A method, system and storage medium for judging equalization capacity of a lithium iron phosphate battery

Abstract

This invention discloses a method, system, and storage medium for determining the equalization capacity of a lithium iron phosphate battery. The method includes the following steps: selecting a starting voltage value; determining that the current highest single-cell voltage value is greater than the starting voltage value; recording the charging trajectory, which is the charging trajectory from the current highest single-cell voltage value to the starting voltage value and then to the charging cutoff voltage; dividing the charging trajectory into multiple capacity zones, setting a corresponding equalization strategy and the charging capacity to be equalized for each capacity zone; recording the voltage value of each single cell at full charge; determining the capacity zone where the voltage value of each single cell belongs based on the divided charging trajectory intervals; and executing the corresponding equalization strategy and the charging capacity to be equalized. This invention can identify the difference in charge capacity between different single cells in a lithium iron phosphate battery system, reduce battery pack inconsistencies, minimize the differences between single cells within the battery system, and improve the usable capacity of the battery pack.

Description

Technical Field

[0001] This invention relates to the field of vehicle power battery equalization capacity detection technology, specifically to a method, system, and storage medium for determining the equalization capacity of lithium iron phosphate batteries. Background Technology

[0002] The vehicle power battery system is composed of multiple cells connected in series and parallel. However, due to the difference in self-discharge rate of each individual cell, the difference between individual cells in the battery system will gradually increase after long-term use, reducing the usable capacity of the battery pack.

[0003] To improve the consistency of individual battery cells, the Battery Management System (BMS) of an onboard battery pack performs equalization control on each cell. Currently, most onboard battery equalization methods on the market are passive, meaning that cells with higher charge levels use equalization circuits to dissipate excess charge, thus improving the consistency of cells within the battery pack system. A common equalization determination method is to check the SOC-OCV curve of each cell after the vehicle has been idle for a sufficient period to obtain the SOC value of each cell, thereby determining the remaining charge of all cells. Then, cells with higher charge levels can be used to dissipate excess charge through the equalization circuit.

[0004] Currently, the most common power batteries on the market are lithium iron phosphate batteries and ternary lithium batteries. Ternary lithium battery cells do not have a voltage plateau region in their SOC-OCV curve, so the aforementioned equalization judgment method can be applied across the entire SOC range. However, lithium iron phosphate batteries have two plateau regions in their SOC-OCV curve: 30%-55% and 65%-99%. Within these two plateau regions, it is impossible to infer the SOC of a single cell using the open-circuit voltage (OCV). Therefore, if users operate the battery in the SOC > 30% range for an extended period, the equalization judgment will not be triggered for a prolonged period, increasing the inconsistency of the battery pack. Summary of the Invention

[0005] To overcome the defects and shortcomings of existing technologies, this invention provides a method for determining the equalization capacity of lithium iron phosphate batteries. Even if the user works for a long time with the battery level above 30%, it can trigger the equalization judgment, identify the difference in charge of different individual cells in the lithium iron phosphate battery system, reduce the inconsistency of the battery pack, reduce the difference in individual cells within the battery system, and improve the usable capacity of the battery pack.

[0006] The second objective of this invention is to provide a system for determining the equalization capacity of lithium iron phosphate batteries.

[0007] A third objective of this invention is to provide a computer-readable storage medium.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a method for determining the equalization capacity of a lithium iron phosphate battery, comprising the following steps:

[0010] Select a starting voltage value. When the current highest single cell voltage value of the battery is greater than the starting voltage value, record the charging trajectory. The charging trajectory is the charging trajectory from the current highest single cell voltage value to the charging cutoff voltage.

[0011] The charging trajectory is divided into multiple capacity zones, and each capacity zone is set with a corresponding balancing strategy and the charging capacity to be balanced.

[0012] The voltage value of each battery cell is recorded at full charge. Based on the divided charging trajectory intervals, the capacity zone in which the voltage value of each battery cell is located is determined, and the corresponding balancing strategy and the charging capacity to be balanced are executed.

[0013] As a preferred technical solution, the selection of the starting voltage value specifically includes:

[0014] When the lithium iron phosphate battery is charged until the charging current is less than or equal to the preset charging current threshold, or / and until the maximum single cell voltage is greater than or equal to the preset charging voltage threshold, the voltage starting value is selected as the voltage value corresponding to the charging curve f'(x)=0, with a floating range of ±0.1V.

[0015] As a preferred technical solution, the starting voltage value is selected by calculation to obtain the total capacity to be charged, which corresponds to the charging capacity from the starting voltage to the cutoff voltage. The starting voltage value is selected by calculating backward from the cutoff voltage.

[0016] As a preferred technical solution, the charging trajectory interval is divided using a uniform or discrete distribution method;

[0017] The specific method of dividing equally is as follows:

[0018] Obtain the charging capacity from the starting voltage value to the charging cutoff voltage, divide the charging capacity from the starting voltage value to the charging cutoff voltage into multiple intervals, evenly distribute the required equalization capacity of each interval according to the charging capacity and the number of intervals, and set the corresponding equalization strategy.

[0019] The specific method of partitioning using discrete distribution is as follows:

[0020] The charging capacity from the starting voltage value to the charging cutoff voltage is obtained. Based on the density distribution of the individual cell voltages, the charging capacity from the starting voltage value to the charging cutoff voltage is divided into multiple intervals. Based on the charging capacity and the number of intervals, the corresponding balancing strategy and the charging capacity to be balanced are set.

[0021] As a preferred technical solution, the balancing strategy includes:

[0022] The charging trajectory is divided into multiple capacity zones. A capacity imbalance strategy is implemented in the first capacity zone below the starting voltage value and above the starting voltage value. This strategy increases the timing of balance judgment, making the balance capacity more accurate and improving the consistency of the battery pack.

[0023] As a preferred technical solution, the specific calculation method for the required balanced capacity is as follows:

[0024] Obtain the self-discharge difference of the individual batteries and the total capacity of the battery pack, and multiply the two to calculate the required balanced capacity.

[0025] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0026] A system for determining the equalization capacity of a lithium iron phosphate battery includes: a starting voltage value selection module, a voltage value determination module, a charging trajectory recording module, an interval division module, a battery cell acquisition module, a capacity zone determination module, and an equalization module.

[0027] The starting voltage value selection module is used to select the starting voltage value;

[0028] The voltage value determination module is used to determine whether the current highest single-cell voltage value of the battery is greater than the initial voltage value;

[0029] The charging trajectory recording module is used to record the charging trajectory, which is the charging trajectory from the current highest single-cell voltage value to the charging cutoff voltage.

[0030] The interval division module is used to divide the charging trajectory into intervals, and divide the charging trajectory into multiple capacity partitions. Each capacity partition is set with a corresponding balancing strategy and the charging capacity to be balanced.

[0031] The battery cell acquisition module is used to record the voltage value of each battery cell at the time of full charge.

[0032] The capacity partition determination module is used to determine the capacity partition in which the voltage value of each battery cell is located based on the divided charging trajectory interval.

[0033] The equalization module is used to execute the corresponding equalization strategy and the charging capacity that needs to be equalized.

[0034] As a preferred technical solution, the starting voltage value selection module is used to select a starting voltage value, specifically including:

[0035] When the lithium iron phosphate battery is charged to a charging current less than or equal to a preset charging current threshold, or / and charged to a maximum single cell voltage greater than or equal to a preset charging voltage threshold, the voltage starting value is selected as the voltage value corresponding to the charging curve f'(x) = 0, with a floating range of ±0.1V.

[0036] Alternatively, a calculation method can be used to select the starting voltage value, obtain the total charging capacity from the starting voltage to the cutoff voltage, and then calculate and select the starting voltage value based on the cutoff voltage.

[0037] As a preferred technical solution, the interval division module is used to divide the charging trajectory into intervals, and divide the charging trajectory into multiple capacity partitions, using an even or discrete distribution method.

[0038] The specific method of dividing equally is as follows:

[0039] Obtain the charging capacity from the starting voltage value to the charging cutoff voltage, divide the charging capacity from the starting voltage value to the charging cutoff voltage into multiple intervals, evenly distribute the required equalization capacity of each interval according to the charging capacity and the number of intervals, and set the corresponding equalization strategy.

[0040] The specific method of partitioning using discrete distribution is as follows:

[0041] The charging capacity from the starting voltage value to the charging cutoff voltage is obtained. Based on the density distribution of the individual cell voltages, the charging capacity from the starting voltage value to the charging cutoff voltage is divided into multiple intervals. Based on the charging capacity and the number of intervals, the corresponding balancing strategy and the charging capacity to be balanced are set.

[0042] A computer-readable storage medium storing a program that, when executed by a processor, implements the above-described method for determining the equalization capacity of a lithium iron phosphate battery.

[0043] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0044] (1) By dividing the charging trajectory interval, this invention determines the capacity zone where the voltage value of each battery cell is located, executes the corresponding balancing strategy and the charging capacity that needs to be balanced, can identify and balance the power difference of different cells in the lithium iron phosphate battery system, reduce the inconsistency of the battery pack, reduce the difference of individual cells in the battery system, and improve the usable capacity of the battery pack.

[0045] (2) The present invention adopts an auxiliary equalization method for end-charge, which enables users to make equalization judgments in the non-SOC range, improves the possibility of equalization judgment, is more practical, and also protects the battery.

[0046] (3) The starting voltage point selected by the present invention is used as the starting point of the equalization capacity, which improves the accuracy of equalization judgment, reduces the inconsistency of battery packs, and improves the usable capacity of battery packs. Attached Figure Description

[0047] Figure 1 This is a flowchart illustrating the method for determining the equalization capacity of a lithium iron phosphate battery according to the present invention.

[0048] Figure 2 This is a schematic diagram illustrating the implementation method of dividing the charging trajectory interval according to the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0050] Example 1

[0051] like Figure 1 As shown, this embodiment provides a method for determining the equalization capacity of a lithium iron phosphate battery. The equalization determination time of this method is when the battery system is nearly fully charged. The "capacity tracking method" is used to determine which cells need to be equalized, thereby improving the timing of equalization determination for lithium iron phosphate batteries.

[0052] The specific steps include:

[0053] S1: The lithium iron phosphate battery pack is charged according to a multi-stage charging strategy. When charging reaches the minimum charging current step, the battery pack is nearly fully charged. The BMS detects that the maximum single-cell voltage is no longer decreasing and is maintaining a stable upward trend. A voltage value, Volt_start, is selected. When the highest single-cell voltage in the battery system, VoltMax, exceeds Volt_start, the charging trajectory of VoltMax from Volt_start to the charging cutoff voltage, Volt_chgend, is recorded. A fully charged battery pack typically refers to any single cell in the battery pack being charged to the cutoff voltage, Volt_chgend. This invention uses the charging trajectory of VoltMax as the basis for determining whether each cell needs balancing and the balancing capacity.

[0054] In this embodiment, the selection steps for Volt_start are as follows: when the charging current switches from a high current step to a low current step, the battery voltage will first drop and then rise. Therefore, it is necessary to select a suitable point as Volt_start during the process of Voltmax maintaining a stable increase.

[0055] In this embodiment, the lithium iron phosphate battery is charged until the charging current is less than or equal to a preset charging current threshold, and / or until the maximum single-cell voltage is greater than or equal to a preset charging voltage threshold. The initial voltage value is selected as the voltage value corresponding to the charging curve f'(x) = 0. Preferably, in this embodiment, the lithium iron phosphate battery is charged until the charging current is ≤0.1C, and / or until the maximum single-cell voltage is ≥3.45V, and maintains a stable upward trend. The initial voltage value is then selected as the voltage value corresponding to the charging curve f'(x) = 0, with a fluctuation range of ±0.1V. On the other hand, the selection of Volt_start is also related to the total capacity charged from Volt_start to Volt_start. The capacity from the starting voltage to the cutoff voltage is the total charged capacity. Therefore, the starting voltage value can be deduced from the known cutoff voltage. If the difference in self-discharge rate of the battery pack is 1%, then a 150Ah battery pack will have a 1.5Ah inconsistency due to the difference in self-discharge. Assuming that the user charges it once a month, then at least 1.2Ah of charge will be guaranteed from Volt_start to Volt_chgend.

[0056] S2: Divide the charging trajectory of VoltMax from Volt_start to the charging cutoff voltage Volt_chgend into multiple capacity partitions Xn, and the charging capacity C_n from Volt_start to Volt_n;

[0057] The division of intervals can be based on two methods: One is equal division. For example, if charging from Volt_start to Volt_chgend for 1.5Ah is divided into 5 intervals, then each interval is divided into 0.3Ah intervals to determine Volt_n. This embodiment uses equal division, preferably dividing into 4-6 intervals. Another method is to observe the voltage distribution of all individual cells after full charging and use a discrete distribution method. In areas with a high concentration of individual cell voltages, the intervals can be divided more densely. In areas with a sparse concentration of individual cell voltages, the intervals can be divided more loosely. If a balanced 1.5Ah charging is required, and there are many individual cells distributed between 0.6-0.9Ah, then the intervals can be divided into 0.3, 0.6, 0.7, 0.8, 0.9, and 1.5Ah intervals.

[0058] In this embodiment, by obtaining the voltage of a single cell, randomly selecting several single cell voltages, calculating the variance, substituting it into the Poisson distribution function, obtaining the density interval distribution based on the distribution function, and dividing the corresponding capacity according to the density interval distribution.

[0059] The interval division and balanced capacity matching in this embodiment are shown in Table 1 below:

[0060] Table 1. Interval Division and Equal Capacity Matching Table

[0061]

[0062] S3: At the moment of full charge, record the voltage value of each individual cell and determine the range in which that voltage value falls. Based on the Voltmax charging trajectory, determine whether equalization is needed and the required equalization capacity according to the range in which the voltage values ​​of the tested individual cells fall. In this embodiment, the required equalization capacity (total capacity multiplied by self-discharge difference) is calculated based on the self-discharge difference of the battery itself and the total capacity of the battery pack. The self-discharge difference is obtained based on the battery pack itself. As shown in Table 2 below, the corresponding equalization strategy and the charging capacity to be equalized are executed.

[0063] Table 2 Equilibrium Strategies and Equilibrium Capacities

[0064]

[0065] like Figure 2 As shown, the charging path of Voltmax from the last charging step until it is fully charged to the cutoff voltage Volt_chgend is divided into seven intervals: A, B, C, D, E, F, and G. At the moment of full charge, the capacity to be balanced for each cell is determined based on the charging path of Voltmax.

[0066] If the voltage of the single cell is in or below region A, it is unbalanced. Using this strategy increases the timing of balance judgment, making the accuracy of balance capacity higher and improving the consistency of the battery pack.

[0067] If the voltage of this single unit is in region B, then it will be equalized to 0.2Ah;

[0068] If the voltage of this single unit is in region C, it will be balanced to 0.4Ah;

[0069] If the voltage of this single unit is in region D, it will be balanced to 0.6Ah;

[0070] If the voltage of this single unit is in region E, it will be balanced to 0.8Ah;

[0071] If the voltage of the single cell is in region F, it will be equalized to 1.0Ah.

[0072] If the voltage of this single unit is in region G, it will be balanced to 1.2Ah.

[0073] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware, and the corresponding program can be stored in a computer-readable storage medium.

[0074] It should be noted that although the method operations of the above embodiments are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown in this embodiment must be performed to achieve the desired result. On the contrary, the described steps may be performed in a different order or simultaneously. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0075] Example 2

[0076] This embodiment provides a system for determining the equalization capacity of a lithium iron phosphate battery, including: a starting voltage value selection module, a voltage value determination module, a charging trajectory recording module, an interval division module, a battery cell acquisition module, a capacity partitioning determination module, and an equalization module;

[0077] In this embodiment, the starting voltage value selection module is used to select the starting voltage value;

[0078] In this embodiment, the voltage value determination module is used to determine whether the current highest single-cell voltage value of the battery is greater than the starting voltage value;

[0079] In this embodiment, the charging trajectory recording module is used to record the charging trajectory, which is the charging trajectory from the current highest single-cell voltage value to the charging cutoff voltage.

[0080] In this embodiment, the interval division module is used to divide the charging trajectory into intervals, and divide the charging trajectory into multiple capacity partitions. Each capacity partition is set with a corresponding balancing strategy and the charging capacity to be balanced.

[0081] In this embodiment, the battery cell acquisition module is used to record the voltage value of each battery cell at the time of full charge;

[0082] In this embodiment, the capacity partition determination module is used to determine the capacity partition in which the voltage value of each battery cell is located based on the divided charging trajectory interval.

[0083] In this embodiment, the balancing module is used to execute the corresponding balancing strategy and the charging capacity that needs to be balanced.

[0084] In this embodiment, the starting voltage value selection module is used to select the starting voltage value, specifically including:

[0085] When the lithium iron phosphate battery is charged until the charging current is less than or equal to a preset charging current threshold, or / and until the maximum single cell voltage is greater than or equal to a preset charging voltage threshold, the voltage starting value is selected as the voltage value corresponding to the charging curve f'(x)=0.

[0086] In this embodiment, the interval division module is used to divide the charging trajectory into intervals, dividing the charging trajectory into multiple capacity partitions, using an even or discrete distribution method.

[0087] The specific method of dividing equally is as follows:

[0088] Obtain the charging capacity from the starting voltage value to the charging cutoff voltage, divide the charging capacity from the starting voltage value to the charging cutoff voltage into multiple intervals, evenly distribute the required equalization capacity of each interval according to the charging capacity and the number of intervals, and set the corresponding equalization strategy.

[0089] The specific method of partitioning using discrete distribution is as follows:

[0090] The charging capacity from the starting voltage value to the charging cutoff voltage is obtained. Based on the density distribution of the individual cell voltages, the charging capacity from the starting voltage value to the charging cutoff voltage is divided into multiple intervals. Based on the charging capacity and the number of intervals, the corresponding balancing strategy and the charging capacity to be balanced are set.

[0091] Example 3

[0092] This embodiment provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the method for determining the equalization capacity of a lithium iron phosphate battery as described in Embodiment 1 above, as follows:

[0093] Select the starting voltage value. When the current highest single cell voltage value of the battery is greater than the starting voltage value, record the charging trajectory. The charging trajectory is the charging trajectory from the current highest single cell voltage value to the charging cutoff voltage.

[0094] The charging trajectory is divided into multiple capacity zones, and each capacity zone is set with a corresponding balancing strategy and the charging capacity to be balanced.

[0095] The voltage value of each battery cell is recorded at full charge. Based on the divided charging trajectory intervals, the capacity zone in which the voltage value of each battery cell is located is determined, and the corresponding balancing strategy and the charging capacity to be balanced are executed.

[0096] Selecting the starting voltage value specifically includes:

[0097] When the lithium iron phosphate battery is charged until the charging current is less than or equal to a preset charging current threshold, or / and until the maximum single cell voltage is greater than or equal to a preset charging voltage threshold, the voltage starting value is selected as the voltage value corresponding to the charging curve f'(x)=0.

[0098] The charging trajectory interval is divided using either a uniform or discrete distribution method.

[0099] The specific method of dividing equally is as follows:

[0100] Obtain the charging capacity from the starting voltage value to the charging cutoff voltage, divide the charging capacity from the starting voltage value to the charging cutoff voltage into multiple intervals, evenly distribute the required equalization capacity of each interval according to the charging capacity and the number of intervals, and set the corresponding equalization strategy.

[0101] The specific method of partitioning using discrete distribution is as follows:

[0102] The charging capacity from the starting voltage value to the charging cutoff voltage is obtained. Based on the density distribution of the individual cell voltages, the charging capacity from the starting voltage value to the charging cutoff voltage is divided into multiple intervals. Based on the charging capacity and the number of intervals, the corresponding balancing strategy and the charging capacity to be balanced are set.

[0103] Equilibrium strategies include:

[0104] The charging trajectory is divided into multiple capacity zones. A capacity imbalance strategy is implemented in the first capacity zone below the starting voltage value and above the starting voltage value.

[0105] The specific calculation method for the required balancing capacity is as follows:

[0106] Obtain the self-discharge difference of the individual batteries and the total capacity of the battery pack, and multiply the two to calculate the required balanced capacity.

[0107] It should be noted that the computer-readable storage medium in this embodiment can be a computer-readable signal medium, a computer-readable storage medium, or any combination thereof. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this embodiment, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this disclosure, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying a computer-readable program. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable storage medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. A computer program contained on a computer-readable storage medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (radio frequency), etc., or any suitable combination thereof.

[0108] The aforementioned computer-readable storage medium can be used to write computer programs for executing this embodiment in one or more programming languages ​​or combinations thereof. These programming languages ​​include object-oriented programming languages—such as Java, Python, and C++—and conventional procedural programming languages—such as C or similar programming languages. The program can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0109] In summary, this invention can divide the overcharge trajectory range, determine the capacity zone where the voltage value of each battery cell is located, execute the corresponding balancing strategy and the charging capacity that needs to be balanced, identify the capacity differences of different cells in the lithium iron phosphate battery system, reduce battery pack inconsistency, reduce the differences between individual cells in the battery system, and improve the usable capacity of the battery pack; and adopts an auxiliary balancing method for end-charge, which can enable users to make balancing judgments in the non-SOC range, improve the possibility of balancing judgment, enhance practicality, and also protect the battery.

[0110] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for determining the equalization capacity of a lithium iron phosphate battery, characterized in that, Includes the following steps: Select a starting voltage value. When the current highest single cell voltage value of the battery is greater than the starting voltage value, record the charging trajectory. The charging trajectory is the charging trajectory from the current highest single cell voltage value to the charging cutoff voltage. The charging trajectory is divided into multiple capacity zones, and each capacity zone is set with a corresponding balancing strategy and the charging capacity to be balanced. Equilibrium strategies include: The charging trajectory is divided into multiple capacity zones. A capacity imbalance strategy is implemented in the first capacity zone below the starting voltage value and above the starting voltage value. The specific calculation method for the required balanced charging capacity is as follows: Obtain the self-discharge difference of the battery itself and the total capacity of the battery pack, and multiply the two to calculate the required equalization charging capacity; The voltage value of each battery cell is recorded at full charge. Based on the divided charging trajectory intervals, the capacity zone in which the voltage value of each battery cell is located is determined, and the corresponding balancing strategy and the charging capacity to be balanced are executed.

2. The method for determining the equalization capacity of a lithium iron phosphate battery according to claim 1, characterized in that, The selection of the starting voltage value specifically includes: When the lithium iron phosphate battery is charged until the charging current is less than or equal to the preset charging current threshold, or / and until the maximum single cell voltage is greater than or equal to the preset charging voltage threshold, the voltage starting value is selected as the voltage value corresponding to the charging curve f'(x)=0, with a floating range of ±0.1V.

3. The method for determining the equalization capacity of a lithium iron phosphate battery according to claim 1, characterized in that, The selection of the starting voltage value specifically includes: The starting voltage value is selected by calculation to obtain the total capacity to be charged, which corresponds to the charging capacity from the starting voltage to the cutoff voltage. The starting voltage value is selected by calculating backward from the cutoff voltage.

4. The method for determining the equalization capacity of a lithium iron phosphate battery according to claim 1, characterized in that, The charging trajectory interval is divided using either a uniform or discrete distribution method; The specific method of dividing equally is as follows: Obtain the charging capacity from the starting voltage value to the charging cutoff voltage, divide the charging capacity from the starting voltage value to the charging cutoff voltage into multiple intervals, evenly distribute the required equalization capacity of each interval according to the charging capacity and the number of intervals, and set the corresponding equalization strategy. The specific method of partitioning using discrete distribution is as follows: The charging capacity from the starting voltage value to the charging cutoff voltage is obtained. Based on the density distribution of the individual cell voltages, the charging capacity from the starting voltage value to the charging cutoff voltage is divided into multiple intervals. Based on the charging capacity and the number of intervals, the corresponding balancing strategy and the charging capacity to be balanced are set.

5. A system for determining the equalization capacity of a lithium iron phosphate battery, characterized in that, include: The module includes a starting voltage value selection module, a voltage value determination module, a charging trajectory recording module, a range division module, a battery cell acquisition module, a capacity zone determination module, and an equalization module. The starting voltage value selection module is used to select the starting voltage value; The voltage value determination module is used to determine whether the current highest single-cell voltage value of the battery is greater than the initial voltage value; The charging trajectory recording module is used to record the charging trajectory, which is the charging trajectory from the current highest single-cell voltage value to the charging cutoff voltage. The interval division module is used to divide the charging trajectory into intervals, and divide the charging trajectory into multiple capacity partitions. Each capacity partition is set with a corresponding balancing strategy and the charging capacity to be balanced. Equilibrium strategies include: The charging trajectory is divided into multiple capacity zones. A capacity imbalance strategy is implemented in the first capacity zone below the starting voltage value and above the starting voltage value. The specific calculation method for the required balanced charging capacity is as follows: Obtain the self-discharge difference of the battery itself and the total capacity of the battery pack, and multiply the two to calculate the required equalization charging capacity; The battery cell acquisition module is used to record the voltage value of each battery cell at the time of full charge. The capacity partition determination module is used to determine the capacity partition in which the voltage value of each battery cell is located based on the divided charging trajectory interval. The equalization module is used to execute the corresponding equalization strategy and the charging capacity that needs to be equalized.

6. The system for determining the equalization capacity of a lithium iron phosphate battery according to claim 5, characterized in that, The starting voltage value selection module is used to select the starting voltage value, specifically including: When the lithium iron phosphate battery is charged to a charging current less than or equal to a preset charging current threshold, or / and charged to a maximum single cell voltage greater than or equal to a preset charging voltage threshold, the voltage starting value is selected as the voltage value corresponding to the charging curve f'(x) = 0, with a floating range of ±0.1V. Alternatively, a calculation method can be used to select the starting voltage value, obtain the total charging capacity from the starting voltage to the cutoff voltage, and then calculate and select the starting voltage value based on the cutoff voltage.

7. The system for determining the equalization capacity of a lithium iron phosphate battery according to claim 5, characterized in that, The interval division module is used to divide the charging trajectory into intervals, and divide the charging trajectory into multiple capacity partitions, using an even or discrete distribution method. The specific method of dividing equally is as follows: Obtain the charging capacity from the starting voltage value to the charging cutoff voltage, divide the charging capacity from the starting voltage value to the charging cutoff voltage into multiple intervals, evenly distribute the required equalization capacity of each interval according to the charging capacity and the number of intervals, and set the corresponding equalization strategy. The specific method of partitioning using discrete distribution is as follows: The charging capacity from the starting voltage value to the charging cutoff voltage is obtained. Based on the density distribution of the individual cell voltages, the charging capacity from the starting voltage value to the charging cutoff voltage is divided into multiple intervals. Based on the charging capacity and the number of intervals, the corresponding balancing strategy and the charging capacity to be balanced are set.

8. A computer-readable storage medium storing a program, characterized in that, When the program is executed by the processor, it implements the method for determining the equalization capacity of a lithium iron phosphate battery as described in any one of claims 1-4.

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