A calibration method and device for the correspondence between SOC and OCV

Abstract

The present invention discloses a method and device for calibrating the correspondence between SOC and OCV. The method for calibrating the correspondence between SOC and OCV includes: obtaining the correspondence between SOC and OCV of the battery pack under BOL, where the capacity under BOL is the initial capacity C0; obtaining the actual capacity C of the battery pack q ; detecting whether the difference between the actual capacity C q and the initial capacity C0 meets a set condition; if so, recalculating the correspondence between SOC and OCV according to a calibration formula; if not, maintaining the current correspondence between SOC and OCV; detecting the actual capacity C q of the battery pack is less than a set capacity; if so, determining that the battery pack has reached the end of its life; if not, returning to the step of obtaining the actual capacity C q of the battery pack. Embodiments of the present invention provide a method and device for calibrating the correspondence between SOC and OCV, which can match an appropriate correspondence between SOC and OCV as the actual capacity of the battery pack changes, so as to accurately reflect the correspondence between SOC and OCV.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle batteries, and particularly to a method and device for calibrating the correspondence between SOC and OCV. Background Art

[0002] For the correspondence between the SOC (State of Charge) and OCV (Open Circuit Voltage) of a battery pack, the mainstream control strategy in the current market is to input the correspondence between SOC and OCV at BOL (Beginning of Life) into the BMS (Battery Management System), and then use a set of data throughout the entire life cycle until the end of the battery pack's life.

[0003] In actual use, for example, after the battery pack has been used for 2 years, as the actual capacity decays, the correspondence between its SOC and OCV will shift. At this time, the charge amount corresponding to the same OCV will shift, usually becoming smaller. Moreover, since the same set of SOC-OCV data is used, the charge amount shift at EOL (Ending of Life) compared to BOL will be very large. Figure 1 is a schematic diagram of the correspondence between SOC and OCV obtained by measuring a battery pack at different capacities. Refer to Figure 1 , at the initial capacity C0, OCV = 3.653V corresponds to 50% SOC. When the actual capacity of the battery pack decays to 75% C0, OCV = 3.653V corresponds to about 30% SOC. It can be seen that as the actual capacity of the battery pack decays, using the correspondence between SOC and OCV at BOL cannot accurately reflect the SOC at OCV. Summary of the Invention

[0004] Embodiments of the present invention provide a method and device for calibrating the correspondence between SOC and OCV, which can match the corresponding relationship between SOC and OCV that adapts to the change of the actual capacity of the battery pack, so as to accurately reflect the correspondence between SOC and OCV.

[0005] According to one aspect of the present invention, a method for calibrating the correspondence between SOC and OCV is provided. The method for calibrating the correspondence between SOC and OCV includes:

[0006] Obtain the correspondence between SOC and OCV of the battery pack at BOL, where the capacity at BOL is the initial capacity C0;

[0007] Obtain the actual capacity C of the battery pack q ;

[0008] Detect the actual capacity C q Whether the difference from the initial capacity C0 meets the set conditions;

[0009] If so, recalculate the corresponding relationship between SOC-OCV according to the calibration formula;

[0010] If not, maintain the current corresponding relationship between SOC-OCV;

[0011] Detect the actual capacity C of the battery pack q Whether it is less than the set capacity;

[0012] If so, determine that the life of the battery pack has ended;

[0013] If not, return to the step of obtaining the actual capacity C of the battery pack q of.

[0014] Optionally, the calibration formula specifically includes:

[0015] The OCV corresponding to n% SOC in the actual capacity C q is the OCV corresponding to [1-(1-n%)*C q / C0] SOC in the initial capacity C0, where 100>n>0.

[0016] Optionally, the OCV corresponding to 100% SOC in the set different actual capacities C q in the calibration formula is equal to the OCV corresponding to 100% SOC in the initial capacity C0.

[0017] Optionally, the set conditions include that the ratio of the actual capacity C q to the initial capacity C0 is a positive integer multiple of the set value.

[0018] Optionally, the set value includes 5%.

[0019] Optionally, after recalculating the corresponding relationship between SOC-OCV according to the calibration formula, it further includes:

[0020] Measure the SOC at the actual capacity C q and calculate the power included in the battery.

[0021] Optionally, the SOC at the actual capacity C q is measured by the ampere-hour integration method or the static voltage calibration method.

[0022] Optionally, the set capacity includes (0.6-0.7)C0.

[0023] Optionally, the correspondence between the SOC and OCV of the battery pack under BOL is determined by the correspondence between the SOC and OCV of at least one of the battery packs under BOL.

[0024] According to another aspect of the present invention, a correction device for the correspondence between SOC and OCV is provided. The correction device includes: an initial SOC-OCV acquisition module, a capacity acquisition module, a detection and correction module, and a life detection module;

[0025] The initial SOC-OCV acquisition module is used to acquire the correspondence between the SOC and OCV of the battery pack under BOL, where the capacity under BOL is the initial capacity C0;

[0026] The capacity acquisition module is used to acquire the actual capacity C of the battery pack q ;

[0027] The detection and correction module is used to detect whether the difference between the actual capacity C q and the initial capacity C0 meets the set conditions, and when the difference between the actual capacity C q and the initial capacity C0 meets the set conditions, recalculate the correspondence between SOC and OCV according to the correction formula, and when the difference between the actual capacity C q and the initial capacity C0 does not meet the set conditions, maintain the current correspondence between SOC and OCV;

[0028] The life detection module is used to detect whether the actual capacity C q of the battery pack is less than the set capacity, and when the actual capacity C q is less than the set capacity, determine that the life of the battery pack has ended, and when the actual capacity C q is not less than the set capacity, control the capacity acquisition module to continue to acquire the actual capacity C of the battery pack q 。

[0029] An embodiment of the present invention provides a method for correcting the correspondence between SOC and OCV. The method for correcting the correspondence between SOC and OCV first acquires the correspondence between the SOC and OCV of the battery pack under BOL, and records the capacity under BOL as the initial capacity C0, and then acquires the actual capacity C of the battery pack q , detects the actual capacity C q and the difference between the initial capacity C0. When the difference between the actual capacity C q and the initial capacity C0 meets the set conditions, update the correspondence between SOC and OCV according to the correction formula so that the updated correspondence between SOC and OCV matches the actual capacity C q , and when the actual capacity C qWhen the difference from the initial capacity C0 does not meet the set condition, maintain the current corresponding relationship between SOC and OCV, and then detect the actual capacity C of the battery pack. q Check whether it is less than the set capacity. If it is less than, determine that the battery pack life has ended. If it is not less than, continue to detect the actual capacity C of the battery pack. q The method for correcting the corresponding relationship between SOC and OCV provided in this embodiment can match the corresponding relationship between SOC and OCV that adapts to the change of the actual capacity of the battery pack, so as to accurately reflect the corresponding relationship between SOC and OCV.

[0030] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a schematic diagram of the corresponding relationship between SOC and OCV obtained by actually measuring a battery pack at different capacities;

[0033] Figure 2 It is a schematic flowchart of a method for correcting the corresponding relationship between SOC and OCV provided in an embodiment of the present invention;

[0034] Figure 3 It is a schematic diagram of the test results obtained by using the method for correcting the corresponding relationship between SOC and OCV provided in an embodiment of the present invention;

[0035] Figure 4 It is a schematic structural diagram of a device for correcting the corresponding relationship between SOC and OCV provided in an embodiment of the present invention. Detailed Embodiments

[0036] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] It should be noted that the terms "including" and "having" and any variations thereof in the description, claims and the above drawings of the present invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily limit to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0038] Figure 2 is a schematic flowchart of a method for calibrating the correspondence between SOC and OCV according to an embodiment of the present invention. Refer to Figure 2 , the method for calibrating the correspondence between SOC and OCV provided in this embodiment includes the following steps:

[0039] S110. Obtain the correspondence between SOC and OCV of the battery pack under BOL, where the capacity under BOL is the initial capacity C0.

[0040] Specifically, under BOL, by measuring the OCV of the battery pack at different SOCs, the correspondence between SOC and OCV under BOL can be obtained, and after obtaining the correspondence between SOC and OCV under BOL, it can be directly input into the BMS.

[0041] S120. Obtain the actual capacity C of the battery pack q .

[0042] Specifically, during the use of the battery pack, the actual capacity C q will change. Therefore, it is necessary to obtain the actual capacity C of the battery pack q , and according to the actual capacity C q adjust the corresponding SOC-OCV correspondence for the battery pack.

[0043] S130. Detect whether the difference between the actual capacity C q and the initial capacity C0 meets the set condition.

[0044] Specifically, as the usage time of the battery pack increases, the actual capacity C of the battery pack q will be less than the initial capacity C0. When the actual capacity C q drops to a certain extent, the SOC-OCV correspondence is updated. The set condition can be that the difference between the actual capacity C q and the initial capacity C0 is within the set threshold range, and the set condition can also be that the ratio of the actual capacity C q to the initial capacity C0 is a positive integer multiple of the set value.

[0045] If so, execute S140.

[0046] S140. Recalculate the correspondence between SOC and OCV according to the calibration formula.

[0047] Specifically, the calibration formula is based on the actual capacity C of the battery pack. q To match a suitable correspondence between SOC and OCV for the battery pack, avoid using only one set of SOC-OCV correspondence from the beginning to the end of the battery pack's life. Dynamically adjust the SOC-OCV correspondence through the calibration formula to make the SOC of the battery pack more accurate. The calibrated SOC-OCV correspondence is closer to the actual SOC-OCV correspondence of the battery pack, and the power of the battery pack calculated according to the calibrated SOC-OCV correspondence is more accurate. Using the calibration method of the SOC-OCV correspondence provided in this embodiment in an electric vehicle can display a more accurate SOC on the display screen of the electric vehicle, thereby improving the user's satisfaction.

[0048] If not, execute S150.

[0049] S150. Maintain the current SOC-OCV correspondence.

[0050] Specifically, if the difference between the actual capacity C of the battery pack q and the initial capacity C0 does not meet the set condition, then maintain the current SOC-OCV correspondence. Exemplarily, the set condition can be that the ratio of the actual capacity C q to the initial capacity C0 is a positive integer multiple of 5%. When the actual capacity C q = 0.96C0, the ratio of the actual capacity C q to the initial capacity C0 is not a positive integer multiple of 5%, then continue to use the SOC-OCV correspondence at the initial capacity C0. When the actual capacity C q = 0.95C0, the ratio of the actual capacity C q to the initial capacity C0 is a positive integer multiple of 5%, then update the SOC-OCV correspondence according to the calibration formula. When the actual capacity C q = 0.93C0, the ratio of the actual capacity C q to the initial capacity C0 is not a positive integer multiple of 5%, then continue to use the SOC-OCV correspondence when C q = 0.95C0.

[0051] S160. Detect whether the actual capacity C of the battery pack q is less than the set capacity.

[0052] If so, execute S170.

[0053] S170. Determine that the battery pack's life has ended.

[0054] Specifically, when the actual capacity C of the battery pack q drops to a certain value, the performance of all aspects of the battery pack will weaken, and the battery pack can no longer be used. Therefore, when the actual capacity C of the battery pack q is less than the set capacity, the life of the battery pack ends.

[0055] If not, return to S120.

[0056] Specifically, if the actual capacity C of the battery pack q is not less than the set capacity, the battery pack can continue to be used. Therefore, it is necessary to continue to detect the actual capacity C of the battery pack q , and update the corresponding relationship between SOC-OCV when the difference between the actual capacity C q and the initial capacity C0 meets the set conditions.

[0057] An embodiment of the present invention provides a method for correcting the corresponding relationship between SOC-OCV. The method for correcting the corresponding relationship between SOC-OCV first obtains the corresponding relationship between SOC-OCV of the battery pack under BOL, and records the capacity under BOL as the initial capacity C0, and then obtains the actual capacity C of the battery pack q , detects the difference between the actual capacity C q and the initial capacity C0. When the difference between the actual capacity C q and the initial capacity C0 meets the set conditions, update the corresponding relationship between SOC-OCV according to the correction formula, so that the updated corresponding relationship between SOC-OCV matches the actual capacity C q . When the difference between the actual capacity C q and the initial capacity C0 does not meet the set conditions, maintain the current corresponding relationship between SOC-OCV, and then detect whether the actual capacity C of the battery pack q is less than the set capacity. If it is less, it is determined that the life of the battery pack ends. If it is not less, continue to detect the actual capacity C of the battery pack q . The method for correcting the corresponding relationship between SOC-OCV provided by this embodiment can match the corresponding relationship between SOC-OCV that adapts to the change of the actual capacity of the battery pack, so as to accurately reflect the corresponding relationship between SOC-OCV.

[0058] Optionally, Figure 3 To obtain a schematic diagram of the test results using the method for correcting the corresponding relationship between SOC-OCV provided by the embodiment of the present invention, the data in Table 1 corresponds to the curve in Figure 3 , referring to Table 1 and Figure 3 , the correction formula specifically includes: the OCV corresponding to n% SOC in the actual capacity C q is the OCV corresponding to [1-(1-n%)*C] in the initial capacity C0 qThe OCV corresponding to the SOC of / C0, where 100 > n > 0.

[0059] Specifically, the calibration formula provided in this embodiment sets different actual capacities C in the battery pack q The corresponding relationship between SOC-OCV is related to the corresponding relationship between SOC-OCV of the battery pack at the initial capacity C0. Exemplarily, it is set that the actual capacity C of the battery pack q = 0.85C0, then for the actual capacity C q The OCV value of 60% SOC is the OCV corresponding to 66% SOC in the initial capacity C0. From Figure 3 Or it can be seen from Table 1 that when C q = 0.85C0, the OCV corresponding to 60% SOC = 3.794V, while the OCV corresponding to 66% SOC in the initial capacity C0 is not directly shown in Table 1, but there is a linear relationship between 60% SOC and 70% SOC in the initial capacity C0. After calculation, the OCV corresponding to 66% SOC in the initial capacity C0 = 3.794.

[0060] The calibration formula in this embodiment enables the corresponding relationship between SOC-OCV of the battery pack to be adjusted accordingly with the change of the actual capacity C q And the adjusted corresponding relationship between SOC-OCV is relatively close to the corresponding relationship obtained by testing under the same actual capacity C of the battery pack (this conclusion can be obtained by comparing through q ). Therefore, the calibration method for the corresponding relationship between SOC-OCV provided in this embodiment can more accurately reflect the power of the battery pack with less computational effort. Figure 1 and Figure 3 ). Therefore, the calibration method for the corresponding relationship between SOC-OCV provided in this embodiment can more accurately reflect the power of the battery pack with less computational effort.

[0061] Table 1

[0062]

[0063]

[0064] Optionally, in the calibration formula, it is set that the OCV corresponding to 100% SOC in different actual capacities C q is equal to the OCV corresponding to 100% SOC in the initial capacity C0.

[0065] Specifically, the BMS sets that the OCV corresponding to 100% SOC at different capacities of the battery pack is the same. Therefore, setting that the OCV corresponding to 100% SOC in different actual capacities C q is equal to the OCV corresponding to 100% SOC in the initial capacity C0 in the calibration formula can meet the setting requirements of the BMS.

[0066] Optionally, the set condition includes the actual capacity C q The ratio to the initial capacity C0 is a positive integer multiple of a set value.

[0067] Specifically, if the actual capacity C of the battery pack q Changes each time, and the corresponding relationship between SOC-OCV is updated, which will increase the corresponding workload. Therefore, the set condition is set to the actual capacity C q The ratio to the initial capacity C0 is a positive integer multiple of a set value, that is, the actual capacity C q Each time it drops by a certain value, the corresponding relationship between SOC-OCV is updated again. This setting not only improves the accuracy of the corresponding relationship between SOC-OCV, but also does not increase the workload too much.

[0068] Optionally, the set value includes 5%.

[0069] Specifically, the set value is set to 5%, that is, the actual capacity C q Each time it drops by 5% of the initial capacity C0, the corresponding relationship between SOC-OCV is updated, that is, when C q = 0.95C0, the corresponding relationship between SOC-OCV is updated according to the calibration formula. When C q = 0.90C0, the corresponding relationship between SOC-OCV is updated according to the calibration formula. When C q = 0.85C0, the corresponding relationship between SOC-OCV is updated according to the calibration formula. When C q = 0.80C0, the corresponding relationship between SOC-OCV is updated according to the calibration formula. When C q = 0.80C0, the corresponding relationship between SOC-OCV is updated according to the calibration formula, and so on until the actual capacity C q Is less than the set capacity.

[0070] Optionally, after recalculating the corresponding relationship between SOC-OCV according to the calibration formula, it further includes: measuring the actual capacity C q The SOC under, and calculating the power included in the battery.

[0071] Specifically, after the corresponding relationship between SOC-OCV under the actual capacity C q Is determined, the value of SOC is measured and displayed on the display screen of the electric vehicle to facilitate the user to view the current battery pack power. According to the corresponding relationship between SOC-OCV, the power of the battery pack can be calculated, and the working performance of the battery pack can be controlled according to the power.

[0072] Optionally, the SOC under the actual capacity C is measured by the ampere-hour integration method or the static voltage calibration method q Of.

[0073] Specifically, both the ampere-hour integration method and the static voltage calibration method can measure the SOC of the battery pack. Compared with the static voltage calibration method, the SOC measured by the ampere-hour integration method is more accurate. Preferably, the ampere-hour integration method is used to measure the actual capacity C q of the SOC under.

[0074] Optionally, the set capacity includes (0.6 - 0.7)C0.

[0075] Specifically, when the actual capacity of the battery pack drops to a certain extent, all aspects of the battery pack's performance will weaken. If it continues to be used, the usage effect will be affected. Therefore, when the actual capacity of the battery pack is lower than (0.6 - 0.7)C0, it is determined that the battery pack's life has ended.

[0076] Optionally, the correspondence between SOC and OCV of the battery pack under BOL is determined by the correspondence between SOC and OCV of at least one battery pack under BOL.

[0077] Specifically, the correspondence between SOC and OCV of the battery pack under BOL can be determined by the correspondence between SOC and OCV of one battery pack under BOL, or can be determined by the correspondence between SOC and OCV of m battery packs under BOL, where m ≥ 2 and m is a positive integer. The correspondence between SOC and OCV of one battery pack under BOL is obtained by measuring the OCV of one battery pack at different SOCs under BOL, thereby obtaining the correspondence between SOC and OCV of one battery pack under BOL. The correspondence between SOC and OCV of m battery packs under BOL is obtained by separately measuring the OCVs of m battery packs at different SOCs under BOL, and then calculating the average value of the OCVs of the m battery packs at the same SOC. The correspondence between SOC and the average value of OCVs is used as the correspondence between SOC and OCV of the battery pack under BOL. Determining the correspondence between SOC and OCV of the battery pack under BOL through the correspondence between SOC and OCV of m battery packs under BOL can make the obtained correspondence between SOC and OCV of the battery pack under BOL more accurate.

[0078] Figure 4 is a schematic structural diagram of a correction device for the correspondence between SOC and OCV provided by an embodiment of the present invention. Refer to Figure 4 , the correction device includes an initial SOC-OCV acquisition module 110, a capacity acquisition module 120, a detection and correction module 130, and a life detection module 140; the initial SOC-OCV acquisition module 110 is used to acquire the correspondence between SOC and OCV of the battery pack under BOL, where the capacity under BOL is the initial capacity C0; the capacity acquisition module 120 is used to acquire the actual capacity C of the battery pack q ; the detection and correction module 130 is used to detect the actual capacity Cq whether the difference from the initial capacity C0 meets the set condition, and at the actual capacity C q when the difference from the initial capacity C0 meets the set condition, recalculate the corresponding relationship between SOC-OCV according to the calibration formula, at the actual capacity C q when the difference from the initial capacity C0 does not meet the set condition, maintain the current corresponding relationship between SOC-OCV; the life detection module 140 is used to detect the actual capacity C of the battery pack q whether it is less than the set capacity, and at the actual capacity C q when it is less than the set capacity, determine that the life of the battery pack ends, at the actual capacity C q when it is not less than the set capacity, control the capacity acquisition module 120 to continue to acquire the actual capacity C of the battery pack q .

[0079] The calibration device for the corresponding relationship between SOC-OCV provided by the embodiment of the present invention has corresponding beneficial effects with the calibration method for the corresponding relationship between SOC-OCV provided by any embodiment of the present invention. The technical details not elaborated in this embodiment are elaborated in the calibration method for the corresponding relationship between SOC-OCV provided by any embodiment of the present invention.

[0080] It should be understood that the various forms of the processes shown above can be used, steps can be reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions of the present invention can be achieved, which are not limited herein.

[0081] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A calibration method for the correspondence between SOC and OCV, characterized in that, Including: Obtain the corresponding relationship between SOC and OCV of the battery pack under BOL, where the capacity under BOL is the initial capacity C0; Obtain the actual capacity C of the battery pack q ; Detect the actual capacity C q Check whether the difference from the initial capacity C0 meets the set conditions; If so, recalculate the corresponding relationship between SOC and OCV according to the correction formula; If not, maintain the current corresponding relationship between SOC and OCV; Detect the actual capacity C of the battery pack q whether it is less than the set capacity; If so, determine that the battery pack has reached the end of its life; If not, return to the step of obtaining the actual capacity C of the battery pack q ; The correction formula specifically includes: The actual capacity C q The OCV corresponding to n% SOC in it is the OCV corresponding to [1 - (1 - n%) * C q / C0] SOC in the initial capacity C0, where 100 > n > 0.

2. The calibration method for the correspondence relationship of SOC-OCV according to claim 1, wherein Set different actual capacities C in the correction formula q The OCV corresponding to 100% SOC in it is equal to the OCV corresponding to 100% SOC in the initial capacity C0.

3. The calibration method for the correspondence relationship of SOC-OCV according to claim 1, characterized in that, The set conditions include the actual capacity C q and the ratio to the initial capacity C0 is a positive integer multiple of a set value.

4. The calibration method for the correspondence of SOC-OCV according to claim 3, characterized in that, The set value includes 5%; 5. The calibration method for the correspondence relationship of SOC-OCV according to claim 1, characterized in that, After recalculating the corresponding relationship between SOC and OCV according to the correction formula, it further includes: Measure the actual capacity C q of the SOC below, and calculate the power included in the battery.

6. The calibration method for the SOC-OCV correspondence relationship according to claim 5, characterized in that, Measure the SOC under the actual capacity C by using the ampere-hour integration method or the static voltage calibration method. q ​ 7. The calibration method for the correspondence relationship of SOC-OCV according to claim 1, characterized in that The set capacity includes (0.6 - 0.7)C0; 8. The calibration method for the correspondence relationship of SOC-OCV according to claim 1, characterized in that, The corresponding relationship between SOC and OCV of the battery pack under BOL is determined by the corresponding relationship between SOC and OCV of at least one of the battery packs under BOL; 9. A calibration device for the correspondence between SOC and OCV, characterized in that Including: an initial SOC-OCV acquisition module, a capacity acquisition module, a detection and correction module, and a life detection module; The initial SOC-OCV acquisition module is used to obtain the corresponding relationship between SOC and OCV of the battery pack under BOL, where the capacity under BOL is the initial capacity C0; The capacity acquisition module is used to acquire the actual capacity C of the battery pack q ; The detection and correction module is used to detect the actual capacity C q to determine whether the difference from the initial capacity C0 meets the set conditions, and when the difference between the actual capacity C q and the initial capacity C0 meets the set conditions, recalculate the corresponding relationship between SOC-OCV according to the correction formula, and when the actual capacity C q and the initial capacity C0 do not meet the set conditions, maintain the current corresponding relationship between SOC-OCV; The service life detection module is used to detect the actual capacity C of the battery pack q whether it is less than the set capacity, and when the actual capacity C q is less than the set capacity, it is determined that the service life of the battery pack ends, and when the actual capacity C q is not less than the set capacity, the capacity acquisition module is controlled to continue to acquire the actual capacity C of the battery pack q ; The correction formula specifically includes: The actual capacity C q The OCV corresponding to n% SOC in it is the OCV corresponding to [1 - (1 - n%) * C q / C0] SOC in the initial capacity C0, where 100 > n > 0.

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