolution and sampling rate of the analog-to-digital converter must match the processing cycle of the controller to avoid misjudgment of the number of series due to sampling delay.

[0038] Optionally, before determining the initial charging current value of the battery pack based on the pre-identified number of battery cells and the preset cell type, the method further includes: if the battery pack includes a battery management system, performing a cell number identification operation; sending a battery status parameter reading instruction to the battery management system to obtain the battery status and charging configuration parameters, wherein the charging configuration parameters include at least the number of battery cells in the battery pack.

[0039] In cases where the battery pack includes a battery management system (BMS), this embodiment sends a battery status parameter reading command to the BMS via a communication interface (this embodiment supports multiple standardized communication protocols, and the communication content follows the open protocol specifications of the BMS) to obtain the battery pack's operating information and charging setting parameters. Upon receiving the command, the BMS responds and returns charging configuration parameters including the number of cell strings, cell chemistry, rated capacity, maximum allowable charging current, temperature threshold, and historical charge / discharge records. The number of cell strings, a key parameter, can be directly provided by the topology identification module within the BMS. This module automatically calculates the number based on the physical connection relationship of the battery series-parallel structure and the configuration information of the equalization circuit, without the need for external sampling circuitry. It should be noted that in this embodiment, the reading operation can be completed before charging begins, avoiding misjudgments of the control strategy due to communication delays or interference during charging.

[0040] Optionally, determining the initial charging current value of the battery pack based on the pre-identified number of battery cells and the preset cell type includes: when the battery pack does not include a battery management system, receiving a setting command issued by the user terminal via a status button, parsing the setting command to obtain the preset cell type and battery capacity, and determining the initial charging current value of the battery pack based on the number of battery cells, the preset cell type, and the battery capacity; when the battery pack includes a battery management system, obtaining the preset cell type and battery capacity through the battery management system, and determining the initial charging current value of the battery pack based on the number of battery cells, the preset cell type, and the battery capacity.

[0041] For battery packs that do not include a battery management system, this embodiment receives charging parameter setting instructions via a user-end input device. These instructions include information on the cell chemical system type and the battery's rated capacity. Users can configure these parameters using buttons, knobs, a touchscreen, or host computer software. The controller parses these instructions, extracting the cell type (e.g., ternary lithium, lithium iron phosphate) and battery capacity (in Ah). Combining this with the previously identified cell string count, and based on a preset charging rate mapping table, it calculates the initial charging current. For example, when the cell type is conventional ternary lithium (cutoff voltage 4.2V), the capacity is 10Ah, and the string count is 12, 0.2C can be selected as the initial charging current, corresponding to a 2A charging current output.

[0042] Furthermore, this embodiment supports users to customize the charging rate, allowing non-standard charging rate values ​​to be input within a preset safety range. The controller recalculates and latches the initial charging current value based on the input cell string number, capacity, and type, thereby adapting to the differentiated requirements of charging speed or lifespan for different application scenarios.

[0043] It should be noted that, for battery packs that include a battery management system (BMS), this embodiment obtains the cell chemistry system and rated capacity parameters stored within the BMS via a communication protocol, eliminating the need for manual configuration by the user. This embodiment processes battery packs with and without BMS through two parallel paths, ensuring that the charging end can obtain accurate cell type, capacity, and series count information regardless of the diverse battery access scenarios, thus forming a consistent current calculation logic.

[0044] Step S102: Control the current regulation switch to turn on and output a pulse width modulation signal. The pulse width modulation signal is used to adjust the charging current of the battery pack based on the initial charging current value to obtain a constant output charging current.

[0045] In this embodiment, the main current path between the front-end constant current source and the rear-end charging circuit is connected by controlling the current regulation switch to open, allowing DC current to flow to the battery pack. The current regulation switch can be triggered by the controller after completing battery parameter identification and initial current calculation. Its action timing is synchronized with the charging logic, avoiding premature power-on before parameters are ready and reducing the risk of system malfunction.

[0046] Furthermore, this embodiment outputs a pulse width modulation (PWM) signal, generated by the controller. This signal has a fixed frequency, and its duty cycle is set based on the calculated initial charging current value. The PWM signal drives a current adjustment switch (SW2 or SW3), which, through periodic switching on and off, performs time averaging on the constant current output from the preceding DC / DC or AC / DC converter, achieving controllable adjustment of the output current. For example, when the initial charging current is set to 2A and the preceding constant current source output is 10A, the controller outputs a PWM signal with a 20% duty cycle, resulting in an average output current of 2A, without relying on a voltage feedback closed loop.

[0047] The duty cycle of the pulse width modulation signal can be dynamically fine-tuned based on the real-time current value fed back by the sensor, forming a control mechanism that combines open-loop setting and closed-loop compensation, making the actual output current closer to the target value. In this embodiment, the constant current source is digitally truncated in the time domain using the pulse width modulation signal, achieving precise current control without a voltage reference. This avoids the dependence on voltage accuracy in traditional constant voltage charging methods, and also supports smooth switching of multi-stage stepped currents by adjusting the duty cycle through software without changing the hardware.

[0048] In step S103, during the constant output of charging current, the voltage value of each individual cell in the battery pack is detected. Based on the comparison between the voltage value and the cutoff voltage threshold of different step voltage ranges, the pulse width modulation signal is adjusted to adjust the battery pack current to the current value corresponding to the cell capacity.

[0049] Furthermore, this embodiment pre-sets multiple cutoff voltage thresholds corresponding to different voltage ranges. These thresholds are pre-stored in the controller based on the cell's chemical system, such as 4.2V for ternary lithium batteries, 4.4V for high-voltage lithium cobalt oxide batteries, and 3.65V for lithium iron phosphate batteries. When any single cell voltage is detected to reach the first threshold (e.g., 4.2V) for the first time, the controller calculates the target current for the next stage based on the cell capacity, i.e., the cell capacity multiplied by 0.1C. Subsequently, it adjusts the duty cycle of the pulse width modulation signal to reduce the average output current from the initial value to the target value. For example, in a 10Ah battery pack, when the single cell voltage reaches 4.2V, the controller lowers the PWM duty cycle from the initial value to the value corresponding to 1A output, achieving a current step switching from 0.2C to 0.1C.

[0050] It should be noted that this embodiment does not introduce a constant voltage control loop during current regulation. The reduction in current is achieved entirely by adjusting the pulse width modulation duty cycle. The voltage increase serves only as a trigger condition for stage switching, not as a control target. When the cell voltage continues to rise and exceeds the second-stage threshold (e.g., 4.3V), the controller again calculates the current value corresponding to 0.05C based on the capacity and further reduces the PWM duty cycle, causing the charging current to enter a lower constant current stage. This process can be extended to three or four stages of current, achieving more refined charging curve control through multi-threshold judgment. The charging process dynamically adjusts the input current based on the battery's own state without relying on the charger's constant voltage accuracy. This helps to mitigate cell polarization effects during high-voltage stages, reduce the temperature rise rate, and avoid overcharging or undercharging due to constant voltage accuracy drift.

[0051] Optionally, detecting the voltage value of each individual cell in the battery pack and adjusting the pulse width modulation signal based on the comparison between the voltage value and the cutoff voltage threshold of different voltage ranges includes: detecting the voltage value of each individual cell in the battery pack using a sensor; adjusting the pulse width modulation signal and outputting a first duty cycle adjustment signal when the voltage value of any individual cell in the battery pack is greater than the cutoff voltage threshold of a preset first voltage range, wherein the first duty cycle adjustment signal is used to adjust the battery pack current to 0.1C of the cell capacity, and to charge the battery pack at a constant current of 0.1C until the battery pack voltage reaches the cutoff voltage threshold; adjusting the pulse width modulation signal and outputting a second duty cycle adjustment signal when the voltage value of any individual cell in the battery pack is greater than the cutoff voltage threshold of a preset second voltage range, wherein the second duty cycle adjustment signal is used to adjust the battery pack current to 0.05C of the cell capacity, and to charge the battery pack at a constant current of 0.05C until the battery pack voltage reaches the cutoff voltage threshold; and charging the battery pack at a constant current of 0.05C.

[0052] Optionally, after charging the battery pack at a constant current of 0.05C, the method further includes: if the voltage of any single cell in the battery pack is detected to be greater than the cutoff voltage threshold, controlling the charging switch to turn off, and the charging is completed.

[0053] This embodiment uses a high-precision voltage sensor (e.g., a Hall sensor) to collect the voltage of each individual cell in the battery pack in real time. The sensor signal is isolated and filtered before being sent to an analog-to-digital converter. The controller synchronously reads the voltage data of each cell and compares the maximum values ​​to ensure timely response when any cell reaches the trigger condition. The voltage acquisition cycle is synchronized with the charging current adjustment frequency to avoid lag in step switching due to sampling delay.

[0054] When the voltage of any single cell in the battery pack exceeds the preset cutoff voltage threshold of the first-stage voltage range (this cutoff voltage threshold can be determined by the battery type; for example, the cutoff voltage threshold is 4.2V for conventional ternary lithium batteries and 3.65V for lithium iron phosphate batteries), this embodiment performs a duty cycle reset operation on the pulse width modulation signal, outputting a first duty cycle adjustment signal. The duty cycle value of this signal is calculated based on the relationship between the cell's rated capacity and the 0.1C rate. For example, when the cell capacity is 15Ah, the target current is 1.5A. The controller resets the PWM duty cycle according to the ratio between the output current of the preceding constant current source and this target value, stabilizing the average output current at the 0.1C level. Furthermore, when the voltage of any single cell in the battery pack exceeds the preset cutoff voltage threshold of the second-stage voltage range, this embodiment further adjusts the pulse width modulation signal, outputting a second duty cycle adjustment signal. After recalculation, the duty cycle corresponding to this signal reduces the charging current to 0.05C of the cell capacity; for example, a 10Ah battery corresponds to a charging current of 0.5A.

[0055] It should be noted that in this embodiment, each step of charging will reach the cutoff voltage threshold corresponding to the cell type, and then the battery pack charging current will be adjusted. For example, when the initial charging current is set to 0.5C, if the voltage of any single cell in the battery pack is detected to be greater than the cutoff voltage threshold of 4.2V (ternary lithium battery), the duty cycle output will be adjusted to adjust the current to 0.1C of the cell capacity (Ah), and the battery pack will be charged at a constant current of 0.1C. When the voltage of any single cell in the battery pack is again greater than the cutoff voltage threshold of 4.2V (ternary lithium battery), the duty cycle output will be adjusted to adjust the current to 0.05C of the cell capacity (Ah), and the battery pack will then be charged at a constant current of 0.05C. When the voltage of any single cell in the battery pack is greater than the cutoff voltage threshold of 4.2V (ternary lithium battery), the control switch will be turned off, and the charging will be completed.

[0056] This embodiment constructs a stepped constant current charging logic without constant voltage stage through a mechanism of multi-level voltage threshold triggering and segmented duty cycle adjustment, so that the charging process is completely dominated by current control, and voltage is only used as a criterion for stage switching.

[0057] By applying the technical solution of this invention, the initial charging current value of the battery pack can be determined based on the pre-identified number of battery cells and the preset cell type. Then, the pulse width modulation signal is adjusted to regulate the charging current of the battery pack. In this embodiment, the number of battery cells can be automatically identified, enabling the charger to adapt to battery pack structures with different numbers of battery cells, improving the versatility of the device. Furthermore, through a stepped cross-current charging method, adaptive charging control of the battery pack under different numbers of cells and different chemical systems is achieved, improving the battery charging adaptability to various scenarios. This solves the technical problems of poor compatibility of battery cells and a single charging mode in related technologies.

[0058] The invention will now be described in conjunction with another alternative embodiment.

[0059] According to another aspect of the present invention, a battery charging control circuit is provided, comprising: a constant current source circuit for generating a constant current source current; and a charging current regulating circuit connected to the constant current source circuit, comprising: a current sensor, a current regulating switch, a controller, and a plurality of voltage dividing resistors, wherein the current sensor is connected to the constant current source circuit, the current regulating switch is connected to the current sensor, and the controller is used to execute the battery charging method of any one of the above.

[0060] Figure 2 This is a schematic diagram of an optional battery charging control circuit according to an embodiment of the present invention, such as... Figure 2 As shown, part 1 is an AC / DC or DC / DC converter, part 2 is a charging current regulation circuit 1, and part 3 is a charging current regulation circuit 2.

[0061] Optionally, the constant current source circuit includes: an AC / DC converter, or a DC / DC converter, for generating a constant current source current.

[0062] like Figure 2 As shown, the front-end input has an AC / DC converter or DC / DC converter circuit that generates a constant current source (I). The constant current source is input to the subsequent charging current regulation circuit (including charging current regulation circuit 1 (for battery packs without a management system (BMS)) and charging current regulation circuit 2 (for battery packs with a management system (BMS)). The constant current source circuit is used to convert the AC or DC input into a stable output constant current source. Its topology can be an AC / DC or DC / DC converter, operating in current control mode. The output current is not affected by load voltage fluctuations and provides a constant current output based only on the set value, providing the basic input for subsequent charging current regulation.

[0063] Optionally, the charging current regulation circuit includes: a first charging current regulation circuit, comprising: a high-voltage multiplexer analog switch, a first linear regulator, a first current sensor, a first current regulation switch, a first controller, and a first analog-to-digital converter group; the high-voltage multiplexer analog switch is used to detect the number of cells in the battery pack; the first current sensor is connected to a constant current source circuit; the first current regulation switch is connected to the first current sensor; and the first controller is connected to the first analog-to-digital converter group; and a second charging current regulation circuit, comprising: a battery management system, a second linear regulator, a second current sensor, a second current regulation switch, a second controller, and a second analog-to-digital converter group; the battery management system detects the number of cells in the battery pack; the second current sensor is connected to a constant current source circuit; the second current regulation switch is connected to the second current sensor; and the second controller is connected to the second analog-to-digital converter group.

[0064] like Figure 2 As shown, the first charging current adjustment circuit corresponds to Figure 2 The charging current regulation circuit 1 includes: a high-voltage multiplexer analog switch ( Figure 2 The schematic diagram of SW1 includes multiple analog switches (S1, S2, S3...Sn-1 and Sn, each corresponding to a single cell), a first linear voltage regulator, a first current sensor, and a first current regulating switch. Figure 2 (SW2 schematic diagram), first controller () Figure 2 (MCU diagram), button module K1 (the cell type (chemical system) and cell type can be selected and set by the user through K1) First analog-to-digital converter group ( Figure 2 The charging current regulation circuit 1 includes two ADC modules connected to the MCU and voltage divider resistors (such as...). Figure 2 In the charging current regulation circuit 1, R1 and R2 are used.

[0065] like Figure 2 As shown, the first charging current adjustment circuit corresponds to Figure 2 The charging current regulation circuit 1 in the middle includes: a battery management system ( Figure 2 The BMS module in the second part of the charging current regulation circuit is connected to the controller MCU via a communication interface, the second linear voltage regulator, the second current sensor, and the second current regulation switch. Figure 2 (Shown as SW3), second controller (e.g.) Figure 2 The MCU in the charging current regulation circuit 2), and the second analog-to-digital converter group ( Figure 2 The charging current regulation circuit 2 includes two ADC modules connected to the MCU and voltage divider resistors (such as...). Figure 2 R1 and R2 are in part 2 of the charging current regulation circuit.

[0066] The charging current regulation circuit is connected to the constant current source circuit to form the subsequent controllable current output module. This circuit includes a current sensor, a current regulation switch, a controller, and multiple voltage divider resistors, with each component deployed hierarchically according to its function. The current sensor can adopt a Hall effect type or a shunt resistor type structure, connected in series between the constant current source output path and the battery pack, to collect the current value flowing through the battery pack in real time, and output an analog signal to the controller as a feedback input for closed-loop regulation, used to correct the set value of the PWM duty cycle, so that the actual output current is consistent with the target value.

[0067] Optionally, the high-voltage multiplex analog switch includes: n analog switches, wherein the input terminal of each analog switch is connected to the voltage interface of a single battery cell, the output terminal of the analog switch is connected to an analog-to-digital converter through a voltage divider resistor, the analog-to-digital converter is connected to a controller, and n is a positive integer.

[0068] The first charging current regulation circuit is used in charging scenarios for battery packs without a battery management system. Its structure includes a high-voltage multiplexer analog switch, a first linear regulator, a first current sensor, a first current regulation switch, a first controller, and a first analog-to-digital converter (ADC) group. The input terminals of the high-voltage multiplexer analog switch are sequentially connected to the positive and negative terminals of each individual cell in the battery pack. Its output terminal is connected to the first ADC group through a voltage divider resistor network. The controller controls the conduction sequence of the analog switches to collect the voltage signal of each individual cell point by point. Based on the number of voltage channels and the effective voltage range collected, it determines the number of connected battery strings, achieving automatic identification of unknown battery pack topologies. The first linear regulator provides a stable bias voltage for the analog switches and ADC, ensuring the accuracy and stability of the sampled signal under high common-mode voltage conditions. The first current sensor is connected in series in the output path of the constant current source to monitor the actual output current and feeds it back to the first controller to correct the PWM duty cycle and maintain constant current output. The first current regulation switch, as the main circuit on / off switch, is controlled by the first controller and conducts after parameter identification and logic confirmation, forming a charging circuit.

[0069] In an optional embodiment, the charging process in the charging current regulation circuit 1 includes: SW1 is a high-voltage multi-channel analog switch, with each multi-channel switch input connected to the individual lithium battery cell voltage interface. The analog switch output is connected to the ADC input via voltage divider resistors R1 and R2. The ADC is connected to the MCU (microcontroller) I / O input. The MCU controls the analog switches to conduct sequentially, measuring the voltage of each individual cell to determine the number of battery strings connected, thus identifying the number of cells in the battery pack. The cell type (chemical system) and type are selected and set by the user via K1 (a button-like module that identifies the cell type and capacity). The MCU automatically sets the initial charging current based on the cell type and capacity. The current is regulated by the MCU outputting a PWM (duty cycle) signal to control the on / off state of SW2. A fixed duty cycle signal from the MCU ensures a constant charging current output. The Hall sensor in the charging circuit monitors the charging current. The MCU adjusts the output duty cycle based on the current value fed back by the Hall sensor to regulate the current, thereby ensuring the stability of the charging current. When the voltage of any single cell in the battery pack is greater than the Vj cutoff voltage, the MCU adjusts the duty cycle output to adjust the current to 0.1C of the cell capacity (Ah), and charges the battery pack at a constant current of 0.1C. When the voltage of any single cell in the battery pack is greater than the Vj cutoff voltage, the MCU adjusts the duty cycle output to adjust the current to 0.05C of the cell capacity (Ah), and charges the battery pack at a constant current of 0.05C again. When the voltage of any single cell in the battery pack is greater than the Vj cutoff voltage, the MCU controls the switch to turn off, and the charging is complete.

[0070] It should be noted that the PWM switching frequency of SW1 (SW2) is f, TON is the on-time of SW1 (SW2), and D=TON. f, where I is the current value of the preceding constant current source, and D is the PWM duty cycle, then the average charging current I_constant_current = D_constant_current. I.

[0071] Furthermore, the second charging current regulation circuit is used in battery pack charging scenarios with a battery management system. The battery management system sends parameters such as cell type, rated capacity, current temperature, and number of cells in series to the charger via a communication interface, enabling proactive reporting of the battery pack structure without the need for external sampling circuitry for physical detection. A second linear voltage regulator provides low-noise power to the communication interface circuit and the analog-to-digital converter group, ensuring reliable data transmission and acquisition. The second current sensor, also connected in series in the constant current source output path, functions identically to the first current sensor, providing real-time feedback on the charging current. The second current regulation switch is controlled by the second controller, responding to the charging command confirmed by the communication protocol to complete the circuit connection.

[0072] In an optional embodiment, the charging process in the charging current regulation circuit 2 includes: when the battery has an internal management system, the charger can interact with the management system to read the battery status and charging configuration parameters, thereby identifying the battery pack type. The MCU identifies the cell type and capacity based on the battery pack type and automatically sets the charging current. The current is regulated by the MCU outputting a PWM (duty cycle) signal to control the on / off state of SW3. A fixed duty cycle signal from the MCU can achieve a constant charging current output. The Hall sensor in the charging circuit can monitor the charging current. The MCU can adjust the output duty cycle based on the current value fed back by the Hall sensor to regulate the current, thereby ensuring the stability of the charging current. When the voltage of any single cell in the battery pack is greater than the Vj cutoff voltage, the MCU adjusts the duty cycle output to adjust the current to 0.1C of the cell capacity (Ah), and charges the battery pack at a constant current of 0.1C. When the voltage of any single cell in the battery pack is greater than the Vj cutoff voltage, the MCU adjusts the duty cycle output to adjust the current to 0.05C of the cell capacity (Ah), and charges the battery pack at a constant current of 0.05C again. When the voltage of any single cell in the battery pack is greater than the Vj cutoff voltage, the MCU controls the switch to turn off, and the charging is complete.

[0073] It should also be noted that C is the cell charging rate, and Ah is the cell capacity; when the cell capacity is 10Ah, the charging current corresponding to 1C is 10A, and the charging current corresponding to 0.05C is 0.5A.

[0074] The cutoff voltage threshold Vj can be determined using the chemical system table in Table 1 below.

[0075] Table 1. Correspondence between chemical systems and cutoff voltage thresholds

[0076]

[0077] By using the parallel design of the first charging current regulation circuit and the second charging current regulation circuit, the charger can obtain accurate cell string count and status information when facing ordinary battery packs without communication capabilities or high-end battery systems with intelligent communication functions.

[0078] It should be noted that the current regulating switch, acting as the main current on / off switch, is located between the current sensor and the battery pack input terminal, and is driven to close or open by the controller. The conduction state of the current regulating switch determines whether a charging circuit is established. Its action is triggered uniformly by the controller after parameter identification is completed and voltage detection is ready, avoiding false charging before initialization is complete. The selection of the current regulating switch takes into account high current carrying capacity and mechanical lifespan, adapting to the frequent switching requirements in medium-power charging scenarios.

[0079] It should be noted that the controller in this embodiment can be an embedded microprocessor unit, such as a single-chip microcomputer (MCU), which can integrate an analog-to-digital conversion interface, a PWM generation module, a communication interface, and a storage unit to execute the entire logic flow of the battery charging method. The controller receives the individual cell voltage sampling signal from the voltage divider resistor network. Based on the collected data, the controller identifies the number of cells in series, determines the voltage step, calculates the target current, and outputs a PWM signal with a corresponding duty cycle to drive the current adjustment switch, thereby completing the step-wise adjustment of the charging current.

[0080] This embodiment provides a stable current input through a constant current source circuit, achieves digital and segmented control of the current through a charging current regulation circuit, provides closed-loop current feedback through a sensor, ensures safe switching through a current regulation switch, coordinates logic and signal processing through a controller, and achieves safe voltage acquisition through a voltage divider resistor. All modules work together to complete a stepped constant current charging process without a constant voltage stage, simplifying the dependence of traditional constant voltage charging on a high-precision voltage reference, supporting a wide range of battery string number adaptations, and helping to improve the adaptability and consistency of the charging system under different load conditions.

[0081] Optionally, the charging current regulation circuit in this embodiment includes two parallel architectures, which are adapted to battery packs with and without battery management systems, respectively, forming a dual-path detection and control mechanism.

[0082] Compared to the traditional charging process where lithium battery packs first undergo constant current charging and then constant voltage (limited voltage) charging using the charger's constant voltage characteristics, the final full charge voltage of the lithium battery depends on the charger's constant voltage accuracy; this embodiment uses the above-mentioned circuit design to employ a variable step-like constant current charging method throughout the entire process, eliminating the need for constant voltage charging during battery charging and avoiding the dependence of traditional charging methods on the charger's constant voltage accuracy.

[0083] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: by constructing a stepped constant current charging architecture without a constant voltage stage, adaptive charging control of lithium battery packs under different series numbers and different chemical systems is realized. The charging process relies entirely on the synergistic effect of the current threshold and voltage triggering logic, without relying on the accuracy of the charger's output voltage, thereby eliminating overcharging or undercharging caused by constant voltage setting deviations.

[0084] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: In terms of charging current regulation, the present invention uses PWM duty cycle to perform time-domain modulation on the front-end constant current source to achieve multi-segment constant current output, supports smooth switching of step currents such as 0.5C, 0.1C, and 0.05C, makes the charging curve more closely match the cell polarization characteristics, helps to reduce the temperature rise rate at the end of charging, reduces the risk of lithium dendrite growth, and improves battery cycle life.

[0085] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: The present invention, through a high-voltage multi-channel analog switch and a voltage divider resistor network, automatically identifies the number of cell strings in battery packs without a BMS, eliminating the need for manual user settings. This allows a single charger to adapt to different battery pack structures ranging from 2 to over 20 strings, improving device versatility. In battery pack scenarios with a BMS, the present invention reads battery pack parameters through a communication interface, enabling parameter verification and current matching in collaboration with the management system, avoiding charging anomalies caused by misidentification.

[0086] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: The present invention continuously monitors the actual current value during the charging process and dynamically corrects the PWM duty cycle through feedback from the Hall sensor, effectively compensating for the current attenuation introduced by the voltage drop of the charging cable and the contact resistance. Especially under low voltage and high current charging conditions, it can avoid the false triggering of the constant voltage mode due to line loss and shorten the overall charging time.

[0087] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: The charging termination mechanism of the present invention is based entirely on the dual judgment of the battery cell voltage threshold and current ratio, without relying on timers or capacity integration, avoiding premature or delayed termination caused by temperature drift, sensor error or communication delay, and improving the accuracy and repeatability of charging completion judgment.

[0088] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0089] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0090] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0091] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A battery charging method, characterized in that, include: The initial charging current value of the battery pack is determined based on the pre-identified number of battery cells in series and the preset cell type. The control current adjustment switch is turned on and a pulse width modulation signal is output. The pulse width modulation signal is used to adjust the charging current of the battery pack based on the initial charging current value to obtain a constant output charging current. During the constant output charging current process, the voltage value of each individual cell in the battery pack is detected. Based on the comparison between the voltage value and the cutoff voltage threshold of different voltage steps, the pulse width modulation signal is adjusted to adjust the battery pack current to the current value corresponding to the cell capacity.

2. The battery charging method according to claim 1, characterized in that, Before determining the initial charging current value of the battery pack based on the pre-identified number of battery cells and the preset cell type, the process also includes: Perform cell string number identification operation when the battery pack does not include a battery management system; The high-voltage multi-channel analog switch is controlled to turn on sequentially to measure the voltage of each individual battery cell. The high-voltage multi-channel analog switch includes n analog switches. The input terminal of each analog switch is connected to the voltage interface of the individual battery cell, and the output terminal of each analog switch is connected to an analog-to-digital converter through a voltage divider resistor. The analog-to-digital converter is connected to a controller. Based on the voltage measurement results, the number of cell strings in the battery pack was identified.

3. The battery charging method according to claim 1, characterized in that, Before determining the initial charging current value of the battery pack based on the pre-identified number of battery cells and the preset cell type, the process also includes: When the battery pack includes a battery management system, perform cell string number identification. Send a battery status parameter read command to the battery management system to obtain the battery status and charging configuration parameters, wherein the charging configuration parameters include at least the number of cells in the battery pack.

4. The battery charging method according to claim 1, characterized in that, Based on the pre-identified number of battery cells in series and the preset cell type, the initial charging current value of the battery pack is determined as follows: In the absence of a battery management system in the battery pack, the system receives a setting command sent by the user terminal via the status button, parses the setting command to obtain the preset cell type and battery capacity, and determines the initial charging current value of the battery pack based on the number of cells in the battery pack, the preset cell type, and the battery capacity. When the battery pack includes a battery management system, the preset cell type and battery capacity are obtained through the battery management system, and the initial charging current value of the battery pack is determined based on the number of cells in series, the preset cell type, and the battery capacity.

5. The battery charging method according to claim 1, characterized in that, Detecting the voltage value of each individual cell in the battery pack, and adjusting the pulse width modulation signal based on the comparison between the voltage value and the cutoff voltage threshold of different voltage steps, includes: The voltage value of each individual cell in the battery pack is detected by sensors; When the voltage of any single cell in the battery pack is greater than the cutoff voltage threshold of the preset first step voltage range, the pulse width modulation signal is adjusted and a first duty cycle adjustment signal is output. The first duty cycle adjustment signal is used to adjust the battery pack current to 0.1C of the cell capacity and charge the battery pack at a constant current of 0.1C until the battery pack voltage reaches the cutoff voltage threshold. When the voltage of any single cell in the battery pack is greater than the cutoff voltage threshold of the preset second-step voltage range, the pulse width modulation signal is adjusted to output a second duty cycle adjustment signal. The second duty cycle adjustment signal is used to adjust the battery pack current to 0.05C of the cell capacity and charge the battery pack at a constant current of 0.05C until the battery pack voltage reaches the cutoff voltage threshold. The battery pack is charged at a constant current of 0.05C.

6. The battery charging method according to claim 5, characterized in that, After the battery pack is charged at a constant current of 0.05C, the following steps are also included: If the voltage of any single cell in the battery pack is detected to be greater than the cutoff voltage threshold, the charging switch is turned off, and charging is complete.

7. A battery charging control circuit, characterized in that, include: A constant current source circuit is used to generate a constant current source current; A charging current adjustment circuit, connected to the constant current source circuit, includes: a current sensor, a current adjustment switch, a controller, and multiple voltage divider resistors, wherein the current sensor is connected to the constant current source circuit, the current adjustment switch is connected to the current sensor, and the controller is used to execute the battery charging method according to any one of claims 1 to 6.

8. The battery charging control circuit according to claim 7, characterized in that, The charging current regulation circuit includes: The first charging current regulation circuit includes: a high-voltage multiplex analog switch, a first linear voltage regulator, a first current sensor, a first current regulation switch, a first controller, and a first analog-to-digital converter group. The high-voltage multiplex analog switch is used to detect the number of cells in the battery pack. The first current sensor is connected to the constant current source circuit. The first current regulation switch is connected to the first current sensor. The first controller is connected to the first analog-to-digital converter group. The second charging current regulation circuit includes: a battery management system, a second linear voltage regulator, a second current sensor, a second current regulation switch, a second controller, and a second analog-to-digital converter group. The battery management system detects the number of cells in the battery pack. The second current sensor is connected to the constant current source circuit. The second current regulation switch is connected to the second current sensor. The second controller is connected to the second analog-to-digital converter group.

9. The battery charging control circuit according to claim 8, characterized in that, The high-voltage multi-channel analog switch includes: There are n analog switches, wherein the input terminal of each analog switch is connected to the voltage interface of a single battery cell, the output terminal of each analog switch is connected to an analog-to-digital converter through a voltage divider resistor, and the analog-to-digital converter is connected to a controller, where n is a positive integer.

10. The battery charging control circuit according to claim 9, characterized in that, The constant current source circuit includes: An AC / DC converter, or DC / DC converter, is used to generate a constant current source.

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