Battery equalization method and device, controller and electric equipment

Abstract

The invention provides a battery equalization method and device, a controller and electric equipment, and the method comprises the steps: determining the characteristic inflection points of a part of cells in a target detection interval during the charging of a battery, carrying out the equalization operation of the part of cells, enabling the current in the target detection interval to be smaller than the current in a non-target detection interval, and enabling the current in the non-target detection interval to be smaller than the characteristic inflection points of the part of cells to be smaller than the characteristic inflection points of the part of cells. According to the invention, only the characteristic inflection points of part of the cells need to be detected in one charging process, so that in the whole 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, so that the charging efficiency can be improved, and the charging duration of the whole charging process is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and in particular to a battery balancing method, device, controller and electrical equipment. Background Art

[0002] Battery cells (such as lithium-ion batteries) have a voltage of only a few volts. Whether used as a power source for electric vehicles or in backup power applications, the electrical characteristics of these cells cannot meet the voltage and current requirements of the load under operating conditions. Therefore, to increase the voltage of the power battery, several battery cells (cells) can be connected in series to form a group.

[0003] When a battery pack is used for a long time, differences in temperature, electrode materials, or usage can cause some cells to have a higher self-discharge rate while others have a lower self-discharge rate. This can cause the battery pack's usable capacity to be less than the capacity of the smallest cell, affecting the overall capacity of the battery pack. Therefore, balancing technology is needed to adjust the capacity of each cell in the battery pack. Summary of the Invention

[0004] The present invention provides a battery balancing method, device, controller and electrical equipment to solve the problem in the prior art that capacity differences exist between multiple battery cells, thereby affecting the capacity of the entire battery pack.

[0005] In a first aspect, the present invention provides a battery balancing method, the method comprising:

[0006] After characteristic inflection points of some cells are determined within a target detection interval during battery charging, a balancing operation is performed on the some cells; wherein the current within the target detection interval is smaller than the current within the non-target detection interval.

[0007] Optionally, after determining characteristic inflection points of some battery cells within a target detection interval during battery charging, performing a balancing operation on the some battery cells includes:

[0008] Based on characteristic inflection points of some of the battery cells determined within a target detection interval during battery charging, a balancing operation of the some of the battery cells is determined.

[0009] Optionally, the method further includes:

[0010] When the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells;

[0011] The target detection interval is an interval in which characteristic inflection points of some battery 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.

[0012] Optionally, the method further includes:

[0013] Determine the target detection interval corresponding to the next charging process;

[0014] During the next charging process, characteristic inflection point detection is performed based on the corresponding target detection interval, and balancing operation is determined based on the detected characteristic inflection point, until characteristic inflection points of all cells are detected based on the target detection interval during one charging process.

[0015] Optionally, determining a target detection interval corresponding to the next charging process includes at least one of the following:

[0016] When the battery cell with the highest voltage value exists in the portion of battery cells and the battery cell with the lowest voltage value does not exist, determining the target detection interval corresponding to the next charging process according to the balancing operation result;

[0017] When the battery cell with the lowest voltage value exists in the portion of battery cells, the target detection interval remains unchanged;

[0018] If the battery cell with the highest voltage value and the battery cell with the lowest voltage value do not exist in the part of the battery cells, the target detection interval is moved along the preset direction to determine the target detection interval corresponding to the next charging process.

[0019] Optionally, the method further includes:

[0020] After charging the battery with the first current is completed, 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;

[0021] Alternatively, after the characteristic inflection points of all the 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.

[0022] Optionally, when a cell with the highest voltage value exists in the portion of cells and a 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 minimum value of the current characteristic inflection points corresponding to each cell;

[0023] 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 during the balancing operation.

[0024] Optionally, when there is a cell with the highest voltage value among the said part of the battery cells, and there is no cell with the lowest voltage value, 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 balance amounts corresponding to each battery cell; or, the target value is a fixed value.

[0025] Optionally, when the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells includes:

[0026] When the current charging process meets the preset conditions, determining the current state parameters of the battery;

[0027] If the current state parameter is less than or equal to the left endpoint of the target detection interval, when the battery state parameter reaches the target detection interval, the battery is charged with a first current and a characteristic inflection point detection is performed on the battery.

[0028] Optionally, when the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells further includes:

[0029] If the current state parameter is greater than the left endpoint of the target detection interval, then when the battery state parameter is in the corrected target detection interval, the battery is charged with a first current and a characteristic inflection point detection is performed on the battery; wherein the corrected target detection interval is an interval with the current state parameter as the left endpoint.

[0030] Optionally, the lengths of the target detection intervals in any of the charging processes are equal.

[0031] Optionally, when the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells includes:

[0032] At the start of charging, if the time difference from the ideal equilibrium state moment is greater than or equal to a preset time difference, the battery is charged with a first current in the target detection interval, and characteristic inflection point detection is performed on multiple cells of the battery to determine characteristic inflection points of some of the cells in the battery; wherein the ideal equilibrium state moment represents: during any charging process, the characteristic inflection points of all cells are detected within the target detection interval, and the balancing operation is completed for all cells.

[0033] Optionally, the method further includes: at the start of charging, if the time difference from the ideal equilibrium state moment is less than the preset time difference, charging the battery with the second current during this charging process.

[0034] Optionally, determining the balancing operation based on the characteristic inflection points of the portion of battery cells includes:

[0035] The balancing operation is determined based on the characteristic inflection points of the said part of the battery cells so that the characteristic inflection points of at least part of the battery cells coincide with each other during the next charging process; or so that the difference between the characteristic inflection points of the said part of the battery cells during the next charging process is smaller than the difference between the characteristic inflection points of the said part of the battery cells during the current charging process.

[0036] Optionally, the absolute value of the difference between the left endpoint of this 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 point of each battery cell in this target detection interval and the characteristic inflection point of the corresponding battery cell in the next target detection interval is Y, where X is less than or equal to Y, and where the characteristic inflection point is the state of charge of the battery cell or the capacity of the battery cell.

[0037] Optionally, determining a balancing operation of the portion of battery cells includes:

[0038] If the target battery cell exists in the portion of battery cells, performing a balancing operation on at least the portion of battery cells;

[0039] The target battery cell is the battery cell with the highest voltage value or the battery cell with the lowest voltage value among the multiple battery cells.

[0040] Optionally, performing a balancing operation on at least some of the battery cells includes:

[0041] In the first battery cell where the characteristic inflection point is detected, a balancing operation is performed on any of the first battery cells except a reference battery cell according to a target balancing amount; the reference battery cell is the battery cell corresponding to the highest value of the characteristic inflection point in the first battery cell; the target balancing 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.

[0042] Optionally, the method further includes:

[0043] If the target battery cell is the battery cell with the lowest voltage value among the multiple battery cells, a balancing operation is performed on any second battery cell for which no characteristic inflection point is detected according to a default balancing amount.

[0044] In a second aspect, the present invention provides a battery balancing device, comprising:

[0045] A balancing module, configured to determine characteristic inflection points of some battery cells within a target detection interval during battery charging and then perform a balancing operation on the battery cells;

[0046] The current in the target detection interval is smaller than the current in the non-target detection interval.

[0047] In a third aspect, the present invention 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 as described in any one of the first aspects.

[0050] In a fourth aspect, the present invention provides an electrical device comprising: a battery and a controller, wherein the battery comprises a plurality of battery cells; and the controller is configured to execute any one of the methods described in the first aspect.

[0051] In a fifth aspect, the present invention provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the method described in any one of the first aspects is implemented.

[0052] In a sixth aspect, the present invention provides a computer program product, comprising a computer program, which, when executed by a processor, implements the method as described in any one of the first aspects.

[0053] The present invention provides a battery balancing method, device, controller, and electrical equipment. The method includes: after determining the characteristic inflection points of some battery cells within a target detection interval during battery charging, performing a balancing operation on the battery cells, wherein the current within the target detection interval is smaller than the current within a non-target detection interval. In this application, since only the characteristic inflection points of some battery cells need to be detected during a single charging process, the time period during which the current needs to be reduced is shortened, while the time period during which the current does not need to be reduced is lengthened during the entire charging process, thereby improving charging efficiency and shortening the charging time of the entire charging process. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0055] Figure 1 A charging voltage curve and a voltage difference curve provided by an embodiment of the present invention;

[0056] Figure 2 A flowchart of a battery balancing method provided by an embodiment of the present invention;

[0057] Figure 3 A schematic diagram of equalization according to a detected characteristic inflection point provided by an embodiment of the present invention;

[0058] Figure 4 A schematic flow chart of another battery balancing method provided by an embodiment of the present invention;

[0059] Figure 5 A schematic structural diagram of a battery balancing device provided by an embodiment of the present invention;

[0060] Figure 6 A schematic diagram of the hardware structure of a controller provided in an embodiment of the present invention.

[0061] The above drawings illustrate specific embodiments of the present invention, which will be described in more detail below. These drawings and the accompanying description are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0062] Exemplary embodiments are described in detail herein, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present invention.

[0063] In this document, it should be understood that the terms involved are only used to facilitate understanding and do not represent any limitation on the meaning. In addition, the number of any element in the drawings is for illustration and not limitation, and any naming is only for distinction and does not have any limiting meaning.

[0064] The data involved in the present invention may be data authorized by the user or fully authorized by all parties, and the collection, dissemination, and use of the data shall comply with the requirements of relevant national laws and regulations.

[0065] Because individual battery cells have low energy, they are often connected in series. After a period of use, the capacities of individual cells can vary due to variations in temperature, electrode materials, and usage. Therefore, balancing technology is required to adjust the capacity of each cell to achieve a balanced battery.

[0066] In the prior art, one balancing method involves adjusting the voltage difference between the cells. Specifically, balancing can be initiated based on the voltage difference between the highest-voltage cell in a series battery pack and the other cells when the cell is fully charged. This process requires that the battery be fully charged to trigger balancing; balancing will not be initiated for batteries that are not fully charged for a long period of time.

[0067] Another balancing method is to find the characteristic inflection point based on the differential of the voltage-capacity curve during charging, and align the battery cells based on the characteristic inflection point. This is because the characteristic inflection point of the battery cell is related to the chemical reaction. For the same battery cell, when the initial charge of the battery cell is the same, the corresponding characteristic inflection points during the charging process are the same. Therefore, the difference in the characteristic inflection points of different battery cells can reflect the capacity difference, thereby performing balancing. The above method can trigger the balancing operation when the battery is not fully charged. However, the detection of the characteristic inflection point needs to be performed in a low-current charging mode. In a high-current charging mode, such as fast charging, the characteristic inflection point of the battery cell cannot be detected.

[0068] Figure 1 A charging voltage curve and a voltage difference curve diagram provided by an embodiment of the present invention, such as Figure 1 As shown in the figure, when charging at 0.1C (charging at one-tenth of the rated charge rate, C represents the rated charge rate of the battery), the characteristic inflection point can be detected; when charging at 0.5C, the characteristic inflection point cannot be detected. Therefore, battery balancing cannot be initiated for vehicles that use fast charging for a long time.

[0069] Therefore, balancing will not be possible for vehicles that have not been fully charged and fast-charged for a long time, such as commercial vehicles. As the self-discharge deviation of the battery cells accumulates, the capacity of the entire battery will decrease, and in extreme cases, it may cause the vehicle to break down.

[0070] Based on the above problems, an embodiment of the present application provides a flow chart of a battery balancing method, which includes:

[0071] Step S201: after determining characteristic inflection points of some battery cells within a target detection interval during battery charging, performing a balancing operation on the battery cells;

[0072] The current in the target detection interval is smaller than the current in the non-target detection interval.

[0073] The above method can determine the inflection points of some battery cells by reducing the current, and can shorten the interval for performing the current reduction operation by detecting the characteristic inflection points of some battery cells, thereby shortening the time used for each charging and improving the user experience.

[0074] Furthermore, after determining the characteristic inflection points of some battery cells within the target detection interval during battery charging, performing a balancing operation on the some battery cells includes:

[0075] Based on characteristic inflection points of some of the battery cells determined within a target detection interval during battery charging, a balancing operation of the some of the battery cells is determined.

[0076] The current in the target detection interval is smaller than the current in the non-target detection interval.

[0077] During the battery charging process, the characteristic inflection point of the cell can only be detected when charging in the low-current charging mode. Therefore, during the charging process, the battery can be charged with a low current in the target detection interval and with a high current in the non-target detection interval. In other words, the current in the target detection interval is smaller than the current in the non-target detection interval.

[0078] like Figure 1 As shown, when charging at 0.1C, the characteristic inflection point can be detected, and when charging at 0.5C, the characteristic inflection point cannot be detected. The current in the target detection interval can be a current size at which the characteristic inflection point can be detected. For example, there may be a current threshold, such as 0.2C. When charging at a current less than or equal to the current threshold, the characteristic inflection point can be detected, and when charging at a current greater than the current threshold, the characteristic inflection point cannot be detected. Among them, the current in the target detection interval is less than or equal to the current threshold.

[0079] When the target detection interval is charged at a reduced current, the characteristic inflection point of each cell in the battery can be detected. Optionally, for each cell, the voltage and capacity of the cell can be collected during the reduced current charging period to plot a charging curve, and a differential curve can be obtained based on the charging interval to determine the corresponding characteristic inflection point.

[0080] Determining the balancing operation of some battery cells based on the characteristic inflection points of these battery cells determined within the target detection interval during battery charging means that a balancing operation can be performed on at least some of the battery cells. Optionally, a balancing operation can be performed on all battery cells in which characteristic inflection points have been detected, or a balancing operation can be performed on all battery cells in which characteristic inflection points have been detected and some battery cells in which characteristic inflection points have not been detected. Balancing the battery cells means determining a target balancing amount for the battery cells and performing a balancing operation on the battery cells according to the target balancing amount. The timing for performing the balancing operation can be within a non-target detection interval, or can be within a certain time period after the current charging is completed.

[0081] For example, after detecting the characteristic inflection points of two battery cells, balancing can be performed on at least these two battery cells. That is, balancing can be performed based on the characteristic inflection points of these two battery cells, or balancing can also be performed on these two battery cells and other battery cells. It should be noted that balancing cannot be performed if the characteristic inflection point of only one battery cell is detected.

[0082] In order to improve charging efficiency and shorten charging time, after the characteristic inflection points of some battery cells are detected, the battery can be charged with a larger current until charging is completed.

[0083] For example, during the battery charging process, after connecting to the charger, a portion of the battery can be charged with a larger current before being charged with a smaller current. For example, 5% of the battery can be charged with a current of 0.5C, and then a current of 0.1C can be used to charge. When charging with a current of 0.1C, the characteristic inflection point of each cell can be detected. For example, if there are 5 cells in the battery, after the characteristic inflection points of 2 cells are detected, balancing operations can be performed on at least these 2 cells. In addition, after the characteristic inflection points of these 2 cells are detected, charging can continue with a current of 0.5C.

[0084] The present invention provides a battery balancing method, which includes: after determining characteristic inflection points of some battery cells within a target detection interval during battery charging, performing a balancing operation on the battery cells, wherein the current within the target detection interval is smaller than the current within a non-target detection interval. In this application, since only the characteristic inflection points of some battery cells need to be detected during a single charging process, the time period during which the current needs to be reduced is shortened and the time period during which the current does not need to be reduced is lengthened during the entire charging process, thereby improving charging efficiency and shortening the charging time of the entire charging process.

[0085] Optionally, the method further includes:

[0086] When the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells;

[0087] The target detection interval is an interval in which characteristic inflection points of some battery 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.

[0088] When determining whether to charge the battery with the first current, the determination may be based on a target detection interval. Optionally, during each charging operation, the target detection interval may be obtained first. When the current state parameter of the battery is within the target detection interval, the battery is charged with the first current, and characteristic inflection points of multiple battery cells of the battery are detected.

[0089] Optionally, the current state parameter may be the current state of charge of the battery, and the target detection interval may be a state of charge interval. Alternatively, the current state parameter may be the current capacity of the battery, and the target detection interval may be a capacity interval.

[0090] The battery's State of Charge (SOC) reflects the ratio of the battery's current capacity to its total capacity. As the battery charges, its SOC changes, gradually increasing, and the battery's capacity also increases.

[0091] The target detection interval is the interval during which current reduction is performed. During charging, when the battery's current state parameters fall within this target detection interval, charging is performed at a first current, thereby enabling characteristic inflection point detection for multiple battery cells. When the battery's current state parameters fall outside this target detection interval, charging is performed at a second current. The first current is smaller than the second current.

[0092] For example, when the current state parameter is the current state of charge, if the target detection interval determined during a certain charge is 40%-55%, then when charging the battery, if the current state of charge of the battery is equal to 40%, charging with the first current begins, and charging with the first current stops when the battery's state of charge is equal to 55%. For non-target detection intervals, that is, when the current state of charge of the battery is less than 40% or when the current state of charge is greater than 55%, charging with the second current is performed.

[0093] Exemplarily, the length of the target detection interval can be 15%. This application does not impose any restrictions on the length of the target detection interval, and it can be set according to actual conditions. When the length of the target detection interval is longer, the number of battery cells that detect the characteristic inflection point each time charging may be more, and the time required for this charging will increase; when the length of the target detection interval is shorter, the number of battery cells that detect the characteristic inflection point may be fewer, and the time required for this charging will decrease. 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. Selecting the above range for the length of the target detection interval can, on the one hand, ensure that a certain number of battery cells can detect the characteristic inflection point within the interval, and on the other hand, it can prevent the charging time of the battery from being further reduced.

[0094] Optionally, in one embodiment, the threshold between the first current and the second current is typically in the range of approximately 0.2C to 0.3C, i.e., when the current is greater than 0.3C, no characteristic inflection point will occur. However, in some embodiments, the threshold between the first current and the second current may also be greater than 0.3C, so the specific value needs to be adjusted based on the voltage characteristic curve of the corresponding battery. That is, the threshold between the first current and the second current is determined by adjusting the battery charging current and performing a differential process on the battery voltage characteristic curve to determine whether an inflection point exists.

[0095] By determining when to perform current reduction during the charging process based on the target detection interval, the current of the entire charging process can be accurately controlled.

[0096] Optionally, the method further includes:

[0097] Determine the target detection interval corresponding to the next charging process;

[0098] During the next charging process, characteristic inflection point detection is performed based on the corresponding target detection interval, and balancing operation is determined based on the detected characteristic inflection point, until characteristic inflection points of all cells are detected based on the target detection interval during one charging process.

[0099] During a single charge, if characteristic inflection points are detected for some cells within the target detection interval, current reduction can be stopped and balancing can be performed on the cells where these inflection points were detected. However, during this process, only the characteristic inflection points of some cells can be detected during a single charge. After balancing, only some of the cells will have the same charge level—that is, the same characteristic inflection points. However, for batteries, balancing means ensuring that all cells in the battery have the same charge level, so multiple charges are required to achieve full battery balancing. To detect the characteristic inflection points of more cells during the next charge, the target detection interval corresponding to the next charge can be determined at the end of the previous charge.

[0100] During the next charging process, the current can be reduced based on the corresponding target detection interval, and the characteristic inflection point of each battery cell can be detected to continue the balancing operation.

[0101] Optionally, the target detection interval may be moved to the left or right to determine a target detection interval corresponding to the next charging process. Figure 3A schematic diagram of balancing based on detected characteristic inflection points is provided for an embodiment of the present invention. For example, there are 5 battery cells, and the characteristic inflection points of 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%, then the characteristic inflection points of the first three battery cells can be detected. After the balancing operation (discharging the battery cells with lower characteristic inflection point values), the characteristic inflection points of the three battery cells are all 55%. The target detection interval of the second charging process is 50%-65%, then the characteristic inflection points of the first three battery cells can be detected to be 55%, and the characteristic inflection point of the fourth battery cell is 60%. After the balancing operation, the characteristic inflection points of the first four battery cells are all 60%. The target detection interval of the third charging process is 60%-75%, then the characteristic inflection points of 5 battery cells can be detected, and balancing of all battery cells can be achieved.

[0102] By determining the target detection interval corresponding to the next charging process, the battery is continuously charged with the first current within the target detection interval of the next charging to perform characteristic inflection point detection, thereby achieving balancing of all battery cells and improving the balancing effect.

[0103] Optionally, determining a target detection interval corresponding to the next charging process includes at least one of the following:

[0104] When a cell with the highest voltage value exists in the portion of the cells and a cell with the lowest voltage value does not exist, determining the target detection interval corresponding to the next charging process according to the balancing operation result;

[0105] When the battery cell with the lowest voltage value exists in the portion of battery cells, the target detection interval remains unchanged;

[0106] If the battery cell with the highest voltage value and the battery cell with the lowest voltage value do not exist in the part of the battery cells, the target detection interval is moved along the preset direction to determine the target detection interval corresponding to the next charging process.

[0107] If the battery does not reach the ideal balanced state after the current charge is completed (the moment when the characteristic inflection points of all cells are detected within the target detection interval and the balancing operation is completed for all cells), it is necessary to continue the current reduction operation during the next charge to detect the characteristic inflection points of more cells.

[0108] When determining the target detection interval corresponding to the next charging process, the target detection interval can be determined in different ways according to different situations, so that the characteristic inflection points of more battery cells can be more easily detected based on the determined target detection interval during the next charging.

[0109] Optionally, when the characteristic inflection points of the battery cell with the highest voltage value and the battery cell with the lowest voltage value are detected at the same time, it means that the characteristic inflection points of all battery cells have been detected during this charging process, and balancing operations can be performed. If the target balancing amount of a certain battery cell is not completed (the target balancing amount of a certain battery cell is 10%, and the actual balancing amount is 5%), there is no need to modify the target detection interval again. The characteristic inflection points of each battery cell can continue to be detected based on the target detection interval during the next charging, and the balancing operation can continue.

[0110] Optionally, when only the characteristic inflection point of the battery cell with the lowest voltage value is detected, there is no need to modify the target detection interval. This is because the balancing process hopes to achieve the characteristic inflection points of all battery cells being the same as the characteristic inflection point of the battery cell with the lowest voltage value. When the target detection interval changes, the characteristic inflection point of the battery cell with the lowest voltage value may not be detected next time, and thus the balancing operation cannot be achieved. Therefore, at this time, the battery cells with detected characteristic inflection points and the battery cells without detected characteristic inflection points can be balanced separately, so that the characteristic inflection points of each battery cell can be close to the characteristic inflection point of the battery cell with the lowest voltage value. After multiple operations, the characteristic inflection points of all battery cells can be detected within the target detection interval, and thus the balancing operation can be performed on each battery cell based on the target balancing amount corresponding to each battery cell.

[0111] By keeping the target detection interval unchanged when the characteristic inflection point of the cell with the lowest voltage is detected, the characteristic inflection point of the cell with the lowest voltage can be detected during each charge, and the other cells can be balanced based on this characteristic inflection point.

[0112] Optionally, when the characteristic inflection point of the cell with the highest voltage value is detected and the characteristic inflection point of the cell with the lowest voltage value is not detected, the balancing operation can be initiated. However, it may not be possible to complete the target balancing amount for each cell with a detected characteristic inflection point during a single balancing process. In this case, when determining the target detection interval for the next charging process, the target detection interval can be determined based on the balancing operation results. The balancing operation results can reflect the characteristic inflection points of each cell after the balancing operation.

[0113] When the cell with the highest voltage value and the cell with the lowest voltage value do not exist among the cells where the characteristic inflection point is detected, the balancing operation cannot be started. Therefore, the target detection interval needs to be adjusted to detect the characteristic inflection point of the cell with the highest voltage value or the characteristic inflection point of the cell with the lowest voltage value.

[0114] From the previous analysis, it can be seen 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 shifted along the 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.

[0115] Optionally, the target detection interval can be shifted to the left to obtain the target detection interval corresponding to the next charging process, so as to perform characteristic inflection point detection 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.

[0116] Optionally, the target detection interval can be shifted to the right to obtain the target detection interval corresponding to the next charging process, so as to perform characteristic inflection point detection 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.

[0117] Optionally, shifting the target detection interval to the left means that the starting point of the target detection interval during the next charge is smaller than the starting point of the target detection interval during the current charge, or that the starting point of the target detection interval during the current charge is subtracted from a preset value to determine the starting point of the target detection interval during the next charge. Shifting the target detection interval to the right means that the starting point of the target detection interval during the next charge is larger than the starting point of the target detection interval during the current charge, or that the starting point of the target detection interval during the current charge is added to a preset value to determine the starting point of the target detection interval during the next charge.

[0118] For example, there are 5 battery cells, and the characteristic inflection points of battery cells 1 to 5 are 35%, 45%, 55%, 60%, and 70% respectively, and the voltage of each battery cell can be known. Battery cell 1 is the battery cell with the highest voltage value, and battery cell 5 is the battery cell with the lowest voltage value. When the target detection interval is 45%-60%, the characteristic inflection points of battery cells 2, 3, and 4 can be detected, and balancing cannot be enabled at this time. Therefore, the target detection interval can be shifted to the left. For example, if it is shifted by 5%, the target detection interval will be 40%-55%, and the characteristic inflection point of battery cell 1 still cannot be detected. At this time, the target detection interval can continue to be shifted to the left. For example, if it is shifted by 5%, the target detection interval will be 35%-50%, and the characteristic inflection point of battery cell 1 can be detected. Similarly, the target detection interval can also be shifted to the right until the characteristic inflection point of battery cell 5 is detected.

[0119] By moving the target detection interval along the preset direction when there is no cell with the highest voltage value or the cell with the lowest voltage value among the cells where the characteristic inflection point is detected, the characteristic inflection point of the cell with the highest voltage value or the characteristic inflection point of the cell with the lowest voltage value can be successfully detected, thereby meeting the conditions for starting the balancing operation.

[0120] The target detection interval for the next charge is determined based on the type of the battery cell in which the characteristic inflection point is detected, so that the characteristic inflection points of more battery cells can be detected during the next charge to avoid ineffective current reduction.

[0121] Optionally, the method further includes:

[0122] After charging the battery with the first current is completed, 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;

[0123] Alternatively, after the characteristic inflection points of all the 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.

[0124] The state parameter may be a state of charge or a battery capacity, and the preset state parameter may be a preset state of charge or a preset battery capacity.

[0125] After charging is complete, if the current state parameter of the cell with the highest voltage is greater than a preset state parameter, for example, if the current state of charge of the cell with the highest voltage is greater than a preset state of charge, such as 95%, then the battery is close to an ideal equilibrium state. In this case, the target detection interval can be adjusted to the default interval, such as 40%-60%.

[0126] Furthermore, when the characteristic inflection points of all cells in the battery are detected and balancing is completed for each cell, that is, after the balancing operation, the characteristic inflection points of each cell are the same, the target detection interval can be adjusted to the default interval. Alternatively, the target detection interval can be adjusted to the target detection interval corresponding to the current charging operation, so that when the current reduction operation is subsequently performed based on the target detection interval, the characteristic inflection points of more cells are likely to be detected.

[0127] For example, when characteristic inflection points of all cells are detected within a target detection interval of 50% to 70% and the balancing operation is completed, the interval of 50%-70% may be determined as the adjusted target detection interval.

[0128] The adjusted target detection interval is not the target detection interval for the next charge. If the battery is already balanced and no further equalization is required for a period of time, and after a period of time, the battery needs to be balanced again through multiple charges, the adjusted target detection interval will become the initial target detection interval for characteristic inflection point detection during the first charge after the need for equalization is detected.

[0129] By adjusting the target detection interval corresponding to the first charge in the balancing operation, the characteristic inflection points of multiple cells can be detected at one time as much as possible, thereby reducing the number of adjustments to the target detection interval to complete battery balancing.

[0130] Optionally, when a cell with the highest voltage value exists in the portion of cells and a 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 minimum value of the current characteristic inflection points corresponding to each cell;

[0131] 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 during the balancing operation.

[0132] When the characteristic inflection point of the cell with the highest voltage is detected and the characteristic inflection point of the cell with the lowest voltage is not detected, the target detection interval for the next charging process can be determined based on the balancing operation results. The actual balancing amount of each cell may be different from the target balancing amount. The current characteristic inflection point of the cell can be determined based on the characteristic inflection point of the cell before balancing and the actual balancing amount of the cell.

[0133] When determining the target detection interval corresponding to the next charging process, it can be determined based on the current characteristic inflection points of each battery cell undergoing the balancing operation, thereby determining the minimum value of the current characteristic inflection points corresponding to each battery cell as the left endpoint of the target detection interval corresponding to the next charging process, wherein the length of the target detection interval can be a fixed length, and exemplarily, the fixed length can be 15%, which is not specifically limited in this application.

[0134] For example, when characteristic inflection points of three cells are detected, the characteristic inflection points of cells 1 to 3 are 40%, 45%, and 55%, respectively. If the target balancing amount is not achieved at the end of a charging process, and the actual balancing amount of cells 1 and 2 is 3%, then the current characteristic inflection point of cell 1 is 43%, the current characteristic inflection point of cell 2 is 48%, and the current characteristic inflection point of cell 3 is 55%. Then 43% can be determined as the left endpoint of the target detection interval corresponding to the next charging process, so that during the next charging, the current can be reduced from the 43% position to just detect the characteristic inflection point of cell 1. On the contrary, if the current is still reduced from the 40% position, since there is no characteristic inflection point of any cell in the interval from 40% to 42%, the current reduction in the interval from 40% to 42% is invalid, and the possibility of detecting more characteristic inflection points of cells is reduced compared to starting the current reduction from the 43% position.

[0135] By determining the minimum value of the current characteristic inflection points corresponding to each battery cell as the left end point of the target detection interval, the invalid current reduction interval in the target detection interval is reduced, which can increase the possibility of detecting more battery cell characteristic inflection points.

[0136] Optionally, when there is a cell with the highest voltage value among the said part of the battery cells, and there is no cell with the lowest voltage value, 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 balance amounts corresponding to each battery cell; or, the target value is a fixed value.

[0137] When the cell with the highest voltage exists in the portion of cells and the cell with the lowest voltage does not exist, the actual balancing amount of each cell may also be determined when determining the target detection interval corresponding to the next charging process. The target detection interval is determined based on a target value, that is, a minimum value or a fixed value among the actual balancing amounts of each cell. For example, the fixed value may be a relatively small value, such as 3%.

[0138] 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. When the target detection interval is adjusted, the length of the target detection interval remains unchanged, and 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.

[0139] For example, the actual balanced amounts of cell 1, cell 2, and cell 3 are 4%, 5%, and 5%, respectively. Then, the target detection interval may be moved by 4% to determine the target detection interval corresponding to the next charging process.

[0140] By determining the target detection interval corresponding to the next charging process based on a fixed value, it has the advantages of simple and convenient operation. The target detection interval corresponding to the next charging process is determined based on the minimum value of the actual balanced amount of each battery cell, which can ensure that at least the characteristic inflection point of each battery cell detected during the current charging is detected during the next charging.

[0141] Optionally, when the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells includes:

[0142] When the current charging process meets the preset conditions, determining the current state parameters of the battery;

[0143] If the current state parameter is less than or equal to the left endpoint of the target detection interval, when the battery state parameter reaches the target detection interval, the battery is charged with a first current and a characteristic inflection point detection is performed on the battery.

[0144] When charging is performed with the first current according to the target detection interval, the current state of charge of the battery may be calculated, and the detection interval for actually performing the current reduction operation may be determined based on the current state of charge and the target detection interval.

[0145] When the battery starts to be charged, it is first determined whether the battery needs to be balanced based on the ideal balanced state. When it is determined that the battery needs to be balanced, a portion of the power can be charged first, for example, 5% of the power. At this time, the detection interval for the actual current reduction operation can be determined.

[0146] The current state parameter is the current state of charge or the current power (capacity). The following uses the current state of charge as an example for explanation.

[0147] Optionally, the current state of charge may be a state of charge independently calculated based on ampere-hour integration. The actual vehicle SOC is not used here to prevent the voltage-corrected SOC from interfering with the selection of the current reduction position.

[0148] Optionally, when the current charging process meets the preset conditions, that is, after a portion of the electricity is charged, the current state of charge of the battery can be determined. When the current state of charge of the battery is less than or equal to the left endpoint of the target detection interval, it means that the current can continue to be reduced within the target detection interval, that is, the detection interval for the actual current reduction operation is the set target detection interval, thereby detecting the characteristic inflection point of each battery cell.

[0149] For example, when the target detection interval is 40%-55%, the length of each detection interval is fixed at 15%. If the current state of charge is 38%, the actual detection interval for the current reduction operation is 40%-55% of the target detection interval.

[0150] Optionally, when the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells further includes:

[0151] If the current state parameter is greater than the left endpoint of the target detection interval, then when the battery state parameter is in the corrected target detection interval, the battery is charged with a first current and a characteristic inflection point detection is performed on the battery; wherein the corrected target detection interval is an interval with the current state parameter as the left endpoint.

[0152] Here, the current state parameter is taken as an example for description.

[0153] When the current state of charge of the battery is greater than the left endpoint of the target detection interval, it means that the current power has exceeded the starting point of the current reduction. At this time, the detection interval for the actual current reduction operation can be re-determined. This interval is an interval with the current state of charge as the left endpoint and a fixed length as the detection interval length.

[0154] For example, if the current state of charge is 50%, the actual detection interval for the current reduction operation is 50%-65%. Conversely, if the target detection interval is not corrected based on the current state of charge, then when the current state of charge is 50%, the actual detection interval for the current reduction operation is 50%-55%. During this charging process, the current reduction interval is too small and the characteristic inflection point of any battery cell may not be detected, resulting in an ineffective current reduction.

[0155] By determining the actual detection interval for current reduction operation according to the current state parameters during the charging process, the re-determined detection interval will move to the right compared to the target detection interval, so that the length of the detection interval remains unchanged, thereby reducing the possibility of not being able to detect the characteristic inflection point of any battery cell.

[0156] Optionally, the lengths of the target detection intervals in any of the charging processes are equal.

[0157] Each time the target detection interval corresponding to the next charging process is determined, the length of the target detection interval is the same. For example, during the first charge, the target detection interval is 40%-60%. After the characteristic inflection points of some cells are detected and balancing is performed, the target detection interval is adjusted to 45%-65% to detect the characteristic inflection points of more cells.

[0158] By controlling the length of the target detection interval to be equal, the interval for reducing the current is not extended, and the charging time of the battery is not further increased, thereby improving the user's usage experience.

[0159] Optionally, when the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells includes:

[0160] At the start of charging, if the time difference from the ideal equilibrium state moment is greater than or equal to a preset time difference, the battery is charged with a first current in the target detection interval, and characteristic inflection point detection is performed on multiple cells of the battery to determine characteristic inflection points of some of the cells in the battery; wherein the ideal equilibrium state moment represents: during any charging process, the characteristic inflection points of all cells are detected within the target detection interval, and the balancing operation is completed for all cells.

[0161] To facilitate determining whether to perform battery balancing during any charging process, the moment when all cell characteristic inflection points are detected and balancing is completed for all cells can be recorded, that is, the moment of ideal balanced state. Later in the charging process, whether to perform balancing can be determined based on the time difference between the current charging moment and the moment of ideal balanced state.

[0162] Since the battery does not need to be re-equalized within a short period of time after reaching the ideal equilibrium state, the time difference between the current charging time and the ideal equilibrium state and the preset time difference can be used to determine whether to perform current reduction operation and characteristic inflection point detection during the current charging process.

[0163] During any charging process, the time difference between the current moment and the ideal equilibrium state moment can be calculated, and a 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 the first current in the target detection interval, and characteristic inflection point detection is performed on multiple battery cells of the battery.

[0164] For example, when the recorded ideal equilibrium state time is 10:00 on May 1, if the preset value is two months, then when the charging time is 10:00 on July 3, the battery is charged with the first current and the characteristic inflection point of each battery cell is detected; if only 3 of the 5 battery cells are balanced during the charging process on July 3, then during the next charging, such as on July 8, since the recorded ideal equilibrium state time has not changed, the battery will still be charged with the first current and the characteristic inflection point of each battery cell will be detected; if the balancing of all battery cells is completed at 15:00 on July 8, 15:00 on July 8 can be stored as the ideal equilibrium state, so that the battery balancing operation can be performed again two months later.

[0165] Optionally, before determining the relationship between the time difference from the ideal equilibrium state and the preset time difference, the charging mode can also be determined. When DC charging is used, the above determination step is performed, and when AC charging is used, the above determination step is not performed. Here, DC charging can be considered a fast charging mode, and AC charging can be considered a slow charging mode.

[0166] By recording the ideal balanced state moment, it is convenient to accurately determine whether the battery needs to be balanced based on the recorded ideal balanced state moment during subsequent charging.

[0167] Optionally, the method further includes:

[0168] At the start of charging, if the time difference from the ideal equilibrium state moment is less than the preset time difference, the battery is charged with the second current during this charging process.

[0169] When the calculated time difference is less than the preset time difference, it means that the battery does not need to be balanced, that is, the current does not need to be reduced in the target detection interval, and the battery is fully charged with the second current during this charging process.

[0170] For example, when the ideal equilibrium state is recorded at 10:00 on May 1, if the preset value is two months, then when the charging time is 10:00 on June 20, the battery is charged with the second current.

[0171] By recording the ideal equilibrium state moment, it is possible to avoid performing the balancing operation for a period of time after the ideal equilibrium state is reached, thereby eliminating the need to reduce the current during each charging process and improving charging efficiency.

[0172] Optionally, determining the balancing operation based on the characteristic inflection points of the portion of battery cells includes:

[0173] The balancing operation is determined based on the characteristic inflection points of the said part of the battery cells so that the characteristic inflection points of at least part of the battery cells coincide with each other during the next charging process; or so that the difference between the characteristic inflection points of the said part of the battery cells during the next charging process is smaller than the difference between the characteristic inflection points of the said part of the battery cells during the current charging process.

[0174] The result of the balancing operation determined based on the characteristic inflection points of some of the battery cells is: the characteristic inflection points of at least some of the battery cells overlap, or the difference between the characteristic inflection points of some of the battery cells decreases, that is, the difference between the characteristic inflection points of some of the battery cells in the next charging process is smaller than the difference between the characteristic inflection points of some of the battery cells in the current charging process.

[0175] For example, when it is detected that the characteristic inflection points of battery cell 1, battery cell 2 and battery cell 3 are 45%, 48% and 50% respectively, balancing operation can be performed according to the characteristic inflection point of battery cell 3, and the target balancing amount of battery cell 1 is determined to be 5%, and the target balancing amount of battery cell 2 is determined to be 2%. Balancing processing is performed according to the target balancing amount so that the characteristic inflection point of battery cell 1 and the characteristic inflection point of battery cell 2 are respectively close to or equal to the characteristic inflection point of battery cell 3.

[0176] The balancing operation is performed to make the characteristic inflection points of some battery cells coincide or approach each other, and after multiple balancing operations, the characteristic inflection points of each battery cell finally coincide.

[0177] Optionally, the absolute value of the difference between the left endpoint of this 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 point of each battery cell in this target detection interval and the characteristic inflection point of the corresponding battery cell in the next target detection interval is Y, where X is less than or equal to Y, and where the characteristic inflection point is the state of charge of the battery cell or the capacity of the battery cell.

[0178] After balancing a cell, its characteristic inflection point changes. Specifically, it increases. The actual balancing amount for each cell can be unequal. The actual balancing amount is the absolute value of the difference between the characteristic inflection point detected in the next target detection interval and the characteristic inflection point detected in the current target detection interval.

[0179] After a balancing operation is performed on one charge, the target detection interval for the next charge can be determined, where the shift of the target detection interval (the difference between the left endpoint of this target detection interval and the left endpoint of the next target detection interval) must be less than or equal to the minimum absolute value of the difference between the characteristic inflection points of all battery cells.

[0180] For example, when it is detected that the characteristic inflection points of battery cell 1, battery cell 2 and battery cell 3 are 45%, 48% and 50% respectively, balancing operation can be performed according to the characteristic inflection point of battery cell 3. After the balancing operation, the characteristic inflection point of battery cell 1 is 49%, and the characteristic inflection point of battery cell 2 is determined to be 50%. Then the actual balancing amount of battery cell 1 is 4%, and the actual balancing amount of battery cell 2 is 2%, then X is less than or equal to 2%.

[0181] By limiting the absolute value of the difference between the left endpoint of the target detection interval and the left endpoint of the next target detection interval, it can be ensured that the characteristic inflection point of each battery cell detected this time can be detected based on the next target detection interval.

[0182] Optionally, determining a balancing operation of the portion of battery cells includes:

[0183] If the target battery cell exists in the portion of battery cells, performing a balancing operation on at least the portion of battery cells;

[0184] The target battery cell is the battery cell with the highest voltage value or the battery cell with the lowest voltage value among the multiple battery cells.

[0185] After characteristic inflection points of some battery cells are detected, the battery cells having the detected characteristic inflection points may be judged, and when these battery cells meet preset conditions, at least the electric quantity of these battery cells may be balanced.

[0186] Since the cell with the highest voltage value has the lowest characteristic inflection point, the cell with the lowest voltage value has the highest characteristic inflection point, and the characteristic inflection points of the other cells are between the lowest and highest characteristic inflection points, in order to achieve a balanced battery state, the cells with lower characteristic inflection points need to be discharged so that the characteristic inflection points of all cells are equal to the characteristic inflection point of the cell with the lowest voltage value. Therefore, when the characteristic inflection point corresponding to the cell with the highest voltage value is detected, the target detection interval can be moved to the right each time to slowly detect the characteristic inflection points of all cells, thereby achieving balance for all cells; when the characteristic inflection point corresponding to the cell with the lowest voltage value is detected, the characteristic inflection points of the other cells can be moved closer to this characteristic inflection point to achieve balance for all cells.

[0187] If the balancing operation is started before the characteristic inflection point corresponding to the target cell is detected, the target detection interval needs to be moved to the left and right respectively, which makes the operation complicated and easily misses the cell that needs to be balanced.

[0188] For example, there are five battery cells, and the characteristic inflection points of battery cells 1 to 5 are 40%, 45%, 55%, 60%, and 70%, respectively. When the target detection interval is 45%-60%, it can be detected that the characteristic inflection points corresponding to battery cells 2 to 4 are 45%, 55%, and 60%, respectively. If the balancing operation is started at this time, then during the next charge, the target detection interval needs to be moved to the left to detect the characteristic inflection point of battery cell 1 and perform balancing again. In addition, the target detection interval also needs to be moved to the right to detect the characteristic inflection point of battery cell 5 and perform balancing. The above process will make the determination of the target detection interval during the next charge more complicated.

[0189] By starting the balancing operation when the target cell exists in some of the cells, compared with starting the balancing operation when no target cell is detected, the operation process is simpler.

[0190] Optionally, performing a balancing operation on at least some of the battery cells includes:

[0191] In the first battery cell where the characteristic inflection point is detected, a balancing operation is performed on any of the first battery cells except a reference battery cell according to a target balancing amount; the reference battery cell is the battery cell corresponding to the highest value of the characteristic inflection point in the first battery cell; the target balancing 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.

[0192] The first battery cell here refers to the battery cell whose characteristic inflection point is detected. When performing a balancing operation on the first battery cell whose characteristic inflection point is detected, a reference battery cell can be first determined from the first battery cells. The reference battery cell refers to the battery cell corresponding to the highest value of the characteristic inflection point among the first battery cells, and balancing is performed based on the characteristic inflection point of the reference battery cell and the characteristic inflection points of other first battery cells. The balancing operation requires discharging the first battery cell with a higher voltage value, that is, it is necessary to discharge each first battery cell with a lower characteristic inflection point value. Therefore, for the first battery cell whose characteristic inflection point is detected, the first battery cell with the highest characteristic 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.

[0193] Optionally, when there is a cell with the highest voltage value or the lowest voltage value in the entire battery among the first cells, the cell corresponding to the highest value of the characteristic inflection point can be determined as the reference cell. For any other first cell, the difference between the characteristic inflection point of the first cell and the characteristic inflection point of the reference cell can be calculated. The difference is the target balancing amount, and the first cell is then balanced based on the target balancing amount, so that the power of the first cell is the same as or close to the power of the reference cell.

[0194] For example, when it is detected that the characteristic inflection points of battery cell 1 to battery cell 3 are 40%, 45%, and 55% respectively, the reference battery cell is battery cell 3. For battery cell 1, the target balancing amount is 15%, and battery cell 1 can be discharged based on the target balancing amount of 15%; for battery cell 2, the target balancing amount is 10%, and battery cell 2 can be discharged based on the target balancing amount of 10%.

[0195] For the first battery cells for which characteristic inflection points are detected, balancing is performed based on the target balancing amount, thereby achieving accurate balancing of each first battery cell.

[0196] Optionally, the method further includes:

[0197] If the target battery cell is the battery cell with the lowest voltage value among the multiple battery cells, a balancing operation is performed on any second battery cell for which no characteristic inflection point is detected according to a default balancing amount.

[0198] If the target cell is the cell with the lowest voltage among multiple cells, it means that the cell with the highest characteristic inflection point has been detected. In this case, in addition to balancing the first cells, the second cells where no characteristic inflection points have been detected can also be balanced. For each first cell with a detected characteristic inflection point, balancing can be enabled based on the target balancing amount; for each second cell without a detected characteristic inflection point, balancing can be enabled based on the default balancing amount, so that the characteristic inflection points of each cell gradually converge, thereby gradually achieving balance for all cells.

[0199] For example, when there are five battery cells, the characteristic inflection points of battery cells 1 to 5 are 40%, 45%, 55%, 60%, and 70%, respectively. If the characteristic inflection points of battery cells 3, 4, and 5 are detected, then when performing the balancing operation, not only can balancing be enabled for battery cells 3 and 4 based on the characteristic inflection point of battery cell 5, but balancing can also be enabled for battery cells 1 and 2. A smaller default balancing amount can be used for balancing battery cells 1 and 2. For example, the default balancing amount can be 3% or 5%. There is no restriction on the value of the default balancing amount, and it can be set according to actual conditions.

[0200] For the target cell with the lowest voltage value, a balancing operation is performed on the second cell where no characteristic inflection point is detected based on a default balancing amount, thereby improving balancing efficiency.

[0201] Figure 4 A flow chart of another battery balancing method provided by an embodiment of the present invention is shown as follows: Figure 4As shown, the method includes: when the battery is powered on and charging begins, it can be detected whether it is DC charging. When it is DC charging, it is detected whether the time difference between the current time and the ideal equilibrium state time is greater than 2 months. If so, it is determined whether 5% of the power is currently charged. If so, SOCAh (the current state of charge calculated based on the ampere-hour integration) is calculated. When SOCAh is less than or equal to SOCAh0 (SOCAh0 is the starting point of the current reduction recorded before each power-off, that is, the left end point of the target detection interval), the current reduction interval is determined to be SOCAh0 to SOCAh0+15%. When SOCAh is greater than SOCAh0, the current reduction interval is determined to be S The current is reduced within the above range from OCAh to SOCAh+15%, and the characteristic inflection point of each battery cell is detected to determine whether the battery cell with the detected characteristic inflection point meets the preset conditions. If so, the balancing operation is performed. If not, the range for performing the current reduction operation is adjusted, and the above steps are performed after the next power-on. After the balancing operation is completed, it is determined whether the ideal balanced state is achieved. If so, the ideal balanced state moment is recorded, and SOCAh0 is adjusted to a default value, for example, 40%, so that the starting point for current reduction is 40% when the next balancing operation is required. If the ideal balanced state is not achieved, the range for performing the current reduction operation is adjusted, and the balancing operation is continued after the next power-on.

[0202] The solution of the present application can perform reduced-current charging for a specific interval length in the battery DC charging mode, and detect the characteristic inflection point of the battery cell within this interval, which not only ensures the charging speed but also solves the problem of long-term fast charging users being unable to start balancing; in addition, by tracking and adjusting the position of the reduced-current starting point, it is not necessary to detect the characteristic inflection points of all battery cells in one charging process. For battery packs with poor balanced state, the balanced state of the pack can still be achieved after multiple charges.

[0203] The specific numerical values in the above method are for illustration only, and this application does not impose any specific limitation on the above numerical values.

[0204] In the embodiment disclosed in the present application, the characteristic inflection point can be determined according to the following steps: when 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 charge of multiple single cells in the battery; then, based on the cell voltage and cell charge, the corresponding voltage-charge curve is determined. Specifically, the corresponding voltage-charge curve can be constructed with the cell charge as the horizontal coordinate and the cell voltage as the vertical coordinate. Next, the controller analyzes and processes the voltage-charge curve corresponding to each single cell, for example, the voltage-charge curve corresponding to each single cell is differentiated to determine the voltage characteristic inflection point corresponding to each single cell. Finally, the controller determines the characteristic inflection point of the single cell based on the voltage characteristic inflection point and the voltage-charge curve corresponding to the single cell, and then determines the inflection point data corresponding to the characteristic inflection point. The inflection point data here includes the cell charge 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 based on the battery's voltage-capacity curve or the battery's voltage-SOC curve. The overall determination method is consistent with the above method and will not be further elaborated. Among them, the characteristic inflection point in the method disclosed in the embodiment of the present application generally refers to the data corresponding to the horizontal axis, that is, the power / SOC / capacity, etc.

[0205] In the embodiments disclosed in the present application, the above-mentioned charge and discharge control method is generally applied to lithium iron phosphate batteries or other types of batteries containing voltage platforms at both ends in the middle section. Specifically, when the battery is charged, there will be a voltage platform area. Because the voltage variation in this platform area is small, the charge and discharge control method disclosed in the present application can be used to judge the capacity of multiple single cells, and then determine the capacity difference between multiple single cells to improve the service life of the battery. Among them, the battery with a voltage platform at both ends in the middle section refers to a battery including two slope sections and a platform end during the battery charging process, wherein the platform end is located between the two slope sections.

[0206] Figure 5 This is a schematic structural diagram of a battery balancing device 50 provided in an embodiment of the present invention, the device comprising:

[0207] A balancing module 501 is configured to determine characteristic inflection points of some battery cells within a target detection interval during battery charging and then perform a balancing operation on the battery cells;

[0208] The current in the target detection interval is smaller than the current in the non-target detection interval.

[0209] Optionally, the balancing module 501 is specifically configured to determine a balancing operation of the part of the battery cells based on characteristic inflection points of the part of the battery cells determined within a target detection interval during battery charging.

[0210] Optionally, the device further includes a charging control module, configured to:

[0211] When the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells;

[0212] The target detection interval is an interval in which characteristic inflection points of some battery 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.

[0213] Optionally, the device further includes: a first processing module, configured to:

[0214] Determine the target detection interval corresponding to the next charging process;

[0215] During the next charging process, characteristic inflection point detection is performed based on the corresponding target detection interval, and balancing operation is determined based on the detected characteristic inflection point, until characteristic inflection points of all cells are detected based on the target detection interval during one charging process.

[0216] 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:

[0217] When the battery cell with the highest voltage value exists in the portion of battery cells and the battery cell with the lowest voltage value does not exist, determining the target detection interval corresponding to the next charging process according to the balancing operation result;

[0218] When the battery cell with the lowest voltage value exists in the portion of battery cells, the target detection interval remains unchanged;

[0219] If the battery cell with the highest voltage value and the battery cell with the lowest voltage value do not exist in the part of the battery cells, the target detection interval is moved along the preset direction to determine the target detection interval corresponding to the next charging process.

[0220] Optionally, the device further includes: a second processing module, configured to:

[0221] After charging the battery with the first current is completed, 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;

[0222] Alternatively, after the characteristic inflection points of all the 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.

[0223] Optionally, when a cell with the highest voltage value exists in the portion of cells and a 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 minimum value of the current characteristic inflection points corresponding to each cell;

[0224] 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 during the balancing operation.

[0225] Optionally, when there is a cell with the highest voltage value among the said part of the battery cells, and there is no cell with the lowest voltage value, 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 balance amounts corresponding to each battery cell; or, the target value is a fixed value.

[0226] Optionally, when the current state parameter of the battery is within the target detection interval, the charging control module charges the battery with a first current and determines characteristic inflection points of some battery cells, specifically for:

[0227] When the current charging process meets the preset conditions, determining the current state parameters of the battery;

[0228] If the current state parameter is less than or equal to the left endpoint of the target detection interval, when the battery state parameter reaches the target detection interval, the battery is charged with a first current and a characteristic inflection point detection is performed on the battery.

[0229] Optionally, when the current state parameter of the battery is within the target detection interval, the charging control module charges the battery with a first current and determines characteristic inflection points of some battery cells, further configured to:

[0230] If the current state parameter is greater than the left endpoint of the target detection interval, then when the battery state parameter is in the corrected target detection interval, the battery is charged with a first current and a characteristic inflection point detection is performed on the battery; wherein the corrected target detection interval is an interval with the current state parameter as the left endpoint.

[0231] Optionally, the lengths of the target detection intervals in any of the charging processes are equal.

[0232] Optionally, when the current state parameter of the battery is within the target detection interval, the charging control module charges the battery with a first current and determines characteristic inflection points of some battery cells, specifically for:

[0233] At the start of charging, if the time difference from the ideal equilibrium state moment is greater than or equal to a preset time difference, the battery is charged with a first current in the target detection interval, and characteristic inflection point detection is performed on multiple cells of the battery to determine characteristic inflection points of some of the cells in the battery; wherein the ideal equilibrium state moment represents: during any charging process, the characteristic inflection points of all cells are detected within the target detection interval, and the balancing operation is completed for all cells.

[0234] Optionally, the charging control module is further configured to: at the start of charging, if the time difference from the ideal equilibrium state moment is less than the preset time difference, charge the battery with the second current during this charging process.

[0235] Optionally, when determining the balancing operation based on the characteristic inflection points of the portion of battery cells, the balancing module 501 is specifically configured to:

[0236] The balancing operation is determined based on the characteristic inflection points of the said part of the battery cells so that the characteristic inflection points of at least part of the battery cells coincide with each other during the next charging process; or so that the difference between the characteristic inflection points of the said part of the battery cells during the next charging process is smaller than the difference between the characteristic inflection points of the said part of the battery cells during the current charging process.

[0237] Optionally, the absolute value of the difference between the left endpoint of this 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 point of each battery cell in this target detection interval and the characteristic inflection point of the corresponding battery cell in the next target detection interval is Y, where X is less than or equal to Y, and where the characteristic inflection point is the state of charge of the battery cell or the capacity of the battery cell.

[0238] Optionally, when determining the balancing operation of the portion of battery cells, the balancing module 501 is specifically configured to:

[0239] If the target battery cell exists in the portion of battery cells, performing a balancing operation on at least the portion of battery cells;

[0240] The target battery cell is the battery cell with the highest voltage value or the battery cell with the lowest voltage value among the multiple battery cells.

[0241] Optionally, when performing a balancing operation on at least some of the battery cells, the balancing module 501 is specifically configured to:

[0242] In the first battery cell where the characteristic inflection point is detected, a balancing operation is performed on any of the first battery cells except a reference battery cell according to a target balancing amount; the reference battery cell is the battery cell corresponding to the highest value of the characteristic inflection point in the first battery cell; the target balancing 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.

[0243] Optionally, the device further includes: a third processing module, configured to:

[0244] If the target battery cell is the battery cell with the lowest voltage value among the multiple battery cells, a balancing operation is performed on any second battery cell for which no characteristic inflection point is detected according to a default balancing amount.

[0245] The battery balancing device provided by the embodiment of the present invention can achieve the above Figure 2 The battery balancing method of the embodiment shown has similar implementation principles and technical effects, which will not be described in detail here.

[0246] Figure 6 Schematic diagram of the hardware structure of a controller provided by an embodiment of the present invention. Figure 6 As shown, the controller provided by this embodiment includes: at least one processor 601 and a memory 602. The processor 601 and the memory 602 are connected via a bus 603.

[0247] During the specific implementation process, at least one processor 601 executes the computer-executable instructions stored in the memory 602, so that the at least one processor 601 executes the method in the above method embodiment.

[0248] The specific implementation process of the processor 601 can be found in the above method embodiment. Its implementation principle and technical effects are similar and will not be repeated here in this embodiment.

[0249] When the battery is used in a vehicle, the controller can be a battery management system BMS or a vehicle controller.

[0250] In the above Figure 6 In the illustrated embodiment, it should be understood that the processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASICs), etc. A general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in the present invention may be directly executed by a hardware processor or by a combination of hardware and software modules within the processor.

[0251] The memory may include a high-speed RAM memory, and may also include a non-volatile storage NVM, such as at least one disk storage.

[0252] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. Buses can be classified into address buses, data buses, and control buses. For ease of illustration, the buses in the drawings of this application are not limited to just one bus or just one type of bus.

[0253] An embodiment of the present invention further provides an electrical device, comprising: a battery and a controller, wherein the battery comprises a plurality of battery cells; and the controller is configured to execute the method of the above method embodiment.

[0254] An embodiment of the present invention further provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the method of the above method embodiment is implemented.

[0255] An embodiment of the present application also provides a computer program product, including a computer program, which implements the method of the above method embodiment when executed by a processor.

[0256] The computer-readable storage medium mentioned above can be implemented by any type of volatile or non-volatile memory device 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 memory, flash memory, magnetic disk, or optical disk. The computer-readable storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0257] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and 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 in the device as discrete components.

[0258] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0259] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0260] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0261] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents 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 balancing method, characterized in that: The method comprises: After determining characteristic inflection points of some battery cells within a target detection interval during battery charging, performing a balancing operation on the battery cells; The current in the target detection interval is smaller than the current in the non-target detection interval.

2. The method according to claim 1, characterized in that After determining characteristic inflection points of some battery cells within a target detection interval during battery charging, performing a balancing operation on the some battery cells includes: Based on characteristic inflection points of some of the battery cells determined within a target detection interval during battery charging, a balancing operation of the some of the battery cells is determined.

3. The method according to claim 2, characterized in that The method further comprises: When the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells; The target detection interval is an interval in which characteristic inflection points of some battery 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.

4. The method according to claim 3, characterized in that The method further comprises: Determine the target detection interval corresponding to the next charging process; During the next charging process, characteristic inflection point detection is performed based on the corresponding target detection interval, and balancing operation is determined based on the detected characteristic inflection point, until characteristic inflection points of all cells are detected based on the target detection interval during one charging process.

5. The method according to claim 4, characterized in that Determining the target detection interval corresponding to the next charging process includes at least one of the following: When a cell with the highest voltage value exists in the portion of the cells and a cell with the lowest voltage value does not exist, determining the target detection interval corresponding to the next charging process according to the balancing operation result; When the battery cell with the lowest voltage value exists in the portion of battery cells, the target detection interval remains unchanged; If the battery cell with the highest voltage value and the battery cell with the lowest voltage value do not exist in the part of the battery cells, the target detection interval is moved along the preset direction to determine the target detection interval corresponding to the next charging process.

6. The method according to claim 4, characterized in that The method further comprises: After charging the battery with the first current is completed, 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; Alternatively, after the characteristic inflection points of all the 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.

7. The method according to claim 5, characterized in that When the cell with the highest voltage value exists in the portion of cells and the 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 minimum value of the current characteristic inflection points corresponding to each cell; 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 during the balancing operation.

8. The method according to claim 5, characterized in that When the cell with the highest voltage value exists in the portion of cells and the 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 balancing amounts corresponding to the respective battery cells; or, the target value is a fixed value.

9. The method according to claim 3, characterized in that When the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells includes: When the current charging process meets the preset conditions, determining the current state parameters of the battery; If the current state parameter is less than or equal to the left endpoint of the target detection interval, when the battery state parameter reaches the target detection interval, the battery is charged with a first current and a characteristic inflection point detection is performed on the battery.

10. The method according to claim 9, characterized in that When the current state parameter of the battery is within the target detection interval, the battery is charged with a first current and characteristic inflection points of some battery cells are determined, further comprising: If the current state parameter is greater than the left endpoint of the target detection interval, then when the battery state parameter is in the corrected target detection interval, the battery is charged with a first current and a characteristic inflection point detection is performed on the battery; wherein the corrected target detection interval is an interval with the current state parameter as the left endpoint.

11. The method according to claim 2, characterized in that The lengths of the target detection intervals in any of the charging processes are equal.

12. The method according to claim 3, characterized in that When the current state parameter of the battery is within the target detection interval, charging the battery with a first current and determining characteristic inflection points of some battery cells includes: At the start of charging, if the time difference from the ideal equilibrium state moment is greater than or equal to a preset time difference, the battery is charged with a first current in the target detection interval, and characteristic inflection point detection is performed on multiple cells of the battery to determine characteristic inflection points of some of the cells in the battery; wherein the ideal equilibrium state moment represents: during any charging process, the characteristic inflection points of all cells are detected within the target detection interval, and the balancing operation is completed for all cells.

13. The method according to claim 12, characterized in that The method further comprises: At the start of charging, if the time difference from the ideal equilibrium state moment is less than the preset time difference, the battery is charged with the second current during this charging process.

14. The method according to any one of claims 1 to 13, characterized in that Determining a balancing operation based on characteristic inflection points of the portion of cells includes: The balancing operation is determined based on the characteristic inflection points of the said part of the battery cells so that the characteristic inflection points of at least part of the battery cells coincide with each other during the next charging process; or so that the difference between the characteristic inflection points of the said part of the battery cells during the next charging process is smaller than the difference between the characteristic inflection points of the said part of the battery cells during 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 point of each battery cell in the current target detection interval and the characteristic inflection point of the corresponding battery cell in the next target detection interval is Y, where X is less than or equal to Y, and 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 Determine the balancing operation of the portion of cells, including: If the target battery cell exists in the portion of battery cells, performing a balancing operation on at least the portion of battery cells; The target battery cell is the battery cell with the highest voltage value or the battery cell with the lowest voltage value among the multiple battery cells.

17. The method according to claim 16, characterized in that Performing a balancing operation on at least some of the cells, including: In the first battery cell where the characteristic inflection point is detected, a balancing operation is performed on any of the first battery cells except a reference battery cell according to a target balancing amount; the reference battery cell is the battery cell corresponding to the highest value of the characteristic inflection point in the first battery cell; the target balancing 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.

18. The method according to claim 16, characterized in that The method further comprises: If the target battery cell is the battery cell with the lowest voltage value among the multiple battery cells, a balancing operation is performed on any second battery cell for which no characteristic inflection point is detected according to a default balancing amount.

19. A battery balancing device, characterized in that: The device comprises: A balancing module, configured to determine characteristic inflection points of some battery cells within a target detection interval during battery charging and then perform a balancing operation on the battery cells; The current in the target detection interval is smaller than the current in the non-target detection interval.

20. A controller, characterized in that: include: at least one processor and 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 performs the method according to any one of claims 1 to 18.

21. An electrical device, characterized in that: include: A battery and a controller, wherein the battery comprises a plurality of battery cells; and the controller is used to execute the method described in any one of claims 1 to 18.

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

23. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 18 when being executed by a processor.

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