Method for predicting available capacity of battery pack, battery pack, and storage medium

Abstract

This application discloses a method for predicting the usable capacity of a battery pack, a battery pack, and a storage medium. The method includes: determining the charging cutoff state of charge and the discharging cutoff state of charge corresponding to each cell in the battery pack; determining the rechargeable capacity of each cell based on its charging cutoff state of charge, current state of charge, and rated charge capacity; determining the discharging capacity of each cell based on its discharging cutoff state of charge, current state of charge, and rated charge capacity; and determining the usable capacity of the battery pack based on the total rechargeable and discharging capacities of all cells. By calculating the rechargeable and discharging capacities of each cell, the usable capacity of the battery pack can be predicted based on the total rechargeable and discharging capacities of all cells. This solves the problem in related technologies that can only predict the usable capacity of a single cell and cannot accurately predict the usable capacity of the entire battery pack, thus improving the accuracy of predicting the usable capacity of the battery pack.

Description

Technical Field

[0001] This application relates to the field of batteries, and more particularly to a method for predicting the usable capacity of a battery pack, a battery pack, and a storage medium. Background Technology

[0002] Battery usable capacity is a crucial parameter for evaluating battery performance. Currently, existing methods for calculating usable capacity are typically used to calculate the usable capacity of a single cell. However, in practical applications, when multiple cells are assembled into a battery pack, or even when different types of cells are used to assemble a battery pack, existing methods cannot accurately calculate the usable capacity of the entire battery pack.

[0003] Therefore, improving the accuracy of calculating the usable capacity of battery packs has become an urgent problem to be solved. Summary of the Invention

[0004] This application provides a method for predicting the available capacity of a battery pack, a battery pack, and a storage medium, which solves the problem in related technologies that can only calculate the available capacity of a single cell but cannot accurately calculate the available capacity of the entire battery pack, thereby improving the accuracy of calculating the available capacity of the battery pack.

[0005] In a first aspect, this application provides a method for predicting the usable capacity of a battery pack, applied to a battery pack comprising at least two cells, the method comprising:

[0006] The charging cutoff state of charge and the discharging cutoff state of charge corresponding to each cell in the battery pack are determined; the rechargeable capacity of each cell is determined based on its charging cutoff state of charge, current state of charge, and rated charge capacity; the discharging capacity of each cell is determined based on its discharging cutoff state of charge, current state of charge, and rated charge capacity; and the usable capacity of the battery pack is predicted based on the total rechargeable and discharging capacities of all cells.

[0007] Secondly, this application also provides a battery pack, the battery pack including a memory and a processor;

[0008] The memory is used to store computer programs;

[0009] The processor is configured to implement the method for predicting the available capacity of the battery pack as described above when executing the computer program.

[0010] Thirdly, this application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for predicting the available capacity of a battery pack as described above.

[0011] This application discloses a method for predicting the available capacity of a battery pack, a battery pack, and a computer-readable storage medium. The embodiments of this application calculate the rechargeable capacity and dischargeable capacity of each cell based on the charging cut-off state of charge and the discharging cut-off state of charge of each cell. Then, the available capacity of the battery pack can be predicted based on the rechargeable capacity and dischargeable capacity of all cells. This solves the problem in related technologies that can only predict the available capacity of a single cell and cannot accurately predict the available capacity of the entire battery pack, thus improving the accuracy of predicting the available capacity of the battery pack. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of a battery pack provided in an embodiment of this application;

[0014] Figure 2 This is a schematic diagram of the structure of a battery pack provided in an embodiment of this application;

[0015] Figure 3 This is a schematic flowchart illustrating a method for predicting the usable capacity of a battery pack, as provided in an embodiment of this application.

[0016] Figure 4 This is a schematic diagram of the charge capacity of a battery cell provided in an embodiment of this application;

[0017] Figure 5 This is a schematic diagram of the charge capacity of another battery cell provided in an embodiment of this application;

[0018] Figure 6 This is a schematic diagram of the charge capacity of another battery cell provided in an embodiment of this application;

[0019] Figure 7 This is a schematic flowchart illustrating a sub-step for determining the charging cut-off state of charge and the discharging cut-off state of charge, as provided in an embodiment of this application.

[0020] Figure 8 This is a schematic flowchart illustrating a sub-step for determining the charging cutoff state of charge, as provided in an embodiment of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0023] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0024] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0025] This application provides a method for predicting the usable capacity of a battery pack, a battery pack, and a computer-readable storage medium. The method for predicting the usable capacity of a battery pack can be applied to a battery pack. By calculating the rechargeable and dischargeable capacities of each cell based on its charging cutoff state of charge and discharging cutoff state of charge, the usable capacity of the battery pack can be predicted based on the total rechargeable and dischargeable capacities of all cells. This solves the problem in related technologies where only the usable capacity of a single cell can be predicted, and the usable capacity of the entire battery pack cannot be accurately predicted, thus improving the accuracy of predicting the usable capacity of the battery pack.

[0026] For example, the battery pack can be a battery pack in an energy storage device, which can be an energy storage device on a vehicle or a portable energy storage device, without limitation.

[0027] For example, an energy storage device can detect and display the remaining discharge time of a battery pack.

[0028] Please see Figure 1 , Figure 1 This is a schematic diagram of a battery pack 1000 provided in an embodiment of this application. Figure 1As shown, the battery pack 1000 includes at least two battery cells. For example, cell 1, cell 2, ..., cell n. The cells can be of the same type or different types. The capacities of the cells can be the same or different.

[0029] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of a battery pack 1000 provided in an embodiment of this application. The battery pack 1000 may include a processor 1001 and a memory 1002, wherein the processor 1001 and the memory 1002 can be connected via a bus, such as an I / O bus. 2 Any applicable bus, such as the C (Inter-integrated Circuit) bus.

[0030] The memory 1002 may include a storage medium and internal memory. The storage medium may store an operating system and a computer program. The computer program includes program instructions that, when executed, cause the processor to perform any method for predicting the available capacity of the battery pack.

[0031] The processor 1001 provides computing and control capabilities to support the operation of the entire battery pack 1000. Of course, the processor 1001 can be built into the battery pack 1000, or it can be the main processor in an energy storage device or a processor in another battery pack.

[0032] The processor 1001 can be a Central Processing Unit (CPU), but it 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, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0033] In one embodiment, the processor 1001 is configured to run a computer program stored in the memory 1002 to perform the following steps:

[0034] Determine the charging cutoff state of charge and the discharging cutoff state of charge for each cell in the battery pack; determine the rechargeable capacity of each cell based on its charging cutoff state of charge, current state of charge, and rated charge capacity; determine the discharging capacity of each cell based on its discharging cutoff state of charge, current state of charge, and rated charge capacity; predict the usable capacity of the battery pack based on the rechargeable and discharging capacities of all cells.

[0035] In one embodiment, when the processor 1001 determines the charging cut-off state of charge and the discharging cut-off state of charge corresponding to each cell in the battery pack, it is used to:

[0036] Each cell in the battery pack is sequentially identified as a target cell, and the charging cut-off voltage and discharging cut-off voltage of the target cell are obtained. Based on the charging cut-off voltage of the target cell, the charging cut-off state of charge corresponding to the target cell is determined. Based on the discharging cut-off voltage of the target cell, the discharging cut-off state of charge corresponding to the target cell is determined.

[0037] In one embodiment, when the processor 1001 determines the charging cutoff state of charge corresponding to the target battery cell based on the charging cutoff voltage of the target battery cell, it is configured to:

[0038] The battery pack is charged based on a series of candidate states of charge that increase sequentially, and the target cell is determined to reach the charging voltage corresponding to each candidate state of charge until the charging voltage is greater than or equal to the charging cutoff voltage, at which point charging is stopped; the charging cutoff state of charge is determined based on the candidate states of charge at the time of stopping charging.

[0039] In one embodiment, when determining the charging voltage corresponding to each candidate state of charge for the target battery cell, the processor 1001 is configured to:

[0040] Determine the internal resistance voltage of the target cell when it reaches each candidate state of charge; determine the open circuit voltage of the target cell when it reaches each candidate state of charge; and determine the charging voltage corresponding to each candidate state of charge based on the sum of the internal resistance voltage and the open circuit voltage corresponding to each candidate state of charge.

[0041] In one embodiment, the processor 1001, when determining the internal resistance voltage of the target cell at each candidate state of charge, is configured to:

[0042] Obtain the charging current of the target cell when it reaches the charging cutoff state of charge; determine the impedance corresponding to each candidate state of charge based on the preset correspondence between state of charge and impedance; calculate the internal resistance voltage corresponding to each candidate state of charge based on the charging current and the impedance corresponding to each candidate state of charge.

[0043] In one embodiment, when the processor 1001 determines the discharge cutoff state of charge corresponding to the target battery cell based on the discharge cutoff voltage of the target battery cell, it is configured to:

[0044] The battery pack is discharged based on multiple candidate states of charge that decrease sequentially, and the discharge voltage corresponding to each candidate state of charge is determined for the target cell until the discharge voltage is less than or equal to the discharge cutoff voltage, at which point the discharge stops; the discharge cutoff state of charge is determined based on the candidate state of charge reached by the target cell when the discharge stops.

[0045] In one embodiment, when the processor 1001 determines the rechargeable capacity of each battery cell based on the charging cutoff state of charge, the current state of charge, and the rated charge capacity of each cell, it is configured to:

[0046] Subtract the charging cutoff state of charge of each cell from the current state of charge to obtain the state of charge difference for each cell; determine the rechargeable capacity of each cell by multiplying the state of charge difference for each cell by the rated charge capacity.

[0047] In one embodiment, when the processor 1001 predicts the usable capacity of the battery pack based on the rechargeable and dischargeable capacities of all battery cells, it is configured to:

[0048] The usable capacity of the battery pack is determined based on the minimum rechargeable capacity and minimum dischargeable capacity of all the cells.

[0049] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of this application. Unless otherwise specified, the following embodiments and features described herein can be combined with each other. Please refer to... Figure 3 , Figure 3 This is a schematic flowchart illustrating a method for predicting the usable capacity of a battery pack, as provided in an embodiment of this application. Figure 3 As shown, the method for predicting the available capacity of the battery pack includes steps S10 to S40.

[0050] Step S10: Determine the charging cutoff state of charge and the discharging cutoff state of charge corresponding to each cell in the battery pack.

[0051] It should be noted that the charging cutoff state of charge refers to the state of charge of the cells in the battery pack when the battery pack is fully charged during charging; the discharging cutoff state of charge refers to the state of charge of the cells when the voltage of the battery pack drops to a level that is not suitable for continued discharging during discharging.

[0052] For example, when charging the battery pack, the charging cutoff state of charge corresponding to each cell in the battery pack is determined, and when discharging the battery pack, the discharging cutoff state of charge corresponding to each cell in the battery pack is determined.

[0053] The charging cutoff state of charge can be represented as SOC_CHG_END. n The discharge cutoff state of charge can be represented as SOC_DSG_END. n N represents the cell number. For example, the state of charge (SOC) of cell 1 in the battery pack can be represented as SOC_CHG_END1 for charging and SOC_DSG_END1 for discharging; the state of charge (SOC) of cell 2 in the battery pack can be represented as SOC_CHG_END2 for charging and SOC_DSG_END2 for discharging, and so on.

[0054] In this embodiment of the application, since there is a correspondence between voltage and state of charge, the cutoff voltage of each cell in the battery pack can be detected. Based on the preset correspondence between voltage and state of charge, the cutoff state of charge of each cell is determined according to the cutoff voltage of each cell.

[0055] It should be noted that due to the power loss of the battery cell, the state of charge of the battery cell at the charging cutoff point may not necessarily reach 100%, and the state of charge of the battery cell at the discharging cutoff point may not necessarily reach 0%.

[0056] By determining the charging cutoff state of charge and the discharging cutoff state of charge for each cell in the battery pack, the usable capacity of the battery pack can be predicted based on the charging cutoff state of charge and the discharging cutoff state of charge for all cells.

[0057] Step S20: Determine the rechargeable capacity of each cell based on its charging cutoff state of charge, current state of charge, and rated charge capacity.

[0058] In this embodiment of the application, after determining the charging cutoff state of charge corresponding to each cell in the battery pack, the rechargeable capacity of each cell can be determined based on the charging cutoff state of charge, the current state of charge, and the rated charge capacity of each cell.

[0059] It should be noted that rechargeable capacity refers to the increase in charge capacity of a battery cell when it is charged from its current state of charge to the charging cutoff state of charge. Here, the current state of charge refers to the cell's state of charge at the current moment, which can be represented as SOC_CELL; the rated charge capacity Q refers to the capacity that the cell can achieve after design. For example, the rated charge capacity of cell 1 in the battery pack can be represented as Q1, and its current state of charge can be represented as SOC_CELL1; the rated charge capacity of cell 2 in the battery pack can be represented as Q2, and its current state of charge can be represented as SOC_CELL2, and so on.

[0060] In some embodiments, determining the rechargeable capacity of each cell based on its charging cutoff state of charge, current state of charge, and rated charge capacity includes: subtracting the charging cutoff state of charge of each cell from its current state of charge to obtain a state of charge difference for each cell; and determining the rechargeable capacity of each cell based on the product of the state of charge difference and the rated charge capacity.

[0061] In this embodiment of the application, the rechargeable capacity of the battery cell can be calculated using the rechargeable capacity calculation formula, which is as follows:

[0062] FCC_CHG = Q n ×(SOC_CHG_END n –SOC_CELL n )

[0063] In the formula, FCC_CHG represents the rechargeable capacity; n represents the cell number.

[0064] For example, for cell 1 in the battery pack, the rechargeable capacity of cell 1 is FCC_CHG = Q1 × (SOC_CHG_END1 – SOC_CELL1); for cell 2 in the battery pack, the rechargeable capacity of cell 2 is FCC_CHG = Q2 × (SOC_CHG_END2 – SOC_CELL2).

[0065] Please see Figure 4 , Figure 4 This is a schematic diagram of the charge capacity of a battery cell provided in an embodiment of this application, as shown below. Figure 4 As shown, region A represents the rechargeable capacity of the battery cell, FCC_CHG.

[0066] In the above embodiments, the rechargeable capacity of each cell can be accurately determined by multiplying the difference in state of charge of each cell by the rated charge capacity.

[0067] Step S30: Determine the discharge capacity of each cell based on its discharge cutoff state of charge, current state of charge, and rated charge capacity.

[0068] In the embodiments of this application, after determining the discharge cutoff state of charge corresponding to each cell in the battery pack, the discharge capacity of each cell can be determined based on the discharge cutoff state of charge, the current state of charge, and the rated charge capacity of each cell.

[0069] It should be noted that the discharge capacity refers to the amount of charge that the battery cell loses when it discharges from its current state of charge to its state of discharge cutoff.

[0070] In some embodiments, determining the dischargeable capacity of each cell based on its discharge cutoff state of charge, current state of charge, and rated charge capacity may include: subtracting the current state of charge of each cell from its discharge cutoff state of charge to obtain the state of charge difference for each cell; and determining the corresponding dischargeable capacity of each cell based on the product of the state of charge difference and the rated charge capacity.

[0071] In this embodiment of the application, the discharge capacity of the battery cell can be calculated using the discharge capacity calculation formula, which is as follows:

[0072] FCC_DSG = Q n ×(SOC_CELL n –SOC_DSG_END n )

[0073] In the formula, FCC_DSG represents the discharge capacity; n represents the cell number.

[0074] For example, for cell 1 in the battery pack, the discharge capacity of cell 1 is FCC_DSG = Q1 × (SOC_CELL1 – SOC_DSG_END1); for cell 2 in the battery pack, the discharge capacity of cell 2 is FCC_DSG = Q2 × (SOC_CELL2 – SOC_DSG_END2).

[0075] Please see Figure 5 , Figure 5 This is a schematic diagram of the charge capacity of another battery cell provided in an embodiment of this application, as shown below. Figure 5 As shown, region B represents the discharge capacity of the battery cell, FCC_DSG.

[0076] In the above embodiments, the discharge capacity of each cell can be accurately determined by multiplying the difference in state of charge of each cell by the rated charge capacity.

[0077] Step S40: Predict the available capacity of the battery pack based on the rechargeable and dischargeable capacities of all battery cells.

[0078] In the embodiments of this application, after determining the rechargeable and dischargeable capacity of each cell, the available capacity of the battery pack can be predicted based on the rechargeable and dischargeable capacities of all cells.

[0079] It should be noted that available capacity refers to the capacity replenished by the battery pack through charging and the capacity consumed through discharging.

[0080] In some embodiments, predicting the available capacity of a battery pack based on the rechargeable and dischargeable capacities of all cells may include: determining the available capacity of the battery pack based on the minimum rechargeable and minimum dischargeable capacities of all cells.

[0081] For example, the usable capacity of the battery pack can be determined by the sum of the minimum rechargeable capacity and the minimum dischargeable capacity of all the cells.

[0082] Please see Figure 6 , Figure 6 This is a schematic diagram of the charge capacity of another battery cell provided in an embodiment of this application, as shown below. Figure 6 As shown, if cell 1 has the smallest rechargeable capacity and cell 4 has the smallest dischargeable capacity, then the sum of the rechargeable capacity of cell 1 and the dischargeable capacity of cell 4 can be used to determine the usable capacity of the battery pack.

[0083] It is understandable that during battery pack charging, the voltage of the cell with the smallest rechargeable capacity will reach the charging cutoff voltage first, causing the entire battery pack to stop charging; similarly, during battery pack discharging, the voltage of the cell with the smallest dischargeable capacity will reach the discharging cutoff voltage first, causing the entire battery pack to stop discharging. Therefore, the sum of the minimum rechargeable capacity and the minimum dischargeable capacity of the cells in the battery pack can be used to reflect the usable capacity of the entire battery pack.

[0084] The above embodiments, by predicting the available capacity of the battery pack based on the rechargeable and dischargeable capacities of all cells, solve the problem in related technologies that can only predict the available capacity of a single cell but cannot accurately predict the available capacity of the entire battery pack, thus improving the accuracy of predicting the available capacity of the battery pack.

[0085] In the embodiments of this application, the method for determining the charging cutoff state of charge and the discharging cutoff state of charge will be described in detail. Please refer to [link to relevant documentation]. Figure 7 , Figure 7 This is a schematic flowchart of a sub-step for determining the charging cut-off state of charge and the discharging cut-off state of charge according to an embodiment of this application. Step S10, which determines the charging cut-off state of charge and the discharging cut-off state of charge, may include the following steps S101 to S103.

[0086] Step S101: Identify each cell in the battery pack as the target cell in sequence, and obtain the charging cut-off voltage and discharging cut-off voltage of the target cell.

[0087] For example, each cell in the battery pack can be sequentially identified as a target cell, and then the charging cut-off voltage and discharging cut-off voltage of the target cell can be obtained.

[0088] For example, the charging and discharging cutoff voltages of a target cell can be read from the Battery Management System (BMS). It should be noted that the charging and discharging cutoff voltages of a cell are usually fixed after manufacturing; the BMS system can measure and store these voltages in advance. The charging and discharging cutoff voltages of each cell in the battery pack can be the same or different.

[0089] For example, the charging cutoff voltage of cell 1 in the battery pack is 4400mV and the discharging cutoff voltage is 3000mV.

[0090] By obtaining the charging cutoff voltage and discharging cutoff voltage of the target cell, the charging cutoff state of charge of the target cell can be determined based on the charging cutoff voltage, and the discharging cutoff state of charge of the target cell can be determined based on the discharging cutoff voltage.

[0091] Step S102: Determine the charging cutoff state of charge corresponding to the target cell based on the charging cutoff voltage of the target cell.

[0092] In this embodiment, after obtaining the charging cutoff voltage of the target battery cell, the charging cutoff state of charge corresponding to the target battery cell can be determined based on the charging cutoff voltage. The following will provide a detailed explanation of how to determine the charging cutoff state of charge.

[0093] Please see Figure 8 , Figure 8 This is a schematic flowchart of a sub-step for determining the charging cutoff state of charge according to an embodiment of this application. Determining the charging cutoff state of charge in step S102 may include the following steps S1021 and S1022.

[0094] Step S1021: Based on multiple candidate states of charge that increase sequentially, charge the battery pack and determine the target cell to reach the charging voltage corresponding to each candidate state of charge until the charging voltage is greater than or equal to the charging cut-off voltage, then stop charging.

[0095] It should be noted that, in this embodiment of the application, the battery pack needs to be charged in order to determine the charging cutoff state of charge of the target cell. Then, during the charging process, the charging cutoff state of charge of the target cell is determined based on the charging cutoff voltage of the target cell.

[0096] For example, multiple candidate states of charge can be pre-defined in ascending order. The increment between adjacent candidate states of charge can be set according to actual conditions, and the specific value is not limited here. For example, the candidate states of charge could be 10%, 20%, 30%, ..., 100%. Or, for another example, the candidate states of charge could be 10%, 15%, 20%, ..., 100%.

[0097] For example, when the target cell's current state of charge is 40%, the battery pack is charged, and the charging voltage corresponding to the target cell reaching a 50% candidate state of charge is determined. If the charging voltage at this time is less than the charging cutoff voltage, the battery pack is charged, and the charging voltage corresponding to the target cell reaching a 60% candidate state of charge is determined, until the charging voltage is greater than or equal to the charging cutoff voltage, at which point charging is stopped.

[0098] In some embodiments, determining the charging voltage corresponding to each candidate state of charge of the target cell may include: determining the internal resistance voltage of the target cell when it reaches each candidate state of charge; determining the open circuit voltage of the target cell when it reaches each candidate state of charge; and determining the charging voltage corresponding to each candidate state of charge based on the sum of the internal resistance voltage and the open circuit voltage corresponding to each candidate state of charge.

[0099] In this embodiment, an equivalent circuit model can be used to calculate the charging voltage corresponding to each candidate state of charge of the target cell. The equivalent circuit model may include, but is not limited to, the Rint equivalent circuit model, the Thevenin equivalent circuit model, or the PNGV equivalent circuit model, etc. In this embodiment, the Rint equivalent circuit model is used as an example to illustrate how to calculate the charging voltage.

[0100] It should be noted that in the Rint equivalent circuit model, the charging voltage U = OCV + IR. Here, OCV represents the open-circuit voltage, and IR represents the internal resistance voltage.

[0101] For example, for a candidate state of charge of 60%, when the target cell reaches the candidate state of charge of 60%, the open circuit voltage OCV of the target cell recorded by the BMS system can be read, and the charging voltage U corresponding to the candidate state of charge of 60% can be determined based on the sum of the internal resistance voltage IR and the open circuit voltage OCV.

[0102] For example, for a candidate state of charge of 70%, when the target cell reaches the candidate state of charge of 70%, the open circuit voltage OCV of the target cell recorded by the BMS system can be read, and the charging voltage U corresponding to the candidate state of charge of 70% can be determined based on the sum of the internal resistance voltage IR and the open circuit voltage OCV.

[0103] In the above embodiments, by determining the internal resistance voltage and open circuit voltage of the target cell when it reaches each candidate state of charge, the charging voltage corresponding to each candidate state of charge can be determined based on the sum of the internal resistance voltage and open circuit voltage corresponding to each candidate state of charge.

[0104] In some embodiments, determining the internal resistance voltage of the target cell when it reaches each candidate state of charge may include: obtaining the charging current of the target cell when it reaches the charging cutoff state of charge; determining the impedance corresponding to each candidate state of charge based on a preset correspondence between state of charge and impedance; and calculating the internal resistance voltage corresponding to each candidate state of charge based on the charging current and the impedance corresponding to each candidate state of charge.

[0105] For example, when the target cell reaches the charging cutoff state of charge, the charging current of the target cell recorded by the BMS system can be read. It should be noted that, in the embodiments of this application, the charging current of the target cell is usually fixed when charging the battery pack.

[0106] In this embodiment of the application, the correspondence between the state of charge and the impedance can be looked up using an open-circuit voltage and state of charge relationship table. This table may include the open-circuit voltage corresponding to the state of charge, the impedance corresponding to the state of charge, and so on.

[0107] For example, the impedance corresponding to each candidate state of charge can be determined based on a preset correspondence between states of charge and impedance. For instance, for a candidate state of charge of 60%, the impedance corresponding to the candidate state of charge can be determined as R1. As another example, for a candidate state of charge of 70%, the impedance corresponding to the candidate state of charge can be determined as R2.

[0108] For example, after determining the impedance corresponding to each candidate state of charge, the internal resistance voltage corresponding to each candidate state of charge can be calculated based on the charging current and the impedance corresponding to each candidate state of charge. For instance, for a candidate state of charge of 60%, the internal resistance voltage IR1 corresponding to the candidate state of charge of 60% can be calculated based on the charging current I and the impedance R1. Similarly, for a candidate state of charge of 70%, the internal resistance voltage IR2 corresponding to the candidate state of charge of 70% can be calculated based on the charging current I and the impedance R2.

[0109] In the above embodiments, by obtaining the charging current and determining the impedance corresponding to each candidate state of charge, the internal resistance voltage corresponding to each candidate state of charge can be accurately calculated based on the charging current and the impedance corresponding to each candidate state of charge.

[0110] Step S1022: Determine the charging cutoff state of charge based on the candidate state of charge reached by the target cell when charging stops.

[0111] For example, when charging stops, the candidate state of charge reached by the target cell can be determined as the charging cutoff state of charge. For instance, if the candidate state of charge reached by the target cell is 80% when charging stops, the charging cutoff state of charge can be determined to be 90%.

[0112] In the above embodiments, the battery pack is charged based on a plurality of candidate states of charge that increase sequentially, and charging is stopped when the charging voltage of the target cell is greater than or equal to the charging cutoff voltage. The charging cutoff state of charge can be determined based on the candidate states of charge reached by the target cell when charging is stopped.

[0113] Step S103: Determine the discharge cutoff state of charge corresponding to the target cell based on the discharge cutoff voltage of the target cell.

[0114] In this embodiment, after obtaining the discharge cutoff voltage of the target battery cell, the corresponding discharge cutoff state of charge of the target battery cell can be determined based on the discharge cutoff voltage. The following will provide a detailed explanation of how to determine the discharge cutoff state of charge.

[0115] In some embodiments, determining the discharge cutoff state of charge corresponding to the target cell based on the discharge cutoff voltage of the target cell may include: discharging the battery pack based on a plurality of candidate states of charge that decrease sequentially, and determining the discharge voltage corresponding to each candidate state of charge for the target cell until the discharge voltage is less than or equal to the discharge cutoff voltage, and stopping the discharge; determining the discharge cutoff state of charge based on the candidate states of charge when the discharge stops.

[0116] It should be noted that, in this embodiment of the application, the battery pack needs to be discharged in order to determine the discharge cutoff state of charge of the target cell. During the discharge process, the discharge cutoff state of charge of the target cell is determined based on the discharge cutoff voltage of the target cell.

[0117] For example, multiple candidate states of charge can be pre-defined in descending order. The decrease in charge between adjacent candidate states can be set according to actual conditions, and the specific value is not limited here. For example, the candidate states of charge could be 100%, 90%, 80%, ..., 10%. Or, for another example, the candidate states of charge could be 100%, 95%, 80%, ..., 5%.

[0118] For example, the discharge voltage corresponding to each candidate state of charge of the target cell can be determined until the discharge voltage is less than or equal to the discharge cutoff voltage, and then the discharge is stopped; the discharge cutoff state of charge is determined based on the candidate state of charge when the discharge stops.

[0119] The method for determining the discharge voltage is similar to that for determining the charging voltage. Please refer to the detailed explanation of step S1021 above. The specific process will not be repeated here.

[0120] For example, when discharging stops, the candidate state of charge reached by the target cell can be determined as the discharge cutoff state of charge. For instance, if the candidate state of charge reached by the target cell is 40% when discharging stops, then the discharge cutoff state of charge can be determined to be 40%.

[0121] In the above embodiments, the battery pack is discharged based on a plurality of candidate states of charge that decrease sequentially, and the discharge is stopped when the discharge voltage of the target cell is less than or equal to the discharge cutoff voltage. The discharge cutoff state of charge can be determined based on the candidate states of charge reached by the target cell when the discharge is stopped.

[0122] The embodiments of this application also provide a computer-readable storage medium storing a computer program, the computer program including program instructions, and a processor executing the program instructions to implement any of the battery pack usable capacity prediction methods provided in the embodiments of this application.

[0123] For example, when the program is loaded by the processor, it can perform the following steps:

[0124] Determine the charging cutoff state of charge and the discharging cutoff state of charge for each cell in the battery pack; determine the rechargeable capacity of each cell based on its charging cutoff state of charge, current state of charge, and rated charge capacity; determine the discharging capacity of each cell based on its discharging cutoff state of charge, current state of charge, and rated charge capacity; predict the usable capacity of the battery pack based on the rechargeable and discharging capacities of all cells.

[0125] The computer-readable storage medium can be an internal storage unit of the battery pack in the aforementioned embodiments, such as a hard drive or memory of the battery pack. Alternatively, the computer-readable storage medium can be an external storage device of the battery pack, such as a plug-in hard drive, smart media card (SMC), secure digital card (SD card), flash card, etc., mounted on the battery pack.

[0126] Furthermore, a computer-readable storage medium may primarily include a program storage area and a data storage area, wherein the program storage area may store the operating system, programs required for at least one function, etc.; and the data storage area may store data created according to each program, etc.

[0127] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for predicting the usable capacity of a battery pack, characterized in that, Applied to a battery pack comprising at least two cells, the method includes: Determine the charging cutoff state of charge and the discharging cutoff state of charge for each cell in the battery pack. The rechargeable capacity of each battery cell is determined based on its charging cutoff state of charge, current state of charge, and rated charge capacity. The discharge capacity of each cell is determined based on its discharge cutoff state of charge, current state of charge, and rated charge capacity. Based on the rechargeable and dischargeable capacities of all the battery cells, the usable capacity of the battery pack is predicted; The step of determining the rechargeable capacity of each battery cell based on its charging cutoff state of charge, current state of charge, and rated charge capacity includes: subtracting the charging cutoff state of charge of each battery cell from its current state of charge to obtain a state of charge difference for each battery cell; and determining the rechargeable capacity of each battery cell by multiplying the state of charge difference for each battery cell by its rated charge capacity. The step of determining the dischargeable capacity of each battery cell based on its discharge cutoff state of charge, current state of charge, and rated charge capacity includes: subtracting the current state of charge of each battery cell from its discharge cutoff state of charge to obtain the state of charge difference for each battery cell; and determining the corresponding dischargeable capacity of each battery cell by multiplying the state of charge difference for each battery cell by its rated charge capacity.

2. The method for predicting the usable capacity of a battery pack according to claim 1, characterized in that, Determining the charging cutoff state of charge and the discharging cutoff state of charge corresponding to each cell in the battery pack includes: Each cell in the battery pack is sequentially identified as a target cell, and the charging cut-off voltage and discharging cut-off voltage of the target cell are obtained. The charging cutoff state of charge corresponding to the target battery cell is determined based on the charging cutoff voltage of the target battery cell. The discharge cutoff state of charge corresponding to the target battery cell is determined based on the discharge cutoff voltage of the target battery cell.

3. The method for predicting the usable capacity of a battery pack according to claim 2, characterized in that, The step of determining the charging cutoff state of charge corresponding to the target battery cell based on the charging cutoff voltage of the target battery cell includes: The battery pack is charged based on a plurality of candidate states of charge that increase sequentially, and the target cell is determined to reach the charging voltage corresponding to each candidate state of charge until the charging voltage is greater than or equal to the charging cut-off voltage, at which point charging is stopped. The charging cutoff state of charge is determined based on the candidate state of charge when charging stops.

4. The method for predicting the usable capacity of a battery pack according to claim 3, characterized in that, Determining that the target cell reaches the charging voltage corresponding to each of the candidate states of charge includes: Determine the internal resistance voltage of the target cell when it reaches each of the candidate states of charge; Determine the open-circuit voltage of the target cell when it reaches each of the candidate states of charge; The charging voltage corresponding to each candidate state of charge is determined based on the sum of the internal resistance voltage and the open circuit voltage corresponding to each candidate state of charge.

5. The method for predicting the usable capacity of a battery pack according to claim 4, characterized in that, Determining the internal resistance voltage of the target cell when it reaches each of the candidate states of charge includes: Obtain the charging current of the target battery cell when it reaches the charging cutoff state of charge; Based on the preset correspondence between the state of charge and impedance, the impedance corresponding to each candidate state of charge is determined. Based on the charging current and the impedance corresponding to each candidate state of charge, the internal resistance voltage corresponding to each candidate state of charge is calculated.

6. The method for predicting the usable capacity of a battery pack according to claim 2, characterized in that, The step of determining the discharge cutoff state of charge corresponding to the target battery cell based on the discharge cutoff voltage of the target battery cell includes: The battery pack is discharged based on a plurality of candidate states of charge that decrease sequentially, and the target cell is determined to reach the discharge voltage corresponding to each candidate state of charge until the discharge voltage is less than or equal to the discharge cutoff voltage, at which point the discharge is stopped. The discharge cutoff charge state is determined based on the candidate state of charge reached by the target cell when the discharge stops.

7. The method for predicting the usable capacity of a battery pack according to claim 1, characterized in that, The step of predicting the usable capacity of the battery pack based on the rechargeable and dischargeable capacities of all the battery cells includes: The usable capacity of the battery pack is determined based on the minimum rechargeable capacity and minimum dischargeable capacity of all the battery cells.

8. A battery pack, characterized in that, The battery pack includes a memory and a processor; The memory is used to store computer programs; The processor is configured to implement the method for predicting the available capacity of a battery pack as described in any one of claims 1 to 7 when executing the computer program.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method for predicting the available capacity of a battery pack as described in any one of claims 1 to 7.

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