BMS equalization control method

Abstract

The invention relates to the technical field of battery management systems, and particularly discloses a BMS equalization control method, which comprises the following steps of: when a battery stands, triggering SOC static correction or when the battery is charged, triggering SOC full charge, and calculating a state-of-charge difference value of a battery pack; when the state-of-charge difference value is greater than a preset value, calculating an initial equalization capacity difference of the battery pack, and marking an equalization state of the battery pack at a position 1 so as to start equalization of the battery pack; when the equalization state flag position of the battery pack is 1, judging whether the battery pack meets an equalization execution condition or not; when the equalization execution condition is met, controlling the single batteries in the battery pack to execute the equalization task; in the process of executing the balancing task, the residual balancing capacity difference of the battery pack is calculated in real time; and when the residual equalization capacity difference is 0, marking the equalization state of the battery pack to be 0 so as to close the equalization of the battery pack and control the single batteries in the battery pack to end the equalization task. The invention can ensure the safety of the battery and prolong the service life of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management systems, and in particular to a BMS balancing control method. Background Art

[0002] Differences in production, manufacturing and use lead to inconsistency in power battery cells. The inconsistency is mainly manifested in the cell capacity, internal resistance, self-discharge rate and charge and discharge efficiency. The inconsistency of the cell is transmitted to the power battery pack, which will inevitably lead to the loss of capacity and shortened life of the power battery pack. Studies have shown that a 20% capacity difference between individual battery cells will lead to a 40% capacity loss in the battery pack, which in turn leads to a reduction in vehicle range. Over time, under the influence of random factors such as temperature and vibration conditions, the inconsistency of battery cells will further deteriorate, and serious safety hazards will exist. This trend cannot be reversed, but intervention measures can be taken to reduce the rate of deterioration. Therefore, it is necessary to balance the battery through a battery management system.

[0003] The balancing function of the battery management system (BMS) is critical for the following reasons:

[0004] Safety: If balancing is not performed, the voltages of the cells inside the battery will be inconsistent, which may cause the cells with high resistance to charge too quickly and become saturated, or discharge too quickly, which may cause damage during long-term use, thus posing a safety hazard to the entire battery.

[0005] Lifespan impact: Voltage inconsistency can also have a serious impact on battery life, because voltage differences can cause certain cells in the battery pack to overcharge and discharge, accelerating their aging. Summary of the invention

[0006] In view of the defects and shortcomings in the prior art, the present invention provides a BMS balancing control method, which can ensure the safety of the battery and extend the battery life.

[0007] As a first aspect of the present invention, a BMS balancing control method is provided, the BMS balancing control method comprising:

[0008] Step S1: When the SOC static correction is triggered when the battery is at rest or the SOC full charge is triggered when the battery is charged, the state of charge difference ΔSOC of the battery pack is calculated;

[0009] Step S2: when the state of charge difference ΔSOC of the battery pack is greater than a preset value, the initial balancing capacity difference ΔCAP0 of the battery pack is calculated, and the balancing state flag of the battery pack is set to 1 to start balancing of the battery pack;

[0010] Step S3: when the battery pack's balancing status flag is at 1, determine whether the battery pack meets the balancing execution condition; when the battery pack meets the balancing execution condition, control the battery cells in the battery pack to perform the current balancing task;

[0011] Step S4: during the execution of this balancing task, the remaining balancing capacity difference ΔCAP1 of the battery group is calculated in real time according to the initial balancing capacity difference ΔCAP0 of the battery group;

[0012] Step S5: when the remaining balancing capacity difference ΔCAP1 of the battery pack is 0, the balancing state flag of the battery pack is set to 0 to turn off the balancing of the battery pack, so as to control the battery cells in the battery pack to end the current balancing task.

[0013] Furthermore, the calculation formula of the state of charge difference ΔSOC of the battery pack is as follows:

[0014] ΔSOC=SOC_MAX-SOC_MIN

[0015] Among them, SOC_MAX is the maximum SOC value of the battery cell, and SOC_MIN is the minimum SOC value of the battery cell.

[0016] Furthermore, when the state of charge difference ΔSOC of the battery pack is greater than a preset value, calculating the initial equalization capacity difference ΔCAP0 of the battery pack further includes:

[0017] When the state of charge difference ΔSOC of the battery pack is greater than a preset value, the initial equalization capacity difference ΔCAP0 of the battery pack is calculated according to the state of charge difference ΔSOC of the battery pack, the health state SOH of the battery pack and the total capacity CAP of the battery pack. The calculation formula is as follows:

[0018] ΔCAP0=ΔSOC*SOH*CAP.

[0019] Furthermore, the step S3 further includes:

[0020] When the battery pack's balancing status flag is at 1, it is determined whether the battery pack satisfies the first balancing execution condition, the second balancing execution condition, and the third balancing execution condition at the same time; wherein the first balancing execution condition is that the actual SOC value of the battery pack is greater than 20%, the second balancing execution condition is that the board temperature is less than or equal to 85°C, and the third balancing execution condition is that the battery cell temperature is greater than or equal to -25°C and less than or equal to 58°C;

[0021] When the battery pack satisfies the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, controlling the battery cells in the battery pack to execute the current balancing task;

[0022] When the battery pack does not meet the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, the process directly jumps to the end state.

[0023] Furthermore, when the battery pack satisfies the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, controlling the battery cells in the battery pack to execute the current balancing task further includes:

[0024] During the process of the battery cells in the battery pack performing the current balancing task, if the battery pack does not meet the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, the battery cells in the battery pack are controlled to suspend the current balancing task.

[0025] Furthermore, when the battery pack meets the balancing execution condition, controlling the battery cells in the battery pack to execute the current balancing task also includes:

[0026] When the battery pack meets the balancing execution condition, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed first, and then the odd-numbered battery cells and the even-numbered battery cells in the battery pack are controlled to stagger and execute the balancing task.

[0027] Furthermore, with 5 times as one cycle and the balancing execution period of 10ms, the execution of this balancing task is carried out according to the following steps:

[0028] The first 10ms: turn off the balancing of the battery pack and execute the conversion and acquisition task of the analog front-end digital-to-analog converter to collect the voltage of the battery cells in the battery pack;

[0029] The second 10ms: if the even-numbered battery cells in the battery pack meet the balancing execution condition, the even-numbered battery cells are controlled to perform the current balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not performed; if the balancing execution condition is not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally;

[0030] The third 10m: if the odd-numbered battery cells in the battery pack meet the balancing execution condition, the odd-numbered battery cells are controlled to perform the current balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not performed; if the balancing execution condition is not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally;

[0031] The fourth 10ms: if the even-numbered battery cells in the battery pack meet the equalization execution condition, the even-numbered battery cells are controlled to perform the current equalization task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not performed; if the equalization execution condition is not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally;

[0032] The fifth 10ms: If the odd-numbered battery cells in the battery pack meet the balancing execution conditions, the odd-numbered battery cells are controlled to perform this balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not performed; if the balancing execution conditions are not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally.

[0033] Furthermore, the calculation formula of the remaining equalization capacity difference ΔCAP1 of the battery pack is as follows:

[0034] ΔCAP1=ΔCAP0-V[i] / R*T

[0035] Wherein, V[i] is the voltage value of the battery cell in the battery pack, R is the balancing resistor, and T is the time for executing this balancing task.

[0036] Furthermore, the step S5 further includes:

[0037] When the remaining balancing capacity difference ΔCAP1 of the battery pack is not zero, the battery cells in the battery pack are controlled to continue to perform the current balancing task until the remaining balancing capacity difference ΔCAP1 of the battery pack is zero.

[0038] Furthermore, the controlling the battery cells in the battery pack to continue to perform the current balancing task also includes:

[0039] When the battery cells in the battery pack continue to perform the current balancing task, the BMS is powered off, and the remaining balancing capacity difference ΔCAP1, the balancing battery cell number and the balancing state of the battery pack are stored in the memory, so that after the BMS is powered on, the balancing of the battery cells that were not balanced last time can be continued;

[0040] Among them, after the BMS is powered on, if the actual SOC value of the battery pack meets the static correction condition and the state of charge difference ΔSOC of the battery pack is greater than the preset value, the remaining equalization capacity difference ΔCAP1 of the battery pack is cleared, and the initial equalization capacity difference ΔCAP0 of the battery pack is recalculated, and then steps S3 to S5 are executed.

[0041] The BMS balancing control method provided by the present invention has the following advantages: after battery balancing is turned on, it is ensured that the battery cells will not be over-discharged; balancing is turned on during charging to ensure that the battery cell voltage will not show a downward trend; when the BMS is powered off and then powered on again, the battery cells that were not balanced last time can be continued; thereby ensuring the safety of the battery and extending the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0043] Figure 1 This is a flow chart of the BMS balancing control method provided by the present invention.

[0044] Figure 2 This is a flow chart of a specific implementation of the BMS balancing control method provided by the present invention. DETAILED DESCRIPTION

[0045] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0046] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0047] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0048] In this embodiment, a BMS balancing control method is provided. Figure 1 The flowchart of the BMS balancing control method provided by the present invention is as follows: Figure 1 As shown, the BMS balancing control method includes:

[0049] Step S1: When the SOC static correction is triggered when the battery is at rest or the SOC full charge is triggered when the battery is charged, the state of charge difference ΔSOC of the battery pack is calculated;

[0050] Preferably, the calculation formula of the state of charge difference ΔSOC of the battery pack is as follows:

[0051] ΔSOC=SOC_MAX-SOC_MIN

[0052] Among them, SOC_MAX is the maximum SOC value of the battery cell, and SOC_MIN is the minimum SOC value of the battery cell.

[0053] It should be noted that before the BMS starts balancing the battery pack, it first determines whether the SOC static correction is triggered when the battery is at rest or whether the SOC full charge is triggered when the battery is charging. If any condition is not met, it jumps directly to the end state.

[0054] Step S2: when the state of charge difference ΔSOC of the battery pack is greater than a preset value, the initial balancing capacity difference ΔCAP0 of the battery pack is calculated, and the balancing state flag of the battery pack is set to 1 to start balancing of the battery pack;

[0055] Preferably, Figure 2 As shown, when the state of charge difference ΔSOC of the battery pack is greater than a preset value, calculating the initial equalization capacity difference ΔCAP0 of the battery pack also includes:

[0056] When the state of charge difference ΔSOC of the battery pack is greater than a preset value (the preset value is, for example, 5%), the initial equalization capacity difference ΔCAP0 of the battery pack is calculated according to the state of charge difference ΔSOC of the battery pack, the health state SOH of the battery pack and the total capacity CAP of the battery pack. The calculation formula is as follows:

[0057] ΔCAP0=ΔSOC*SOH*CAP.

[0058] It should be noted that when the state of charge difference ΔSOC of the battery pack is not greater than a preset value, the process directly jumps to the end state.

[0059] Step S3: when the battery pack's balancing status flag is set to 1, determine whether the battery pack meets the balancing execution condition; when the battery pack meets the balancing execution condition, control the battery cells in the battery pack to perform the current balancing task;

[0060] Preferably, Figure 2 As shown, the step S3 further includes:

[0061] When the battery pack's balancing status flag is set to 1, it is determined whether the battery pack satisfies the first balancing execution condition, the second balancing execution condition, and the third balancing execution condition at the same time; wherein the first balancing execution condition is that the actual SOC value of the battery pack is greater than 20%, the second balancing execution condition is that the board temperature is less than or equal to 85°C, and the third balancing execution condition is that the battery cell temperature is greater than or equal to -25°C and less than or equal to 58°C;

[0062] When the battery pack satisfies the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, controlling the battery cells in the battery pack to execute the current balancing task;

[0063] Specifically, when the battery pack satisfies the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, controlling the battery cells in the battery pack to execute the current balancing task also includes:

[0064] During the process of the battery cells in the battery pack performing the current balancing task, if the battery pack does not meet the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, the battery cells in the battery pack are controlled to suspend the current balancing task.

[0065] When the battery pack does not meet the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, the process directly jumps to the end state.

[0066] Specifically, when the battery pack meets the balancing execution condition, controlling the battery cells in the battery pack to execute the current balancing task also includes:

[0067] When the battery pack meets the balancing execution conditions, the conversion and acquisition task of the analog front end digital-to-analog converter (AFEADC) is first executed, and then the odd-numbered battery cells and the even-numbered battery cells in the battery pack are controlled to stagger and execute the balancing task.

[0068] In the embodiment of the present invention, 5 times is a cycle, and the balancing execution period is 10ms. The execution of this balancing task is performed according to the following steps:

[0069] The first 10ms: turn off the balancing of the battery pack and execute the conversion and acquisition task of the analog front-end digital-to-analog converter to collect the voltage of the battery cells in the battery pack;

[0070] The second 10ms: if the even-numbered battery cells in the battery pack meet the balancing execution condition, the even-numbered battery cells are controlled to perform the current balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not performed; if the balancing execution condition is not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally;

[0071] The third 10m: if the odd-numbered battery cells in the battery pack meet the balancing execution condition, the odd-numbered battery cells are controlled to perform the current balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not performed; if the balancing execution condition is not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally;

[0072] The fourth 10ms: if the even-numbered battery cells in the battery pack meet the equalization execution condition, the even-numbered battery cells are controlled to perform the current equalization task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not performed; if the equalization execution condition is not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally;

[0073] The fifth 10ms: If the odd-numbered battery cells in the battery pack meet the balancing execution conditions, the odd-numbered battery cells are controlled to perform this balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not performed; if the balancing execution conditions are not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally.

[0074] Step S4: during the execution of this balancing task, the remaining balancing capacity difference ΔCAP1 of the battery group is calculated in real time according to the initial balancing capacity difference ΔCAP0 of the battery group;

[0075] Preferably, the calculation formula of the remaining equalization capacity difference ΔCAP1 of the battery pack is as follows:

[0076] ΔCAP1=ΔCAP0-V[i] / R*T

[0077] Wherein, V[i] is the voltage value of the battery cell in the battery pack, R is the balancing resistor, and T is the time for executing this balancing task.

[0078] Step S5: when the remaining balancing capacity difference ΔCAP1 of the battery pack is 0, the balancing state flag of the battery pack is set to 0 to turn off the balancing of the battery pack, so as to control the battery cells in the battery pack to end the current balancing task.

[0079] Preferably, if Figure 2 As shown, the step S5 further includes:

[0080] When the remaining balancing capacity difference ΔCAP1 of the battery pack is not zero, the battery cells in the battery pack are controlled to continue to perform the current balancing task until the remaining balancing capacity difference ΔCAP1 of the battery pack is zero.

[0081] Specifically, the controlling the battery cells in the battery pack to continue to perform the current balancing task also includes:

[0082] When the battery cells in the battery pack continue to perform the current balancing task, the BMS is powered off, and the remaining balancing capacity difference ΔCAP1, the balancing battery cell number and the balancing state of the battery pack are stored in the memory (EEPROM), so that the battery cells that were not balanced last time can be balanced again after the BMS is powered on next time;

[0083] Among them, the next time the BMS is powered on, if the actual SOC value of the battery pack meets the static correction condition and the state of charge difference ΔSOC of the battery pack is greater than the preset value, the remaining equalization capacity difference ΔCAP1 of the battery pack is cleared, and the initial equalization capacity difference ΔCAP0 of the battery pack is recalculated, and then steps S3 to S5 are executed.

[0084] The BMS balancing control method provided by the present invention first determines whether to start balancing, then determines the balancing execution conditions, and finally exits balancing when the balancing shutdown conditions are met; the present invention ensures that the battery cells will not be over-discharged after the battery balancing is started; ensures that when the balancing is turned on during the charging process, the battery cell voltage will not show a downward trend; ensures that when the BMS is powered off and then powered on again, the battery cells that were not balanced last time can be continued; thereby ensuring the safety of the battery and extending the battery life.

[0085] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A BMS balancing control method, characterized in that: The BMS balancing control method comprises: Step S1: When the SOC static correction is triggered when the battery is at rest or the SOC full charge is triggered when the battery is charged, the state of charge difference ΔSOC of the battery pack is calculated; Step S2: when the state of charge difference ΔSOC of the battery pack is greater than a preset value, the initial balancing capacity difference ΔCAP0 of the battery pack is calculated, and the balancing state flag of the battery pack is set to 1 to start balancing of the battery pack; Step S3: when the battery pack's balancing status flag is at 1, determine whether the battery pack meets the balancing execution condition; when the battery pack meets the balancing execution condition, control the battery cells in the battery pack to perform the current balancing task; Step S4: during the execution of this balancing task, the remaining balancing capacity difference ΔCAP1 of the battery group is calculated in real time according to the initial balancing capacity difference ΔCAP0 of the battery group; Step S5: when the remaining balancing capacity difference ΔCAP1 of the battery pack is 0, the balancing state flag of the battery pack is set to 0 to turn off the balancing of the battery pack, so as to control the battery cells in the battery pack to end the current balancing task.

2. The BMS balancing control method according to claim 1, characterized in that: The calculation formula of the state of charge difference ΔSOC of the battery pack is as follows: ΔSOC=SOC_MAX-SOC_MIN Among them, SOC_MAX is the maximum SOC value of the battery cell, and SOC_MIN is the minimum SOC value of the battery cell.

3. The BMS balancing control method according to claim 1, characterized in that: When the state of charge difference ΔSOC of the battery pack is greater than a preset value, calculating the initial equalization capacity difference ΔCAP0 of the battery pack further includes: When the state of charge difference ΔSOC of the battery pack is greater than a preset value, the initial equalization capacity difference ΔCAP0 of the battery pack is calculated according to the state of charge difference ΔSOC of the battery pack, the health state SOH of the battery pack and the total capacity CAP of the battery pack. The calculation formula is as follows: ΔCAP0=ΔSOC*SOH*CAP.

4. The BMS balancing control method according to claim 1, characterized in that: The step S3 further includes: When the battery pack's balancing status flag is at 1, it is determined whether the battery pack satisfies the first balancing execution condition, the second balancing execution condition, and the third balancing execution condition at the same time; wherein the first balancing execution condition is that the actual SOC value of the battery pack is greater than 20%, the second balancing execution condition is that the board temperature is less than or equal to 85°C, and the third balancing execution condition is that the battery cell temperature is greater than or equal to -25°C and less than or equal to 58°C; When the battery pack satisfies the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, controlling the battery cells in the battery pack to execute the current balancing task; When the battery pack does not meet the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, the process directly jumps to the end state.

5. The BMS balancing control method according to claim 4, characterized in that: When the battery pack satisfies the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, controlling the battery cells in the battery pack to execute the current balancing task also includes: During the process of the battery cells in the battery pack performing the current balancing task, if the battery pack does not meet the first balancing execution condition, the second balancing execution condition and the third balancing execution condition at the same time, the battery cells in the battery pack are controlled to suspend the current balancing task.

6. The BMS balancing control method according to claim 1, characterized in that: When the battery pack meets the balancing execution condition, controlling the battery cells in the battery pack to execute the current balancing task also includes: When the battery pack meets the balancing execution condition, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed first, and then the odd-numbered battery cells and the even-numbered battery cells in the battery pack are controlled to stagger and execute the balancing task.

7. The BMS balancing control method according to claim 6, characterized in that: With 5 times as a cycle and the balancing execution period of 10ms, the execution of this balancing task is carried out according to the following steps: The first 10ms: turn off the balancing of the battery pack and execute the conversion and acquisition task of the analog front-end digital-to-analog converter to collect the voltage of the battery cells in the battery pack; The second 10ms: if the even-numbered battery cells in the battery pack meet the balancing execution condition, the even-numbered battery cells are controlled to execute the current balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not executed; If the equalization execution condition is not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally; The third 10m: if the odd-numbered battery cells in the battery pack meet the balancing execution condition, the odd-numbered battery cells are controlled to execute the current balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not executed; If the equalization execution condition is not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally; The fourth 10ms: if the even-numbered battery cells in the battery pack meet the balancing execution condition, the even-numbered battery cells are controlled to execute the current balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not executed; If the equalization execution condition is not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally; The fifth 10ms: If the odd-numbered battery cells in the battery pack meet the balancing execution conditions, the odd-numbered battery cells are controlled to perform this balancing task, and the conversion and acquisition task of the analog front-end digital-to-analog converter is not performed; if the balancing execution conditions are not met, the conversion and acquisition task of the analog front-end digital-to-analog converter is performed normally.

8. The BMS balancing control method according to claim 1, characterized in that: The calculation formula of the remaining equalization capacity difference ΔCAP1 of the battery pack is as follows: ΔCAP1=ΔCAP0-V[i] / R*T Wherein, V[i] is the voltage value of the battery cell in the battery pack, R is the balancing resistor, and T is the time for executing this balancing task.

9. The BMS balancing control method according to claim 1, characterized in that: The step S5 further includes: When the remaining balancing capacity difference ΔCAP1 of the battery pack is not zero, the battery cells in the battery pack are controlled to continue to perform the current balancing task until the remaining balancing capacity difference ΔCAP1 of the battery pack is zero.

10. The BMS balancing control method according to claim 9, characterized in that: The controlling the battery cells in the battery pack to continue to perform the current balancing task also includes: When the battery cells in the battery pack continue to perform the current balancing task, the BMS is powered off, and the remaining balancing capacity difference ΔCAP1, the balancing battery cell number and the balancing state of the battery pack are stored in the memory, so that after the BMS is powered on, the balancing of the battery cells that were not balanced last time can be continued; Among them, after the BMS is powered on, if the actual SOC value of the battery pack meets the static correction condition and the state of charge difference ΔSOC of the battery pack is greater than the preset value, the remaining equalization capacity difference ΔCAP1 of the battery pack is cleared, and the initial equalization capacity difference ΔCAP0 of the battery pack is recalculated, and then steps S3 to S5 are executed.

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