Balance strategy and system based on SOC maximum value

Abstract

The embodiment of the present invention provides a balancing strategy and system based on SOC maximum value, which relates to the field of power battery technology. The balancing strategy includes: obtaining the single SOC value and the average SOC value of the battery pack; judging whether the battery pack needs to perform a balancing operation; in the case where it is judged that the battery pack needs to perform a balancing operation, determining the single SOC extreme value and the single SOC sub-extreme value of the battery pack; taking the intermediate value of the average SOC value and the single SOC sub-extreme value as the target SOC, balancing the battery pack. The balancing strategy and system predict the SOC of the battery pack, and timely balance the single cell with the highest SOC during charging and the single cell with the lowest SOC during discharging, thereby ensuring full utilization of the battery pack capacity, achieving balancing of the entire battery pack, and achieving high balancing efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of electric batteries, and in particular to a balancing strategy and system based on a maximum SOC value. Background Art

[0002] Since the capacity and voltage of battery cells are small, it is necessary to gradually expand the capacity through series and parallel connection to form a battery pack. However, due to factors such as inconsistent production processes and ambient temperature, the inconsistency of cells caused by them objectively exists, which will hinder the efficient use of battery packs. During the charging process of the battery pack, when the cell with the largest SOC is full, the BMS will end the charging regardless of whether the other cells are full, otherwise the battery cell will be damaged. During the discharge process, when the cell with the lowest SOC is fully discharged, the discharge will end regardless of whether the other cells have power. This will cause the capacity of the battery pack to not be fully utilized. Summary of the invention

[0003] The purpose of the present invention is to provide a balancing strategy and system based on SOC maximum value. The balancing strategy predicts the SOC of the battery pack and timely balances the single cell with the highest SOC during charging and the single cell with the lowest SOC during discharging, thereby ensuring full utilization of the battery pack capacity and achieving balancing of the entire battery pack with high balancing efficiency.

[0004] In order to achieve the above object, the present invention provides a balancing strategy based on SOC maximum value, including:

[0005] Get the single cell SOC value and average SOC value of the battery pack;

[0006] Determining whether the battery pack needs to perform a balancing operation;

[0007] In the case where it is determined that the battery pack needs to perform a balancing operation, determining a single cell SOC extreme value and a single cell SOC sub-extreme value of the battery pack;

[0008] The battery pack is balanced by taking the middle value between the average SOC value and the next-highest SOC value of the single cell as the target SOC.

[0009] Optionally, determining a single cell SOC extreme value and a single cell SOC sub-extreme value of the battery pack includes:

[0010] Determining an operating state of the battery pack;

[0011] When the battery pack is in a charging state, the highest single-cell SOC value and the second highest single-cell SOC value are determined.

[0012] Optionally, determining a single cell SOC extreme value and a single cell SOC sub-extreme value of the battery pack includes:

[0013] Determining an operating state of the battery pack;

[0014] When the battery pack is in a discharging state, the lowest single cell SOC value and the second lowest single cell SOC value are determined.

[0015] Optionally, taking the middle value between the average SOC value and the next-highest SOC value of a single cell as the target SOC, balancing the battery pack includes:

[0016] Determining a theoretical control amount for balancing the battery pack according to the target SOC;

[0017] Calculate the theoretical SOC after executing the theoretical control amount according to the objective function;

[0018] Executing the theoretical control amount and obtaining the actual SOC of the battery pack;

[0019] Determine the single cell SOC of the battery pack according to the theoretical SOC and the actual SOC;

[0020] Determining whether the battery pack meets a balancing condition according to the single cell SOC;

[0021] In the case where it is determined that the battery pack meets the balancing condition, updating the objective function according to the theoretical SOC and the actual SOC, and returning to execute the step of determining the theoretical control amount for balancing the battery pack according to the target SOC;

[0022] In the case where it is determined that the battery group does not meet the balancing condition, it is determined that the balancing of the battery group is completed.

[0023] Optionally, the balancing strategy includes:

[0024] The objective function is determined using formula (1):

[0025]

[0026] Among them, minJ is the minimization of the objective function, U(k) T is the transpose of the battery pack balancing state matrix, is the internal resistance matrix, U(k) is the battery pack equilibrium state matrix, α, β, η, is the intermediate variable matrix.

[0027] Optionally, obtaining the actual SOC of the battery pack includes:

[0028] Collecting the cell terminal voltage of the battery pack;

[0029] The actual SOC is determined according to a preset battery model.

[0030] Optionally, the balancing strategy further includes:

[0031] The actual SOC is determined according to formula (2):

[0032] U=E0-I c R in +k1lnSOC+k2ln(1-SOC), (2)

[0033] Among them, U is the single-cell terminal voltage, E0 is the open circuit voltage, I c is the discharge current, R in is the internal resistance of the battery, k1 and k2 are fitting coefficients.

[0034] Optionally, determining the single cell SOC of the battery pack according to the theoretical SOC and the actual SOC includes:

[0035] The monomer SOC is determined according to formula (3):

[0036] SOC0=SOC1+SOC2 / 2, (3)

[0037] Among them, SOC1 is the theoretical SOC, SOC2 is the actual SOC, and SOC0 is the single body SOC.

[0038] On the other hand, the present invention further provides a balancing system based on a maximum SOC value, wherein the balancing system comprises a processor, and the processor is configured to execute any of the above-mentioned balancing strategies.

[0039] Through the above technical scheme, the present invention provides a balancing strategy and system based on SOC maximum value, by obtaining the single SOC value and average SOC value of the battery pack, when the battery pack needs to perform a balancing operation, the single SOC extreme value and single SOC sub-extreme value of the battery pack are determined, and the intermediate value between the average SOC value and the single SOC sub-extreme value is used as the target SOC to balance the battery pack. The balancing strategy and system predicts the SOC of the battery pack, timely balances the single cell with the highest SOC during charging and the single cell with the lowest SOC during discharging, ensures full utilization of the battery pack capacity, realizes balancing of the entire battery pack, and has high balancing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flow chart of a balancing strategy based on SOC maximum value according to an embodiment of the present invention;

[0041] Figure 2 is a flow chart of determining a single cell SOC extreme value and a single cell SOC sub-extreme value of a battery pack according to one embodiment of the present invention;

[0042] Figure 3is a flow chart of determining a single cell SOC extreme value and a single cell SOC sub-extreme value of a battery pack according to one embodiment of the present invention;

[0043] Figure 4 is a flow chart of balancing a battery pack according to an embodiment of the present invention;

[0044] Figure 5 The following is a flowchart of obtaining the actual SOC of a battery pack according to one embodiment of the present invention. DETAILED DESCRIPTION

[0045] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0046] like Figure 1 FIG. 1 is a flow chart of a balancing strategy based on SOC maximum value according to an embodiment of the present invention. Figure 1 In the example, the balancing strategy may include:

[0047] In step S1, a single cell SOC value and an average SOC value of a battery pack are obtained;

[0048] In step S2, it is determined whether the battery pack needs to perform a balancing operation;

[0049] In step S3, when it is determined that the battery pack needs to perform a balancing operation, a single cell SOC extreme value and a single cell SOC sub-extreme value of the battery pack are determined;

[0050] In step S4, the battery pack is balanced using the intermediate value between the average SOC value and the next-highest SOC value of the cell as the target SOC.

[0051] In this Figure 1 In the method shown, step S1 is used to obtain the single SOC value and the average SOC value of the battery pack. The specific method for obtaining the single SOC value can be various methods known to those skilled in the art. For example, it can be obtained by the ampere-hour integration method, or by the open circuit voltage-SOC curve. As for the method for obtaining the average SOC value, the average value can be further calculated for the single SOC value.

[0052] Step S2 can be used to determine whether the battery pack needs to perform a balancing operation. The specific determination method for whether to perform a balancing operation can be various known to those skilled in the art. In one example of the present invention, the determination method can be to compare the difference between the maximum and minimum SOC values ​​with a preset value. If the difference is greater than the preset value, it means that the difference between the single SOC values ​​in the battery pack is too large, so balancing is performed. Otherwise, balancing may not be performed.

[0053] In step S3, the cell SOC extreme value and the cell SOC sub-extreme value may be, for example, the cell SOC maximum value and the cell SOC sub-highest value. Then, when the cell SOC extreme value and the cell SOC sub-extreme value are respectively the cell SOC maximum value and the cell SOC sub-highest value, step S3 may include: Figure 2 The method shown. Figure 2 In the step S3, the step S3 may further include the following steps:

[0054] In step S10, the operating state of the battery pack is determined;

[0055] In step S11 , when the battery pack is in a charging state, a cell SOC maximum value and a cell SOC second highest value are determined.

[0056] In step S3, the cell SOC extreme value and the cell SOC sub-extreme value may also be, for example, the cell SOC minimum value and the cell SOC second-lowest value. Then, when the cell SOC extreme value and the cell SOC sub-extreme value are respectively the cell SOC minimum value and the cell SOC second-lowest value, step S3 may include the following steps: Figure 3 The method shown. Figure 3 In the step S3, the step S3 may further include the following steps:

[0057] In step S20, the operating state of the battery pack is determined;

[0058] In step S21 , when the battery pack is in a discharging state, the lowest cell SOC value and the second lowest cell SOC value are determined.

[0059] In the case where it is determined that the balancing operation needs to be turned on, steps S3 and S4 can be executed to perform balancing. In the prior art, the commonly used balancing strategy is mainly to directly compare the difference between the maximum and minimum values ​​of the SOC value or voltage value of the single cell in the battery pack to perform balancing, and the target of balancing is generally the average value. This method will have the technical problem of over-balancing, thereby affecting the balancing efficiency. Therefore, in steps S3 and S4 provided by the present invention, firstly, by determining the single cell SOC value and the single cell SOC sub-extreme value, and then combining step S4, balancing is performed by taking the middle value of the average SOC value and the single cell SOC sub-extreme value as the target SOC. Since the target SOC used in steps S3 and S4 is the middle value of the average SOC value and the single cell SOC sub-extreme value, compared with the prior art, the middle value is closer to the average value, so it can overcome the technical problem of over-balancing in the prior art.

[0060] Step S4 uses the middle value between the average SOC value and the next-highest value of the single-cell SOC as the target SOC to balance the battery pack. Generally speaking, the next-highest (or next-lowest) value of the single-cell SOC is higher (or lower) than the average SOC value, and it is not necessary to balance the single-cell SOC extreme value toward the average SOC value. As long as the single-cell SOC extreme value is closer to the average SOC value than the next-highest value of the single-cell SOC, the state in which the battery pack capacity cannot be fully utilized will be improved, and the technical problem of over-balancing can be alleviated. The method of balancing the battery pack may include the following: Figure 4 The steps shown. Specifically:

[0061] In step S30, a theoretical control amount for balancing the battery pack is determined according to the target SOC;

[0062] In step S31, the theoretical SOC after executing the theoretical control amount is calculated according to the objective function;

[0063] In step S32, the theoretical control amount is executed, and the actual SOC of the battery pack is obtained;

[0064] In step S33, the single cell SOC of the battery pack is determined according to the theoretical SOC and the actual SOC;

[0065] In step S34, judging whether the battery pack meets the balancing condition according to the single cell SOC;

[0066] In step S35, when it is determined that the battery pack meets the balancing condition, the objective function is updated according to the theoretical SOC and the actual SOC, and the process returns to the step of determining the theoretical control amount for balancing the battery pack according to the target SOC, that is, returns to step S30;

[0067] In step S36, when it is determined that the battery pack does not meet the balancing condition, it is determined that the balancing of the battery pack is completed.

[0068] In this Figure 4 In the method shown, step S30 can be used to determine the theoretical control amount for balancing the battery pack according to the target SOC, thereby determining the switch control operation to be performed by the battery pack in the next step. However, due to the relatively limited accuracy of the SOC estimation of the battery pack, it is impossible to directly determine the real SOC of the battery pack by estimating the SOC of the battery pack after executing the theoretical control amount. Therefore, in this balancing strategy, the theoretical SOC after executing the theoretical control amount can be first calculated in combination with the preset objective function through step S31, and then the actual SOC of the battery pack after executing the theoretical control amount can be directly estimated through step S32, and finally the theoretical SOC and the actual SOC can be combined at the same time through step S33 to obtain the real SOC, that is, the single cell SOC.

[0069] In addition, the objective function in step S31 can be in various forms known to those skilled in the art. In one example of the present invention, the objective function can be determined using the following formula (1):

[0070]

[0071] Among them, minJ is the minimization of the objective function, U(k) T is the transpose of the battery pack balancing state matrix, is the internal resistance matrix, U(k) is the battery pack equilibrium state matrix, α, β, η, is the intermediate variable matrix.

[0072] The method for determining the actual SOC of the battery pack in step S32 may be in various forms known to those skilled in the art, including but not limited to the ampere-hour integration method, the curve fitting method, etc. In one example of the present invention, the method for determining the actual SOC may include: Figure 5 The steps shown. Figure 5 In the method of determining the actual SOC, the method may include the following steps:

[0073] In step S40, the cell terminal voltage of the battery pack is collected;

[0074] In step S41 , the actual SOC is determined according to a preset battery model.

[0075] The battery model in step S41 may be in various forms known to those skilled in the art. In this example, the battery model may be as shown in the following formula (2):

[0076] U=E0-I c R in +k1lnSOC+k2ln(1-SOC), (2)

[0077] Among them, U is the single-cell terminal voltage, E0 is the open circuit voltage, I c is the discharge current, R in is the internal resistance of the battery, k1 and k2 are fitting coefficients.

[0078] In step S33, the specific method of obtaining the single-cell SOC by using the theoretical SOC and the actual SOC may also be various forms known to those skilled in the art. In one example of the present invention, the single-cell SOC may be determined by using formula (3):

[0079] SOC0=SOC1+SOC2 / 2, (3)

[0080] Among them, SOC1 is the theoretical SOC, SOC2 is the actual SOC, and SOC0 is the single body SOC.

[0081] After determining the single cell SOC representing the actual SOC of the single cell, it is possible to determine whether the battery pack meets the balancing condition based on the single cell SOC, i.e., step S34. At this time, if the battery pack still meets the balancing condition, it means that the battery pack needs to continue to perform switch control to jump out of the balancing condition, so it can return to step S30. Otherwise, it can exit the control, i.e., step S36.

[0082] On the other hand, the present invention also provides a balancing system based on SOC maximum value, the balancing system includes a processor, and the processor is configured to execute any of the above-mentioned balancing strategies. Specifically, the balancing strategy can be Figures 1 to 5 The steps shown. Figure 1 In the example, the balancing strategy may include:

[0083] In step S1, a single cell SOC value and an average SOC value of a battery pack are obtained;

[0084] In step S2, it is determined whether the battery pack needs to perform a balancing operation;

[0085] In step S3, when it is determined that the battery pack needs to perform a balancing operation, a single cell SOC extreme value and a single cell SOC sub-extreme value of the battery pack are determined;

[0086] In step S4, the battery pack is balanced using the intermediate value between the average SOC value and the next-highest SOC value of the cell as the target SOC.

[0087] In this Figure 1In the method shown, step S1 is used to obtain the single SOC value and the average SOC value of the battery pack. The specific method for obtaining the single SOC value can be various methods known to those skilled in the art. For example, it can be obtained by the ampere-hour integration method, or by the open circuit voltage-SOC curve. As for the method for obtaining the average SOC value, the average value can be further calculated for the single SOC value.

[0088] Step S2 can be used to determine whether the battery pack needs to perform a balancing operation. The specific determination method for whether to perform a balancing operation can be various known to those skilled in the art. In one example of the present invention, the determination method can be to compare the difference between the maximum and minimum SOC values ​​with a preset value. If the difference is greater than the preset value, it means that the difference between the single SOC values ​​in the battery pack is too large, so balancing is performed. Otherwise, balancing may not be performed.

[0089] In step S3, the cell SOC extreme value and the cell SOC sub-extreme value may be, for example, the cell SOC maximum value and the cell SOC sub-highest value. Then, when the cell SOC extreme value and the cell SOC sub-extreme value are respectively the cell SOC maximum value and the cell SOC sub-highest value, step S3 may include: Figure 2 The method shown. Figure 2 In the step S3, the step S3 may further include the following steps:

[0090] In step S10, the operating state of the battery pack is determined;

[0091] In step S11 , when the battery pack is in a charging state, a cell SOC maximum value and a cell SOC second highest value are determined.

[0092] In step S3, the cell SOC extreme value and the cell SOC sub-extreme value may also be, for example, the cell SOC minimum value and the cell SOC second-lowest value. Then, when the cell SOC extreme value and the cell SOC sub-extreme value are respectively the cell SOC minimum value and the cell SOC second-lowest value, step S3 may include the following steps: Figure 3 The method shown. Figure 3 In the step S3, the step S3 may further include the following steps:

[0093] In step S20, the operating state of the battery pack is determined;

[0094] In step S21 , when the battery pack is in a discharging state, the lowest cell SOC value and the second lowest cell SOC value are determined.

[0095] In the case where it is determined that the balancing operation needs to be turned on, steps S3 and S4 can be executed to perform balancing. In the prior art, the commonly used balancing strategy is mainly to directly compare the difference between the maximum and minimum values ​​of the SOC value or voltage value of the single cell in the battery pack to perform balancing, and the target of balancing is generally the average value. This method will have the technical problem of over-balancing, thereby affecting the balancing efficiency. Therefore, in steps S3 and S4 provided by the present invention, firstly, by determining the single cell SOC value and the single cell SOC sub-extreme value, and then combining step S4, balancing is performed by taking the middle value of the average SOC value and the single cell SOC sub-extreme value as the target SOC. Since the target SOC used in steps S3 and S4 is the middle value of the average SOC value and the single cell SOC sub-extreme value, compared with the prior art, the middle value is closer to the average value, so it can overcome the technical problem of over-balancing in the prior art.

[0096] Step S4 uses the middle value between the average SOC value and the next-highest value of the single-cell SOC as the target SOC to balance the battery pack. Generally speaking, the next-highest (or next-lowest) value of the single-cell SOC is higher (or lower) than the average SOC value, and it is not necessary to balance the single-cell SOC extreme value toward the average SOC value. As long as the single-cell SOC extreme value is closer to the average SOC value than the next-highest value of the single-cell SOC, the state in which the battery pack capacity cannot be fully utilized will be improved, and the technical problem of over-balancing can be alleviated. The method of balancing the battery pack may include the following: Figure 4 The steps shown. Specifically:

[0097] In step S30, a theoretical control amount for balancing the battery pack is determined according to the target SOC;

[0098] In step S31, the theoretical SOC after executing the theoretical control amount is calculated according to the objective function;

[0099] In step S32, the theoretical control amount is executed, and the actual SOC of the battery pack is obtained;

[0100] In step S33, the single cell SOC of the battery pack is determined according to the theoretical SOC and the actual SOC;

[0101] In step S34, judging whether the battery pack meets the balancing condition according to the single cell SOC;

[0102] In step S35, when it is determined that the battery pack meets the balancing condition, the objective function is updated according to the theoretical SOC and the actual SOC, and the process returns to the step of determining the theoretical control amount for balancing the battery pack according to the target SOC, that is, returns to step S30;

[0103] In step S36, when it is determined that the battery pack does not meet the balancing condition, it is determined that the balancing of the battery pack is completed.

[0104] In this Figure 4 In the method shown, step S30 can be used to determine the theoretical control amount for balancing the battery pack according to the target SOC, thereby determining the switch control operation to be performed by the battery pack in the next step. However, due to the relatively limited accuracy of the SOC estimation of the battery pack, it is impossible to directly determine the real SOC of the battery pack by estimating the SOC of the battery pack after executing the theoretical control amount. Therefore, in this balancing strategy, the theoretical SOC after executing the theoretical control amount can be first calculated in combination with the preset objective function through step S31, and then the actual SOC of the battery pack after executing the theoretical control amount can be directly estimated through step S32, and finally the theoretical SOC and the actual SOC can be combined at the same time through step S33 to obtain the real SOC, that is, the single cell SOC.

[0105] In addition, the objective function in step S31 can be in various forms known to those skilled in the art. In one example of the present invention, the objective function can be determined using the following formula (1):

[0106]

[0107] Among them, minJ is the minimization of the objective function, U(k) T is the transpose of the battery pack balancing state matrix, is the internal resistance matrix, U(k) is the battery pack equilibrium state matrix, α, β, η, is the intermediate variable matrix.

[0108] The method for determining the actual SOC of the battery pack in step S32 may be in various forms known to those skilled in the art, including but not limited to the ampere-hour integration method, the curve fitting method, etc. In one example of the present invention, the method for determining the actual SOC may include: Figure 5 The steps shown. Figure 5 In the method of determining the actual SOC, the method may include the following steps:

[0109] In step S40, the cell terminal voltage of the battery pack is collected;

[0110] In step S41 , the actual SOC is determined according to a preset battery model.

[0111] The battery model in step S41 may be in various forms known to those skilled in the art. In this example, the battery model may be as shown in the following formula (2):

[0112] U=E0-I c R in +k1lnSOC+k2ln(1-SOC), (2)

[0113] Among them, U is the single-cell terminal voltage, E0 is the open circuit voltage, I c is the discharge current, R in is the internal resistance of the battery, k1 and k2 are fitting coefficients.

[0114] In step S33, the specific method of obtaining the single-cell SOC by using the theoretical SOC and the actual SOC may also be various forms known to those skilled in the art. In one example of the present invention, the single-cell SOC may be determined by using formula (3):

[0115] SOC0=SOC1+SOC2 / 2, (3)

[0116] Among them, SOC1 is the theoretical SOC, SOC2 is the actual SOC, and SOC0 is the single body SOC.

[0117] After determining the single cell SOC representing the actual SOC of the single cell, it is possible to determine whether the battery pack meets the balancing condition based on the single cell SOC, i.e., step S34. At this time, if the battery pack still meets the balancing condition, it means that the battery pack needs to continue to perform switch control to jump out of the balancing condition, so it can return to step S30. Otherwise, it can exit the control, i.e., step S36.

[0118] Through the above technical scheme, the present invention provides a balancing strategy and system based on SOC maximum value, by obtaining the single SOC value and average SOC value of the battery pack, when the battery pack needs to perform a balancing operation, the single SOC extreme value and single SOC sub-extreme value of the battery pack are determined, and the intermediate value between the average SOC value and the single SOC sub-extreme value is used as the target SOC to balance the battery pack. The balancing strategy and system predicts the SOC of the battery pack, timely balances the single cell with the highest SOC during charging and the single cell with the lowest SOC during discharging, ensures full utilization of the battery pack capacity, realizes balancing of the entire battery pack, and has high balancing efficiency.

[0119] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0120] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0121] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0122] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0123] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0124] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0125] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0126] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0127] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A balancing strategy based on SOC maximum value, characterized in that: The balancing strategy includes: Get the single cell SOC value and average SOC value of the battery pack; Determining whether the battery pack needs to perform a balancing operation; In the case where it is determined that the battery pack needs to perform a balancing operation, determining a single cell SOC extreme value and a single cell SOC sub-extreme value of the battery pack; The battery pack is balanced by taking the middle value between the average SOC value and the next-highest SOC value of the single cell as the target SOC, including: Determining a theoretical control amount for balancing the battery pack according to the target SOC; Calculate the theoretical SOC after executing the theoretical control amount according to the objective function; Executing the theoretical control amount and obtaining the actual SOC of the battery pack; Determine the single cell SOC of the battery pack according to the theoretical SOC and the actual SOC; Determining whether the battery pack meets a balancing condition according to the single cell SOC; In the case where it is determined that the battery pack meets the balancing condition, updating the objective function according to the theoretical SOC and the actual SOC, and returning to execute the step of determining the theoretical control amount for balancing the battery pack according to the target SOC; In the case where it is determined that the battery group does not meet the balancing condition, determining that the balancing of the battery group is completed; Formula (1) is used to determine the objective function: ，（1） in, is the minimization of the objective function, is the transpose of the battery pack balancing state matrix, is the internal resistance matrix, is the battery pack balancing state matrix, , , , is the intermediate variable matrix.

2. The balancing strategy according to claim 1, characterized in that: Determine the single cell SOC extreme value and single cell SOC sub-extreme value of the battery pack, including: Determining an operating state of the battery pack; When the battery pack is in a charging state, the highest single-cell SOC value and the second highest single-cell SOC value are determined.

3. The balancing strategy according to claim 1, characterized in that: Determine the single cell SOC extreme value and single cell SOC sub-extreme value of the battery pack, including: Determining an operating state of the battery pack; When the battery pack is in a discharging state, the lowest single cell SOC value and the second lowest single cell SOC value are determined.

4. The balancing strategy according to claim 1, characterized in that: Obtaining the actual SOC of the battery pack, including: Collecting the cell terminal voltage of the battery pack; The actual SOC is determined according to a preset battery model.

5. The balancing strategy according to claim 4, characterized in that: The balancing strategy also includes: The actual SOC is determined according to formula (2): ，（2） in, is the single-cell terminal voltage, is the open circuit voltage, is the discharge current, is the internal resistance of the battery, and is the fitting coefficient.

6. The balancing strategy according to claim 5, characterized in that: Determining the single cell SOC of the battery pack according to the theoretical SOC and the actual SOC includes: The monomer SOC is determined according to formula (3): ，（3） in, is the theoretical SOC, is the actual SOC, It is a single SOC.

7. A balancing system based on SOC maximum value, characterized in that: The balancing system comprises a processor, and the processor is configured to execute the balancing strategy according to any one of claims 1 to 6.

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