A cell control method, apparatus and BMS equipment

Abstract

This invention discloses a cell control method, device, and BMS (Battery Management System) equipment. The method is applied to the BMS equipment, which collects voltage data from multiple acquisition units within the battery pack. Each acquisition unit has acquisition lines connected to its positive and negative terminals, and multiple individual battery cells are connected in series within each acquisition unit. The method includes: acquiring the overall voltage of each acquisition unit; determining whether each overall voltage reaches a preset voltage threshold, where the preset voltage threshold is generated based on the cutoff voltage of the individual battery cell at its corresponding operating state and the number of individual battery cells in the acquisition unit. If the preset voltage threshold is less than the cutoff voltage of the acquisition unit, the operating state is either charging or discharging; if any overall voltage reaches the preset voltage threshold, the corresponding operation of the battery pack is stopped. The technical solution provided by this invention reduces the use of acquisition lines and chips, thereby lowering the cost of the acquisition scheme, while ensuring the safety and reliability of the battery cells.

Description

Technical Field

[0001] This invention relates to the field of new energy batteries, specifically to a cell control method, device, and BMS equipment. Background Technology

[0002] In the field of new energy batteries, to ensure battery safety and quality, the charging and discharging processes are typically configured within the Battery Management System (BMS) to forcibly stop the corresponding processes. The charging process generally stops when the highest voltage of any individual cell reaches the upper charging limit, and the discharging process generally stops when the lowest voltage of any individual cell reaches the lower discharging limit. To meet these conditions, current BMS methods collect cell voltages by acquiring the voltage of each individual cell. BMS integration methods include integrated BMS (slave board and master control board combined) and master-slave publishing BMS. The slave board can be independently arranged within the battery pack and connected to the module via acquisition wiring harnesses, or it can be integrated into the module. The independent slave board arrangement requires a large number of acquisition wiring harnesses, occupying internal battery pack space and increasing assembly complexity. The module-integrated BMS slave board arrangement requires a large number of acquisition channels because each cell needs individual voltage acquisition, resulting in a large number of acquisition boards with a large area and significant space occupation, especially for cells with terminals on both sides, requiring slave boards on both sides. In summary, existing data acquisition solutions all consume excessive hardware resources and space, resulting in high acquisition costs. Therefore, reducing the cost of data acquisition solutions while ensuring safe charging and discharging of battery cells is an urgent problem to be solved. Summary of the Invention

[0003] In view of this, embodiments of the present invention provide a cell control method, apparatus and BMS device, thereby reducing the cost of data acquisition schemes while safely charging and discharging the cells.

[0004] According to a first aspect, the present invention provides a cell control method applied to a BMS device. The BMS device collects voltage data from multiple acquisition units within a battery pack. Each acquisition unit has acquisition lines connected to its positive and negative terminals, and multiple individual battery cells are connected in series within each acquisition unit. The method includes: acquiring the overall voltage of each acquisition unit; determining whether each overall voltage reaches a preset voltage threshold, the preset voltage threshold being generated based on the cutoff voltage of the individual battery cell in its corresponding operating state and the number of individual battery cells in the acquisition unit, the preset voltage threshold being less than the cutoff voltage of the acquisition unit, the cutoff voltage of the acquisition unit being the product of the cutoff voltage of the individual battery cell in its corresponding operating state and the number of individual battery cells in the acquisition unit, the operating state being either a charging state or a discharging state; and stopping the corresponding operating process of the battery pack if any of the overall voltages reaches the preset voltage threshold.

[0005] Optionally, before stopping the corresponding operation of the battery pack, the method further includes: calculating the overall voltage change of the target overall voltage relative to the previous acquisition time, wherein the target overall voltage is the overall voltage that reaches the preset voltage threshold; determining whether the overall voltage change reaches the preset voltage change threshold, wherein the preset voltage change threshold is generated based on the cell capacity-voltage change curve of the individual cell in the corresponding operating state and the number of individual cells in the acquisition unit; if the overall voltage change reaches the preset voltage change threshold, then returning to the step of stopping the corresponding operation of the battery pack.

[0006] Optionally, if the working state is a charging state, the step of generating the preset voltage threshold based on the cutoff voltage of the corresponding working state of a single cell and the number of single cells in the acquisition unit includes: calculating the deviation voltage when a deviation occurs in a single cell based on the maximum charging capacity deviation between single cells; calculating the product of the deviation voltage and a first quantity to obtain an intermediate quantity, where the first quantity is the number of single cells in the acquisition unit minus 1; and calculating the sum of the charging cutoff voltage and the intermediate quantity to obtain the preset voltage threshold corresponding to the charging state.

[0007] Optionally, if the operating state is a discharge state, the step of generating the preset voltage threshold based on the cutoff voltage of the corresponding operating state of a single cell and the number of single cells in the acquisition unit includes: calculating a second deviation voltage when a deviation occurs in a single cell based on the maximum discharge capacity deviation between single cells; calculating the product of the second deviation voltage and a first quantity to obtain a second intermediate quantity, where the first quantity is the number of single cells in the acquisition unit minus 1; and calculating the sum of the discharge cutoff voltage and the second intermediate quantity to obtain the preset voltage threshold corresponding to the discharge state.

[0008] Optionally, the method further includes: if none of the overall voltages reach the preset voltage threshold, then returning to the step of acquiring the overall voltage of each acquisition unit.

[0009] Optionally, the method further includes: if the overall voltage change does not reach the preset voltage change threshold, then returning to the step of acquiring the overall voltage of each acquisition unit.

[0010] According to a second aspect, the present invention provides a cell control device applied to a BMS device. The BMS device collects voltage data from multiple acquisition units within a battery pack. Each acquisition unit has acquisition lines connected to the BMS device at its positive and negative terminals. Multiple individual battery cells are connected in series within each acquisition unit. The device includes: a voltage acquisition module for acquiring the overall voltage of each acquisition unit; a first judgment module for judging whether each overall voltage reaches a preset voltage threshold. The preset voltage threshold is generated based on the cutoff voltage of the corresponding operating state of an individual battery cell and the number of individual battery cells in the acquisition unit. The preset voltage threshold is less than the cutoff voltage of the acquisition unit. The cutoff voltage of the acquisition unit is the product of the cutoff voltage of the corresponding operating state of the individual battery cell and the number of individual battery cells in the acquisition unit. The operating state is either a charging state or a discharging state; and a control module for stopping the corresponding operating process of the battery pack if any of the overall voltages reaches the preset voltage threshold.

[0011] Optionally, before stopping the corresponding operation of the battery pack, the device further includes: a calculation module for calculating the overall voltage change of the target overall voltage relative to the previous acquisition time, wherein the target overall voltage is the overall voltage that reaches the preset voltage threshold; a second judgment module for judging whether the overall voltage change reaches the preset voltage change threshold, wherein the preset voltage change threshold is generated based on the cell capacity-voltage change curve of the individual cell in the corresponding operating state and the number of individual cells in the acquisition unit; and a second control module for returning to the step of stopping the corresponding operation of the battery pack if the overall voltage change reaches the preset voltage change threshold.

[0012] According to a third aspect, embodiments of the present invention provide a BMS device, including: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the method described in the first aspect, or any optional embodiment of the first aspect.

[0013] According to a fourth aspect, embodiments of the present invention provide a computer-readable storage medium storing computer instructions for causing the computer to perform the method described in the first aspect, or any alternative embodiment of the first aspect.

[0014] The technical solution provided in this application has the following advantages:

[0015] The technical solution provided in this application divides multiple individual battery cells into a single acquisition unit. The positive and negative terminals of the series-connected individual battery cells serve as the positive and negative terminals of the acquisition unit, respectively. Each acquisition unit uses an acquisition line or acquisition channel to acquire the voltage of the battery cells. Since the rate of capacity change of each battery cell may differ during charging or discharging, resulting in inconsistent voltage rates, to ensure safety during charging or discharging, the voltage threshold of the acquisition unit during charging or discharging can be set to be less than the ideal cutoff voltage (the ideal cutoff voltage is the cutoff voltage of an individual battery cell multiplied by the number of individual battery cells in the acquisition unit). Therefore, when the overall voltage of the acquisition unit reaches the preset voltage threshold, the voltage of the individual battery cell with the highest or lowest voltage does not exceed, or significantly exceeds, the cutoff voltage of the individual battery cell. This reduces the use of acquisition lines and chips, lowering the cost of the acquisition solution while ensuring the safety and reliability of the battery cells.

[0016] Furthermore, since the preset voltage threshold is lower than the ideal cutoff voltage, some battery cells may not be fully charged or fully discharged. To reduce battery capacity waste, a voltage change threshold is set as a criterion based on the faster and more sensitive cell capacity-voltage change curve. Once a cell meets the preset voltage threshold, charging or discharging continues. The charging or discharging of the battery pack stops only when the voltage change at the next moment relative to the current moment meets the voltage change threshold condition. This fine-tunes the charging or discharging process of the battery pack, slightly extending the charging or discharging time and reducing battery capacity waste while ensuring battery safety and reliability. Attached Figure Description

[0017] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0018] Figure 1 A schematic diagram of the steps of a cell control method according to one embodiment of the present invention is shown;

[0019] Figure 2 A schematic diagram of a battery cell voltage acquisition device according to one embodiment of the present invention is shown;

[0020] Figure 3The figure shows the capacity-voltage variation curves of a single cell during the charging and discharging processes according to one embodiment of the present invention.

[0021] Figure 4 A schematic flowchart of a cell control method according to one embodiment of the present invention is shown;

[0022] Figure 5 This invention illustrates the capacity-voltage increment variation curves of a single cell during the charging and discharging processes, according to one embodiment of the invention.

[0023] Figure 6 The following diagram illustrates the capacity-voltage variation curve and the capacity-voltage increment variation curve of a data acquisition unit composed of two strings of cells during the charging process in one embodiment of the present invention.

[0024] Figure 7 The following diagram illustrates the capacity-voltage variation curve and the capacity-voltage increment variation curve of a data acquisition unit composed of three strings of cells during the charging process in one embodiment of the present invention.

[0025] Figure 8 The following diagram illustrates the capacity-voltage variation curve and the capacity-voltage increment variation curve of a data acquisition unit composed of eight battery cells in one embodiment of the present invention during the charging process.

[0026] Figure 9 A schematic diagram of a battery cell control device according to one embodiment of the present invention is shown;

[0027] Figure 10 A schematic diagram of a BMS device according to one embodiment of the present invention is shown. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 a part of the embodiments of the present invention, and not all of them. 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.

[0029] Please see Figure 1 and Figure 2 In one embodiment, a cell control method is applied to a BMS device. The BMS device collects voltage data from multiple acquisition units within the battery pack. Each acquisition unit has acquisition lines connected to its positive and negative terminals, and multiple individual battery cells are connected in series within each acquisition unit. The method specifically includes the following steps:

[0030] Step S101: Obtain the overall voltage of each acquisition unit.

[0031] Step S102: Determine whether the overall voltage of each cell has reached the preset voltage threshold. The preset voltage threshold is generated based on the cutoff voltage of the corresponding working state of the individual cell and the number of individual cells in the acquisition unit. The preset voltage threshold is less than the cutoff voltage of the acquisition unit. The cutoff voltage of the acquisition unit is the product of the cutoff voltage of the individual cell and the number of individual cells in the acquisition unit. The working state is either charging state or discharging state.

[0032] Step S103: If any overall voltage reaches a preset voltage threshold, the corresponding working process of the battery pack is stopped.

[0033] Specifically, in this embodiment, multiple individual battery cells are grouped into one acquisition unit. The positive and negative terminals of the series-connected individual cells serve as the positive and negative terminals of the acquisition unit, respectively. Each acquisition unit uses one acquisition line or acquisition channel to acquire the voltage of the battery cells. The number of individual cells in series within an acquisition unit is typically 2-20, and the upper limit of the acquisition unit voltage is 10-100V. Considering that too many series in the acquisition unit may lead to greater loss of usable capacity, 2-16 series are recommended, with an upper limit of the acquisition unit voltage of 10-80V. In practical applications, to comply with the standards of most enterprises, 2, 3, 4, 6, 8, 12, and 16 series are usually used as one acquisition unit. Figure 3 As shown, taking lithium iron phosphate batteries as an example, their charge-discharge curves exhibit a distinct characteristic of being flat in the middle and steep at both ends. When the cell's capacity approaches 100% during charging or discharging, its voltage value also falls near a certain threshold. To reduce the cost of the data acquisition scheme, this embodiment is based on acquiring the total voltage of several adjacent series-connected cells. However, this approach makes it impossible to distinguish the individual cell voltages within each acquisition unit, leading to the risk of overcharging or over-discharging individual cells. For example, the voltage range of ternary lithium batteries is generally 2.8-4.3V. If each pair of cells forms an acquisition unit with an 8.4V acquisition unit voltage, and the charging and discharging processes of the two cells are highly consistent, both cells will be at 4.2V, without overcharging. However, if the consistency between the two cells is poor, assuming the two cells are at 4.0V and 4.4V respectively, one cell will be at risk of overcharging. Therefore, in this embodiment, in order to ensure the safety of the battery cell during charging or discharging, the voltage threshold of the acquisition unit during charging or discharging can be set to be less than the ideal cutoff voltage (the ideal cutoff voltage is the cutoff voltage of a single battery cell multiplied by the number of single battery cells in the acquisition unit). Thus, when the overall voltage of the acquisition unit reaches the preset voltage threshold, the voltage of the single battery cell with the highest or lowest voltage does not exceed or significantly exceed the cutoff voltage of the single battery cell. This reduces the use of acquisition lines and acquisition chips and lowers the cost of the acquisition scheme while ensuring the safety and reliability of the battery cell.

[0034] Specifically, such as Figure 4 As shown, in one embodiment, before stopping the corresponding operation of the battery pack, the cell control method provided by this embodiment of the invention further includes the following steps:

[0035] Step 1: Calculate the change in the overall target voltage relative to the previous acquisition time. The overall target voltage is the overall voltage that has reached the preset voltage threshold.

[0036] Step 2: Determine whether the overall voltage change has reached the preset voltage change threshold. The preset voltage change threshold is generated based on the cell capacity-voltage change curve of the individual cell in the corresponding working state and the number of individual cells in the acquisition unit.

[0037] Step 3: If the overall voltage change reaches the preset voltage change threshold, return to the step of stopping the corresponding working process of the battery pack.

[0038] Specifically, because the preset voltage threshold is lower than the ideal cutoff voltage, the battery cell may not be able to fully charge or fully discharge. For example... Figure 5 The figure shows the cell capacity-voltage change curve (hereinafter referred to as the voltage increment curve) of a single battery cell. During charging, the voltage increment curve rises rapidly above 98% SOC, from a few millivolts / 1% SOC to 700 millivolts / 1% SOC; during discharging, the voltage increment curve drops rapidly below 2% SOC, from a few millivolts / 1% SOC to nearly 3000 millivolts / 1% SOC. The voltage increment values ​​at the end of charging and discharging both increase rapidly by 2-3 orders of magnitude. The unit of voltage increment in the figure is mV / Ah. This value will vary for different capacities, but the proportion is the same. Therefore, when the cell capacity is about to be fully charged or fully discharged, the corresponding voltage change will change significantly. This is used as a standard to set the voltage change threshold as a second indicator. Taking charging as an example, when the acquisition unit meets the preset voltage threshold, the voltage change threshold may not yet be met. Even if charging continues, the voltage change threshold will be met relatively quickly, preventing excessively long charging times. This allows the battery pack to achieve full charge or discharge as safely as possible. Compared to existing technologies that control the voltage of individual cells, the lost capacity can typically be kept within 1%. The specific steps for setting the voltage change threshold can be based on practical experience. First, identify the voltage change corresponding to when a single cell's capacity is not fully charged or discharged. Then, calculate the product of the voltage change and the number of cells in the acquisition unit to obtain the overall voltage change threshold for the acquisition unit. Alternatively, after calculating the product, multiple experiments can be conducted, and the product can be fine-tuned based on expert experience to obtain the voltage change threshold. This invention is not limited to these methods.

[0039] Specifically, in one embodiment, if the current state is charging, the specific steps for generating a preset voltage threshold include:

[0040] Step 4: Calculate the deviation voltage when a deviation occurs in a single cell based on the maximum charging capacity deviation between individual cells.

[0041] Step 5: Calculate the intermediate quantity by multiplying the deviation voltage and the first quantity. The first quantity is the number of individual cells in the acquisition unit minus 1.

[0042] Step 6: Calculate the sum of the charging cutoff voltage and the intermediate quantity to obtain the preset voltage threshold corresponding to the charging state.

[0043] Specifically, in this embodiment, to further improve the accuracy of the preset voltage threshold setting and ensure that individual battery cells are not overcharged to the greatest extent possible, the maximum charging capacity deviation between individual battery cells is first obtained. Assuming poor consistency among the cells within the acquisition unit, the worst-case capacity deviation would reach 40%, meaning that when the fastest-charging cell reaches 100% capacity, other cells would only reach 60%. The maximum capacity deviation is 40%. Since cell capacity and voltage are positively correlated during charging, the deviation voltage at which a deviation occurs can be obtained by consulting the voltage-capacity change curve based on the maximum capacity deviation and the cutoff voltage. Assuming the cutoff voltage for 100% SOC is 3.7V, and consulting the voltage-capacity change curve, the voltage for 60% SOC is found to be 3.35V, then the deviation voltage at this point is 3.35V. Except for the cells that have reached the cutoff voltage, the other cells are calculated based on a voltage of 3.35V: the deviation voltage is multiplied by a first quantity to obtain an intermediate value. The first quantity is the number of individual cells in the acquisition unit minus 1. For example, if there are 10 cells in the acquisition unit, the total voltage threshold of the other cells, excluding the cell that first reaches the cutoff voltage, is set to 9 multiplied by 3.35, which is the intermediate value. Then, the intermediate value is summed with the cutoff voltage of 3.7V to obtain the preset voltage threshold corresponding to the charging state. This ensures that when the overall voltage of the acquisition unit reaches the preset voltage threshold, no cell in the acquisition unit will be overcharged, further improving the safety and reliability of the cells.

[0044] Specifically, in one embodiment, if the current state is a discharge state, the specific steps for generating a preset voltage threshold include:

[0045] Step 7: Calculate the second deviation voltage when a deviation occurs in a single cell based on the maximum discharge capacity deviation between individual cells.

[0046] Step 8: Calculate the product of the second deviation voltage and the first quantity to obtain the second intermediate quantity. The first quantity is the number of individual cells in the acquisition unit minus 1.

[0047] Step 9: Calculate the sum of the discharge cutoff voltage and the second intermediate quantity to obtain the preset voltage threshold corresponding to the discharge state.

[0048] Specifically, the principle of setting the preset voltage threshold in the discharge process is the same as that in the charging process. Please refer to the detailed description of steps four to six above, which will not be repeated here.

[0049] Specifically, in one embodiment, the battery cell control method provided by this invention further includes the following steps:

[0050] Step 10: If none of the overall voltages reach the preset voltage threshold, return to the step of obtaining the overall voltage of each acquisition unit.

[0051] Specifically, if the overall voltage of each acquisition unit fails to reach the preset voltage threshold in the first indicator judgment, the next acquisition and judgment will proceed, thereby enabling the acquisition work to be executed periodically, further ensuring that the battery pack can stop working in time, avoiding safety hazards and preventing damage to the battery pack.

[0052] Specifically, in one embodiment, the battery cell control method provided by this invention further includes the following steps:

[0053] Step 11: If the overall voltage change does not reach the preset voltage change threshold, return to the step of obtaining the overall voltage of each acquisition unit.

[0054] Specifically, if the overall voltage of each acquisition unit that meets the first indicator does not reach the preset voltage change threshold during the second indicator judgment, the next cell voltage acquisition step will be initiated. This allows the acquisition work to be executed periodically, further ensuring that the battery pack can stop working in time, avoiding safety hazards and preventing damage to the battery pack.

[0055] Specifically, in one embodiment, the technical solution provided in this application is explained in detail based on the following specific embodiments:

[0056] (1) Two sets of acquisition units

[0057] like Figure 6 As shown, the first charging cutoff threshold is set to 3.5V (i.e., the total voltage threshold is 7V), and the second cutoff threshold is set to 350mV / Ah. Even in the worst-case scenario, where one cell is 3.35V and another is 3.65V—an extreme case where the SOC difference between the two cells exceeds 40%—overcharging will not occur. In the best-case scenario, charging can continue until both cells reach 3.5V, and then until the voltage increment of both cells reaches 350mV / Ah. It is estimated that 99.8% SOC can be achieved, resulting in only a 0.2% loss of SOC capacity compared to controlling individual cell voltage.

[0058] (2) Three-string acquisition units

[0059] like Figure 7 As shown, the first charging cutoff threshold is set to 3.45V (i.e., the total voltage threshold is 10.35V), and the second cutoff threshold is set to 225mV / Ah. Even in the worst-case scenario, where two cells are at 3.35V and one cell is at 3.65V (an extreme case where one cell's SOC is more than 40% out of bounds), overcharging will not occur. In the best-case scenario, charging can continue until all three cells reach 3.45V, and then until the voltage increment of two cells reaches 225mV / Ah. It is estimated that 99.7% SOC can be achieved, resulting in only a 0.3% loss of SOC compared to the single-cell voltage control scheme.

[0060] (3) Eight-string acquisition units

[0061] like Figure 8 As shown, the first charging cutoff threshold is set to 3.4V (i.e., the total voltage threshold is 27.2V), and the second cutoff threshold is set to 90mV / Ah. Even in the worst-case scenario, where all seven cells are at 3.365V and one cell is at 3.65V (an extreme case where one cell's SOC is more than 40% out of bounds), overcharging will not occur. In the best-case scenario, charging can proceed until all eight cells reach 3.4V, and then further until two cells reach 90mV / Ah. This suggests a possible charge to 99.35% SOC, resulting in only a 0.65% loss of SOC compared to the single-cell voltage control scheme.

[0062] Through the above steps, the technical solution provided in this application divides multiple individual battery cells into one acquisition unit. The positive and negative terminals of the series-connected individual battery cells serve as the positive and negative terminals of the acquisition unit, respectively. Each acquisition unit uses one acquisition line or acquisition channel to acquire the voltage of the battery cells. Since the rate of capacity change of each battery cell may differ during charging or discharging, resulting in inconsistent voltage rates, to ensure the safety of the battery cells during charging or discharging, the voltage threshold of the acquisition unit during charging or discharging can be set to be less than the ideal cutoff voltage (the ideal cutoff voltage is the cutoff voltage of an individual battery cell multiplied by the number of individual battery cells in the acquisition unit). Thus, when the overall voltage of the acquisition unit reaches the preset voltage threshold, the voltage of the individual battery cell with the highest or lowest voltage does not exceed, or significantly exceeds, the cutoff voltage of the individual battery cell. This reduces the use of acquisition lines and acquisition chips, thereby lowering the cost of the acquisition scheme while ensuring the safety and reliability of the battery cells.

[0063] Furthermore, since the preset voltage threshold is lower than the ideal cutoff voltage, some battery cells may not be fully charged or fully discharged. To reduce battery capacity waste, a voltage change threshold is set as a criterion based on the faster and more sensitive cell capacity-voltage change curve. Once a cell meets the preset voltage threshold, charging or discharging continues. The charging or discharging of the battery pack stops only when the voltage change at the next moment relative to the current moment meets the voltage change threshold condition. This fine-tunes the charging or discharging process of the battery pack, slightly extending the charging or discharging time and reducing battery capacity waste while ensuring battery safety and reliability.

[0064] like Figure 9 As shown, this embodiment also provides a cell control device applied to a BMS device. The BMS device collects voltage data from multiple acquisition units within the battery pack. Each acquisition unit has acquisition lines connected to its positive and negative terminals to the BMS device. Multiple individual battery cells are connected in series within each acquisition unit. The device includes:

[0065] The voltage acquisition module 101 is used to acquire the overall voltage of each acquisition unit. For details, please refer to the relevant description of step S101 in the above method embodiment, which will not be repeated here.

[0066] The first judgment module 102 is used to determine whether the overall voltage of each cell has reached a preset voltage threshold. The preset voltage threshold is generated based on the cutoff voltage of the corresponding working state of the individual cell and the number of individual cells in the acquisition unit. The preset voltage threshold is less than the cutoff voltage of the acquisition unit. The cutoff voltage of the acquisition unit is the product of the cutoff voltage of the individual cell and the number of individual cells in the acquisition unit. The working state is either charging or discharging. For details, please refer to the relevant description of step S102 in the above method embodiment, which will not be repeated here.

[0067] The control module 103 is used to stop the corresponding operation of the battery pack if any overall voltage reaches a preset voltage threshold. For details, please refer to the relevant description of step S103 in the above method embodiments, which will not be repeated here.

[0068] Specifically, in one embodiment, before stopping the corresponding operation of the battery pack, the cell control device provided in this embodiment of the invention further includes:

[0069] The calculation module is used to calculate the change in the overall target voltage relative to the previous acquisition time. The overall target voltage is the overall voltage that reaches a preset voltage threshold. For details, please refer to the relevant description in step one of the above method embodiments, which will not be repeated here.

[0070] The second judgment module is used to determine whether the overall voltage change reaches a preset voltage change threshold. The preset voltage change threshold is generated based on the cell capacity-voltage change curve of the individual cell at the corresponding working state and the number of individual cells in the acquisition unit. For details, please refer to the relevant description of step two in the above method embodiment, which will not be repeated here.

[0071] The second control module is used to stop the corresponding operation of the battery pack if the overall voltage change reaches a preset voltage change threshold. For details, please refer to the relevant description in step three of the above method embodiments, which will not be repeated here.

[0072] The present invention provides a battery cell control device for executing a battery cell control method provided in the above embodiments. Its implementation method and principle are the same. For details, please refer to the relevant description of the above method embodiments, which will not be repeated here.

[0073] Through the collaborative operation of the aforementioned components, the technical solution provided in this application divides multiple individual battery cells into a single acquisition unit. The positive and negative terminals of the series-connected individual battery cells serve as the positive and negative terminals of the acquisition unit, respectively. Each acquisition unit uses an acquisition line or acquisition channel to acquire the voltage of the battery cells. Since the rate of capacity change of each battery cell may differ during charging or discharging, resulting in inconsistent voltage rates, to ensure safety during charging or discharging, the voltage threshold of the acquisition unit during charging or discharging can be set to be less than the ideal cutoff voltage (the ideal cutoff voltage is the cutoff voltage of an individual battery cell multiplied by the number of individual battery cells in the acquisition unit). Therefore, when the overall voltage of the acquisition unit reaches the preset voltage threshold, the voltage of the individual battery cell with the highest or lowest voltage does not exceed, or significantly exceeds, the cutoff voltage of the individual battery cell. This reduces the use of acquisition lines and chips, thereby lowering the cost of the acquisition solution while ensuring the safety and reliability of the battery cells.

[0074] Furthermore, since the preset voltage threshold is lower than the ideal cutoff voltage, some battery cells may not be fully charged or fully discharged. To reduce battery capacity waste, a voltage change threshold is set as a criterion based on the faster and more sensitive cell capacity-voltage change curve. Once a cell meets the preset voltage threshold, charging or discharging continues. The charging or discharging of the battery pack stops only when the voltage change at the next moment relative to the current moment meets the voltage change threshold condition. This fine-tunes the charging or discharging process of the battery pack, slightly extending the charging or discharging time and reducing battery capacity waste while ensuring battery safety and reliability.

[0075] Figure 10An embodiment of the BMS device of the present invention is shown. The device includes a processor 901 and a memory 902, which can be connected via a bus or other means. Figure 10 Taking the example of a connection between China and Israel via a bus.

[0076] Processor 901 can be a Central Processing Unit (CPU). Processor 901 can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips.

[0077] The memory 902, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the methods in the above method embodiments. The processor 901 executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions, and modules stored in the memory 902, thereby implementing the methods in the above method embodiments.

[0078] The memory 902 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created by the processor 901, etc. Furthermore, the memory 902 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 902 may optionally include memory remotely located relative to the processor 901, and these remote memories may be connected to the processor 901 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0079] One or more modules are stored in memory 902, and when executed by processor 901, they perform the methods described in the above method embodiments.

[0080] For details regarding the BMS device, please refer to the relevant descriptions and effects in the above method embodiments; they will not be repeated here.

[0081] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The implemented program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.

[0082] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method of controlling a battery cell, characterized by, The method is applied to a BMS device, the BMS device collects voltages of a plurality of collecting units in a battery pack, positive and negative electrodes of each collecting unit are connected with collecting lines to the BMS device, a plurality of single batteries are connected in series in the collecting unit, and the method comprises the following steps: Obtaining overall voltages of each collecting unit; Judging whether each overall voltage reaches a preset voltage threshold, the preset voltage threshold is generated based on a cutoff voltage of a corresponding working state of a single battery and a number of single batteries in the collecting unit, the preset voltage threshold is less than a collecting unit cutoff voltage, the collecting unit cutoff voltage is a product of the cutoff voltage of the corresponding working state of the single battery and the number of single batteries in the collecting unit, and the working state is a charging state or a discharging state; if the working state is the charging state, the step of generating the preset voltage threshold based on the cutoff voltage of the corresponding working state of the single battery and the number of single batteries in the collecting unit comprises the following steps: calculating a deviation voltage when the single battery deviates based on a maximum charging capacity deviation between the single batteries; calculating a product of the deviation voltage and a first number to obtain an intermediate quantity, the first number being the number of single batteries in the collecting unit minus 1; and calculating a sum of a charging cutoff voltage and the intermediate quantity to obtain the preset voltage threshold corresponding to the charging state; if the working state is the discharging state, calculating a second deviation voltage when the single battery deviates based on a maximum discharging capacity deviation between the single batteries; calculating a product of the second deviation voltage and the first number to obtain a second intermediate quantity, the first number being the number of single batteries in the collecting unit minus 1; and calculating a sum of a discharging cutoff voltage and the second intermediate quantity to obtain the preset voltage threshold corresponding to the discharging state; If any overall voltage reaches the preset voltage threshold, stopping a corresponding working process of the battery pack.

2. The method of claim 1, wherein, Before the step of stopping the corresponding working process of the battery pack, the method further comprises the following steps: Calculating a voltage change amount of a target overall voltage relative to an overall voltage at a previous collecting time, the target overall voltage being the overall voltage reaching the preset voltage threshold; Judging whether the voltage change amount reaches a preset voltage change amount threshold, the preset voltage change amount threshold being generated based on a battery capacity-voltage change amount curve of a corresponding working state of a single battery and the number of single batteries in the collecting unit; If the voltage change amount reaches the preset voltage change amount threshold, returning to the step of stopping the corresponding working process of the battery pack.

3. The method of claim 1, wherein, The method further comprises the following steps: If each overall voltage does not reach the preset voltage threshold, returning to the step of obtaining the overall voltage of each collecting unit.

4. The method of claim 2, wherein, The method further comprises the following steps: If the voltage change amount does not reach the preset voltage change amount threshold, returning to the step of obtaining the overall voltage of each collecting unit.

5. An electric cell control device characterized by comprising: The device is applied to a BMS device, the BMS device collects voltages of a plurality of collecting units in a battery pack, positive and negative electrodes of each collecting unit are connected with collecting lines to the BMS device, a plurality of single batteries are connected in series in the collecting unit, and the device comprises the following steps: The voltage acquisition module is configured to acquire overall voltages of each acquisition unit. The first judging module is configured to judge whether each overall voltage reaches a preset voltage threshold, the preset voltage threshold being generated based on a cutoff voltage of a single battery cell in a corresponding working state and a number of single battery cells in the acquisition unit, the preset voltage threshold being less than an acquisition unit cutoff voltage, the acquisition unit cutoff voltage being a product of the cutoff voltage of the single battery cell in the corresponding working state and the number of single battery cells in the acquisition unit, the working state being a charging state or a discharging state; if the working state is the charging state, the step of generating the preset voltage threshold based on the cutoff voltage of the single battery cell in the corresponding working state and the number of single battery cells in the acquisition unit comprises: calculating a deviation voltage when the single battery cell deviates based on a maximum charging capacity deviation between the single battery cells; calculating a product of the deviation voltage and a first number to obtain an intermediate quantity, the first number being the number of single battery cells in the acquisition unit minus 1; and calculating a sum of a charging cutoff voltage and the intermediate quantity to obtain the preset voltage threshold corresponding to the charging state; if the working state is the discharging state, a second deviation voltage when the single battery cell deviates is calculated based on a maximum discharging capacity deviation between the single battery cells; a second intermediate quantity is calculated by multiplying the second deviation voltage and the first number, the first number being the number of single battery cells in the acquisition unit minus 1; and a sum of a discharging cutoff voltage and the second intermediate quantity is calculated to obtain the preset voltage threshold corresponding to the discharging state. The control module is configured to stop a corresponding working process of the battery pack if any of the overall voltages reaches the preset voltage threshold.

6. The apparatus of claim 5, wherein, Before the step of stopping the corresponding working process of the battery pack, the device further comprises: The calculation module is configured to calculate a variation of a target overall voltage relative to an overall voltage at a previous acquisition time, the target overall voltage being the overall voltage reaching the preset voltage threshold. The second judging module is configured to judge whether the variation of the overall voltage reaches a preset voltage variation threshold, the preset voltage variation threshold being generated based on a battery cell capacity-voltage variation curve of the single battery cell in the corresponding working state and the number of single battery cells in the acquisition unit. The second control module is configured to return to the step of stopping the corresponding working process of the battery pack if the variation of the overall voltage reaches the preset voltage variation threshold.

7. A BMS device, characterized by, The device comprises: The memory and the processor are communicatively connected, the memory stores computer instructions, and the processor executes the computer instructions to perform the method of any one of claims 1-4.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer instructions for causing the computer to perform the method of any one of claims 1-4.

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