Calculation method, equalization method and system for capacity to be equalized of battery cell of battery pack

Abstract

The invention discloses a method for calculating the to-be-balanced capacity of a battery pack cell, and the method comprises the steps: charging a battery, and obtaining a corresponding relation between a voltage and an accumulated charging integral capacity; when the highest voltage cell reaches a preset full charge voltage threshold and the voltage of the lowest voltage cell in the battery is lower than the upwarp voltage, determining a to-be-equalized cell; determining the accumulated charging integral capacity corresponding to the final voltage of the battery cell to be equalized according to the final voltage of the battery cell to be equalized at the end of charging and the corresponding relation between the voltage and the accumulated charging integral capacity; and determining the to-be-balanced capacity of the to-be-balanced battery cell according to the accumulated charging integral capacity corresponding to the final voltage of the to-be-balanced battery cell. According to the method, the corresponding relation between the voltage and the accumulated charging integral capacity is determined according to the actually measured voltage and current, the capacity to be balanced can be calculated more accurately, and the overall consistency of the battery pack is improved. The invention further discloses an equalization method and system for the to-be-equalized capacity of the battery pack cells, electronic equipment and a computer readable storage medium.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and specifically to a calculation method, an equalization method and system, and an electronic device for the to-be-equalized capacity of battery pack cells. Background Art

[0002] The popularization of electric vehicles has led to an increasing demand for high-performance battery systems. To meet the high-voltage requirements of electric vehicles, it is usually necessary to connect hundreds of individual cells in series to form a battery pack. However, the series connection of cells brings a series of problems, especially the consistency problem between cells. The emergence of these consistency problems is mainly attributed to the following factors: it is difficult to achieve exactly the same conditions during the production process of cells, and the slight differences in the production and manufacturing process will lead to slight differences in performance; during the use process of cells, the performance parameters will diverge due to different aging degrees; in the battery pack, due to the differences in characteristics such as the internal resistance of cells, the current distribution may be uneven during the charge and discharge process. These inconsistency problems will have a negative impact on the overall performance of the battery pack, including reducing the driving range, decreasing the power output, and may accelerate the aging of some cells, and even cause safety problems.

[0003] Especially in the application of cells with a voltage plateau period, this problem is more prominent. In the charge and discharge curve of the battery, it can be observed that within a certain capacity range, the voltage will remain at a relatively stable level, and this stable interval is the voltage plateau area. In this area, the voltage change of the cell is small, and it is difficult for traditional equalization methods, such as resistor discharge equalization, capacitor equalization, etc., to play an effective role. Because these traditional equalization methods mainly rely on the voltage difference to trigger the equalization action. And within the voltage plateau area, due to the insignificant voltage change, the effect of these methods is greatly weakened.

[0004] One of the main functions of the battery management system is to monitor and manage the balance of the battery to ensure that each battery cell in the battery pack can work in the best state, thereby extending the overall life of the battery pack and improving its performance. At present, the technology used to determine the capacity to be balanced of the battery in the battery management system is mainly based on the estimation of SOC. SOC is the ratio of the remaining capacity of the battery to its full charge capacity, and is usually estimated by calculating the charge and discharge history of the battery. However, the method of capacity to be balanced based on SOC estimation has the following deficiencies. The estimation of SOC depends on the accuracy of the battery model, and the battery model may have estimation errors due to factors such as battery aging, temperature change, and inconsistency. The update of SOC usually has a certain delay and cannot reflect the actual state of the battery in real time, which may lead to untimely adjustment of the balancing strategy. Due to the limitations of the estimation method itself, it is difficult to achieve high accuracy in calculating the capacity to be balanced based on SOC, thus affecting the effect of battery balancing. In short, the method of estimating the capacity to be balanced based on SOC has the problem of being unable to reflect the actual state of the battery cells in real time and accurately. Summary of the Invention

[0005] In a first aspect, to solve the above technical problems, an embodiment of the present invention discloses a method for calculating the capacity to be balanced of battery pack cells, including: charging the battery to obtain the corresponding relationship between voltage and cumulative charging integral capacity, where the corresponding relationship between voltage and cumulative charging integral capacity is the cumulative charging integral capacity of the highest voltage cell in the battery from the starting voltage to different voltages during the end period of charging; when the highest voltage cell reaches the preset full charge voltage threshold and the voltage of the lowest voltage cell in the battery is lower than the up-turn voltage, determining the cell to be balanced, and determining the cumulative charging integral capacity corresponding to the final voltage of the cell to be balanced according to the final voltage of the cell to be balanced at the end of charging and the corresponding relationship between voltage and cumulative charging integral capacity, where the up-turn voltage is the voltage corresponding to the up-turn point in the voltage curve of cell charging, and the up-turn point is the inflection point from the charging plateau period to the end period of charging; determining the capacity to be balanced of the cell to be balanced according to the cumulative charging integral capacity corresponding to the final voltage of the cell to be balanced.

[0006] By adopting the above technical solution, the corresponding relationship between voltage and cumulative charging integral capacity is determined according to the measured voltage and current to calculate the capacity to be balanced of the battery pack cells. Compared with estimating the capacity to be balanced of the battery pack cells based on SOC, the measured voltage and current can more accurately reflect the actual working state of the battery, so as to calculate a more accurate capacity to be balanced. Accurately calculating the capacity to be balanced can reduce the difference between battery monomers through balancing and improve the overall consistency of the battery pack. The more accurate and efficient method for calculating the capacity to be balanced of the cells provided by the present invention also helps to improve the overall performance of the battery management system.

[0007] According to another specific embodiment of the present invention, the starting voltage is the upturn voltage.

[0008] According to another specific embodiment of the present invention, determining the unbalanced capacity of the cell to be balanced according to the accumulated charging integral capacity corresponding to the final voltage of the cell to be balanced includes: the unbalanced capacity of the cell to be balanced is within the redundancy range of the accumulated charging integral capacity corresponding to the final voltage of the cell to be balanced.

[0009] According to another specific embodiment of the present invention, when the highest voltage cell reaches the preset full charge voltage threshold and the voltage of the lowest voltage cell in the battery is lower than the upturn voltage, determine the cells with a final voltage higher than the upturn voltage as the cells to be balanced.

[0010] According to another specific embodiment of the present invention, charging the battery to obtain the corresponding relationship between voltage and charging capacity includes: whenever charging the battery, obtaining the corresponding relationship between voltage and accumulated charging integral capacity during the current charging process and replacing the original corresponding relationship between voltage and accumulated charging integral capacity.

[0011] In a second aspect, the present invention provides a method for balancing the unbalanced capacity of battery pack cells, including: using the calculation method for the unbalanced capacity of battery pack cells in any one of the foregoing first aspects to determine the cells to be balanced and the unbalanced capacity of the cells to be balanced, and performing power balancing on the cells to be balanced.

[0012] By adopting the above technical solutions, through the balancing operation, overcharging or over-discharging of battery monomers can be prevented, the aging rate of the battery can be reduced, thereby extending the overall service life of the battery; for the balanced battery pack, the voltages and capacities of its individual monomers are more consistent, which can improve the energy utilization efficiency of the battery pack and increase the available capacity of the battery pack; the balancing operation can reduce the performance differences between battery monomers, thereby providing a more stable and reliable voltage output, which is particularly important for applications such as electric vehicles and energy storage systems; the imbalance between battery monomers may cause some monomers to overheat or be damaged, and the balancing operation helps to reduce this risk and improve the safety of the battery system; the balancing operation can ensure that the battery pack operates in the best working state, thereby improving the energy conversion efficiency of the entire battery system; for electric vehicle users, the balancing technology can provide a longer cruising range and more stable vehicle performance, thereby enhancing the user experience.

[0013] According to another specific embodiment of the present invention, performing power balancing on the cells to be balanced includes: determining the balancing current of the cells to be balanced according to the balancing period, duty cycle, current cell voltage, and balancing resistance of the cells to be balanced; obtaining the balancing power by performing time integration on the balancing current to perform power balancing on the cells to be balanced.

[0014] In a third aspect, the present invention provides a calculation system for the capacity to be balanced of battery pack cells, including: a power control module configured to charge the battery to obtain the correspondence between voltage and the cumulative charge integral capacity, wherein the correspondence between voltage and the cumulative charge integral capacity is the cumulative charge integral capacity of the cell with the highest voltage in the battery from the starting voltage to different voltages during the end period of charging; an equalizing cell determination module configured to determine the cell to be equalized when the cell with the highest voltage reaches a preset full charge voltage threshold and the voltage of the cell with the lowest voltage in the battery is lower than the upturn voltage, and determine the cumulative charge integral capacity corresponding to the final voltage of the cell to be equalized according to the final voltage of the cell to be equalized and the correspondence between voltage and the cumulative charge integral capacity, wherein the upturn voltage is the voltage corresponding to the upturn point in the voltage curve of cell charging, and the upturn point is the inflection point from the charging plateau period to the end period of charging; an equalizing capacity calculation module configured to determine the capacity to be balanced of the cell to be equalized according to the cumulative charge integral capacity corresponding to the final voltage of the cell to be equalized.

[0015] With the above technical solution, the power control module, the equalizing cell determination module, and the equalizing capacity calculation module are interconnected and work together to calculate a more accurate capacity to be balanced. After that, through equalization, the differences between battery monomers are reduced, the overall consistency of the battery pack is improved, and the overall performance of the battery management system is enhanced.

[0016] In a fourth aspect, the present invention provides a battery management system, including: the calculation system for the capacity to be balanced of battery pack cells as described in the third aspect above, and a power equalization module configured to perform power equalization on the cells to be equalized.

[0017] With the above technical solution, the calculation system for the capacity to be balanced of battery pack cells is connected to the power equalization module and works together to perform equalization operations on the battery, improving the overall consistency of the battery, extending the overall service life of the battery, improving the energy utilization efficiency of the battery pack, increasing the available capacity of the battery pack, ensuring a more stable and reliable voltage output, improving the safety of the battery system, and improving the energy conversion efficiency of the entire battery system.

[0018] In a fifth aspect, the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that when the processor executes the computer program, it implements the method for calculating the capacity to be balanced of battery pack cells according to any one of the first aspects above or the method for equalizing the capacity to be balanced of battery pack cells according to any one of the second aspects above.

[0019] With the above technical solutions, the electronic device can calculate the capacity to be balanced more accurately. Through the balancing operation, the differences between battery cells are reduced, the overall consistency of the battery pack is improved, the overall service life of the battery is extended, and the overall performance of the battery management system is enhanced. For electric vehicle users, the balancing technology can provide a longer driving range and more stable vehicle performance, thus enhancing the user experience.

[0020] In a sixth aspect, the present invention provides a computer-readable storage medium storing a computer program, characterized in that when the computer program is executed by a processor, it implements the method for calculating the capacity to be balanced of battery pack cells as described in any one of the foregoing first aspects or the method for balancing the capacity to be balanced of battery pack cells as described in any one of the foregoing second aspects.

[0021] With the above technical solutions, the computer-readable storage medium can calculate the capacity to be balanced more accurately. Through the balancing operation, the differences between battery cells are reduced, the overall consistency of the battery pack is improved, the overall service life of the battery is extended, and the overall performance of the battery management system is enhanced. For electric vehicle users, the balancing technology can provide a longer driving range and more stable vehicle performance, thus enhancing the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shows the charging curve of battery pack cells in an embodiment of the present invention;

[0023] Figure 2 Shows the flow of the method for calculating the capacity to be balanced of battery pack cells in an embodiment of the present invention Figure 1 ;

[0024] Figure 3 Shows the flow of the method for calculating the capacity to be balanced of battery pack cells in an embodiment of the present invention Figure 2 ;

[0025] Figure 4 Shows the flow of the method for calculating the capacity to be balanced of battery pack cells in an embodiment of the present invention Figure 3 ;

[0026] Figure 5 Shows the flow of the method for calculating the capacity to be balanced of battery pack cells in an embodiment of the present invention Figure 4 ;

[0027] Figure 6 Shows the flow of the method for balancing the capacity to be balanced of battery pack cells in an embodiment of the present invention Figure 1 ;

[0028] Figure 7 Shows the flow of the method for balancing the capacity to be balanced of battery pack cells in an embodiment of the present invention Figure 2 ;

[0029] Figure 8 Schematic diagram showing a calculation system for the capacity to be balanced of battery pack cells in an embodiment of the present invention;

[0030] Figure 9 Schematic diagram showing a battery management system in an embodiment of the present invention;

[0031] Figure 10 Schematic diagram showing the structure of an electronic device in an embodiment of the present invention. Detailed implementation manners

[0032] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be introduced in conjunction with preferred embodiments, this does not mean that the features of this invention are limited to this implementation manner. On the contrary, the purpose of introducing the invention in conjunction with the implementation manner is to cover other alternatives or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, many specific details will be included in the following description. The present invention can also be implemented without using these details. In addition, in order to avoid confusing or obscuring the key points of the present invention, some specific details will be omitted in the description. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0033] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0034] In the description of this embodiment, it should also be noted that unless otherwise clearly specified and limited, the terms "arranged", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific situations.

[0035] To make the purpose, technical solutions, and advantages of the present invention clearer, the implementation manners of the present invention will be further described in detail below with reference to the drawings.

[0036] In a first aspect, the present invention provides a method for calculating the capacity to be balanced of battery pack cells, which is applicable to cells having a voltage plateau period. Exemplarily, cells having a voltage plateau period are, for example, lithium iron phosphate cells (LFP) and lithium manganese iron phosphate cells (LMFP). Refer to Figure 1, during the charging process, the battery cell will go through different stages, including the initial charging stage, the charging plateau stage, and the end charging stage.

[0037] Specifically, the initial charging stage is Figure 1 the charging process of the OA segment shown in [figure], where point O is the initial point, which represents the voltage at the start of charging. Point A is the plateau point, which represents the voltage at the last moment of the initial charging stage and the voltage at the earliest moment of the charging plateau stage. After point A, it will enter the charging plateau stage, that is, point A is the intersection or inflection point between the initial charging stage and the charging plateau stage. During the initial charging stage, the voltage of the battery cell is relatively low. At this time, the charger will charge the battery cell with a constant current until the voltage of the battery cell reaches a predetermined threshold. In this stage, the voltage of the battery cell will gradually increase, while the charging current remains relatively stable. This stage is mainly for rapid charging of the battery cell and is also the period when the internal chemical reactions of the battery cell are the most active.

[0038] The charging plateau stage is Figure 1 the charging process of the AB segment shown in [figure], where point A is the plateau point. Point B is the upturn point, which represents the voltage at the last moment of the charging plateau stage and the voltage at the earliest moment of the end charging stage. After point B, it will enter the end charging stage, that is, point B is the intersection or inflection point between the charging plateau stage and the end charging stage. The so-called voltage plateau stage means that in the charge-discharge curve of the battery, it can be observed that within a certain capacity range, the voltage will remain at a relatively stable level, and this stable interval is the voltage plateau area. Within this area, the voltage change of the battery cell is relatively small.

[0039] The end charging stage is the charging process of the BC segment shown in the figure, where point B is the upturn point and point C is the full charge point, that is, the voltage of the battery cell reaches the full charge voltage. After point B, it will enter the end charging stage, that is, point B is the intersection or inflection point between the charging plateau stage and the end charging stage. At the end charging stage, when the charging current decreases to a certain extent, it indicates that the battery cell is close to being fully charged. At this time, the charger will further reduce the charging current or even completely stop charging to prevent overcharging of the battery cell.

[0040] Referring to Figure 2 , the calculation method for the capacity to be balanced of the battery cell of the battery pack provided by the present invention includes:

[0041] S1: Charge the battery to obtain the corresponding relationship between voltage and cumulative charging integral capacity.

[0042] Among them, the corresponding relationship between voltage and cumulative charging integral capacity is the cumulative charging integral capacity of the battery cell with the highest voltage in the battery from the starting voltage to different voltages during the end charging stage.

[0043] Within the same battery pack, due to factors such as manufacturing processes, aging degrees, usage conditions, and temperature differences, there are voltage differences among the battery cells. Among them, individual cells may reach a higher voltage level than other cells, and the cell with the highest voltage is called the highest-voltage cell. Individual cells may reach a lower voltage level than other cells, and the cell with the lowest voltage is called the lowest-voltage cell. In this embodiment, the cumulative charging integral capacity is obtained by integrating the measured current and time during the charging process.

[0044] The starting voltage of the highest-voltage cell in the battery during the end period of charging is the voltage of the highest-voltage cell when starting to charge during the end period of charging. The different voltages refer to the voltage when ending the charging during the end period of charging, or the preset voltage when ending the charging.

[0045] In this embodiment, since the highest cell voltage is the cell that first enters the end period of charging among all cells and is also the cell that first reaches the different voltages and the full-charge voltage point C. That is to say, the cumulative charging integral capacity of the highest-voltage cell from the starting voltage to the different voltages during the end period of charging contains the most comprehensive corresponding relationship between voltage and cumulative charging integral capacity. And, compared with obtaining the corresponding relationship between the voltage and cumulative charging integral capacity of all cells, obtaining the corresponding relationship between the voltage and cumulative charging integral capacity of the highest-voltage cell in the battery requires less data processing volume and is convenient for improving the data processing speed. Therefore, in this embodiment, the corresponding relationship between the voltage and cumulative charging integral capacity of the highest-voltage cell in the battery will be selected to be obtained.

[0046] In some possible embodiments, the battery is charged to obtain the corresponding relationship between the voltage and cumulative charging integral capacity of all cells. Compared with only obtaining the corresponding relationship between the voltage and cumulative charging integral capacity of the highest-voltage cell, obtaining the corresponding relationship between the voltage and cumulative charging integral capacity of all cells is the real-time and actual corresponding relationship for each cell, and the obtained corresponding relationship is more accurate, making the result obtained by calculating the capacity to be balanced later more accurate.

[0047] In this embodiment, the corresponding relationship between voltage and cumulative charging integral capacity is obtained during the charging process rather than the discharging process because the working conditions of the battery during the charging process are relatively stable, while the working conditions during the discharging process may be unstable due to the uneven throttle, resulting in unstable and inaccurate collected voltage values.

[0048] S2: When the highest-voltage cell reaches the preset full-charge voltage threshold and the voltage of the lowest-voltage cell in the battery is lower than the upward-sloping voltage, determine the cells to be balanced, and determine the cumulative charging integral capacity corresponding to the final voltage of the cells to be balanced according to the final voltage of the cells to be balanced at the end of charging and the corresponding relationship between voltage and cumulative charging integral capacity.

[0049] Among them, the reference Figure 1 , the buckling voltage is the voltage corresponding to the buckling point B on the voltage curve for charging the battery cell. The buckling point is the inflection point from the charging plateau period (i.e., the AB segment) to the end of charging (i.e., the BC segment), and it is also the mutation point of the voltage.

[0050] In this embodiment, the full charge voltage is the voltage when the battery cell is fully charged. The preset full charge voltage threshold is the voltage that is less than the preset value of the full charge voltage. For example, if the full charge voltage is 3.65V and the preset value is -0.03, then the preset full charge voltage threshold is 3.62V. That is, when the highest voltage battery cell reaches 3.62V, the condition that the highest voltage battery cell reaches the preset full charge voltage threshold is satisfied.

[0051] In this embodiment, whenever the highest voltage battery cell reaches the preset full charge voltage threshold and the voltage of the lowest voltage battery cell in the battery is lower than the buckling voltage, the battery cells to be balanced and the cumulative charging integral capacity corresponding to the final voltage of the battery cells to be balanced are re-determined, realizing timely updating of the unbalanced capacity of the battery cells to be balanced and obtaining a relatively accurate unbalanced capacity.

[0052] In this embodiment, when the highest voltage battery cell reaches the preset full charge voltage threshold and the voltage of the lowest voltage battery cell in the battery is lower than the buckling voltage, the battery cells to be balanced are determined. Compared with the method of triggering the determination of the battery cells to be balanced according to whether the voltage difference between the highest voltage battery cell and the lowest voltage battery cell reaches a certain threshold, the method for determining the battery cells to be balanced adopted in this embodiment is more accurate. Because for the battery cells with a plateau period targeted by this application, if only the method of determining the battery cells to be balanced based on whether the voltage difference between the highest voltage battery cell and the lowest voltage battery cell reaches a certain threshold is used, it will lead to misjudgment.

[0053] In some possible embodiments, determining the cumulative charging integral capacity corresponding to the final voltage of the battery cells to be balanced according to the final voltage of the battery cells to be balanced at the end of charging and the corresponding relationship between the voltage and the cumulative charging integral capacity includes:

[0054] Determining the final voltage of the battery cells to be balanced at the end of charging; finding the cumulative charging integral capacity corresponding to the final voltage of the battery cells to be balanced in the corresponding relationship between the voltage and the cumulative charging integral capacity, and taking it as the unbalanced capacity of the battery cells to be balanced.

[0055] Exemplarily, the corresponding relationship between the voltage and the cumulative charging integral capacity (that is, the cumulative charging integral capacity of the highest voltage battery cell in the battery from the starting voltage to different voltages during the end of charging) is shown in Table 1.

[0056] Table 1 Corresponding relationship between voltage and cumulative charging integral capacity

[0057]

[0058] For example, if the final voltage of the battery cell to be balanced at the end of charging is determined to be 3.3V, then according to the final voltage of 3.3V of the battery cell to be balanced at the end of charging and the corresponding relationship between the voltage and the cumulative charging integral capacity shown in Table 1, the cumulative charging integral capacity corresponding to the final voltage of 3.3V of the battery cell to be balanced is determined to be 10Ah. Another example, if the final voltage of the battery cell to be balanced at the end of charging is determined to be 3.4V, then the cumulative charging integral capacity corresponding thereto can be determined to be 20Ah according to the above method.

[0059] In some possible embodiments, determining the cumulative charging integral capacity corresponding to the final voltage of the battery cell to be balanced according to the final voltage of the battery cell to be balanced at the end of charging and the corresponding relationship between the voltage and the cumulative charging integral capacity includes:

[0060] If the exact final voltage of the battery cell to be balanced and the cumulative charging integral capacity corresponding thereto cannot be found in the corresponding relationship between the voltage and the cumulative charging integral capacity, then find the highest value lower than the final voltage of the battery cell to be balanced and the lowest value higher than the final voltage of the battery cell to be balanced, and perform interpolation calculation based thereon. That is to say, find two voltage values adjacent to the final voltage of the battery cell to be balanced and the cumulative charging integral capacity corresponding thereto, and perform interpolation calculation based thereon. This method can improve the accuracy of calculating the capacity to be balanced of the battery cell to be balanced.

[0061] Exemplarily, for example, if the final voltage of the battery cell to be balanced at the end of charging is determined to be 3.35V, then according to the final voltage of 3.35V of the battery cell to be balanced at the end of charging and the corresponding relationship between the voltage and the cumulative charging integral capacity shown in Table 1, find two voltage values adjacent to the final voltage of 3.35V of the battery cell to be balanced, namely 3.3V and 3.4V, and perform interpolation calculation based on the cumulative charging integral capacity of 10Ah corresponding to 3.3V and the cumulative charging integral capacity of 20Ah corresponding to 3.4V to obtain the capacity to be balanced of the battery cell to be balanced.

[0062] In some possible embodiments, when entering the end stage of charging, that is, when the voltage of the highest voltage battery cell in the battery is greater than the upward-sloping voltage, data storage starts. That is, when the BMS (Battery Manager System) determines that the current is in the charging process, and enters the end stage of charging, and the change in the highest battery cell voltage (in units of V / s) exceeds a certain value, that is, when it starts to significantly upward-slope, data storage starts.

[0063] In this embodiment, at the end of the battery cell charging, because the current is small and the working condition is stable, the corresponding relationship between the collected voltage and the cumulative charging integral capacity is relatively accurate, which will make the calculation more accurate.

[0064] In some possible embodiments, storage is performed at the same voltage difference interval (e.g., 10 mV), and the integrated charge capacity accumulated from the starting voltage to different voltages of the highest voltage cell in the battery during the end of charging at different times is stored.

[0065] S3: Determine the capacity to be balanced of the cell to be balanced according to the integrated charge capacity accumulated corresponding to the final voltage of the cell to be balanced.

[0066] In some possible embodiments, S3: Determine the capacity to be balanced of the cell to be balanced according to the integrated charge capacity accumulated corresponding to the final voltage of the cell to be balanced, including: Determine the capacity to be balanced of the cell to be balanced according to the starting voltage and the final voltage.

[0067] Exemplarily, referring to Table 1, if the starting voltage is 3.2 V and the final voltage of the cell to be balanced is 3.5 V, correspondingly, the integrated charge capacity corresponding to the starting voltage is 0 Ah, and the integrated charge capacity corresponding to the final voltage of the cell to be balanced is 30 Ah, then the capacity to be balanced of the cell to be balanced is 30 Ah - 0 Ah = 30 Ah.

[0068] In some other possible embodiments, S3: Determine the capacity to be balanced of the cell to be balanced according to the integrated charge capacity accumulated corresponding to the final voltage of the cell to be balanced, including: Determine the capacity to be balanced of the cell to be balanced according to a preset voltage and the final voltage, where the preset voltage is greater than the starting voltage.

[0069] Exemplarily, referring to Table 1, set the preset voltage to 3.3 V, which is greater than the aforementioned starting voltage of 3.2 V, and the final voltage of the cell to be balanced is 3.5 V. Correspondingly, the integrated charge capacity corresponding to the preset voltage is 10 Ah, and the integrated charge capacity corresponding to the final voltage of the cell to be balanced is 30 Ah. Then the capacity to be balanced of the cell to be balanced is 30 Ah - 10 Ah = 20 Ah.

[0070] In some other possible embodiments, S3: Determine the capacity to be balanced of the cell to be balanced according to the integrated charge capacity accumulated corresponding to the final voltage of the cell to be balanced, where the capacity to be balanced of the cell to be balanced is slightly lower than the integrated charge capacity accumulated corresponding to the final voltage of the cell to be balanced, that is, the capacity to be balanced of the cell to be balanced is a certain threshold lower than the integrated charge capacity accumulated corresponding to the final voltage of the cell to be balanced.

[0071] Exemplarily, if it is determined that the integrated charge capacity corresponding to the final voltage of the cell to be balanced is 30 Ah, and a certain threshold range lower than the integrated charge capacity accumulated corresponding to the final voltage of the cell to be balanced is set to 3 Ah, then the capacity to be balanced of the cell to be balanced is 30 Ah - 3 Ah = 27 Ah.

[0072] With the above technical solution, the corresponding relationship between voltage and cumulative charging integral capacity is determined based on the measured voltage and current to calculate the capacity to be balanced of the battery pack cells. Compared with estimating the capacity to be balanced of the battery pack cells based on SOC, the measured voltage and current can more accurately reflect the actual working state of the battery, thereby calculating a more accurate capacity to be balanced. Accurately calculating the capacity to be balanced can reduce the differences between battery monomers through balanced charging or discharging, and improve the overall consistency of the battery pack. The more accurate and efficient method for calculating the capacity to be balanced of cells provided by the present invention also helps to improve the overall performance of the battery management system.

[0073] In some possible embodiments provided by the present invention, the starting voltage is the upward voltage. That is, in this embodiment, the battery is charged to obtain the cumulative charging integral capacity of the highest-voltage cell in the battery from the upward voltage to different voltages during the end of charging.

[0074] With the above technical solution, after the upward voltage, the cell will enter the end of charging. Since the current is small and the working condition is stable at the end of charging, the corresponding relationship between the collected voltage and the cumulative charging integral capacity is relatively accurate, which makes the calculation more accurate. At the same time, collecting the cumulative charging integral capacity of the highest-voltage cell from the upward voltage to different voltages can obtain the most and most comprehensive corresponding relationship between voltage and cumulative charging integral capacity, which also makes the calculation of the capacity to be balanced more accurate.

[0075] In some possible embodiments provided by the present invention, refer to Figure 3 , S2: Determine the capacity to be balanced of the cell to be balanced according to the cumulative charging integral capacity corresponding to the final voltage of the cell to be balanced, including: S21: The capacity to be balanced of the cell to be balanced is within the redundancy range of the cumulative charging integral capacity corresponding to the final voltage of the cell to be balanced.

[0076] That is to say, the capacity to be balanced of the cell to be balanced is within a certain threshold range of the cumulative charging integral capacity corresponding to the final voltage of the cell to be balanced. Exemplarily, the preset redundancy range is ±1 Ah, and the final voltage of the cell to be balanced is 3.3 V, then its capacity to be balanced is 10 ± 1 Ah.

[0077] In this embodiment, by setting the capacity to be balanced of the cell to be balanced within the redundancy range of the cumulative charging integral capacity corresponding to the final voltage of the cell to be balanced, allowing a certain error range for the capacity to be balanced, a balance can be found among battery performance, safety, life, and cost, ensuring that the battery pack can operate safely and efficiently.

[0078] In some possible embodiments provided by the present invention, refer to Figure 4, S22: When the highest-voltage cell reaches the preset full-charge voltage threshold and the voltage of the lowest-voltage cell in the battery is lower than the up-bending voltage, determine the cells with a final voltage higher than the up-bending voltage as the cells to be balanced.

[0079] In this embodiment, the final voltage refers to the voltage of the cell at the last charging moment.

[0080] If the highest-voltage cell reaches the preset full-charge voltage threshold and the voltage of the lowest-voltage cell in the battery is higher than the up-bending voltage, it means that the balancing effect of the battery pack is good and it may be considered unnecessary to balance. If, when the highest-voltage cell reaches the preset full-charge voltage threshold and the voltage of the lowest-voltage cell in the battery is lower than the up-bending voltage, it means that the balancing effect of the battery pack is not good and balancing needs to be enabled. The calculation and balancing of the capacity to be balanced are both for achieving the consistency of the battery pack cells. In this embodiment, what needs to be achieved is the consistency between the cells with a final voltage higher than the up-bending voltage and the cells with a final voltage lower than the up-bending voltage. Therefore, it is necessary to calculate the capacity to be balanced of the cells with a final voltage higher than the up-bending voltage and balance the cells with a final voltage higher than the up-bending voltage according to the capacity to be balanced.

[0081] In some possible embodiments provided by the present invention, refer to Figure 5 , S1: Charge the battery to obtain the corresponding relationship between voltage and charge capacity, including: S11: Whenever the battery is charged, obtain the corresponding relationship between voltage and cumulative charge integral capacity during the current charging process and replace the original corresponding relationship between voltage and cumulative charge integral capacity.

[0082] In this embodiment, the corresponding relationship between voltage and cumulative charge integral capacity during the current charging process is obtained and used each time of charging, that is, the actual working condition of each cell in the battery at the time of charging is obtained. The capacity to be balanced calculated based on this is more accurate.

[0083] In a second aspect, refer to Figure 6 , the present invention provides a method for balancing the capacity to be balanced of battery pack cells, including: using the method for calculating the capacity to be balanced of battery pack cells in any one of the foregoing first aspects to determine the cells to be balanced and the capacity to be balanced of the cells to be balanced (i.e., steps S1 to S3), S4: Perform charge balancing on the cells to be balanced.

[0084] By adopting the above technical solution, through the balancing operation, overcharging or over-discharging of individual battery cells can be prevented, the aging rate of the battery can be reduced, and thus the overall service life of the battery can be extended; for the balanced battery pack, the voltages and capacities of its individual cells are more consistent, which can improve the energy utilization efficiency of the battery pack and increase the available capacity of the battery pack; the balancing operation can reduce the performance differences between individual battery cells, thereby providing a more stable and reliable voltage output, which is particularly important for applications such as electric vehicles and energy storage systems; the imbalance between individual battery cells may cause some cells to overheat or be damaged, and the balancing operation helps to reduce this risk and improve the safety of the battery system; the balancing operation can ensure that the battery pack operates in the best working state, thereby improving the energy conversion efficiency of the entire battery system; for electric vehicle users, the balancing technology can provide a longer driving range and more stable vehicle performance, thus enhancing the user experience.

[0085] In some possible embodiments provided by the present invention, referring to Figure 7 , S4: Perform charge balancing on the cells to be balanced, including:

[0086] S41: Determine the balancing current of the cells to be balanced according to the balancing period, duty cycle, current cell voltage, and balancing resistance of the cells to be balanced;

[0087] S42: Obtain the balancing charge by integrating the balancing current over time to perform charge balancing on the cells to be balanced.

[0088] Exemplarily, the calculation formula for deducting the single-step balancing capacity during balancing is: function operation period * current cell voltage / balancing resistance * duty cycle.

[0089] Among them, the "function operation period" refers to the frequency of performing the balancing operation on the cells. Selecting the balancing period is to ensure that the cells are balanced within an appropriate time, rather than being over-balanced or under-balanced. An appropriate balancing period can prevent the cells from being over-discharged or over-charged in a short time, thereby extending the life of the cells. At the same time, a reasonable balancing period can balance the balancing effect and the power consumption of the battery management system. The unit of the function operation period is seconds (s).

[0090] The current cell voltage, which is an important parameter for measuring the charge state of the cell. By monitoring the voltage, the charge level of the cell can be judged, so as to determine whether balancing is needed. Real-time monitoring of the cell voltage helps to start balancing when the voltage difference between cells reaches a certain degree, so that the charge difference between cells can be adjusted in time to avoid too large a voltage difference. The unit of the current cell voltage is volts (V).

[0091] The balancing resistor is a key component in the balancing circuit, which determines the size of the balancing current. The purpose of selecting a suitable balancing resistor is to ensure that the balancing current is within a safe range. The selection of the balancing resistor directly affects the balancing efficiency and the safety of the battery cell. A suitable balancing resistor can ensure that the current is not too large during the balancing process, thereby avoiding damage to the battery cell. The unit of the balancing resistor is ohm (Ω).

[0092] "Balancing duty cycle" refers to the proportion of time that the system charges or discharges each cell in order to keep the power of multiple batteries or multiple power modules consistent. "Balancing duty cycle" refers to the ratio of the time that the battery cells are balanced (charged or discharged) in a control cycle to the entire control cycle. For example, if the balancing duty cycle is 50%, then half of the battery cells will be balanced in a control cycle. The balancing duty cycle is selected to control the size of the balancing current and thus the balancing rate. By adjusting the duty cycle, the balancing current can be precisely controlled to avoid damage to the battery cells. A higher duty cycle can quickly balance the battery cells, but may increase the heat and loss of the battery cells; a lower duty cycle can reduce losses, but the balancing speed will be slower. The balancing duty cycle is dimensionless and ranges from [0, 1].

[0093] In the lithium-ion battery management system, it is a complex process to balance the cells to be balanced. The selection of data such as the balancing cycle, the balancing duty cycle, the current cell voltage, and the balancing resistance is to accurately control the balancing process. By accurately controlling the balancing parameters, the balancing of the cells can be achieved more efficiently, improving the balancing efficiency; avoiding the cell loss caused by excessive balancing, thereby extending the service life of the cells; reasonable balancing parameters can prevent the cells from being overcharged or over-discharged, reducing the safety risks of the battery system.

[0094] In summary, the method for calculating the capacity to be balanced provided by the present invention does not require complex parameter calibration, so that the method can be directly applied to different projects, greatly simplifying the engineering implementation and the configuration process of the battery management system (BMS), and improving the work efficiency and ease of use of the system. The equalization method for the capacity to be balanced provided by the present invention is not related to the state of health (SOH) of the battery, and is therefore not affected by the aging of the battery cell. This means that even when the battery cell service life is extended and the performance gradually decreases, the equalization method can still maintain high efficiency and accuracy, ensuring the long-term stable operation of the battery pack. The equalization method for the capacity to be balanced provided by the present invention is not affected by temperature changes, which means that the equalization system can maintain consistent performance regardless of whether it is in a high or low temperature environment. This feature makes the method suitable for various climatic conditions and enhances the environmental adaptability of the battery management system.

[0095] Thirdly, reference Figure 8, the present invention provides a calculation system 1 for the capacity to be balanced of battery pack cells, including a power control module 11, an equalization cell determination module 12, and an equalization capacity calculation module 13.

[0096] Among them, the power control module 11 is configured to charge the battery to obtain the corresponding relationship between voltage and cumulative charge integral capacity, where the corresponding relationship between voltage and cumulative charge integral capacity is the cumulative charge integral capacity of the highest voltage cell in the battery from the starting voltage to different voltages during the end period of charging.

[0097] The equalization cell determination module 12 is configured to determine the cells to be equalized when the highest voltage cell reaches the preset full charge voltage threshold and the voltage of the lowest voltage cell in the battery is lower than the up-curve voltage, and determine the cumulative charge integral capacity corresponding to the final voltage of the cells to be equalized according to the final voltage of the cells to be equalized and the corresponding relationship between voltage and cumulative charge integral capacity. Here, the up-curve voltage is the voltage corresponding to the up-curve point in the voltage curve of cell charging, and the up-curve point is the inflection point from the charging plateau period to the end period of charging.

[0098] The equalization capacity calculation module 13 is configured to determine the capacity to be balanced of the cells to be equalized according to the cumulative charge integral capacity corresponding to the final voltage of the cells to be equalized.

[0099] Adopting the above technical solution, the power control module 11, the equalization cell determination module 12, and the equalization capacity calculation module 13 are interconnected and work together, so as to calculate a more accurate capacity to be balanced. Then, through equalization charging or discharging, the differences between battery monomers are reduced, the overall consistency of the battery pack is improved, and the overall performance of the battery management system is enhanced.

[0100] In the fourth aspect, referring to Figure 9 , the present invention provides a battery management system 0, including: the calculation system 1 for the capacity to be balanced of battery pack cells in the third aspect as described above and a power equalization module 01. Among them, the power equalization module 01 is configured to perform power equalization on the cells to be equalized.

[0101] Adopting the above technical solution, the calculation system 1 for the capacity to be balanced of battery pack cells is connected to the power equalization module 01 and works together to perform equalization operations on the battery, improve the overall consistency of the battery, extend the overall service life of the battery, improve the energy utilization efficiency of the battery pack, increase the available capacity of the battery pack, ensure a more stable and reliable voltage output, improve the safety of the battery system, and improve the energy conversion efficiency of the entire battery system.

[0102] In the fifth aspect, referring to Figure 10, the present invention provides an electronic device 2, including a memory 201, a processor 202, and a computer program stored in the memory 201 and executable on the processor 202. When the processor 202 executes the computer program, it implements the calculation method for the capacity to be balanced of the battery pack cells according to any one of the foregoing first aspects or the balancing method for the capacity to be balanced of the battery pack cells according to any one of the foregoing second aspects. Among them, the memory 201 may include, for example, a system memory, a fixed non-volatile storage medium, etc. The system memory stores, for example, an operating system, application programs, a boot loader, and other programs.

[0103] By adopting the above technical solution, the electronic device 2 realizes more accurate calculation of the capacity to be balanced. Through the balancing operation, the differences between battery cells are reduced, the overall consistency of the battery pack is improved, the overall service life of the battery is extended, and the overall performance of the battery management system is enhanced. For electric vehicle users, the balancing technology can provide a longer cruising range and more stable vehicle performance, thus enhancing the user experience.

[0104] In a sixth aspect, an embodiment of the present invention further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it implements the calculation method for the capacity to be balanced of the battery pack cells according to any one of the foregoing first aspects or the balancing method for the capacity to be balanced of the battery pack cells according to any one of the foregoing second aspects.

[0105] The computer-readable storage medium realizes more accurate calculation of the capacity to be balanced. Through the balancing operation, the differences between battery cells are reduced, the overall consistency of the battery pack is improved, the overall service life of the battery is extended, and the overall performance of the battery management system is enhanced. For electric vehicle users, the balancing technology can provide a longer cruising range and more stable vehicle performance, thus enhancing the user experience.

[0106] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable non-transitory storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program code.

[0107] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to produce a machine, such that the instructions executed by the processors of the computer or other programmable data processing devices produce means for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or in multiple blocks.

[0108] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or in multiple blocks.

[0109] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or in multiple blocks.

[0110] Although the present invention has been illustrated and described with reference to certain preferred embodiments of the present invention, those of ordinary skill in the art should understand that the above content is a further detailed description of the present invention in combination with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. Those skilled in the art can make various changes in form and detail, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A method for calculating the capacity to be balanced of a battery pack cell, characterized in that: include: Charging the battery to obtain a corresponding relationship between the voltage and the accumulated charging integral capacity, wherein the corresponding relationship between the voltage and the accumulated charging integral capacity is the accumulated charging integral capacity of the highest voltage cell in the battery from the starting voltage to different voltages during the charging terminal period; When the highest voltage cell reaches the preset full charge voltage threshold and the voltage of the lowest voltage cell in the battery is lower than the upturn voltage, the cell to be balanced is determined, and the accumulated charging integral capacity corresponding to the final voltage of the cell to be balanced is determined according to the final voltage of the cell to be balanced at the end of charging and the corresponding relationship between the voltage and the accumulated charging integral capacity, wherein the upturn voltage is the voltage corresponding to the upturn point in the voltage curve of the cell charging, and the upturn point is the inflection point from the charging platform period to the charging end; The capacity to be balanced of the battery cell to be balanced is determined according to the accumulated charging integral capacity corresponding to the final voltage of the battery cell to be balanced.

2. The method for calculating the capacity to be balanced of the battery pack cells according to claim 1, characterized in that: The starting voltage is a rising voltage.

3. The method for calculating the capacity to be balanced of the battery pack cells according to claim 1, characterized in that: Determining the to-be-balanced capacity of the to-be-balanced cell according to the accumulated charging integral capacity corresponding to the final voltage of the to-be-balanced cell includes: the to-be-balanced capacity of the to-be-balanced cell is within a redundant range of the accumulated charging integral capacity corresponding to the final voltage of the to-be-balanced cell.

4. The method for calculating the capacity to be balanced of the battery pack cells according to claim 1, characterized in that: When the highest voltage cell reaches a preset full charge voltage threshold and the voltage of the lowest voltage cell in the battery is lower than the warping voltage, the cell whose final voltage is higher than the warping voltage is determined as the cell to be balanced.

5. The method for calculating the capacity to be balanced of the battery pack cells according to claim 1, characterized in that: The step of charging the battery to obtain a corresponding relationship between voltage and charging capacity includes: Whenever the battery is charged, the corresponding relationship between the voltage and the accumulated charging integral capacity in the current charging process is obtained and the original corresponding relationship between the voltage and the accumulated charging integral capacity is replaced.

6. A method for equalizing the capacity of battery cells to be equalized, characterized in that: include: The method for calculating the capacity to be balanced of the battery pack cells according to any one of claims 1 to 5 is used to determine the cells to be balanced and the capacity to be balanced of the cells to be balanced, and the cells to be balanced are charged and balanced.

7. The method for equalizing the capacity of battery cells to be equalized as claimed in claim 6, characterized in that: Performing power balancing on the battery cells to be balanced includes: Determine the balancing current of the battery cell to be balanced according to the balancing period, the balancing duty cycle, the current battery cell voltage and the balancing resistance of the battery cell to be balanced; The balanced electric quantity is obtained by time integration according to the balanced current, so as to balance the electric quantity of the battery cells to be balanced.

8. A system for calculating the capacity to be balanced of battery cells, characterized in that: include: A power control module is configured to charge the battery to obtain a corresponding relationship between voltage and accumulated charging integral capacity, wherein the corresponding relationship between voltage and accumulated charging integral capacity is the accumulated charging integral capacity of the highest voltage cell in the battery from the starting voltage to different voltages during the charging terminal period; A balanced cell determination module is configured to determine the cell to be balanced when the highest voltage cell reaches a preset full charge voltage threshold and the voltage of the lowest voltage cell in the battery is lower than the upward voltage, and determine the accumulated charging integral capacity corresponding to the final voltage of the cell to be balanced according to the final voltage of the cell to be balanced at the end of charging and the corresponding relationship between the voltage and the accumulated charging integral capacity, wherein the upward voltage is the voltage corresponding to the upward point in the voltage curve of the cell charging, and the upward point is the inflection point from the charging platform period to the charging end; The balancing capacity calculation module is configured to determine the to-be-balanced capacity of the to-be-balanced battery cells according to the accumulated charging integral capacity corresponding to the final voltage of the to-be-balanced battery cells.

9. A battery management system, characterized in that: include: The system for calculating the capacity to be balanced of the battery cells of claim 8, The power balancing module is configured to balance the power of the battery cells to be balanced.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for calculating the capacity of the battery cells to be balanced as described in any one of claims 1 to 5 or the method for balancing the capacity of the battery cells to be balanced as described in any one of claims 6 to 7 is implemented.

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