Battery pack electric quantity correction method, controller and energy storage system

Abstract

The invention discloses a battery pack electric quantity correction method, a controller and an energy storage system. The method comprises the following steps: acquiring voltage values of a plurality of battery cells; when the voltage values of the plurality of battery cells meet a preset condition, executing the following correction operation; according to the voltage value, a first electric quantity value of the corresponding battery cell is corrected, and the first electric quantity value is used for representing the relative ratio of the electric quantity value of the battery cell to the reachable maximum electric quantity value of the battery cell. The first electric quantity value of each battery cell is pertinently corrected, so that parameters obtained by a final user can clearly reflect the difference between the current total electric quantity value of the battery pack and the reachable total electric quantity value of the battery pack, and can also reflect the states of other battery cells except the fully charged battery cells in the battery pack.

Description

Technical Field

[0001] This application relates to the field of energy storage equipment technology, and in particular to a battery pack power correction method, controller and energy storage system. Background Technology

[0002] As battery packs age or operate under different conditions, parameters such as capacity, internal resistance, and consistency will drift, causing a deviation between the actual usable capacity of the cells and the nominal value. This drift phenomenon manifests during the charging process as follows: towards the end of the charging process, due to capacity decay and polarization effects, when the cell voltage reaches the full charge voltage threshold, its actual capacity is lower than the theoretical upper limit.

[0003] To correct the aforementioned error, the common practice in the art is to mark the battery pack's charge value as 100% when at least one cell in the battery pack is detected to have reached the full charge voltage threshold, even if its actual charge value has not reached the nominal value, and to determine that the battery pack is fully charged.

[0004] However, the above approach only corrects the cells that have reached full charge, without simultaneously calibrating other cells in the same group that have not yet reached the full charge threshold. This results in a systematic bias in the distribution of charge values ​​within the group. On the one hand, judging the battery pack as fully charged when most cells are not yet fully charged leads to a significant difference between the actual charge value of the battery pack and its maximum achievable charge value. This can easily cause inaccurate battery pack range estimation, premature power limiting, or delayed protection triggering. On the other hand, ignoring the differences in charge values ​​between cells is detrimental to subsequent balancing and energy management strategies. Summary of the Invention

[0005] One objective of this application is to provide a battery pack charge correction method, controller, and energy storage system, which aims to solve the technical problem in the prior art where different cells in a battery pack have different charging progress, resulting in the omission of cells that are not fully charged during the full charge correction process.

[0006] To achieve the above objectives, in a first aspect, this application provides a battery pack power correction method. The battery pack includes multiple battery cells. The method includes the following steps: obtaining the voltage values ​​of the multiple battery cells; when the voltage values ​​of the multiple battery cells meet preset conditions, performing the following correction operation: correcting the first power value of the corresponding battery cell according to the voltage value, wherein the first power value is used to characterize the relative ratio of the power value of the battery cell to its maximum achievable power value.

[0007] In this application, the first charge value of each cell is corrected based on the voltage value of each cell to uniquely obtain the current first charge value of each cell. In other words, after the correction method of this application, the current charge value of each cell in the battery pack is characterized one-to-one with its maximum charge value, which is beneficial for users to grasp the actual charging and discharging progress of the battery pack and provides a more reliable parameter basis for subsequent balancing or system correction.

[0008] Compared with the related technologies that correct the entire battery pack to a fully charged state based on the full charge of a single cell, this application makes targeted corrections to the first charge value of each cell, so that the parameters obtained by the end user can clearly reflect the difference between the current total charge value of the battery pack and the total charge value it can achieve, and can also reflect the status of other cells in the battery pack except for the fully charged cells.

[0009] In conjunction with the first aspect, according to one embodiment of this application, correcting the first energy value of a corresponding battery cell based on the voltage value includes: comparing the voltage value of each battery cell with a energy correction table to obtain a second energy value, the energy correction table including at least the mapping relationship between the voltage value of the battery cell and the second energy value, the second energy value being used to characterize the actual energy storage state of the battery cell; and correcting the first energy value of the battery cell based on the second energy value.

[0010] In conjunction with the first aspect, according to one embodiment of this application, correcting the first charge value of a corresponding battery cell based on a second charge value includes: correcting the first charge value of a reference battery cell to a reference charge value representing a fully charged state, wherein the reference battery cell is the battery cell corresponding to the largest second charge value; and correcting the first charge value of each battery cell to be corrected based on the ratio of the second charge value of the battery cell to be corrected to the second charge value of the reference battery cell, wherein the battery cells to be corrected are a plurality of battery cells excluding the reference battery cell.

[0011] In conjunction with the first aspect, according to one embodiment of this application, the first charge value of each battery cell is corrected based on the ratio of the second charge value of the battery cell to be corrected to the second charge value of the reference battery cell, including: calculating a correction ratio between the second charge value of each battery cell to be corrected and the second charge value of the reference battery cell; and correcting the first charge value of each battery cell to be corrected to the product of its corresponding correction ratio and the reference charge value.

[0012] In conjunction with the first aspect, according to one embodiment of this application, the reference power value is 100%.

[0013] In conjunction with the first aspect, according to one embodiment of this application, there are multiple power correction tables, and the multiple different power correction tables correspond to the mapping relationship between the voltage value of the battery cell and the second power value at different temperatures; comparing the voltage value of each battery cell with the power correction table to obtain the second power value includes: selecting one power correction table as the target correction table from the multiple power correction tables according to the current temperature of the battery cell; comparing the voltage value of each battery cell with the target correction table to obtain the second power value of each battery cell representing the actual energy storage state.

[0014] In conjunction with the first aspect, according to one embodiment of this application, there are multiple power correction tables, and different power correction tables correspond to the mapping relationship between the voltage value of the battery cell and the second power value under different charging current values; comparing the voltage value of each battery cell with the power correction table to obtain the second power value includes: selecting one power correction table as the target correction table from the multiple power correction tables according to the charging current value of the battery cell; comparing the voltage value of each battery cell with the target correction table to obtain the second power value of each battery cell representing the actual energy storage state.

[0015] In conjunction with the first aspect, according to one embodiment of this application, the preset conditions include: the voltage value of at least one battery cell is greater than or equal to the full charge cutoff voltage.

[0016] In conjunction with the first aspect, according to one embodiment of this application, the preset condition further includes: the voltage values ​​of multiple battery cells are all within a preset voltage range, whereby the preset voltage range is a voltage interval that characterizes a preset linear relationship between the voltage value of the battery cell and the second charge value, where the slope is greater than a preset slope.

[0017] Secondly, this application also provides a controller, including a memory and a processor, wherein the memory is used to store computer programs or instructions; when the computer programs or instructions are executed by the processor, the modified method of the above-described embodiments is implemented.

[0018] Thirdly, this application also provides an energy storage system, including a controller and a battery pack, wherein the controller is used to execute the modified method of the above-described embodiments.

[0019] The beneficial effects of the second and third aspects mentioned above can be referred to the first aspect or any possible implementation of the first aspect, and will not be elaborated here. Based on the implementations provided in the above aspects, this application can also be further combined to provide more implementations.

[0020] Other advantages, objectives and features of this application will be partly apparent from the description below, and partly understood by those skilled in the art through study and practice of this application. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0022] Figure 1 It is a graph showing the voltage value of each cell as a function of time during the charging process of the battery pack; Figure 2 This is a schematic flowchart of the battery pack power correction method provided in the embodiments of this application; Figure 3 This is one of the flowcharts illustrating the correction operation provided in the embodiments of this application; Figure 4 This is the second flowchart illustrating the correction operation provided in the embodiments of this application; Figure 5 This is the third flowchart illustrating the correction operation provided in the embodiments of this application; Figure 6 This is the fourth flowchart illustrating the correction operation provided in the embodiments of this application; Figure 7 This is the fifth flowchart illustrating the correction operation provided in the embodiments of this application; Figure 8 This is the second diagram showing the relationship between the charge value and voltage value of a lithium iron phosphate battery cell. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0024] In existing technologies, changes in capacity, internal resistance, and consistency of battery packs under long-term use or different operating conditions are typically addressed by monitoring the voltage values ​​of each cell during charging for capacity estimation and status updates. When the voltage of any cell in the battery pack reaches a preset full-charge voltage threshold, even if the actual usable capacity of that cell has not reached its nominal capacity, the cell's capacity scale is set to full charge (e.g., 100%), and the battery pack is determined to be fully charged accordingly. Existing improved technologies typically revolve around this triggering condition: using cells that have reached the threshold as calibration benchmarks, their capacity displays or status values ​​are updated, thereby providing a reference for subsequent charging control and management strategies.

[0025] Please refer to Figure 1 As shown, the voltage of each cell increases over time during the charging process. However, due to differences between cells, when one cell reaches the full charge threshold, the others are not fully charged. The aforementioned technical approach focuses on calibrating the individual cells that have reached the full charge threshold, without simultaneously correcting other cells in the same group that have not yet reached the threshold. This can easily lead to systematic deviations in the battery pack's capacity representation. Determining the battery pack as fully charged when most cells are still not fully charged will create a discrepancy between the displayed capacity and the maximum usable capacity under current operating conditions, thus affecting the accuracy of range estimation and power management. Furthermore, the lack of synchronous calibration for the capacity differences among individual cells hinders the effective implementation of subsequent equalization strategies and the refined control of energy management.

[0026] To solve the above technical problems, please refer to Figure 2 As shown, in a first aspect, this application provides a battery pack power correction method, the battery pack including multiple cells, the method including the following steps: S201. Obtain the voltage values ​​of multiple battery cells; S203. When the voltage values ​​of multiple cells meet the preset conditions, perform the following correction operation: Based on the voltage value, correct the first charge value of the corresponding cell. The first charge value is used to characterize the relative ratio of the charge value of the cell to the maximum charge value it can reach.

[0027] In this application, the first charge value of each cell is corrected based on the voltage value of each cell to uniquely obtain the current first charge value of each cell. In other words, after the correction method of this application, the current charge value of each cell in the battery pack is characterized one-to-one with its maximum charge value, which is beneficial for users to grasp the actual charging and discharging progress of the battery pack and provides a more reliable parameter basis for subsequent balancing or system correction.

[0028] Compared with the related technologies that correct the entire battery pack to a fully charged state based on the full charge of a single cell, this application makes targeted corrections to the first charge value of each cell, so that the parameters obtained by the end user can clearly reflect the difference between the current total charge value of the battery pack and the total charge value it can achieve, and can also reflect the status of other cells in the battery pack except for the fully charged cells.

[0029] It should be understood that the term "correction" refers only to adjusting the initial charge value to more accurately represent the relationship between the current charge value of the battery cell and its maximum achievable charge value, providing users with a reference for judging charging and discharging progress or planning energy usage. The "maximum achievable charge value" here should be understood as the maximum charge value that a specific battery cell can achieve under specific operating conditions. Due to cell aging and operation in low-temperature or vibration environments, this value is usually lower than the cell's factory calibration value, which is one of the reasons why the initial charge value of the battery cell needs to be corrected.

[0030] Please refer to Figure 3 As shown, in conjunction with the first aspect, according to one embodiment of this application, correcting the first charge value of a corresponding battery cell based on a voltage value includes: S301. The voltage value of each cell is compared with the energy correction table to obtain the second energy value. The energy correction table includes at least the mapping relationship between the voltage value of the cell and the second energy value. The second energy value is used to characterize the actual energy storage state of the cell. S303. Correct the first charge value of the battery cell based on the second charge value.

[0031] Because the first energy value of a battery cell is affected by the maximum energy value that the cell can currently achieve, and the latter is greatly limited by the actual application scenario, it is difficult to establish a mapping relationship between the first energy value and the voltage value. However, the second energy value reflects the actual energy storage state of the battery cell, and the mapping relationship between the second energy value and the battery cell's voltage value is more explicit, which is beneficial for setting a reference function. In this embodiment, the second energy value is first calculated from the battery cell's voltage value. Then, the first energy value is corrected based on the second energy value. Step S301 can be implemented according to a preset simple mapping relationship, and step S303 is the scaling of the second energy value array according to pure mathematical rules. The calculation of both is not constrained by the maximum energy value that the battery cell can currently achieve, avoiding the defects of directly converting the first energy value from the voltage value, which is greatly affected by the operating conditions and makes it difficult to set a mapping relationship.

[0032] Please refer to Figure 4 As shown, in conjunction with the first aspect, according to one embodiment of this application, correcting the first charge value of a corresponding battery cell based on a second charge value includes: S401. Correct the first charge value of the reference cell to a reference charge value representing a fully charged state, where the reference cell is the cell corresponding to the largest second charge value. S403. Correct the first charge value of each battery cell to be corrected according to the ratio of the second charge value of the battery cell to be corrected to the second charge value of the reference battery cell. The battery cells to be corrected are multiple battery cells other than the reference battery cell.

[0033] This embodiment provides a specific adjustment method applicable to full-charge correction. The cell with the highest second-highest charge value in the battery pack is set as the reference cell. The first charge value of the reference cell is corrected. Subsequently, the remaining cells are corrected based on the first charge value of the reference cell. Step S401 is a correction logic commonly used in the charging process of battery packs in related technologies. The reference cell is the only fully charged and corrected cell in related technologies. Only step S403 needs to be additionally executed to achieve the solution of this embodiment. This embodiment has good industrial adaptability and is conducive to rapid updates and deployment on existing production lines and even existing products.

[0034] Please refer to Figure 5 As shown, further, the first charge value of each cell is corrected according to the ratio of the second charge value of the cell to be corrected to the second charge value of the reference cell, including: S501. Calculate the correction ratio between the second charge value of each cell to be corrected and the second charge value of the reference cell; S503. Correct the first charge value of each cell to be corrected to the product of its corresponding correction ratio and the reference charge value.

[0035] This embodiment provides a specific method for correcting the second charge value of each cell. Typically, the aging degree and operating conditions of the cells within the same battery pack are similar, and the maximum charge value that each cell can reach is similar. The difference in the second charge value of each cell comes from the difference in charging rate caused by circuit settings and physical arrangement. Therefore, the reference charge value obtained from the reference cell can also be approximately regarded as the second charge value of the cell to be corrected when fully charged. The first charge value of each cell to be corrected is corrected by multiplying its corresponding correction ratio by the reference charge value. That is, the first charge value represents the ratio of the cell to be corrected to its fully charged state. The calculation is simple and conforms to the general user logic.

[0036] Optional, the reference battery level is 100%.

[0037] The reference charge value is used to represent the fully charged state. In this embodiment, the reference charge value is set to 100%, which is consistent with the user's general understanding and is also convenient for calculation.

[0038] For example, in the embodiment described above where the first charge value of each cell to be corrected is corrected to the product of its corresponding correction ratio and the reference charge value, the calculation formula can be expressed as: SOC1 = SOC2 * k, where SOC1 is the first charge value, SOC2 is the reference charge value, and k is the correction ratio.

[0039] If the reference battery level is 100%, the formula can be simplified to SOC1=k.

[0040] Please refer to Figure 6As shown, in conjunction with the first aspect, according to one embodiment of this application, there are multiple power correction tables, and different power correction tables correspond to the mapping relationship between the voltage value of the battery cell and the second power value at different temperatures; the second power value is obtained by comparing the voltage value of each battery cell with the power correction table, including: S601. Based on the current temperature of the battery cell, select one power correction table from multiple power correction tables as the target correction table. S603. Compare the voltage value of each cell with the target correction table to obtain the second energy value of each cell, which represents the actual energy storage state.

[0041] Please refer to Table 1 below. The charging data of the battery cell is not the same at different temperatures. Therefore, selecting the appropriate power correction table as the target correction table according to different temperatures can make the second power value obtained by mapping the voltage value more accurate.

[0042] Table 1 Examples of Multiple Battery Level Correction Tables

[0043] Please refer to Figure 7 As shown, in conjunction with the first aspect, according to one embodiment of this application, there are multiple power correction tables, and different power correction tables correspond to the mapping relationship between the voltage value of the battery cell and the second power value under different charging current values; the second power value is obtained by comparing the voltage value of each battery cell with the power correction table, including: S701. Based on the charging current value of the battery cell, select one power correction table from multiple power correction tables as the target correction table. S703. Compare the voltage value of each cell with the target correction table to obtain the second energy value of each cell, which represents the actual energy storage state.

[0044] Similarly, the charging data of a battery cell varies under different charging current values. Besides the common 1A charging current, there are other charging strategies. Therefore, selecting the appropriate capacity correction table as the target correction table based on different charging current values ​​can make the second capacity value obtained from voltage value mapping more accurate.

[0045] In conjunction with the first aspect, according to one embodiment of this application, the preset conditions include: the voltage value of at least one battery cell is greater than or equal to the full charge cutoff voltage.

[0046] The full charge cutoff voltage should be understood as: when the current voltage value of the battery cell reaches the full charge cutoff voltage, it means that the second charge value of the battery cell has reached the maximum value that can be reached at present. In other words, when the current voltage value of the battery cell reaches the full charge cutoff voltage, the battery cell is fully charged.

[0047] The specific value of the full charge cutoff voltage varies depending on the type of battery cell, and may include, but is not limited to: estimating the voltage value of the battery cell when it is fully charged based on the current state of the battery cell and appropriately increasing it as the full charge cutoff voltage; or setting a higher voltage value so that the battery cell can only reach the full charge cutoff voltage when the voltage value surges after it is fully charged under various operating conditions.

[0048] In conjunction with the first aspect, according to one embodiment of this application, the preset condition further includes: the voltage values ​​of multiple battery cells are all within a preset voltage range, wherein the preset voltage range is a voltage interval that characterizes a preset linear relationship between the voltage value of the battery cell and the second charge value with a slope greater than a preset slope.

[0049] Please refer to Figure 8 As shown, to ensure stable charging voltage and energy input, most rechargeable batteries exhibit a relatively long voltage plateau in the middle charge region of their charging curves. This means the slope of the voltage-charge curve is approximately 0, typically encompassing at least 5%-95% of the charge. However, the charging curve enters a high-slope region at the beginning and end of the charging process, especially near full charge. In this region, the voltage is extremely sensitive to minute changes in charge level; a 0.01% change in charge can result in a voltage difference of over 50mV between cells. This characteristic of the cell charging curve means that during the near-empty and full-charge stages, the voltage amplifies even the slightest differences in charge levels between cells.

[0050] The correction scheme in this embodiment triggers and executes equalization within a voltage range where the slope between the voltage and charge values ​​approaches a preset linear relationship greater than a preset slope. This balances accuracy and computability: on the one hand, a large slope means that the same charge difference will be amplified into a voltage difference that is easier to distinguish and judge, and can more sensitively reflect the subtle differences in the degree of charge between the cell to be corrected and the reference cell; on the other hand, limiting the preset voltage range to a near-linear segment allows the mapping relationship between the voltage value and the second charge value to be mapped once using an approximately constant slope. This facilitates the stable and rapid conversion of the voltage value into the second charge value and further application to the correction operation, reducing model complexity and real-time computational burden, while also reducing the impact of noise and estimation errors on the correction decision.

[0051] Secondly, this application also provides a controller, including a memory and a processor, wherein the memory is used to store computer programs or instructions; when the computer programs or instructions are executed by the processor, the modified method of the above embodiments is implemented.

[0052] Thirdly, this application also provides an energy storage system, including a controller and a battery pack, wherein the controller is used to execute the modified method of the above embodiments.

[0053] Since both the second and third aspects can achieve the modification method of the first aspect, they also possess the technical effects of the first aspect. The beneficial effects of the second and third aspects can be referred to the first aspect or any possible implementation of the first aspect, and will not be elaborated here. Based on the implementation methods provided by the above aspects, this application can be further combined to provide more implementation methods.

[0054] Other advantages, objectives and features of this application will be partly apparent from the description below, and partly understood by those skilled in the art through study and practice of this application.

[0055] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0056] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural transformations made based on the design concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A battery pack electric quantity correction method, the battery pack including a plurality of battery cells, characterized by, The method comprises the following steps: obtaining voltage values of the plurality of battery cells; when the voltage values of the plurality of battery cells meet a preset condition, performing the following correction operation: correcting, according to the voltage values, first electric quantity values of the battery cells corresponding to the voltage values, the first electric quantity values being used to represent relative ratios of electric quantity values of the battery cells to maximum electric quantity values that can be reached by the battery cells.

2. The correction method of claim 1, wherein The correction of the first electric quantity values of the battery cells corresponding to the voltage values according to the voltage values comprises: comparing the voltage values of each of the battery cells with an electric quantity correction table to obtain second electric quantity values, the electric quantity correction table comprising at least a mapping relationship between voltage values of the battery cells and the second electric quantity values, the second electric quantity values being used to represent actual energy storage states of the battery cells; correcting the first electric quantity values of the battery cells according to the second electric quantity values.

3. The correction method of claim 2, wherein The correction of the first electric quantity values of the battery cells corresponding to the voltage values according to the second electric quantity values comprises: correcting a first electric quantity value of a reference battery cell to a reference electric quantity value representing a full-charge state, the reference battery cell being the battery cell corresponding to the maximum second electric quantity value; correcting the first electric quantity values of each of the battery cells according to a ratio of the second electric quantity value of each of the battery cells to the second electric quantity value of the reference battery cell.

4. The correction method of claim 3, wherein The correction of the first electric quantity values of the battery cells according to the ratio of the second electric quantity value of each of the battery cells to the second electric quantity value of the reference battery cell comprises: calculating a correction ratio of the second electric quantity value of each of the battery cells to the second electric quantity value of the reference battery cell; correcting the first electric quantity value of each of the battery cells to a product of the correction ratio of the battery cell and the reference electric quantity value.

5. The correction method of claim 3, wherein The reference electric quantity value is 100%.

6. The correction method of claim 2, wherein There are a plurality of electric quantity correction tables, and different electric quantity correction tables correspond to mapping relationships between voltage values of the battery cells and the second electric quantity values of the battery cells at different temperatures. The comparison of the voltage values of each of the battery cells with the electric quantity correction table to obtain the second electric quantity values comprises: selecting, according to a current temperature of the battery cells, one of the plurality of electric quantity correction tables as a target correction table; comparing the voltage values of each of the battery cells with the target correction table to obtain the second electric quantity values of each of the battery cells representing actual energy storage states of the battery cells.

7. The correction method of claim 2, wherein There are a plurality of electric quantity correction tables, and different electric quantity correction tables correspond to mapping relationships between voltage values of the battery cells and the second electric quantity values of the battery cells at different charging current values. The comparison of the voltage values of each of the battery cells with the electric quantity correction table to obtain the second electric quantity values comprises: selecting, according to a charging current value of the battery cells, one of the plurality of electric quantity correction tables as a target correction table; comparing the voltage values of each of the battery cells with the target correction table to obtain the second electric quantity values of each of the battery cells representing actual energy storage states of the battery cells.

8. The correction method according to any one of claims 1 to 6, characterized in that, The preset condition comprises: the voltage value of at least one of the battery cells being greater than or equal to a full-charge cutoff voltage.

9. The correction method of claim 8, wherein, The preset condition further includes that voltage values of the plurality of battery cells are all in a preset voltage range, and the preset voltage range is a voltage interval representing a preset linear relationship between the voltage value of the battery cell and the second electric quantity value, and a slope of the preset linear relationship is greater than a preset slope.

10. A controller characterized by comprising: A computer program product, comprising a memory for storing a computer program or instructions; and a processor, wherein the computer program or instructions, when executed by the processor, implement the method of any one of claims 1-9.

11. An energy storage system characterized by, A controller and a battery pack, wherein the controller is configured to implement the method of any one of claims 1-9.

Images