Battery balancing method and apparatus, controller, and electrical device

Abstract

The present application provides a battery balancing method and apparatus, a controller, and an electrical device. The method comprises: when characteristic inflection points of some cells are determined in a target detection interval during battery charging, performing a balancing operation on the some cells, wherein the current in the target detection interval is less than the current in a non-target detection interval. In the present application, because only characteristic inflection points of some cells need to be detected in a single charging process, throughout the entire charging process, the time period in which the current needs to be reduced is shortened and the time period in which the current does not need to be reduced is prolonged, thereby improving the charging efficiency and shortening the charging time of the entire charging process.

Description

Battery equalization method, device, controller and electric device

[0001] The present application claims priority to the Chinese patent application No. 202411369027.8, filed on September 27, 2024, and entitled "Battery equalization method, device, controller and electric device", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery management, in particular to a battery equalization method, device, controller and electric device. BACKGROUND

[0003] The voltage of a battery monomer (such as a lithium ion battery monomer) is only a few volts. Whether in the application of electric vehicles as a power source or in the application of standby power supply, the electrical characteristics of the power battery monomer cannot meet the demand of voltage and current under working conditions. Therefore, in order to improve the voltage of the power battery, a plurality of battery monomers (battery cells) can be connected in series for use.

[0004] When the battery pack is used for a long time, the temperature, electrode material or use of each link may be different, which may cause some battery cells to have a large self-discharge rate, while another part of the battery cells has a small self-discharge rate, thereby causing the capacity that can be used by the battery pack to be less than the capacity of the smallest battery cell, thereby affecting the capacity of the overall battery pack. Therefore, it is necessary to use equalization technology to adjust the capacity of each battery cell in the battery pack. SUMMARY

[0005] The present application provides a battery equalization method, device, controller and electric device to solve the problem that the capacity difference between multiple battery cells in the prior art affects the capacity of the overall battery pack.

[0006] In a first aspect, the present application provides a battery equalization method, the method comprising:

[0007] After determining the characteristic inflection point of the part of battery cells in the target detection interval during battery charging, performing equalization operation on the part of battery cells; wherein the current in the target detection interval is less than the current in the non-target detection interval.

[0008] Optionally, the equalization operation on the part of battery cells after determining the characteristic inflection point of the part of battery cells in the target detection interval during battery charging comprises:

[0009] Based on the characteristic inflection point of the part of battery cells determined in the target detection interval during battery charging, determining the equalization operation of the part of battery cells.

[0010] Optionally, the method further comprises:

[0011] when the current state parameter of the battery is in the target detection interval, charging the battery with a first current, and determining a characteristic inflection point of the partial battery cells;

[0012] wherein the target detection interval is an interval in which the characteristic inflection point of the partial battery cells can be detected; in a non-target detection interval, the battery is charged with a second current, and the first current is less than the second current.

[0013] Optionally, the method further comprises:

[0014] determining a target detection interval corresponding to the next charging process;

[0015] in the next charging process, performing characteristic inflection point detection based on the corresponding target detection interval, determining a balancing operation based on the detected characteristic inflection point, and repeating until the characteristic inflection points of all battery cells are detected based on the target detection interval in a charging process.

[0016] Optionally, determining a target detection interval corresponding to the next charging process comprises at least one of:

[0017] when there is a battery cell with the highest voltage value and there is no battery cell with the lowest voltage value in the partial battery cells, determining the target detection interval corresponding to the next charging process according to the balancing operation result;

[0018] when there is a battery cell with the lowest voltage value in the partial battery cells, the target detection interval remains unchanged;

[0019] if there is no battery cell with the highest voltage value and no battery cell with the lowest voltage value in the partial battery cells, moving the target detection interval in a preset direction to determine the target detection interval corresponding to the next charging process.

[0020] Optionally, the method further comprises:

[0021] when the battery is charged with the first current, if the current state parameter of the battery cell with the highest voltage value is greater than a preset state parameter, adjusting the target detection interval to a default interval;

[0022] or, when the characteristic inflection points of all battery cells in the battery are detected, adjusting the target detection interval to the default interval, or adjusting the target detection interval to the target detection interval corresponding to the current charging.

[0023] Optionally, when there is a battery cell with the highest voltage value and there is no battery cell with the lowest voltage value in the partial battery cells, the left end point of the target detection interval corresponding to the next charging process is the minimum value of the current characteristic inflection points corresponding to each battery cell.

[0024] The current characteristic inflection point of the battery cell is determined by the characteristic inflection point of the battery cell before the equalization and the actual equalization amount of the battery cell in the equalization operation.

[0025] Optionally, when the highest voltage exists in the partial battery cells and the lowest voltage does not exist in the partial battery cells, a left end point of a target detection interval corresponding to a next charging process is a sum of a current left end point and a target value; the target value is a minimum value in the actual equalization amounts corresponding to the battery cells respectively; or the target value is a fixed value.

[0026] Optionally, when the current state parameter of the battery is in the target detection interval, the battery is charged with the first current, and the characteristic inflection points of the partial battery cells are determined, including:

[0027] The current state parameter of the battery is determined when the current charging process meets a preset condition.

[0028] If the current state parameter is less than or equal to the left end point of the target detection interval, the battery is charged with the first current when the state parameter of the battery reaches the target detection interval, and the characteristic inflection points of the battery are detected.

[0029] Optionally, when the current state parameter of the battery is in the target detection interval, the battery is charged with the first current, and the characteristic inflection points of the partial battery cells are determined, further including:

[0030] If the current state parameter is greater than the left end point of the target detection interval, the battery is charged with the first current when the state parameter of the battery is in the corrected target detection interval, and the characteristic inflection points of the battery are detected; wherein the corrected target detection interval is an interval with the current state parameter as the left end point.

[0031] Optionally, lengths of the target detection intervals in any of the charging processes are equal.

[0032] Optionally, when the current state parameter of the battery is in the target detection interval, the battery is charged with the first current, and the characteristic inflection points of the partial battery cells are determined, including:

[0033] When the charging starts, if a time difference from an ideal equalization state moment is greater than or equal to a preset time difference, the battery is charged with the first current in the target detection interval, and the characteristic inflection points of the battery cells are detected to determine the characteristic inflection points of the partial battery cells; wherein the ideal equalization state moment represents a moment when the characteristic inflection points of all the battery cells are detected in the target detection interval in any charging process, and the equalization operation of all the battery cells is completed.

[0034] Optionally, the method further comprises: at the beginning of charging, if the time difference from the ideal equalization state time point is less than the preset time difference, charging the battery with the second current during the current charging process.

[0035] Optionally, determining the equalization operation based on the characteristic inflection point of the partial battery cells comprises:

[0036] determining the equalization operation based on the characteristic inflection point of the partial battery cells so that the characteristic inflection points of at least partial battery cells coincide in the next charging process; or so that the difference between the characteristic inflection points of the partial battery cells in the next charging process is less than the difference between the characteristic inflection points of the partial battery cells in the current charging process.

[0037] Optionally, the absolute value of the difference between the left end point of the current target detection interval and the left end point of the next target detection interval is X, and the minimum value of the absolute values of the differences between the characteristic inflection points of each battery cell in the current target detection interval and the characteristic inflection points of the corresponding battery cells in the next target detection interval is Y, wherein X is less than or equal to Y, and wherein the characteristic inflection points are the state of charge of the battery cell or the capacity of the battery cell.

[0038] Optionally, determining the equalization operation of the partial battery cells comprises:

[0039] if there is a target battery cell in the partial battery cells, performing equalization operation on at least the partial battery cells;

[0040] wherein the target battery cell is the battery cell with the highest voltage value or the battery cell with the lowest voltage value in the plurality of battery cells.

[0041] Optionally, performing equalization operation on at least the partial battery cells comprises:

[0042] in the first battery cells in which the characteristic inflection points are detected, performing equalization operation on any of the first battery cells other than the reference battery cell according to a target equalization amount; the reference battery cell is the battery cell corresponding to the highest value of the characteristic inflection points in the first battery cells; and the target equalization amount is the difference between the characteristic inflection point corresponding to the first battery cell and the characteristic inflection point corresponding to the reference battery cell.

[0043] Optionally, the method further comprises:

[0044] if the target battery cell is the battery cell with the lowest voltage value in the plurality of battery cells, performing equalization operation on any second battery cell in which the characteristic inflection point is not detected according to a default equalization amount.

[0045] In a second aspect, the present application provides a battery equalization device, which comprises:

[0046] The balancing module is configured to perform balancing operation on the partial battery cells after determining the characteristic inflection point of the partial battery cells in the target detection interval.

[0047] In a third aspect, the present application provides a controller, comprising at least one processor and a memory.

[0048] The memory stores computer-executable instructions.

[0049] The at least one processor executes the computer-executable instructions stored in the memory, so that the at least one processor performs the method according to any one of the first aspect.

[0050] In a fourth aspect, the present application provides a power consumption device, comprising a battery and a controller, wherein the battery comprises a plurality of battery cells, and the controller is configured to perform the method according to any one of the first aspect.

[0051] In a fifth aspect, the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and when the processor executes the computer-executable instructions, the method according to any one of the first aspect is implemented.

[0052] In a sixth aspect, the present application provides a computer program product, comprising a computer program, and when the processor executes the computer program, the method according to any one of the first aspect is implemented.

[0053] The present application provides a battery balancing method, device, controller and power consumption device, the method comprising: after determining the characteristic inflection point of partial battery cells in a target detection interval during battery charging, performing balancing operation on the partial battery cells, wherein the current in the target detection interval is smaller than the current in a non-target detection interval. In the present application, only the characteristic inflection point of partial battery cells needs to be detected in a charging process, so that the time period requiring current reduction is shortened and the time period without current reduction is lengthened in the whole charging process, thereby improving the charging efficiency and shortening the charging time of the whole charging process. BRIEF DESCRIPTION OF DRAWINGS

[0054] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and serve to explain the principles of the present application together with the specification.

[0055] FIG. 1 is a charging voltage curve and voltage difference curve diagram provided by an embodiment of the present application;

[0056] FIG. 2 is a flow diagram of a battery balancing method provided by an embodiment of the present application;

[0057] FIG. 3 is a diagram illustrating a method of balancing according to a detected characteristic inflection point, according to an embodiment of the present application;

[0058] FIG. 4 is a diagram illustrating a method of balancing, according to another embodiment of the present application;

[0059] FIG. 5 is a diagram illustrating a structure of a balancing device, according to an embodiment of the present application;

[0060] FIG. 6 is a diagram illustrating a hardware structure of a controller, according to an embodiment of the present application.

[0061] The above-described embodiments have been shown and described, and more detailed descriptions will be given hereinafter. The drawings and the written description are not intended to limit the scope of the present application in any way, but are merely meant to illustrate the concept of the present application to a person skilled in the art by reference to a specific embodiment. DETAILED DESCRIPTION

[0062] The exemplary embodiments will be described in detail herein below with reference to the accompanying drawings. In the following description, the same numbers refer to the same elements throughout the drawings, unless otherwise represented. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application.

[0063] In this document, the terms "comprise", "comprising", "include", "including", "contain", "containing", "have", "having", or "hold", are intended to be open-ended terms that do not exclude additional elements or steps. In other words, these terms are intended to mean "including, but not limited to".

[0064] The data involved in the present application can be data authorized by a user or sufficiently authorized by all parties, and the collection, transmission, and use of the data comply with the requirements of relevant national laws and regulations.

[0065] A single battery cell has low energy, and thus, a plurality of battery cells are often connected in series for use. After a plurality of battery cells are used in series for a period of time, the capacities of the battery cells will be different due to differences in temperature, electrode material, or use of each battery cell. Therefore, a balancing technique is needed to adjust the capacities of the battery cells to achieve balancing of the entire battery.

[0066] In the prior art, one balancing method is to perform balancing adjustment according to a voltage difference of the battery cells. Specifically, balancing can be started according to a voltage difference between other battery cells and a battery cell with the highest voltage in a series battery pack when the battery cell with the highest voltage is fully charged. The above process needs to trigger the balancing operation when the battery is in a fully charged state, and the balancing operation cannot be started for a battery that is not fully charged for a long time.

[0067] Another balancing method is to find the characteristic inflection point according to the differential of the voltage capacity curve during charging, and to perform alignment between the battery cells based on the characteristic inflection point. The characteristic inflection point of the battery cell is related to the chemical reaction. For the same type of battery cell, when the initial capacity of the battery cell is the same, the corresponding characteristic inflection points during the charging process are the same. Therefore, the difference between the characteristic inflection points of different battery cells can reflect the capacity difference, so as to perform balancing. The above method can trigger the balancing operation in the case of not full charging. However, the detection of the characteristic inflection point needs to be performed in the small current charging mode. In the large current charging mode such as fast charging, the characteristic inflection point of the battery cell cannot be detected.

[0068] FIG. 1 is a charging voltage curve and a voltage differential curve diagram provided by an embodiment of the present application. As shown in FIG. 1, when charging at 0.1C (charging at one-tenth of the rated charging rate, C represents the rated charging rate of the battery), the characteristic inflection point can be detected. When charging at 0.5C, the characteristic inflection point cannot be detected. Therefore, for vehicles that have been charged by fast charging for a long time, the battery balancing cannot be started.

[0069] Therefore, for vehicles that have been charged by fast charging for a long time and not full charging, such as operation vehicles, the balancing cannot be started. With the accumulation of the self-discharge deviation of the battery cell, the capacity of the entire battery will become lower and lower, and in the extreme case, the vehicle may be stranded.

[0070] Based on the above problems, an embodiment of the present application provides a flowchart of a battery balancing method. The method comprises the following steps:

[0071] In step S201, after determining the characteristic inflection point of part of the battery cells in the target detection interval during battery charging, the part of the battery cells is subjected to balancing operation. The current in the target detection interval is smaller than the current in the non-target detection interval.

[0072] The above method can determine the inflection point of part of the battery cells by reducing the current, detect the characteristic inflection point of part of the battery cells, shorten the interval of performing the current reduction operation, and thus shorten the time used for each charging, and improve the user experience.

[0073] Further, after determining the characteristic inflection point of part of the battery cells in the target detection interval during battery charging, the part of the battery cells is subjected to balancing operation, which comprises the following steps:

[0074] Based on the characteristic inflection point of part of the battery cells determined in the target detection interval during battery charging, the balancing operation of the part of the battery cells is determined.

[0075] The current in the target detection interval is smaller than the current in the non-target detection interval.

[0076] In the charging process of the battery, the characteristic inflection point of the battery cell can be detected only when the battery is charged in the small current charging mode. Therefore, in the charging process, the battery can be charged in the small current in the target detection interval and can be charged in the large current in the non-target detection interval, that is, the current in the target detection interval is smaller than the current in the non-target detection interval.

[0077] As shown in FIG. 1, when the battery is charged at 0.1C, the characteristic inflection point can be detected, and when the battery is charged at 0.5C, the characteristic inflection point cannot be detected. The current in the target detection interval can be the current size in which the characteristic inflection point can be detected. For example, there can be a current threshold, such as 0.2C, when the battery is charged at a current smaller than or equal to the current threshold, the characteristic inflection point can be detected, and when the battery is charged at a current larger than the current threshold, the characteristic inflection point cannot be detected. The current in the target detection interval is smaller than or equal to the current threshold.

[0078] When the battery is charged in the small current in the target detection interval, the characteristic inflection point of each battery cell in the battery can be detected. Optionally, for each battery cell, the voltage and capacity of the battery cell during the charging in the small current can be collected, so as to draw a charging curve, and a differential curve is obtained based on the charging interval, so as to determine the corresponding characteristic inflection point.

[0079] Based on the characteristic inflection points of the part of the battery cells determined in the target detection interval when the battery is charged, the equalization operation of the part of the battery cells is determined, which means that the equalization operation can be performed on at least part of the battery cells. Optionally, the equalization operation can be performed on all the battery cells in which the characteristic inflection points are detected, or the equalization operation can be performed on all the battery cells in which the characteristic inflection points are detected and part of the battery cells in which the characteristic inflection points are not detected. The equalization operation of the battery cell means that the target equalization amount of the battery cell is determined, and the equalization operation of the battery cell is performed according to the target equalization amount. The timing of performing the equalization operation can be in the non-target detection interval, or can be in a certain time period after the completion of the current charging.

[0080] For example, when the characteristic inflection points of two battery cells are detected, the equalization operation can be performed on at least the two battery cells. That is, the equalization operation can be performed according to the characteristic inflection points of the two battery cells, or the equalization operation can be performed on the two battery cells and other battery cells. It should be noted that when only the characteristic inflection point of one battery cell is detected, the equalization operation cannot be performed.

[0081] In order to improve the charging efficiency and shorten the charging time, when the characteristic inflection points of part of the battery cells are detected, the battery can be charged in the large current until the charging is completed.

[0082] For example, for the charging process of the battery, after connecting the charger, a part of the charge can be charged with a large current first, and then charged with a small current, for example, 5% of the charge is charged with a current of 0.5C first, and then charged with a current of 0.1C. When charging with a current of 0.1C, the characteristic inflection points of each cell can be detected, for example, there are 5 cells in the battery, and when the characteristic inflection points of 2 cells are detected, at least the 2 cells can be balanced.

[0083] The application provides a battery balancing method, which comprises: determining the characteristic inflection points of part of the cells in the target detection interval of the battery during charging, and then balancing the part of the cells, wherein the current in the target detection interval is smaller than the current in the non-target detection interval. In the present application, only part of the characteristic inflection points of the cells need to be detected in the charging process, so the time period of current reduction is shortened and the time period of no current reduction is lengthened in the whole charging process, thereby improving the charging efficiency and shortening the charging time of the whole charging process.

[0084] Optionally, the method further comprises: charging the battery with a first current when the current state parameter of the battery is in the target detection interval, and determining the characteristic inflection points of part of the cells; wherein the target detection interval is an interval in which the characteristic inflection points of part of the cells can be detected; in the non-target detection interval, the battery is charged with a second current, and the first current is smaller than the second current.

[0085] When determining whether to charge the battery with the first current, the target detection interval can be used for determination. Optionally, the target detection interval can be obtained before each charging, and when the current state parameter of the battery is in the target detection interval, the battery is charged with the first current, and the characteristic inflection points of the cells of the battery are detected.

[0086] Optionally, the current state parameter can be the current state of charge of the battery, and the target detection interval can be a state of charge interval. The current state parameter can also be the current capacity of the battery, and the target detection interval can be a capacity interval.

[0087] The state of charge (SOC) of the battery can be used to reflect the ratio of the current capacity of the battery to the total capacity of the battery. When the battery is charging, the state of charge of the battery changes, that is, the state of charge gradually increases, and at the same time, the capacity of the battery also gradually increases.

[0088] The target detection interval is an interval for performing the current reduction operation. During the charging process, when the current state parameter of the battery is in the target detection interval, the battery is charged with the first current, so that the feature inflection point of the battery can be detected. When the current state parameter of the battery is not in the target detection interval, the battery is charged with the second current. The first current is less than the second current.

[0089] For example, when the current state parameter is the current state of charge, if the target detection interval is 40%-55% during charging, when the current state of charge of the battery is equal to 40%, the battery is charged with the first current. When the state of charge of the battery is equal to 55%, the battery stops being charged with the first current. For a non-target detection interval, that is, when the current state of charge of the battery is less than 40% or the current state of charge is greater than 55%, the battery is charged with the second current.

[0090] For example, the length of the target detection interval can be 15%. The length of the target detection interval is not limited in the present application, and can be set according to actual conditions. When the length of the target detection interval is longer, the number of cells that detect the feature inflection point during each charging may be more, and the time required for this charging is increased. When the length of the target detection interval is shorter, the number of cells that detect the feature inflection point may be less, and the time required for this charging is reduced. Optionally, the length of the target detection interval is generally between 10% and 20%. For example, the length of the target detection interval can be set to 15% or other fixed values. The length of the target detection interval is selected in the above range, which can ensure that a certain number of cells in the interval can detect the feature inflection point, and on the other hand, it can not further reduce the charging time of the battery.

[0091] Optionally, in an embodiment, the threshold value between the first current and the second current is generally in the range of 0.2C-0.3C, that is, when the current is greater than 0.3C, there is no feature inflection point. However, in some embodiments, the threshold value between the first current and the second current is also greater than 0.3C, so the specific value needs to be adjusted according to the voltage characteristic curve of the corresponding battery, that is, by adjusting the charging current of the battery and differentiating the voltage characteristic curve of the battery to determine whether there is an inflection point to determine the threshold value between the first current and the second current.

[0092] By determining when to perform the current reduction operation based on the target detection interval, the current of the entire charging process can be accurately controlled.

[0093] Optionally, the method further comprises:

[0094] determining a target detection interval corresponding to the next charging process;

[0095] In the next charging process, feature inflection point detection is performed based on the corresponding target detection interval, and balancing operation is determined based on the detected feature inflection points, until feature inflection points of all the battery cells are detected in the target detection interval in one charging process.

[0096] When feature inflection points of part of the battery cells are detected in the target detection interval in one charging process, the current can be stopped to decrease and the balancing operation can be performed on the battery cells whose feature inflection points are detected. However, in the above process, only part of the feature inflection points of the battery cells can be detected in one charging process, and only part of the battery cells can reach the same capacity after the balancing operation, that is, the feature inflection points are the same. However, for the battery, balancing means that the capacities of all the battery cells in the battery are the same, and therefore, multiple charging processes are required to achieve the balancing of the entire battery. In order to detect more feature inflection points of the battery cells in the next charging process, the target detection interval corresponding to the next charging process can be determined when the current charging process is completed.

[0097] In the next charging process, the current can be decreased based on the corresponding target detection interval, and the feature inflection points of the battery cells can be detected, so that the balancing operation can be continuously performed.

[0098] Optionally, the target detection interval can be moved to the left or right to determine the target detection interval corresponding to the next charging process. FIG. 3 is a schematic diagram of balancing according to the detected feature inflection points provided by an embodiment of the present application. For example, there are five battery cells, and the feature inflection points of the battery cells 1 to 5 are 40%, 45%, 55%, 60%, and 70%, respectively. The target detection interval of the first charging process is 40%-55%, and the feature inflection points of the first three battery cells can be detected. After the balancing operation (discharging the battery cells with lower feature inflection points), the feature inflection points of the first three battery cells are all 55%. The target detection interval of the second charging process is 50%-65%, and the feature inflection points of the first three battery cells are 55%, and the feature inflection point of the fourth battery cell is 60%. After the balancing operation, the feature inflection points of the first four battery cells are all 60%. The target detection interval of the third charging process is 60%-75%, and the feature inflection points of the five battery cells can be detected, and the balancing of all the battery cells can be achieved.

[0099] By determining the target detection interval corresponding to the next charging process, the battery can be continuously charged at the first current in the target detection interval of the next charging process to perform feature inflection point detection, so that the balancing of all the battery cells can be achieved, and the balancing effect can be improved.

[0100] Optionally, determining the target detection interval corresponding to the next charging process comprises at least one of the following:

[0101] When the highest voltage cell exists in the part of cells and the lowest voltage cell does not exist, the target detection interval corresponding to the next charging process is determined according to the equalization operation result;

[0102] When the lowest voltage cell exists in the part of cells, the target detection interval remains unchanged;

[0103] If the highest voltage cell and the lowest voltage cell do not exist in the part of cells, the target detection interval is moved in a preset direction to determine the target detection interval corresponding to the next charging process.

[0104] When the battery does not reach the ideal equalization state (the moment when the feature inflection points of all cells are detected in the target detection interval and the equalization operation on all cells is completed) after the current charging is completed, the current charging operation needs to be continued in the next charging to detect more feature inflection points of cells.

[0105] When the target detection interval corresponding to the next charging process is determined, different ways can be used to determine the target detection interval according to different situations, so that more feature inflection points of cells can be detected based on the determined target detection interval in the next charging.

[0106] Optionally, when the feature inflection points of the highest voltage cell and the lowest voltage cell are detected at the same time, it indicates that the feature inflection points of all cells are detected in the current charging process, and the equalization operation can be performed. If the target equalization amount of a cell (the target equalization amount of a cell is 10%, and the actual equalization amount is 5%) is not completed, the target detection interval does not need to be modified again, and the feature inflection points of each cell can be detected based on the target detection interval in the next charging, and the equalization operation can be continued.

[0107] Optionally, when only the feature inflection point of the lowest voltage cell is detected, the target detection interval does not need to be modified. This is because the equalization process is expected to achieve the same feature inflection point as the lowest voltage cell, and when the target detection interval changes, the feature inflection point of the lowest voltage cell may not be detected in the next time, so that the equalization operation cannot be realized. Therefore, at this time, the equalization operation can be performed on the cells with detected feature inflection points and the cells without detected feature inflection points, so that the feature inflection points of each cell can approach the feature inflection point of the lowest voltage cell, and after multiple operations, the feature inflection points of all cells can be detected in the target detection interval, so that the equalization operation can be performed on each cell based on the target equalization amount corresponding to each cell.

[0108] By keeping the target detection interval unchanged when the characteristic inflection point of the battery cell with the lowest voltage value is detected, it is ensured that the characteristic inflection point of the battery cell with the lowest voltage value can be detected in each charging process, and the equalization of other battery cells based on the characteristic inflection point is realized.

[0109] Optionally, when the characteristic inflection point of the battery cell with the highest voltage value is detected and the characteristic inflection point of the battery cell with the lowest voltage value is not detected, the equalization operation can be started. However, the target equalization amount of each battery cell whose characteristic inflection point is detected can not be completed in one equalization process, and therefore, when the target detection interval corresponding to the next charging process is determined, the target detection interval can be determined according to the equalization operation result. The equalization operation result can reflect the characteristic inflection points of the battery cells after the equalization operation.

[0110] When the battery cell with the highest voltage value and the battery cell with the lowest voltage value do not exist in the battery cells whose characteristic inflection points are detected, the equalization operation cannot be started, and therefore, the target detection interval needs to be adjusted to detect the characteristic inflection point of the battery cell with the highest voltage value or the characteristic inflection point of the battery cell with the lowest voltage value.

[0111] Through the foregoing analysis, it is known that the characteristic inflection point of the battery cell with the highest voltage value is the lowest, and the characteristic inflection point of the battery cell with the lowest voltage value is the highest. When the characteristic inflection point of the battery cell with the highest voltage value and the characteristic inflection point of the battery cell with the lowest voltage value are not detected, the target detection interval can be translated in a preset direction until the characteristic inflection point of the battery cell with the highest voltage value or the characteristic inflection point of the battery cell with the lowest voltage value is detected.

[0112] Optionally, the target detection interval can be translated to the left to obtain the target detection interval corresponding to the next charging process, so that the characteristic inflection point detection is performed based on the corresponding target detection interval in the next charging process until the characteristic inflection point of the battery cell with the highest voltage value is detected.

[0113] Optionally, the target detection interval can be translated to the right to obtain the target detection interval corresponding to the next charging process, so that the characteristic inflection point detection is performed based on the corresponding target detection interval in the next charging process until the characteristic inflection point of the battery cell with the lowest voltage value is detected.

[0114] Optionally, the translation of the target detection interval to the left means that the starting point of the target detection interval in the next charging process is smaller than the starting point of the target detection interval in the current charging process, or the starting point of the target detection interval in the next charging process is determined by subtracting a preset value from the starting point of the target detection interval in the current charging process. The translation of the target detection interval to the right means that the starting point of the target detection interval in the next charging process is greater than the starting point of the target detection interval in the current charging process, or the starting point of the target detection interval in the next charging process is determined by adding a preset value to the starting point of the target detection interval in the current charging process.

[0115] For example, there are five battery cells, the feature inflection points of battery cell 1 to battery cell 5 are 35%, 45%, 55%, 60%, and 70% respectively, and the voltage of each battery cell is known. Battery cell 1 has the highest voltage value and battery cell 5 has the lowest voltage value. When the target detection interval is 45%-60%, the feature inflection points of battery cell 2, battery cell 3, and battery cell 4 can be detected, and the equalization cannot be started at this time. Therefore, the target detection interval can be shifted to the left, for example, by 5%, and the target detection interval is 40%-55%. At this time, the feature inflection point of battery cell 1 cannot be detected, and the target detection interval can be further shifted to the left, for example, by 5%, and the target detection interval is 35%-50%. At this time, the feature inflection point of battery cell 1 can be detected. Similarly, the target detection interval can also be shifted to the right until the feature inflection point of battery cell 5 is detected.

[0116] By shifting the target detection interval in a preset direction when the battery cell with the highest voltage value and the battery cell with the lowest voltage value do not exist in the battery cells whose feature inflection points are detected, the feature inflection point of the battery cell with the highest voltage value or the feature inflection point of the battery cell with the lowest voltage value can be successfully detected, so that the condition for starting the equalization operation is met.

[0117] The target detection interval for the next charging is determined based on the type of the battery cell whose feature inflection point is detected, so that the feature inflection points of more battery cells can be detected at the next charging, and invalid current reduction is avoided.

[0118] Optionally, the method further comprises:

[0119] When the battery is charged at the first current, if the current state parameter of the battery cell with the highest voltage value is greater than the preset state parameter, the target detection interval is adjusted to a default interval.

[0120] Alternatively, when the feature inflection points of all battery cells in the battery are detected, the target detection interval is adjusted to the default interval, or the target detection interval is adjusted to the target detection interval corresponding to the current charging.

[0121] The state parameter can be a state of charge or a battery capacity, and the preset state parameter is a preset state of charge or a preset battery capacity.

[0122] When the battery is charged, if the current state parameter of the battery cell with the highest voltage value is greater than the preset state parameter, for example, the current state of charge of the battery cell with the highest voltage value is greater than the preset state of charge, for example, 95%, it indicates that the battery is close to the ideal equalization state. At this time, the target detection interval can be adjusted to a default interval, for example, 40%-60%.

[0123] In addition, when the characteristic turning points of all the battery cells are detected and the balancing operation is completed for each battery cell, that is, after the balancing operation is performed, the characteristic turning points of each battery cell are the same, at this time, the target detection interval can be adjusted to the default interval. Alternatively, the target detection interval can also be adjusted to the target detection interval corresponding to the current charging, so that the possibility of detecting the characteristic turning points of more battery cells is greater when the drop operation is subsequently performed based on the target detection interval.

[0124] For example, when the characteristic turning points of all the battery cells are detected in the target detection interval of 50% to 70% and the balancing operation is completed, the interval of 50%-70% can be determined as the adjusted target detection interval.

[0125] The above-mentioned adjusted target detection interval is not the target detection interval for the next charging. When the current battery is already in a balanced state, there is no need to perform balancing operation again for a period of time, and after a period of time, when the battery needs to perform balancing operation again through multiple charging, the adjusted target detection interval is the initial target detection interval for detecting the characteristic turning point when charging for the first time after detecting the need for balancing operation.

[0126] By adjusting the target detection interval corresponding to the first charging in the balancing operation, the characteristic turning points of as many battery cells as possible can be detected at one time, so as to reduce the number of adjustments of the target detection interval to complete the balancing of the battery.

[0127] Optionally, when there is a battery cell with the highest voltage value and there is no battery cell with the lowest voltage value in the part of the battery cells, the left end point of the target detection interval corresponding to the next charging process is the minimum value of the current characteristic turning points corresponding to each battery cell;

[0128] The current characteristic turning point of the battery cell is determined by the characteristic turning point of the battery cell before balancing and the actual balancing amount of the battery cell in the balancing operation.

[0129] When the characteristic turning point of the battery cell with the highest voltage value is detected and the characteristic turning point of the battery cell with the lowest voltage value is not detected, the target detection interval corresponding to the next charging process can be determined according to the balancing operation result. The actual balancing amount of each battery cell can be different from the target balancing amount, and the current characteristic turning point of the battery cell can be determined based on the characteristic turning point of the battery cell before balancing and the actual balancing amount of the battery cell.

[0130] When the target detection interval corresponding to the next charging process is determined, the left end point of the target detection interval corresponding to the next charging process can be determined according to the current characteristic turning points of each battery cell for which the balancing operation is performed, so that the minimum value of the current characteristic turning points corresponding to each battery cell is determined as the left end point of the target detection interval corresponding to the next charging process. The length of the target detection interval can be a fixed length, for example, the fixed length can be 15%, which is not limited in the present application.

[0131] For example, when the characteristic turning points of three battery cells are detected, the characteristic turning points of battery cell 1 to battery cell 3 are 40%, 45%, and 55% respectively, if the actual equalization amounts of battery cell 1 and battery cell 2 are both 3% when the target equalization amount is not completed at the end of the charging process, the current characteristic turning point of battery cell 1 is 43%, the current characteristic turning point of battery cell 2 is 48%, and the current characteristic turning point of battery cell 3 is 55%, 43% can be determined as the left endpoint of the target detection interval corresponding to the next charging process, so that the next time the battery is charged, the current can be started from the position of 43% to reduce the flow, so as to just detect the characteristic turning point of battery cell 1. On the contrary, if the current is started from the position of 40%, there is no characteristic turning point in the interval of 40% to 42%, so the current in the interval of 40% to 42% is invalid, compared with the current started from the position of 43%, the possibility of detecting more battery cell characteristic turning points is reduced.

[0132] By determining the minimum value of the current characteristic turning points corresponding to each battery cell as the left endpoint of the target detection interval, the invalid current interval in the target detection interval is reduced, and the possibility of detecting more battery cell characteristic turning points is improved.

[0133] Optionally, when the battery cell with the highest voltage value exists in the part of battery cells and the battery cell with the lowest voltage value does not exist, the left endpoint of the target detection interval corresponding to the next charging process is the sum of the current left endpoint and the target value; the target value is the minimum value of the actual equalization amounts of each battery cell; or the target value is a fixed value.

[0134] When the battery cell with the highest voltage value exists in the part of battery cells and the battery cell with the lowest voltage value does not exist, when determining the target detection interval corresponding to the next charging process, the actual equalization amount of each battery cell can also be determined, and the target detection interval is determined based on the target value, that is, the minimum value of the actual equalization amounts of each battery cell or a fixed value. For example, the fixed value can be a small value, such as 3%.

[0135] Optionally, the sum of the current left endpoint and the target value can be determined as the left endpoint of the target detection interval corresponding to the next charging process, and when adjusting the target detection interval, the length of the target detection interval remains unchanged, so the sum of the current right endpoint and the target value can be determined as the right endpoint of the target detection interval corresponding to the next charging process.

[0136] For example, the actual equalization amounts of battery cell 1, battery cell 2, and battery cell 3 are 4%, 5%, and 5% respectively, and the target detection interval can be moved by 4% to determine the target detection interval corresponding to the next charging process.

[0137] By determining the target detection interval corresponding to the next charging process based on a fixed value, the operation is simple and convenient. By determining the target detection interval corresponding to the next charging process based on the minimum actual balancing amount of each battery cell, it can be ensured that the feature inflection point of each battery cell detected in the last charging process is detected at least in the next charging process.

[0138] Optionally, when the current state parameter of the battery is in the target detection interval, the battery is charged at the first current, and the feature inflection point of the partial battery cell is determined, comprising:

[0139] When the current charging process meets the preset condition, the current state parameter of the battery is determined.

[0140] If the current state parameter is less than or equal to the left endpoint of the target detection interval, the battery is charged at the first current when the state parameter of the battery reaches the target detection interval, and the feature inflection point detection of the battery is performed.

[0141] When charging at the first current according to the target detection interval, the current state of charge of the battery can be calculated, and the detection interval for actual current reduction operation is determined based on the current state of charge and the target detection interval.

[0142] When the battery starts to be charged, it is first determined whether the battery needs to be balanced based on the ideal balancing state time, and when it is determined that the balancing operation is needed, a part of the power can be charged first, for example, 5% of the power, at this time the detection interval for actual current reduction operation can be determined.

[0143] The current state parameter is the current state of charge or the current power (capacity). The current state of charge is taken as an example for description.

[0144] Optionally, the current state of charge can be the state of charge calculated independently based on ampere-hour integration. Here, the voltage correction SOC is not used to prevent interference with the selection of the current reduction position.

[0145] Optionally, when the current charging process meets the preset condition, that is, after charging a part of the power, the current state of charge of the battery can be determined, and when the current state of charge of the battery is less than or equal to the left endpoint of the target detection interval, it indicates that the current reduction can continue in the target detection interval, that is, the detection interval for actual current reduction operation is the set target detection interval, so as to detect the feature inflection point of each battery cell.

[0146] For example, when the target detection interval is 40%-55%, the length of each detection interval is fixed at 15%, and if the current state of charge is 38%, the detection interval for actual current reduction operation is the target detection interval 40%-55%.

[0147] Optionally, when the current state parameter of the battery is in the target detection interval, the battery is charged with the first current, and the feature inflection point of the partial battery cell is determined, and the method further comprises:

[0148] If the current state parameter is greater than the left end point of the target detection interval, the battery is charged with the first current when the state parameter of the battery is in the corrected target detection interval, and the feature inflection point detection of the battery is performed; wherein the corrected target detection interval is an interval with the current state parameter as the left end point.

[0149] Here, the current state parameter is taken as the current state of charge as an example.

[0150] When the current state of charge of the battery is greater than the left end point of the target detection interval, it indicates that the current capacity has exceeded the position of the drop current starting point, at which time the detection interval for actually performing the drop operation can be re-determined, and the interval is an interval with the current state of charge as the left end point and a fixed length as the detection interval length.

[0151] For example, if the current state of charge is 50%, the detection interval for actually performing the drop operation is 50%-65%. Conversely, if the target detection interval is not corrected based on the current state of charge, when the current state of charge is 50%, the detection interval for actually performing the drop operation is 50%-55%, and the drop interval is smaller in the current charging process, which can not detect the feature inflection point of any battery cell, resulting in invalid drop in this drop process.

[0152] By determining the detection interval for actually performing the drop operation according to the current state parameter during the charging process, the re-determined detection interval is moved to the right compared to the target detection interval, so that the length of the detection interval remains unchanged to reduce the possibility of not detecting the feature inflection point of any battery cell.

[0153] Optionally, the lengths of the target detection intervals in any of the charging processes are equal.

[0154] The length of the target detection interval is equal when determining the target detection interval corresponding to the next charging process each time. For example, when charging for the first time, the target detection interval is 40%-60%, and after detecting the feature inflection point of the partial battery cell and performing the balancing operation, the target detection interval is adjusted to 45%-65% to detect the feature inflection point of more battery cells.

[0155] By controlling the length of the target detection interval to be equal, the interval for reducing the current is not prolonged, and thus the charging time of the battery is not further increased, providing a good user experience.

[0156] Optionally, when the current state parameter of the battery is in the target detection interval, the battery is charged with a first current, and a characteristic inflection point of a part of the battery cells is determined, comprising:

[0157] When the charging starts, if the time difference between the current time and the ideal equilibrium state time is greater than or equal to a preset time difference, the battery is charged with a first current in the target detection interval, and a characteristic inflection point detection is performed on the battery cells to determine the characteristic inflection point of a part of the battery cells; wherein the ideal equilibrium state time represents the time when the characteristic inflection points of all the battery cells are detected in the target detection interval and the balancing operation is completed for all the battery cells in any charging process.

[0158] In order to facilitate the determination of whether the battery balancing operation is performed in any charging process, the time when the characteristic inflection points of all the battery cells are detected and the balancing operation is completed for all the battery cells, that is, the ideal equilibrium state time, can be recorded. In the subsequent charging process, whether the balancing operation is performed can be determined according to the time difference between the current time of charging and the ideal equilibrium state time.

[0159] Since the battery does not need to be balanced again in a short time after reaching the ideal equilibrium state time, the time difference between the current time of charging and the ideal equilibrium state time and the preset time difference can be used to determine whether the current charging process is performed with a current reduction operation and a characteristic inflection point detection.

[0160] When in any charging process, the time difference between the current time and the ideal equilibrium state time can be calculated, and the preset time difference can be set in advance. When the calculated time difference is greater than or equal to the preset time difference, the battery is charged with a first current in the target detection interval, and a characteristic inflection point detection is performed on the battery cells.

[0161] For example, when the recorded ideal equilibrium state time is May 1, 10:00, and the preset value is two months, if the charging time is July 3, 10:00, the battery is charged with a first current, and the characteristic inflection points of the battery cells are detected. If only three of the five battery cells are balanced in the charging process on July 3, the battery will be charged with a first current and the characteristic inflection points of the battery cells will be detected in the next charging on July 8, since the recorded ideal equilibrium state time has not been changed. If the balancing of all the battery cells is completed at 15:00 on July 8, July 8, 15:00 can be stored as the ideal equilibrium state, so that the balancing operation of the battery is performed again after two months.

[0162] Optionally, before judging the size relationship between the time difference from the ideal equalization state moment and the preset time difference, the charging mode can be judged, when it is direct current charging, the above judging step is executed, when it is alternating current charging, the above judging step is not needed to be executed. Here, the direct current charging can be considered as fast charging mode, and the alternating current charging can be considered as slow charging mode.

[0163] By recording the ideal equalization state moment, it is convenient to accurately determine whether the battery needs to be equalized based on the recorded ideal equalization state moment in subsequent charging.

[0164] Optionally, the method further comprises: at the beginning of charging, if the time difference from the ideal equalization state moment is less than the preset time difference, the second current is used to charge the battery in the present charging process.

[0165] When the calculated time difference is less than the preset time difference, it means that the battery does not need to be equalized, that is, the current does not need to be reduced in the target detection interval, and then the second current is used to charge the battery in the present charging process.

[0166] For example, when the recorded ideal equalization state moment is May 1, 10:00, and the preset value is two months, when the charging moment is June 20, 10:00, the second current is used to charge the battery.

[0167] By recording the ideal equalization state moment, it is convenient to accurately determine whether the battery needs to be equalized based on the recorded ideal equalization state moment in subsequent charging.

[0168] Optionally, the equalization operation is determined based on the characteristic inflection point of the part of the battery cells, comprising:

[0169] The equalization operation is determined based on the characteristic inflection point of the part of the battery cells, so that the characteristic inflection points of at least part of the battery cells coincide in the next charging process; or, the difference between the characteristic inflection points of the part of the battery cells is less than the difference between the characteristic inflection points of the part of the battery cells in the present charging process.

[0170] The result of determining the equalization operation based on the characteristic inflection point of the part of the battery cells is that the characteristic inflection points of at least part of the battery cells coincide, or the difference between the characteristic inflection points of the part of the battery cells is reduced, that is, the difference between the characteristic inflection points of the part of the battery cells in the next charging process is less than the difference between the characteristic inflection points of the part of the battery cells in the present charging process.

[0171] For example, when the characteristic turning points of the battery cell 1, the battery cell 2 and the battery cell 3 are detected as 45%, 48% and 50% respectively, the equalization operation can be performed according to the characteristic turning point of the battery cell 3, the target equalization amount of the battery cell 1 is determined as 5%, the target equalization amount of the battery cell 2 is determined as 2%, and the equalization processing is performed according to the target equalization amount, so that the characteristic turning point of the battery cell 1 and the characteristic turning point of the battery cell 2 respectively approach or equal to the characteristic turning point of the battery cell 3.

[0172] Through the equalization operation, the characteristic turning points of the partial battery cells are coincided or approached, so that through multiple equalization operations, the characteristic turning points of the battery cells are finally coincided.

[0173] Optionally, the absolute value of the difference between the left end point of the current target detection interval and the left end point of the next target detection interval is X, and the minimum value of the absolute value of the difference between the characteristic turning point of each battery cell in the current target detection interval and the characteristic turning point of the corresponding battery cell in the next target detection interval is Y, wherein X is less than or equal to Y, and the characteristic turning point is the state of charge of the battery cell or the capacity of the battery cell.

[0174] When the equalization operation is performed on the battery cell, the characteristic turning point of the battery cell will change. Specifically, the characteristic turning point of the battery cell will increase. The actual equalization amount of each battery cell can be unequal, and the actual equalization amount is the absolute value of the difference between the characteristic turning point detected in the next target detection interval and the characteristic turning point detected in the current target detection interval.

[0175] After the equalization operation is performed through one charging, the target detection interval of the next charging can be determined, wherein the translation amount (the difference between the left end point of the current target detection interval and the left end point of the next target detection interval) of the target detection interval is less than or equal to the minimum value of the absolute value of the difference between the characteristic turning points of all battery cells.

[0176] For example, when the characteristic turning points of the battery cell 1, the battery cell 2 and the battery cell 3 are detected as 45%, 48% and 50% respectively, the equalization operation can be performed according to the characteristic turning point of the battery cell 3, the characteristic turning point of the battery cell 1 is 49% after the equalization operation, the characteristic turning point of the battery cell 2 is determined as 50%, the actual equalization amount of the battery cell 1 is 4%, the actual equalization amount of the battery cell 2 is 2%, and X is less than or equal to 2%.

[0177] By limiting the absolute value of the difference between the left end point of the target detection interval and the left end point of the next target detection interval, it can be ensured that the characteristic turning points of each battery cell detected this time can be detected based on the next target detection interval.

[0178] Optionally, the equalization operation of the partial battery cells comprises:

[0179] if the target battery cell exists in the part of battery cells, performing at least the equalization operation on the part of battery cells;

[0180] The target battery cell is the battery cell with the highest voltage value or the battery cell with the lowest voltage value in the plurality of battery cells.

[0181] When the feature turning points of the part of battery cells are detected, the battery cells with the feature turning points are determined, and when the battery cells meet preset conditions, at least the equalization operation is performed on the electric quantity of the battery cells.

[0182] Since the feature turning point of the battery cell with the highest voltage value is the lowest, the feature turning point of the battery cell with the lowest voltage value is the highest, and the feature turning points of the other battery cells are between the lowest feature turning point and the highest feature turning point, in order to make the battery reach an equalization state, the battery cells with lower feature turning points need to be discharged to make the feature turning points of all the battery cells equal to the feature turning point of the battery cell with the lowest voltage value. Therefore, when the feature turning point corresponding to the battery cell with the highest voltage value is detected, the target detection range can be moved to the right each time to slowly detect the feature turning points of all the battery cells, so that the equalization of all the battery cells is achieved. When the feature turning point corresponding to the battery cell with the lowest voltage value is detected, the feature turning points of the other battery cells can be moved close to the feature turning point, so that the equalization of all the battery cells is achieved.

[0183] If the equalization operation is started before the feature turning point corresponding to the target battery cell is detected, the target detection range needs to be moved to the left and the right respectively, which is complicated and easy to miss the battery cells that need to be equalized.

[0184] For example, there are five battery cells, and the feature turning points of the battery cells 1 to 5 are 40%, 45%, 55%, 60%, and 70% respectively. When the target detection range is 45%-60%, the feature turning points corresponding to the battery cells 2 to 4 are 45%, 55%, and 60% respectively. If the equalization operation is started at this time, the target detection range needs to be moved to the left to detect the feature turning point of the battery cell 1 and equalize again next time. In addition, the target detection range also needs to be moved to the right to detect the feature turning point of the battery cell 5 and equalize. The above process will make the determination of the target detection range more complicated next time.

[0185] By starting the equalization operation when the target battery cell exists in the part of battery cells, compared with starting the equalization operation when the target battery cell is not detected, the operation process is simple.

[0186] Optionally, the equalization operation on the part of battery cells comprises:

[0187] In the first battery cell in which the feature inflection point is detected, any of the first battery cells except for a reference battery cell is subjected to the equalization operation according to a target equalization amount; the reference battery cell is the battery cell corresponding to the highest value of the feature inflection point in the first battery cells; and the target equalization amount is the difference between the feature inflection point of the first battery cell and the feature inflection point of the reference battery cell.

[0188] Here, the first battery cell refers to the battery cell in which the feature inflection point is detected. When the equalization operation is performed on the first battery cell in which the feature inflection point is detected, the reference battery cell can be determined from the first battery cells first, which refers to the battery cell corresponding to the highest value of the feature inflection point in the first battery cells, and the equalization is performed based on the feature inflection point of the reference battery cell and the feature inflection points of the other first battery cells. The equalization operation requires discharging the first battery cell with a higher voltage value, that is, discharging each of the first battery cells with a lower feature inflection point value. Therefore, for the first battery cell in which the feature inflection point is detected, the first battery cell with the highest feature inflection point can be determined as the reference battery cell, so that the other first battery cells are discharged based on the reference battery cell.

[0189] Optionally, when the first battery cell has the battery cell with the highest voltage value or the battery cell with the lowest voltage value in the entire battery, the battery cell corresponding to the highest value of the feature inflection point can be determined as the reference battery cell, and for any other first battery cell, the difference between the feature inflection point of the first battery cell and the feature inflection point of the reference battery cell can be calculated, which is the target equalization amount, so that the equalization operation is performed on the first battery cell based on the target equalization amount, so that the electric quantity of the first battery cell is the same as or close to the electric quantity of the reference battery cell.

[0190] For example, when the feature inflection points of the battery cell 1 to the battery cell 3 are detected as 40%, 45%, and 55% respectively, the reference battery cell is the battery cell 3, for the battery cell 1, the target equalization amount is 15%, and the battery cell 1 can be discharged based on the target equalization amount of 15%; for the battery cell 2, the target equalization amount is 10%, and the battery cell 2 can be discharged based on the target equalization amount of 10%.

[0191] For the first battery cell in which the feature inflection point is detected, the equalization is performed based on the target equalization amount, which can realize accurate equalization of each of the first battery cells.

[0192] Optionally, the method further includes: if the target battery cell is the battery cell with the lowest voltage value in the plurality of battery cells, any second battery cell in which the feature inflection point is not detected is subjected to the equalization operation according to a default equalization amount.

[0193] If the target battery cell is the battery cell with the lowest voltage among the plurality of battery cells, it means that the battery cell with the highest characteristic inflection point is detected. In this case, in addition to balancing each first battery cell, each second battery cell without the detected characteristic inflection point can also be balanced. For each first battery cell with the detected characteristic inflection point, balancing can be started based on the target balancing amount. For each second battery cell without the detected characteristic inflection point, balancing can be started based on the default balancing amount, so that the characteristic inflection points of the battery cells gradually approach each other, and the balancing of all the battery cells is gradually achieved.

[0194] For example, when there are five battery cells, the characteristic inflection points of the battery cells 1 to 5 are 40%, 45%, 55%, 60%, and 70% respectively. If the characteristic inflection points of the battery cells 3, 4, and 5 are detected, when the balancing operation is performed, balancing can be started for the battery cells 3 and 4 based on the characteristic inflection point of the battery cell 5, and balancing can also be started for the battery cells 1 and 2. The battery cells 1 and 2 can be balanced by using a smaller default balancing amount. For example, the default balancing amount can be 3% or 5%. The value of the default balancing amount is not limited here and can be set according to actual conditions.

[0195] For the target battery cell being the battery cell with the lowest voltage, the second battery cell without the detected characteristic inflection point is balanced based on the default balancing amount, so that the balancing efficiency is improved.

[0196] FIG. 4 is a flowchart of another battery balancing method provided by an embodiment of the present application. As shown in FIG. 4, the method comprises the following steps. When the battery is powered on to start charging, it is detected whether it is direct current charging. When it is direct current charging, it is detected whether the time difference between the current time and the ideal balancing state time is greater than 2 months. If yes, it is determined whether 5% of the power is charged. If yes, the SOCAh (the current state of charge based on ampere-hour integration) is calculated. When the SOCAh is less than or equal to SOCAh0 (SOCAh0 is the drop current starting point recorded before each power-off, that is, the left end point of the target detection interval), it is determined that the drop current interval is SOCAh0 to SOCAh0+15%. When the SOCAh is greater than SOCAh0, it is determined that the drop current interval is SOCAh to SOCAh+15%. The drop current is performed in the above interval, and the characteristic inflection points of the battery cells are detected. It is determined whether the battery cell with the detected characteristic inflection point meets the preset condition. If yes, the balancing operation is performed. If no, the interval for performing the drop current operation is adjusted, and the above steps are performed in the next power-on. After the balancing operation is completed, it is determined whether the ideal balancing state is reached. If yes, the ideal balancing state time is recorded, and SOCAh0 is adjusted to a default value, for example, 40%. The drop current starting point is 40% when the next balancing operation is needed. If the ideal balancing state is not reached, the interval for performing the drop current operation is adjusted, and the balancing operation is continued in the next power-on.

[0197] The scheme of the present application can perform current reduction charging on a specific interval length in a battery direct current charging mode, detect the characteristic inflection point of the battery cell in the interval, ensure the charging speed, and solve the problem of the inability to start the long-term fast charging user balancing. In addition, by tracking and adjusting the position of the current reduction starting point, it is not necessary to detect all the characteristic inflection points of the battery cells in one charging process, and the battery pack in a poor balancing state can still achieve a balanced state of the battery pack through multiple charging.

[0198] The specific values in the above method are an example, and the present application does not specifically limit each value.

[0199] In the embodiments disclosed in the present application, the characteristic inflection point can be determined according to the following steps: in the process of charging the battery based on the charging current value in the current current reduction interval, the battery needs to be detected to determine the cell voltage and cell capacity of the plurality of single battery cells in the battery; then, the voltage-capacity curve corresponding to the cell voltage and cell capacity is determined, and specifically, the cell capacity can be taken as the horizontal coordinate, and the cell voltage can be taken as the vertical coordinate to construct the voltage-capacity curve corresponding thereto. Next, the controller analyzes and processes the voltage-capacity curve corresponding to each single battery cell, for example, differentiates the voltage-capacity curve corresponding to each single battery cell to determine the voltage characteristic inflection point corresponding to each single battery cell. Finally, the controller determines the characteristic inflection point of the single battery cell based on the voltage characteristic inflection point and the voltage-capacity curve corresponding to the single battery cell, and further determines the inflection point data corresponding to the characteristic inflection point, wherein the inflection point data includes the cell capacity corresponding to the horizontal coordinate and the cell voltage corresponding to the vertical coordinate, so as to perform subsequent control based on the determined characteristic inflection point and inflection point data. In addition, the characteristic inflection point can also be determined according to the voltage-capacity curve of the battery or the voltage-SOC curve of the battery, and the overall determination method is consistent with the foregoing manner, which will not be further described. In the method disclosed in the embodiments of the present application, the characteristic inflection point generally refers to the data corresponding to the horizontal coordinate, i.e., the capacity / SOC / capacity, etc.

[0200] In the embodiments disclosed in the present application, the above charging and discharging control method is generally applied to a lithium iron phosphate battery or other battery types containing a two-end voltage platform existing in the middle section. Specifically, when charging the battery, a voltage platform region is included, because the voltage variation amplitude is small in the platform region, and therefore the charging and discharging control method disclosed in the present application can be used to determine the capacity of the plurality of single battery cells, and further determine the capacity difference between the plurality of single battery cells to improve the service life of the battery. The battery containing a two-end voltage platform existing in the middle section refers to a battery including two slope sections and a platform end in the battery charging process, wherein the platform end is located between the two slope sections.

[0201] FIG. 5 is a structural schematic diagram of a battery balancing device 50 provided by an embodiment of the present application, and the device comprises:

[0202] a balancing module 501, configured to perform a balancing operation on the partial battery cells after determining the feature inflection point of the partial battery cells in the target detection interval during the battery charging;

[0203] wherein the current in the target detection interval is less than the current in the non-target detection interval.

[0204] Optionally, the balancing module 501 is specifically configured to determine the balancing operation of the partial battery cells based on the feature inflection point of the partial battery cells determined in the target detection interval during the battery charging.

[0205] Optionally, the apparatus further comprises a charging control module configured to:

[0206] when the current state parameter of the battery is in the target detection interval, charge the battery with a first current and determine the feature inflection point of the partial battery cells;

[0207] wherein the target detection interval is an interval in which the feature inflection point of the partial battery cells can be detected; in the non-target detection interval, the battery is charged with a second current, and the first current is less than the second current.

[0208] Optionally, the apparatus further comprises a first processing module configured to:

[0209] determine a target detection interval corresponding to a next charging process;

[0210] in the next charging process, perform feature inflection point detection based on the corresponding target detection interval, and determine a balancing operation based on the detected feature inflection point, until the feature inflection points of all battery cells are detected based on the target detection interval in a charging process.

[0211] Optionally, when determining the target detection interval corresponding to the next charging process, the first processing module is specifically configured to perform at least one of the following:

[0212] when there is a battery cell with the highest voltage value and there is no battery cell with the lowest voltage value in the partial battery cells, determining the target detection interval corresponding to the next charging process according to the balancing operation result;

[0213] when there is a battery cell with the lowest voltage value in the partial battery cells, keeping the target detection interval unchanged;

[0214] if there is no battery cell with the highest voltage value and no battery cell with the lowest voltage value in the partial battery cells, moving the target detection interval in a preset direction to determine the target detection interval corresponding to the next charging process.

[0215] Optionally, the apparatus further comprises a second processing module configured to:

[0216] when the battery is charged with the first current, if the current state parameter of the battery cell with the highest voltage value is greater than the preset state parameter, the target detection interval is adjusted to a default interval;

[0217] or, when the feature turning points of all battery cells in the battery are detected, the target detection interval is adjusted to the default interval, or the target detection interval is adjusted to the target detection interval corresponding to the current charging.

[0218] Optionally, when the part of the battery cells has the battery cell with the highest voltage value and does not have the battery cell with the lowest voltage value, the left end point of the target detection interval corresponding to the next charging process is the minimum value in the current feature turning points corresponding to each battery cell;

[0219] wherein, the current feature turning point of the battery cell is determined by the feature turning point of the battery cell before the equalization and the actual equalization amount of the battery cell in the equalization operation.

[0220] Optionally, when the part of the battery cells has the battery cell with the highest voltage value and does not have the battery cell with the lowest voltage value, the left end point of the target detection interval corresponding to the next charging process is the sum of the current left end point and a target value; the target value is the minimum value in the actual equalization amount corresponding to each battery cell; or, the target value is a fixed value.

[0221] Optionally, the charging control module, when the current state parameter of the battery is in the target detection interval, charges the battery with the first current and determines the feature turning points of the part of the battery cells, is specifically configured to:

[0222] determine the current state parameter of the battery when the current charging process meets a preset condition;

[0223] if the current state parameter is less than or equal to the left end point of the target detection interval, charge the battery with the first current when the state parameter of the battery reaches the target detection interval, and detect the feature turning points of the battery.

[0224] Optionally, the charging control module, when the current state parameter of the battery is in the target detection interval, charges the battery with the first current and determines the feature turning points of the part of the battery cells, is further configured to:

[0225] if the current state parameter is greater than the left end point of the target detection interval, charge the battery with the first current when the state parameter of the battery is in the corrected target detection interval, and detect the feature turning points of the battery; wherein, the corrected target detection interval is an interval with the current state parameter as the left end point.

[0226] Optionally, lengths of the target detection intervals in any of the charging processes are equal.

[0227] Optionally, the charging control module charges the battery with the first current when the current state parameter of the battery is in the target detection interval, and determines the characteristic inflection point of the partial battery cells, and specifically is configured to:

[0228] At the beginning of the charging, if a time difference from an ideal balanced state time is greater than or equal to a preset time difference, the battery is charged with the first current in the target detection interval, and the characteristic inflection points of the battery cells are detected to determine the characteristic inflection points of the partial battery cells; wherein the ideal balanced state time represents a time when the characteristic inflection points of all battery cells are detected in the target detection interval in any charging process, and the balancing operation of all battery cells is completed.

[0229] Optionally, the charging control module is further configured to: at the beginning of the charging, if a time difference from the ideal balanced state time is less than the preset time difference, the battery is charged with the second current in the current charging process.

[0230] Optionally, the balancing module 501 is configured to, when determining the balancing operation based on the characteristic inflection points of the partial battery cells:

[0231] determine the balancing operation based on the characteristic inflection points of the partial battery cells, so that the characteristic inflection points of at least part of the battery cells coincide in the next charging process; or so that the difference between the characteristic inflection points of the partial battery cells in the next charging process is less than the difference between the characteristic inflection points of the partial battery cells in the current charging process.

[0232] Optionally, an absolute value of a difference between a left end point of the current target detection interval and a left end point of the next target detection interval is X, and a minimum value of absolute values of differences between the characteristic inflection points of each battery cell in the current target detection interval and the characteristic inflection points of the corresponding battery cells in the next target detection interval is Y, wherein X is less than or equal to Y, and wherein the characteristic inflection points are the state of charge of the battery cell or the capacity of the battery cell.

[0233] Optionally, the balancing module 501 is configured to, when determining the balancing operation of the partial battery cells:

[0234] if there is a target battery cell in the partial battery cells, at least balancing operation is performed on the partial battery cells;

[0235] wherein the target battery cell is the battery cell with the highest voltage value or the battery cell with the lowest voltage value in the plurality of battery cells.

[0236] Optionally, the equalization module 501 is specifically configured to:

[0237] In the first battery cell in which the feature inflection point is detected, any of the first battery cells other than the reference battery cell is equalized according to a target equalization amount; the reference battery cell is the battery cell corresponding to the highest value of the feature inflection point in the first battery cell; and the target equalization amount is the difference between the feature inflection point corresponding to the first battery cell and the feature inflection point corresponding to the reference battery cell.

[0238] Optionally, the apparatus further comprises a third processing module configured to:

[0239] If the target battery cell is the battery cell with the lowest voltage value among the plurality of battery cells, any of the second battery cells in which the feature inflection point is not detected is equalized according to a default equalization amount.

[0240] The battery equalization apparatus provided by the embodiments of the present application can implement the battery equalization method of the embodiments shown in FIG. 2, and has similar implementation principles and technical effects, which will not be described here.

[0241] FIG. 6 is a schematic diagram of the hardware structure of a controller provided by an embodiment of the present application. As shown in FIG. 6, the controller provided by the embodiment of the present application comprises at least one processor 601 and a memory 602. The processor 601 and the memory 602 are connected through a bus 603.

[0242] In the specific implementation process, the at least one processor 601 executes the computer execution instructions stored in the memory 602, so that the at least one processor 601 executes the method in the above method embodiments.

[0243] The specific implementation process of the processor 601 can refer to the above method embodiments, which has similar implementation principles and technical effects, and will not be described here.

[0244] When the battery is applied in a vehicle, the controller can be a battery management system BMS, and can also be a vehicle controller.

[0245] In the embodiment shown in FIG. 6, it should be understood that the processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), etc. The general-purpose processor can be a microprocessor or can also be any conventional processor, etc. The steps of the method disclosed in the application can be directly embodied as hardware processor execution, or executed by a combination of hardware and software modules in the processor.

[0246] The memory can include a high-speed RAM memory, and can also include a non-volatile storage NVM, such as at least one disk memory.

[0247] The bus can be an industry standard architecture (ISA) bus, a peripheral component (PCI) bus, or an extended industry standard architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the convenience of representation, the bus in the drawings of the present application does not limit only one bus or one type of bus.

[0248] The embodiment of the present application also provides a power utilization device, comprising: a battery comprising a plurality of battery cells; and a controller configured to perform the method of the method embodiment.

[0249] The embodiment of the present application also provides a computer readable storage medium, and the computer readable storage medium stores computer execution instructions, and when the processor executes the computer execution instructions, the method of the method embodiment is implemented.

[0250] The embodiment of the present application also provides a computer program product, comprising a computer program, and when the processor executes the computer program, the method of the method embodiment is implemented.

[0251] The computer readable storage medium described above can be realized by any type of volatile or nonvolatile storage devices or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special purpose computer.

[0252] An exemplary readable storage medium is coupled to the processor, so that the processor can read information from the readable storage medium, and can write information to the readable storage medium. Of course, the readable storage medium can also be an integral part of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (ASIC). Of course, the processor and the readable storage medium can also exist as discrete components in the device.

[0253] It should be noted that in this paper, the term "include", "contain" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0254] The above-mentioned sequence numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0255] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment method can be realized by software and necessary general hardware platform, of course, it can also be realized by hardware, but in many cases, the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), including a plurality of instructions for making a terminal device (which can be a mobile phone, computer, server, air conditioner or network device) execute the method described in each embodiment of the present application.

[0256] The above merely preferred embodiments of the present application and are not intended to limit the patent scope of the present application, any equivalent structure or equivalent process transformation using the content of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A battery equalization method characterized by, The method comprises: After determining the characteristic inflection point of the partial battery cell in the target detection interval during battery charging, performing balancing operation on the partial battery cell; Wherein, the current in the target detection interval is less than the current in the non-target detection interval.

2. The method of claim 1, wherein, The balancing operation on the partial battery cell after determining the characteristic inflection point of the partial battery cell in the target detection interval during battery charging comprises: Determining the balancing operation of the partial battery cell based on the characteristic inflection point of the partial battery cell determined in the target detection interval during battery charging.

3. The method according to claim 1 or 2, characterized in that, The method further comprises: When the current state parameter of the battery is in the target detection interval, charging the battery with a first current and determining the characteristic inflection point of the partial battery cell; Wherein, the target detection interval is an interval in which the characteristic inflection point of the partial battery cell can be detected; in the non-target detection interval, the battery is charged with a second current, and the first current is less than the second current.

4. The method of claim 3, wherein, The method further comprises: Determining the target detection interval corresponding to the next charging process; In the next charging process, performing characteristic inflection point detection based on the corresponding target detection interval, and determining the balancing operation based on the detected characteristic inflection point, until the characteristic inflection points of all battery cells are detected based on the target detection interval in one charging process.

5. The method of claim 4, wherein, Determining the target detection interval corresponding to the next charging process comprises at least one of the following: When there is a battery cell with the highest voltage value in the partial battery cell and there is no battery cell with the lowest voltage value, determining the target detection interval corresponding to the next charging process according to the balancing operation result; When there is a battery cell with the lowest voltage value in the partial battery cell, the target detection interval remains unchanged; If there is no battery cell with the highest voltage value and no battery cell with the lowest voltage value in the partial battery cell, moving the target detection interval in a preset direction to determine the target detection interval corresponding to the next charging process.

6. The method of claim 4, wherein, The method further comprises: When the battery is charged with the first current, if the current state parameter of the battery cell with the highest voltage value is greater than the preset state parameter, adjusting the target detection interval to a default interval; Or, when the characteristic inflection points of all battery cells in the battery are detected, adjusting the target detection interval to the default interval, or adjusting the target detection interval to the target detection interval corresponding to the current charging.

7. The method of claim 5, wherein, When there is a battery cell with the highest voltage value in the partial battery cell and there is no battery cell with the lowest voltage value, the left end point of the target detection interval corresponding to the next charging process is the minimum value of the current characteristic inflection points corresponding to each battery cell respectively; Wherein, the current characteristic inflection point of the battery cell is determined by the characteristic inflection point of the battery cell before balancing and the actual balancing amount of the battery cell in the balancing operation.

8. The method of claim 5, wherein, When there is a battery cell with the highest voltage value in the partial battery cell and there is no battery cell with the lowest voltage value, the left end point of the target detection interval corresponding to the next charging process is the sum of the current left end point and a target value; The target value is the minimum value of the actual balancing amounts corresponding to each battery cell respectively; or, the target value is a fixed value.

9. The method of claim 3, wherein, charging the battery with a first current when the current state parameter of the battery is in the target detection interval, and determining the characteristic inflection point of the partial battery cells, comprising: determining the current state parameter of the battery when the current charging process meets a preset condition; if the current state parameter is less than or equal to the left endpoint of the target detection interval, charging the battery with a first current when the state parameter of the battery reaches the target detection interval, and detecting the characteristic inflection point of the battery.

10. The method of claim 9, wherein, charging the battery with a first current when the current state parameter of the battery is in the target detection interval, and determining the characteristic inflection point of the partial battery cells, further comprising: if the current state parameter is greater than the left endpoint of the target detection interval, charging the battery with a first current when the state parameter of the battery is in the corrected target detection interval, and detecting the characteristic inflection point of the battery; wherein the corrected target detection interval is an interval with the current state parameter as the left endpoint.

11. The method of claim 4 or 5, wherein, The length of the target detection interval in any of the charging processes is equal.

12. The method of claim 3, wherein, charging the battery with a first current when the current state parameter of the battery is in the target detection interval, and determining the characteristic inflection point of the partial battery cells, comprising: at the beginning of charging, if the time difference from the ideal equilibrium state time is greater than or equal to a preset time difference, charging the battery with a first current in the target detection interval, and detecting the characteristic inflection point of the battery cells to determine the characteristic inflection point of the partial battery cells; wherein the ideal equilibrium state time represents the time when all battery cells detect the characteristic inflection point in the target detection interval and complete the balancing operation of all battery cells in any charging process.

13. The method of claim 12, wherein, The method further comprises: at the beginning of charging, if the time difference from the ideal equilibrium state time is less than the preset time difference, charging the battery with the second current in the current charging process.

14. The method according to any one of claims 1 to 13, characterized in that, determining the balancing operation based on the characteristic inflection point of the partial battery cells, comprising: determining the balancing operation based on the characteristic inflection point of the partial battery cells, so that at least part of the characteristic inflection points of the battery cells coincide in the next charging process; or so that the difference between the characteristic inflection points of the partial battery cells in the next charging process is less than the difference between the characteristic inflection points of the partial battery cells in the current charging process.

15. The method according to any one of claims 1 to 13, characterized in that, The absolute value of the difference between the left endpoint of the current target detection interval and the left endpoint of the next target detection interval is X, and the minimum value of the absolute value of the difference between the characteristic inflection points of each battery cell in the current target detection interval and the characteristic inflection points of the corresponding battery cells in the next target detection interval is Y, wherein X is less than or equal to Y, and wherein the characteristic inflection point is the state of charge of the battery cell or the capacity of the battery cell.

16. The method according to any one of claims 1 to 13, characterized in that, determining the balancing operation of the partial battery cells, comprising: if there is a target battery cell in the partial battery cells, at least balancing the partial battery cells; wherein the target battery cell is the battery cell with the highest voltage or the battery cell with the lowest voltage among the plurality of battery cells.

17. The method of claim 16, wherein, at least balancing the partial battery cells, comprising: In the first battery cell in which the feature inflection point is detected, any of the first battery cells except a reference battery cell is subjected to the equalization operation according to a target equalization amount; the reference battery cell is the battery cell corresponding to the highest value of the feature inflection point in the first battery cells; and the target equalization amount is the difference between the feature inflection point corresponding to the first battery cell and the feature inflection point corresponding to the reference battery cell.

18. The method of claim 16, wherein, The method further comprises: If the target battery cell is the battery cell with the lowest voltage value among the plurality of battery cells, any second battery cell in which the feature inflection point is not detected is subjected to the equalization operation according to a default equalization amount.

19. A battery equalization device, characterized by, The device comprises: An equalization module configured to, after determining the feature inflection point of the part of the battery cells in the target detection interval during the charging of the battery, subject the part of the battery cells to the equalization operation. The current in the target detection interval is less than the current in a non-target detection interval.

20. A controller, comprising: Comprise: At least one processor and a memory; The memory stores computer-executable instructions; The at least one processor executes the computer-executable instructions stored in the memory, so that the at least one processor executes the method according to any one of claims 1-18.

21. An electrical device, comprising: Comprise: A battery and a controller, the battery comprising a plurality of battery cells; and the controller configured to execute the method according to any one of claims 1-18.

22. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, and when the processor executes the computer-executable instructions, the method according to any one of claims 1-18 is implemented.

23. A computer program product, characterised in that, A computer program is executed by the processor to implement the method according to any one of claims 1-18.

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