A battery offline equalization method, device and medium
Patent Information
- Application Number
- CN202510489560.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2026-10-27
AI Technical Summary
[0031]当使用传统均衡时间计算方案，即将所有SOC不分段直接计算均衡时间，由于OCV_SOC曲线的非线性数据特征，计算得到的均衡时间可能超过实际需要均衡时间的导致能源浪费，也可能低地实际需要均衡的时间导致电芯一致性变差。本发明在电池管理系统在进入休眠之前采用分段离散的方法估算离线均衡的时间，降低了因OCV_SOC曲线非线性导致的均衡时间估算误差；在电池管理系统进入休眠后，对电池单体执行估算的均衡方案，有效提升了电池离线均衡的控制精度。
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Figure CN122993133A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery technology, and in particular to a battery offline balancing method, apparatus, and medium. Background Technology
[0002] A battery pack consists of numerous cells connected in series. When the cells have inconsistent charge or voltage, the cell with the lower charge or voltage determines the lower discharge limit of the battery pack, resulting in a reduced capacity due to the bottleneck effect. To maintain cell consistency, the Battery Management System (BMS) reduces the charge or voltage differences between individual cells through a balancing function. Based on the BMS controller's operating state, balancing can be divided into online balancing and offline balancing. When the BMS main controller is in wake-up mode, it can monitor, calculate, and control the balancing needs of each individual cell in real time, achieving online balancing. However, during actual vehicle use, the BMS main controller is in a dormant state most of the time, and online balancing cannot meet the battery pack's balancing requirements. In this case, offline balancing is needed, which maintains the balancing state through the AFE chip on the slave board, improving overall balancing efficiency.
[0003] The offline balancing function calculates the remaining balancing power demand for each cell before the BMS master controller goes into sleep mode and converts it into remaining balancing time. Data such as the target cell and remaining balancing time are written to the slave board AFE register. When the master controller goes into sleep mode, the AFE controls the cells to perform balancing based on the information in the register, achieving offline balancing. When calculating the remaining balancing time Δt, the balancing current I_bal needs to be calculated based on the cell's resting voltage u and balancing resistance R_bal. Then, the balancing power ΔQ_bal is divided by the balancing current to obtain the balancing time, i.e., Δt = ΔQ_bal / I_bal = ΔQ_bal * R_bal / u. Currently, most offline balancing calculations use the cell voltage before sleep mode or the average of the cell voltages before and after sleep mode. Because cell voltages exhibit non-linear trends under different SOCs, the estimated remaining balancing time may have significant deviations, potentially leading to over-balancing or under-balancing. Summary of the Invention
[0004] This invention discloses a battery offline equalization method, apparatus, and medium, which can improve the accuracy of battery offline equalization.
[0005] To achieve the above objectives, on the one hand, an offline battery balancing method is provided. When the battery management system meets the hibernation conditions and there is a need for offline battery balancing, offline balancing is initiated. The specific method is as follows:
[0006] The remaining equalization capacity of each battery cell is divided into segments according to a fixed SOC. The equalization time of each battery cell in each SOC segment is calculated, and the segment equalization time is accumulated to obtain the total offline equalization time of the battery cell.
[0007] When the battery management system enters sleep mode, offline balancing is performed on individual battery cells.
[0008] Furthermore, the remaining balanced charge of each battery cell is obtained based on the online balancing results, and the specific method for obtaining this information is as follows:
[0009] When sufficient wake-up conditions are met, the wake-up source wakes up the main controller of the battery management system.
[0010] When the online equalization activation conditions are met, the equalization power demand of each battery cell is calculated online.
[0011] The remaining balance capacity is calculated based on the battery cell demand for equalization and the already equalized capacity.
[0012] Furthermore, the wake-up source is a T15, a CAN, or a timed wake-up device.
[0013] Furthermore, the segmented equalization time of each battery cell in each SOC segment is calculated, using the following method:
[0014] Based on the remaining equalization power, determine the start and end SOC of offline equalization;
[0015] Segmentation is performed between the start SOC and the end SOC, with a fixed SOC as the interval.
[0016] The corresponding OCV voltage is obtained by looking up the table in the OCV_SOC curve for the starting SOC of each SOC segment, and is used as the offline equalization voltage for each SOC segment.
[0017] The equalization time for each SOC segment is calculated based on the offline equalization voltage, equalization resistance, and equalization charge of each SOC segment.
[0018] Furthermore, when the battery management system enters sleep mode, offline balancing is performed on individual battery cells, as follows:
[0019] Store the individual battery cell, the corresponding segment balancing time, and the total offline balancing time into the register;
[0020] After the battery management system enters sleep mode, the AFE controls the individual battery cells to perform offline equalization based on the information stored in the register.
[0021] Offline balancing ends when the balancing time is completed or when the balancing conditions are no longer met.
[0022] Furthermore, the fixed SOC is less than or equal to 2%.
[0023] Preferably, the fixed SOC is 1%.
[0024] To achieve the above objectives, another aspect is to provide a battery offline balancing device, comprising: a remaining balancing capacity calculation module, an offline balancing parameter calculation module, and an execution module;
[0025] The remaining balanced power calculation module obtains the remaining balanced power of each battery cell.
[0026] The offline balancing parameter calculation module divides the remaining balancing capacity of each battery cell into segments according to a fixed SOC, calculates the segment balancing time of each battery cell in each SOC segment, and accumulates the segment balancing time as the total offline balancing time of the battery cell.
[0027] The execution module performs offline balancing on individual battery cells after the battery management system enters sleep mode.
[0028] To achieve the above objectives, another aspect is to provide a storage medium storing several instructions, which a processor loads to execute the aforementioned battery offline balancing method.
[0029] To achieve the above objectives, another aspect is to provide a battery management system, including the aforementioned offline battery balancing device and / or the aforementioned storage medium.
[0030] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:
[0031] Traditional equalization time calculation schemes, which directly calculate equalization time for all SOCs without segmentation, may result in energy waste due to the nonlinear characteristics of the OCV_SOC curve, either exceeding the actual required equalization time or falling short, leading to poor cell consistency. This invention uses a segmented, discrete method to estimate offline equalization time before the battery management system enters sleep mode, reducing the estimation error caused by the nonlinearity of the OCV_SOC curve. After the battery management system enters sleep mode, the estimated equalization scheme is executed on individual battery cells, effectively improving the control accuracy of offline battery equalization.
[0032] It should be noted that the terms "first," "second," and similar terms used in this article are merely for describing the constituent elements of the technical solution and do not constitute a limitation on the technical solution, nor should they be interpreted as an indication or implication of the importance of the corresponding elements; elements with terms such as "first," "second," or similar terms indicate that at least one of the elements is included in the corresponding technical solution. Attached Figure Description
[0033] To more clearly illustrate the technical solution of the present invention and facilitate a further understanding of its technical effects, features, and objectives, the present invention will be described in detail below with reference to the accompanying drawings. The drawings constitute an essential part of the specification and are used together with Embodiment 1 of the present invention to illustrate the technical solution of the present invention, but do not constitute a limitation on the present invention.
[0034] The same reference numerals in the attached diagrams represent the same parts, specifically:
[0035] Figure 1 This is a schematic diagram of the overall process of Example 1.
[0036] Figure 2 This is a schematic diagram of the piecewise discrete equilibrium time estimation. Detailed Implementation
[0037] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described below are merely illustrative of the technical solutions of the present invention, and not intended to limit the invention. Furthermore, the parts described in the embodiments or drawings are merely illustrative examples of relevant parts of the present invention, and not the entirety of the invention.
[0038] Example 1:
[0039] An offline battery equalization method, such as Figure 1 As shown, the specific steps are as follows:
[0040] S1. When the battery management system is in a wake-up state, determine whether the battery meets the equalization activation conditions. If it does, proceed to step S2.
[0041] In step S1, when the wake-up source such as T15 / CAN / timed wake-up meets the conditions, the BMS main controller is woken up.
[0042] S2. Calculate the required power balance and enable online power balancing.
[0043] S3. Determine whether the power-down sleep conditions and offline balancing requirements are met. If yes, proceed to step S4.
[0044] S4. Set the fixed SOC to 1%, i.e., Δsoc = 1%. Divide the remaining equalization capacity of each battery cell into segments according to the fixed SOC. Calculate the segment equalization time of each battery cell in each SOC segment. Add up the segment equalization time as the total offline equalization time of the battery cell and store it in the AFE register.
[0045] Step S4 uses a piecewise discrete approach to estimate the equalization time of each SOC segment. The specific estimation steps are as follows: Figure 2As shown. Before hibernation, the starting SOC1 and ending SOC2 for offline balancing are calculated based on the individual unit SOC and remaining balancing power. Segmentation is performed between SOC1 and SOC2 using a Δsoc interval; in this embodiment, Δsoc is selected as 1%. The balancing power is divided into segments 1, 2, 3, 4, ..., n. For each segment, the corresponding OCV voltage is obtained by looking up the table in the OCV_SOC curve based on the starting SOC of that segment, serving as the offline balancing voltage u1, u2, u3, u4, ..., un for each segment. The balancing time for each segment is calculated based on the balancing voltage, balancing resistance, and balancing power of each segment.
[0046] Δt1=Δsoc*Q*R / u1
[0047] Δt2=Δsoc*Q*R / u2
[0048] Δt3=Δsoc*Q*R / u3
[0049] Δt4=Δsoc*Q*R / u4
[0050] Calculate the total equilibrium time:
[0051]
[0052] In the above formula, R is the resistance value of the equalization resistor, Q is the cell capacity, ui is the equalization voltage within the segment, Δti is the equalization time of segment i, and Δt is the total equalization time.
[0053] S5. Based on the AFE register data, complete the offline balancing; or wake up the battery management system by low-voltage power-on and proceed to step S1.
[0054] Example 2:
[0055] A battery offline equalization method, the specific steps of which are as follows:
[0056] S1. When the battery management system is in a wake-up state, determine whether the battery meets the equalization activation conditions. If it does, proceed to step S2.
[0057] In step S1, when the wake-up source such as T15 / CAN / timed wake-up meets the conditions, the BMS main controller is woken up.
[0058] S2. Calculate the required power balance and enable online power balancing.
[0059] S3. When the battery management system is in online balancing, determine whether the power-off hibernation conditions are met and whether the offline balancing requirements are met. If yes, proceed to step S4.
[0060] S4. Set the fixed SOC to 0.5%, i.e., Δsoc = 0.5%. Divide the remaining equalization capacity of each battery cell into segments according to the fixed SOC. Calculate the segment equalization time of each battery cell in each SOC segment. Add up the segment equalization times as the total offline equalization time of the battery cell and store it in the AFE register.
[0061] Example 3:
[0062] S1. When the battery management system is in a wake-up state, determine whether the battery meets the equalization activation conditions. If it does, proceed to step S2.
[0063] In step S1, when the wake-up source such as T15 / CAN / timed wake-up meets the conditions, the BMS main controller is woken up.
[0064] S2. Calculate the required power balance and enable online power balancing.
[0065] S3. When the battery management system is in online balancing, determine whether the power-off hibernation conditions are met and whether the offline balancing requirements are met. If yes, proceed to step S4.
[0066] S4. Set the fixed SOC to 0.5%, i.e., Δsoc = 0.5%. Divide the remaining equalization capacity of each battery cell into segments according to the fixed SOC. Obtain the equalization voltage of each SOC segment by looking up the table, and calculate the segment equalization time of each SOC segment. Accumulate the segment equalization time as the total offline equalization time of the battery cell and store it in the AFE register.
[0067] As can be seen from Examples 1, 2 and 3, the fixed SOC can be set manually. The lower the fixed SOC value, the closer the estimated offline balancing time is to the actual value.
[0068] As can be seen from Examples 1, 2 and 3, after the SOC is segmented, the segment balancing time of each segment can be calculated by formula, or the balancing voltage of each segment can be obtained by obtaining the table to calculate the segment balancing time of each segment.
[0069] Example 4:
[0070] A battery offline balancing device includes: a remaining balancing capacity calculation module, an offline balancing parameter calculation module, and an execution module;
[0071] The remaining balanced power calculation module obtains the remaining balanced power of each battery cell.
[0072] The offline balancing parameter calculation module divides the remaining balancing capacity of each battery cell into segments according to a fixed SOC, calculates the segment balancing time of each battery cell in each SOC segment, and accumulates the segment balancing time as the total offline balancing time of the battery cell.
[0073] The execution module performs offline balancing on individual battery cells after the battery management system enters sleep mode.
[0074] It should be noted that the above embodiments are only for more clearly illustrating the technical solution of the present invention. Those skilled in the art will understand that the implementation of the present invention is not limited to the above content. Any obvious changes, substitutions or replacements made based on the above content do not exceed the scope of the technical solution of the present invention. Other implementations will also fall within the scope of the present invention without departing from the concept of the present invention.
Claims
1. A battery offline equalization method, characterized in that, When the battery management system meets the sleep conditions and there is a need for offline battery balancing, enable offline balancing. The specific method is as follows: The remaining equalization capacity of each battery cell is divided into segments according to a fixed SOC. The equalization time of each battery cell in each SOC segment is calculated, and the segment equalization time is accumulated to obtain the total offline equalization time of the battery cell. When the battery management system enters sleep mode, offline balancing is performed on individual battery cells.
2. The battery offline equalization method as described in claim 1, characterized in that, The remaining balanced charge of a single battery cell is obtained based on the online balancing results, and the specific method for obtaining it is as follows: When sufficient wake-up conditions are met, the wake-up source wakes up the main controller of the battery management system. When the online equalization activation conditions are met, the equalization power demand of each battery cell is calculated online. The remaining balance capacity is calculated based on the battery cell demand for equalization and the already equalized capacity.
3. The battery offline equalization method as described in claim 2, characterized in that, The wake-up source is a T15, a CAN, or a timed wake-up device.
4. The battery offline equalization method as described in claim 1, characterized in that, The method for calculating the equalization time of a single battery cell in each SOC segment is as follows: Based on the remaining equalization power, determine the start and end SOC of offline equalization; Segmentation is performed between the start SOC and the end SOC, with a fixed SOC as the interval. The corresponding OCV voltage is obtained by looking up the table in the OCV_SOC curve for the starting SOC of each SOC segment, and is used as the offline equalization voltage for each SOC segment. The equalization time for each SOC segment is calculated based on the offline equalization voltage, equalization resistance, and equalization charge of each SOC segment.
5. The battery offline equalization method as described in claim 1, characterized in that, When the battery management system enters sleep mode, offline balancing is performed on individual battery cells. The specific method is as follows: Store the individual battery cell, the corresponding segment balancing time, and the total offline balancing time into the register; After the battery management system enters sleep mode, the AFE controls the individual battery cells to perform offline equalization based on the information stored in the register. Offline balancing ends when the balancing time is completed or when the balancing conditions are no longer met.
6. The battery offline equalization method as described in claim 1, characterized in that, The fixed SOC is less than or equal to 2%.
7. The battery offline equalization method as described in claim 6, characterized in that, The fixed SOC is 1%.
8. A battery offline balancing device, characterized in that, include: The remaining balancing power calculation module, the offline balancing parameter calculation module, and the execution module; The remaining balanced power calculation module obtains the remaining balanced power of each battery cell. The offline balancing parameter calculation module divides the remaining balancing capacity of each battery cell into segments according to a fixed SOC, calculates the segment balancing time of each battery cell in each SOC segment, and accumulates the segment balancing time as the total offline balancing time of the battery cell. The execution module performs offline balancing on individual battery cells after the battery management system enters sleep mode.
9. A storage medium, characterized in that, The system stores several instructions, and the processor loads these instructions to execute the battery offline balancing method according to any one of claims 1 to 7.
10. A battery management system, characterized in that, Includes the battery offline equalization device of claim 8, and / or the storage medium of claim 9.