Battery pack life attenuation estimation method and device, electronic equipment and storage medium

Abstract

The embodiment of the invention provides a service life attenuation estimation method and device of a battery pack, electronic equipment and a storage medium. According to the method, data such as the first charge-discharge cycle number when the capacity of a single battery cell is attenuated to a preset proportion, the capacity retention rate change rate of the single battery cell and a battery pack, the internal resistance change rate of the battery pack and the like are obtained, and then the service life correction factor of the battery pack is calculated through the data. And then, combining with the first charge-discharge cycle number, calculating the second charge-discharge cycle number of the battery pack under the same capacity attenuation ratio. The method effectively solves the problem of long time consumption of the cycle life test of the power battery pack in the prior art, and avoids the dilemma that the research and development progress of the power battery pack is delayed due to the long test period, so that the requirement of project emergency development time cannot be met.

Description

Technical Field

[0001] The present application relates to the field of intelligent analysis of vehicle-mounted batteries, and in particular to a method, device, electronic device and storage medium for estimating the life attenuation of a battery pack. Background Art

[0002] With the rapid development of the new energy vehicle market, the performance and quality of power battery packs, as the core components of electric vehicles, have a direct impact on the range, safety and service life of electric vehicles. Therefore, the development requirements of power battery packs are also constantly increasing, especially in terms of the number of cycles, which need to meet the high requirements of the entire life cycle of the vehicle.

[0003] In the prior art, the number of cycles of a power battery pack is evaluated through an experimental verification method, that is, the power battery pack is subjected to a cyclic charge and discharge test until its capacity retention rate drops to a threshold value of 80%.

[0004] However, this testing method is time-consuming and increases the R&D cycle of the power battery pack, resulting in the inability to meet the tight development time requirements of the project. Summary of the invention

[0005] The embodiments of the present application provide a method, device, electronic device and storage medium for estimating the life attenuation of a battery pack, so as to solve the problem that the cycle life test of a power battery pack takes a long time, thereby increasing the development cycle and failing to meet the tight time requirements of project development.

[0006] In a first aspect, an embodiment of the present application provides a method for estimating the life attenuation of a battery pack, comprising:

[0007] Obtaining the first charge and discharge cycle number of the battery cell when the capacity decays to a preset ratio, the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack;

[0008] Determining a service life correction factor of the battery pack based on the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack;

[0009] Based on the first charge and discharge cycle number and the service life correction factor, a second charge and discharge cycle number of the battery pack when the capacity decays to the preset ratio is determined.

[0010] In a possible implementation, determining the service life correction factor of the battery pack based on the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack includes:

[0011] Determine a first ratio of a capacity retention rate change rate of the battery pack to a capacity retention rate change rate of the battery cell;

[0012] The first ratio is multiplied by the internal resistance change rate of the battery pack to obtain a service life correction factor of the battery pack.

[0013] In a possible implementation, determining, based on the first charge-discharge cycle number and the service life correction factor, the second charge-discharge cycle number of the battery pack when the capacity decays to the preset ratio includes:

[0014] The first charge-discharge cycle number is multiplied by the service life correction factor to obtain a second charge-discharge cycle number of the battery pack when the capacity decays to the preset ratio.

[0015] In a possible implementation manner, obtaining the capacity retention rate change rate of the battery cell monomer includes:

[0016] Acquire the first capacity of the battery cell after each charge-discharge cycle in the process in which the capacity of the battery cell decays to the preset ratio;

[0017] Determining the capacity retention rate of the battery cell in each charge and discharge cycle based on the first capacity after each charge and discharge cycle and the initial capacity of the battery cell;

[0018] Based on the capacity retention rate of the battery cell in each charge and discharge cycle, the capacity retention rate change rate of the battery cell is determined.

[0019] In a possible implementation manner, obtaining the capacity retention rate change rate of the battery pack includes:

[0020] Performing a first number of charge-discharge cycles on the battery pack, and obtaining a second capacity after each charge-discharge cycle;

[0021] Determining a capacity retention rate of the battery pack during each charge and discharge cycle based on the second capacity after each charge and discharge cycle and the initial capacity of the battery pack;

[0022] Based on the capacity retention rate of the battery pack during each charge and discharge cycle, a capacity retention rate change rate of the battery pack is determined.

[0023] In a possible implementation manner, obtaining the internal resistance change rate of the battery pack includes:

[0024] In the process of performing a first number of charge-discharge cycles on the battery pack, after each second number of charge-discharge cycles, obtaining an internal resistance of the battery pack;

[0025] Based on the internal resistance of the battery pack acquired multiple times, a change rate of the internal resistance of the battery pack is determined.

[0026] In a possible implementation, it further includes:

[0027] Determining a required number of charge and discharge cycles of the vehicle based on the vehicle's mileage requirement, the power consumption per unit mileage, and the capacity of the battery pack;

[0028] When the second number of charge and discharge cycles is greater than the required value of the charge and discharge cycles, it is determined that the battery pack meets the performance requirement of the vehicle.

[0029] In a second aspect, an embodiment of the present application provides a battery pack life attenuation estimation device, including:

[0030] An acquisition module, used to acquire the first charge and discharge cycle number of the battery cell when the capacity decays to a preset ratio, the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack;

[0031] A determination module, configured to determine a service life correction factor of the battery pack based on a capacity retention rate change rate of the battery cell, a capacity retention rate change rate of the battery pack, and an internal resistance change rate of the battery pack;

[0032] The determination module is further configured to determine, based on the first charge-discharge cycle number and the service life correction factor, a second charge-discharge cycle number of the battery pack when the capacity decays to the preset ratio.

[0033] In a possible implementation manner, the determination module is further used to determine a first ratio of a capacity retention rate change rate of the battery pack to a capacity retention rate change rate of the battery cell;

[0034] The determination module is specifically configured to multiply the first ratio by the internal resistance change rate of the battery pack to obtain a service life correction factor of the battery pack.

[0035] In a possible implementation, the determination module is specifically configured to multiply the first charge and discharge cycle number by the service life correction factor to obtain a second charge and discharge cycle number of the battery pack when the capacity decays to the preset ratio.

[0036] In a possible implementation manner, the acquisition module is further used to acquire the first capacity of the battery cell after each charge and discharge cycle in the process in which the capacity of the battery cell decays to the preset ratio;

[0037] The determination module is specifically used to determine the capacity retention rate of the battery cell monomer in each charge and discharge cycle based on the first capacity after each charge and discharge cycle and the initial capacity of the battery cell monomer;

[0038] The determination module is specifically used to determine the capacity retention rate change rate of the battery cell based on the capacity retention rate of the battery cell in each charge and discharge cycle.

[0039] In a possible implementation, the device further includes: a circulation module;

[0040] The cycle module is used to perform a first number of charge and discharge cycles on the battery pack;

[0041] The acquisition module is further used to acquire the second capacity after each charge and discharge cycle;

[0042] The determination module is further configured to determine a capacity retention rate of the battery pack in each charge and discharge cycle based on the second capacity after each charge and discharge cycle and the initial capacity of the battery pack;

[0043] The determination module is specifically used to determine the capacity retention rate change rate of the battery pack based on the capacity retention rate of the battery pack in each charge and discharge cycle.

[0044] In a possible implementation manner, the acquisition module is further configured to acquire the internal resistance of the battery pack after each second number of charge and discharge cycles are performed during the process of performing the first number of charge and discharge cycles on the battery pack;

[0045] The determination module is specifically used to determine the internal resistance change rate of the battery pack based on the internal resistance of the battery pack obtained multiple times.

[0046] In a possible implementation manner, the determination module is further configured to determine a required value of the number of charge and discharge cycles of the vehicle based on the vehicle's mileage requirement, the power consumption per unit mileage, and the capacity of the battery pack;

[0047] The determination module is further configured to determine that the battery pack meets the performance requirement of the vehicle when the second number of charge and discharge cycles is greater than the required value of the charge and discharge cycles.

[0048] In a third aspect, an embodiment of the present application provides a battery pack life attenuation estimation device, including: a memory, a processor;

[0049] The memory stores computer-executable instructions;

[0050] The processor executes the computer-executable instructions stored in the memory, so that the processor executes the above first aspect and / or various possible implementations of the first aspect.

[0051] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the first aspect above and / or various possible implementations of the first aspect.

[0052] In a fifth aspect, an embodiment of the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above first aspect and / or various possible implementation methods of the first aspect.

[0053] The battery pack life attenuation estimation method, device, electronic device and storage medium provided in the embodiments of the present application obtain the first charge and discharge cycle number of the battery cell when the capacity decays to a preset ratio, as well as the capacity retention rate change rate of the battery cell and the battery pack, the internal resistance change rate of the battery pack and other data, and then use these data to calculate the service life correction factor of the battery pack. Then, combined with the first charge and discharge cycle number, the second charge and discharge cycle number of the battery pack at the same capacity decay ratio can be calculated. This method effectively solves the problem of long cycle life test of power battery packs in the prior art, and avoids the dilemma of delaying the development progress of power battery packs due to long test cycles, thereby failing to meet the urgent development time requirements of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0055] Figure 1 Schematic diagram of the process of estimating the life attenuation of the battery pack provided in this application Figure 1 ;

[0056] Figure 2 Schematic diagram of the process of estimating the life attenuation of the battery pack provided in this application Figure 2 ;

[0057] Figure 3 A schematic diagram of the structure of a battery pack life attenuation estimation device provided in the present application;

[0058] Figure 4 A schematic diagram of the structure of the battery pack life attenuation estimation device provided in this application.

[0059] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0060] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0061] First, the terms involved in this application are explained.

[0062] A battery cell, also known as a battery cell, is the basic unit that makes up a battery pack. It is usually an electrochemical device that can independently store and release electrical energy. In a battery pack, multiple cells are electrically connected (in series or in parallel) to form a whole, which together provide the required voltage and current.

[0063] Battery pack: refers to a device that is composed of multiple battery cells connected in series or in parallel to form an overall battery pack. This combination can improve the energy storage capacity of the battery and facilitate its application in electric vehicles, energy storage systems and other fields.

[0064] With the rapid development of the new energy vehicle market, the performance and quality of power battery packs, as the core components of electric vehicles, are directly related to the driving range, safety and service life of electric vehicles. The development requirements of power battery packs are also constantly increasing, especially in terms of the number of cycles, which need to meet the high requirements of the entire life cycle of the vehicle. This requires that the power battery pack can still maintain a high capacity retention rate after multiple charge and discharge cycles to ensure the continuous and stable operation of electric vehicles. Therefore, accurate estimation and evaluation of the number of cycles of power battery packs has become a key link in the research and development and production of new energy vehicles.

[0065] At present, the conventional method for evaluating the number of cycles of power battery packs is mainly achieved through experimental verification. The experimental verification method usually takes half a year or even a year to reduce the capacity retention rate of the power battery pack to 80%.

[0066] However, this testing method is time-consuming and increases the R&D cycle of the power battery pack, resulting in the inability to meet the project's development time requirements.

[0067] In response to the above problems, the present application provides a method for estimating the life attenuation of a battery pack, which obtains the first number of charge and discharge cycles of the battery cell when the capacity decays to a preset ratio, as well as the capacity retention rate change rate of the battery cell and the battery pack, the internal resistance change rate of the battery pack and other data, and then uses these data to calculate the service life correction factor of the battery pack. Then, combined with the first number of charge and discharge cycles, the second number of charge and discharge cycles of the battery pack at the same capacity decay ratio can be calculated. This method effectively solves the problem of time-consuming cycle life testing of power battery packs in the prior art, and avoids the dilemma of delaying the research and development progress of power battery packs due to long test cycles, thereby failing to meet the urgent development time requirements of the project.

[0068] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0069] Figure 1 Schematic diagram of the process of estimating the life attenuation of the battery pack provided in this application Figure 1 ,like Figure 1 As shown, the method includes:

[0070] S101, obtaining the first charge and discharge cycle number of a battery cell when the capacity decays to a preset ratio, the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack.

[0071] The capacity is used to indicate how much electrical energy a cell can store. For example, if the capacity of a cell is 60Ah, it means that the cell can store 60Ah of electrical energy.

[0072] The preset ratio may be, for example, a specific value, such as 80% or 85%, or a ratio variation range, such as 80%-85%. This application does not impose any special restrictions on this.

[0073] The first charge and discharge cycle number refers to the total number of complete charge and discharge processes that the battery cell has undergone before its capacity drops to a preset ratio. For example, assuming the preset ratio is 80%. It is known that the battery cell has undergone a total of 100 charge and discharges before its capacity drops to 80% (that is, the battery cell capacity drops from 60Ah to 48Ah), so it can be determined that the first charge and discharge cycle number of the battery cell is 100.

[0074] The capacity retention rate change rate of a cell is used to characterize the performance decay rate of the cell. The capacity retention rate change rate is obtained based on the capacity retention rate corresponding to the cell in each charge and discharge cycle.

[0075] The capacity retention rate change rate of a battery pack is used to characterize the performance decay rate of the battery pack. The capacity retention rate change rate is obtained based on the capacity retention rate of the battery pack corresponding to each charge and discharge cycle.

[0076] The internal resistance change rate of a battery pack refers to the change ratio of the internal resistance of the battery pack relative to the number of cycles during a certain number of charge and discharge cycles. The internal resistance change rate of a battery pack is affected by many factors, including electrical components (such as connectors, fuses, etc.), busbars, mechanical connection resistors, and changes in the internal resistance of the battery cells themselves.

[0077] The acquisition method in this step may be, for example, acquisition through a cycle test cabinet or other test cabinets, and this application does not impose any special restrictions on this.

[0078] S102 : Determine a service life correction factor of the battery pack based on the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack.

[0079] Among them, the service life correction factor is used to correct and predict how many charge and discharge cycles the battery pack can complete when the battery pack capacity decays to a preset ratio.

[0080] It is understandable that during the use of the battery pack, the capacity retention rate of the battery cells and the battery pack as a whole will change over time, and the internal resistance of the battery pack will gradually increase. These are direct manifestations of the battery pack performance degradation.

[0081] Therefore, by comprehensively considering the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack, we can fully understand the health status and performance degradation trend of the battery pack, and thus develop a service life correction factor that is more in line with the actual situation of the battery pack, so as to more accurately predict the number of charge and discharge cycles of the battery pack.

[0082] S103: Based on the first charge-discharge cycle number and the service life correction factor, determine the second charge-discharge cycle number of the battery pack when the capacity decays to a preset ratio.

[0083] The purpose of this step is to predict the number of charge and discharge cycles that the battery pack can complete when the capacity of the battery pack decays to a preset ratio.

[0084] The method of determining the second charge-discharge cycle number in this step may be, for example, multiplying the first charge-discharge cycle number of the battery cell before the capacity decays to a preset ratio by the service life correction factor. This application does not impose any special restrictions on this.

[0085] For example, suppose the first charge and discharge cycle number of the battery cell before the capacity decays to 80% is 1000 times, and the service life correction factor calculated based on the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate is 0.85. Then, based on the above information, the first charge and discharge cycle number can be multiplied by the service life correction factor, that is, 1000 times * 0.85 = 840 times, to predict the second charge and discharge cycle number of the battery pack when the capacity decays to 80%.

[0086] The method for estimating the life attenuation of a battery pack provided in an embodiment of the present application first performs a cycle test on the battery cell in advance to determine the number of charge and discharge cycles of the battery cell when the capacity decays to a preset ratio, and records key data such as the capacity retention change rate of the battery cell and the battery pack and the internal resistance change rate of the battery pack. Next, the service life correction factor of the battery pack is calculated using these key data. Then, the number of charge and discharge cycles of the battery cell and the service life correction factor of the battery pack are combined to deduce the number of charge and discharge cycles of the battery pack for the second time at the same capacity decay ratio.

[0087] In addition, the method also includes performing 200 to 300 cycle tests on the battery pack to obtain the cycle test results of the battery pack. Based on the test results of the battery cell and the battery pack, the method can more quickly and accurately evaluate the number of cycles of the power battery pack.

[0088] Compared with the testing methods in the prior art, this method avoids the time-consuming cyclic charge and discharge test, thereby greatly shortening the testing cycle, solving the problem of delays in the development of power battery packs caused by long testing cycles, and meeting the requirements of the project's urgent development time.

[0089] Figure 2 Schematic diagram of the process of estimating the life attenuation of the battery pack provided in this application Figure 2 ,like Figure 2 As shown, in this embodiment Figure 1 Based on the embodiment, a method for estimating the life attenuation of a battery pack is described in detail. The method includes:

[0090] S201, obtaining the first charge and discharge cycle number of a battery cell when the capacity decays to a preset ratio, the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack.

[0091] Optionally, the present application provides a specific implementation method for obtaining the capacity retention rate change rate of a battery cell, which specifically includes:

[0092] The first step is to obtain the first capacity of the battery cell after each charge and discharge cycle when the capacity of the battery cell decays to a preset ratio.

[0093] The first capacity refers to the actual remaining capacity of the battery cell after each charge and discharge cycle. For example, assume that the initial capacity of the battery cell is 100Ah. It is known that the remaining capacity of the battery cell after the first complete charge and discharge cycle is 99.8Ah. Based on the above information, it can be determined that the first capacity of the battery cell after the first charge and discharge cycle is 99.8Ah.

[0094] By obtaining the first capacity of the battery cell after each charge and discharge cycle when the capacity of the battery cell decays to a preset ratio, it is possible to obtain the capacity change of the battery cell under different charge and discharge cycle numbers.

[0095] It is understandable that during the use of the battery cell, its capacity will gradually decrease with the increase of the number of charge and discharge cycles. In order to accurately evaluate the capacity change of the battery cell under different charge and discharge cycles, it is necessary to obtain the first capacity of the battery cell after each charge and discharge cycle when the capacity decays to a preset ratio.

[0096] The second step is to determine the capacity retention rate of the battery cell in each charge and discharge cycle based on the first capacity after each charge and discharge cycle and the initial capacity of the battery cell.

[0097] The capacity retention rate of a cell refers to the ratio of the first capacity after any charge-discharge cycle to the initial capacity of the cell. For example, if the initial capacity of the cell is 60Ah, and after the cell completes the current charge-discharge cycle, the first capacity is 58Ah. Then the capacity retention rate of the cell is 58Ah divided by 60Ah, which is 96.7%.

[0098] The purpose of this step is to quantify the performance degradation of the battery cell during use by calculating the capacity retention rate of the battery cell after each charge and discharge cycle.

[0099] It can be understood that the capacity retention rate is obtained by dividing the first capacity measured after any charge and discharge cycle of the battery cell by its initial capacity. This ratio intuitively reflects the performance retention of the battery cell after the charge and discharge cycle. The higher the capacity retention rate, the smaller the performance degradation of the battery cell, and its ability to store electrical energy is relatively stronger; conversely, the lower the capacity retention rate, the more obvious the performance degradation of the battery cell, and its ability to store electrical energy has decreased.

[0100] Therefore, by comprehensively considering the first capacity of the battery cell after each charge and discharge cycle and the initial capacity of the battery cell, the performance degradation degree of the battery cell can be more effectively evaluated.

[0101] The third step is to determine the capacity retention rate change rate of the battery cell based on the capacity retention rate of the battery cell in each charge and discharge cycle.

[0102] The purpose of this step is to quantify the performance degradation trend of the battery cell during continuous charge and discharge cycles.

[0103] It can be understood that the capacity retention rate change rate can characterize the degree to which the capacity retention ability of the battery cell gradually decreases during the continuous charge and discharge cycle. Therefore, by comprehensively considering the capacity retention rate of the battery cell in each charge and discharge cycle, it means that the performance degradation trend of the battery cell during the continuous charge and discharge cycle can be accurately analyzed.

[0104] The method of determining the capacity retention rate change rate of the battery cell in this step can be, for example, a data fitting method, which is obtained by performing data fitting on the capacity retention rate of the battery cell in each charge and discharge cycle. This application does not impose any special restrictions on this.

[0105] For example, suppose the initial capacity of the battery cell is 60Ah. It is known that the battery cell undergoes continuous charge and discharge cycles from the 1st to the 100th time, and the capacity retention rate after each cycle is measured to be 100.05%, 101.00%, 99.88%... until 99.7% after the 121st cycle. Based on the above information, and using the data fitting method, these data are fitted to first obtain the trend of the capacity retention rate of the battery cell as the number of cycles increases, and then determine the capacity retention rate change rate of the battery cell from the trend.

[0106] Optionally, the present application provides a specific implementation method for obtaining the capacity retention rate change rate of a battery pack, specifically including:

[0107] In the first step, the battery pack is charged and discharged for a first number of times, and a second capacity is obtained after each charge and discharge cycle.

[0108] The first number of times may be, for example, a specific number, such as 200 times or 300 times, or an interval, such as 200 times-300 times, and this application does not impose any special limitation on this.

[0109] The second capacity refers to the actual remaining capacity of the battery pack after each charge and discharge cycle. For example, suppose the initial capacity of the battery pack is 16kWh. It is known that the remaining capacity of the battery pack after the first complete charge and discharge cycle is 15.8kWh. Based on the above information, it can be determined that the second capacity of the battery pack after the first charge and discharge cycle is 15.8kWh.

[0110] By obtaining the second capacity after each charge and discharge cycle, it means that the capacity change of the battery pack under different charge and discharge cycle numbers can be obtained.

[0111] It is understandable that during the use of the battery pack, its capacity will gradually decrease as the number of charge and discharge cycles increases. Therefore, in order to accurately evaluate the capacity change of the battery pack under different charge and discharge cycles, it is necessary to obtain the second capacity of the battery pack after each charge and discharge cycle.

[0112] In the second step, based on the second capacity after each charge and discharge cycle and the initial capacity of the battery pack, the capacity retention rate of the battery pack during each charge and discharge cycle is determined.

[0113] The capacity retention rate of a battery pack refers to the ratio of the second capacity after any charge and discharge cycle to the initial capacity of the battery pack. For example, assuming that the initial capacity of the battery pack is 16kWh, and after the battery pack completes the current charge and discharge cycle, the remaining capacity is 15.8kWh. Then the capacity retention rate of the battery cell is 15.8kWh divided by 16kWh, which is 98.75%.

[0114] The purpose of this step is to quantify the performance degradation of the battery pack during use by calculating the capacity retention rate of the battery pack after each charge and discharge cycle.

[0115] It can be understood that the capacity retention rate is obtained by dividing the first capacity measured after any charge and discharge cycle of the battery pack by its initial capacity. This ratio intuitively reflects the performance retention of the battery pack after the charge and discharge cycle. The higher the capacity retention rate, the smaller the performance degradation of the battery pack, and its ability to store electrical energy is relatively stronger; conversely, the lower the capacity retention rate, the more obvious the performance degradation of the battery pack, and its ability to store electrical energy has decreased.

[0116] Therefore, by comprehensively considering the second capacity of the battery pack after each charge and discharge cycle and the initial capacity of the battery pack, the performance degradation of the battery pack can be more effectively evaluated.

[0117] The third step is to determine the capacity retention rate change rate of the battery pack based on the capacity retention rate of the battery pack during each charge and discharge cycle.

[0118] The purpose of this step is to quantify the performance degradation trend of the battery pack during continuous charge and discharge cycles.

[0119] It can be understood that the capacity retention rate can characterize the degree to which the capacity retention ability of the battery pack gradually decreases during continuous charge and discharge cycles. Therefore, by comprehensively considering the capacity retention rate of the battery pack in each charge and discharge cycle, it means that the performance degradation trend of the battery pack during continuous charge and discharge cycles can be accurately analyzed.

[0120] The method of determining the capacity retention rate change rate of the battery pack in this step can be, for example, a data fitting method, which is obtained by performing data fitting on the capacity retention rate of the battery pack in each charge and discharge cycle. This application does not impose any special restrictions on this.

[0121] For example, suppose the first number of times is 120 times. It is known that the initial capacity of the battery pack is 16kWh. During the continuous charge and discharge cycles from the 1st to the 120th time, the capacity retention rate after each cycle was measured to be 98.8%, 98.6%, 97.55%... until 97.12% after the 120th cycle. Based on the above information and using the data fitting method, these data are fitted to first obtain the trend of the capacity retention rate of the battery pack as the number of cycles increases, and then determine the capacity retention rate change rate of the battery pack from the trend.

[0122] Optionally, the present application provides a specific implementation method for obtaining the internal resistance change rate of a battery pack, which specifically includes:

[0123] The first step is to obtain the internal resistance of the battery pack after each second number of charge and discharge cycles during the process of performing a first number of charge and discharge cycles on the battery pack.

[0124] The second number of times may be, for example, 50 times, or 60 times, and this application does not impose any special limitation on this.

[0125] It is understandable that as the number of charge and discharge cycles increases, the internal resistance of the battery pack will generally increase gradually. Therefore, in the process of charging and discharging the battery pack for the first number of times, by measuring the internal resistance of the battery pack once every second number of charge and discharge cycles, the change in the internal resistance of the battery pack during the first number of charge and discharge cycles can be obtained.

[0126] For example, assuming that the first number of times is 300 times and the second number of times is 50 times, then in the process of charging and discharging the battery pack 300 times, it is necessary to obtain the internal resistance of the battery pack after every 50 charge and discharge cycles until all 300 charge and discharge cycles are completed.

[0127] The second step is to determine the internal resistance change rate of the battery pack based on the internal resistance of the battery pack obtained multiple times.

[0128] The purpose of this step is to evaluate the trend of the internal resistance of the battery pack as the number of cycles increases during continuous charge and discharge cycles.

[0129] It can be understood that the internal resistance change rate can characterize the trend of the internal resistance value of the battery pack changing with the increase of the number of cycles during the continuous charge and discharge cycle. Therefore, by comprehensively considering the battery pack internal resistance data obtained after each charge and discharge cycle, the internal resistance change rate of the battery pack can be determined, so as to help understand the performance change of the battery pack.

[0130] The method of determining the internal resistance change rate of the battery pack in this step may be, for example, a data fitting method, which is obtained by performing data fitting on the internal resistance of the battery pack obtained multiple times. This application does not impose any special restrictions on this.

[0131] S202: Determine a first ratio of a capacity retention rate change rate of the battery pack to a capacity retention rate change rate of a battery cell.

[0132] The purpose of this step is to evaluate the difference in performance degradation between the battery pack and the battery cell during continuous charge and discharge cycles.

[0133] It can be understood that the capacity retention rate change rate of the battery pack can represent the performance decay rate of the battery pack, while the capacity retention rate change rate of the battery cell can represent the performance decay rate of the battery cell.

[0134] Because the battery pack is composed of multiple battery cells, by comparing the capacity retention rate change rate of the battery pack with the capacity retention rate change rate of the battery cell, the difference in performance degradation between the battery pack and the battery cell during continuous charge and discharge cycles can be evaluated and presented with specific numerical values.

[0135] S203: Multiply the first ratio by the internal resistance change rate of the battery pack to obtain a service life correction factor of the battery pack.

[0136] It can be understood that, based on the first ratio of the capacity retention rate change rate of the battery pack to the capacity retention rate change rate of the battery cell, by multiplying it by the internal resistance change rate of the battery pack, it means that a more comprehensive service life correction factor can be obtained, so as to help more accurately correct and predict how many complete charge and discharge cycles the battery pack can complete when the capacity decays to a preset ratio.

[0137] S204: multiply the first charge and discharge cycle number by the service life correction factor to obtain a second charge and discharge cycle number when the capacity of the battery pack decays to a preset ratio.

[0138] It is understandable that the first charge and discharge cycle number can represent the total number of completed charge and discharge processes that the battery cell has undergone before its capacity drops to a preset ratio. The service life correction factor can correct and predict how many complete charge and discharge cycles the battery pack can continue to complete when its capacity also decays to the preset ratio by comprehensively considering the performance degradation of the battery cell and the battery pack in continuous charge and discharge cycles.

[0139] Therefore, by multiplying the first charge and discharge cycle number by the service life correction factor, a predicted value can be obtained, that is, the number of charge and discharge cycles that the battery pack can complete when the capacity decays to the same preset proportion as the battery cell.

[0140] For example, assuming that the service life correction factor is 0.5, and it is known that the number of first charge and discharge cycles that a cell can complete when the capacity decays to 80% is 238. Based on the above information, it can be predicted that the number of charge and discharge cycles that the battery pack can complete when the capacity decays to 80% (i.e., the number of second charge and discharge cycles) is 238 times 0.5, which equals 119.

[0141] S205: Determine the required number of charge and discharge cycles of the vehicle based on the required mileage of the vehicle, the power consumption per unit mileage, and the capacity of the battery pack.

[0142] The vehicle's mileage requirement is used to indicate the total distance the vehicle needs to travel.

[0143] The mileage power consumption is used to indicate the amount of electricity consumed by a vehicle for every kilometer it travels.

[0144] The capacity of a battery pack is used to indicate the total amount of electricity that the battery pack on a vehicle can store.

[0145] The purpose of this step is to accurately calculate the number of charge and discharge cycles required for the vehicle based on the vehicle's mileage requirements, power consumption per unit mileage, and battery pack capacity to ensure that the vehicle can meet the expected driving requirements.

[0146] S206: When the second number of charge and discharge cycles is greater than the required number of charge and discharge cycles, determine that the battery pack meets the performance requirements of the vehicle.

[0147] The purpose of judging whether the second charge and discharge cycle number is greater than the charge and discharge cycle number requirement value is to determine whether the battery pack currently installed in the vehicle meets the performance requirements of the vehicle.

[0148] If the second charge and discharge cycle number is greater than the charge and discharge cycle number requirement value, it indicates that the battery pack currently installed in the vehicle meets the performance requirements of the vehicle. At this time, the battery pack can be used in the vehicle.

[0149] It is understandable that if the second charge-discharge cycle number is greater than the charge-discharge cycle number requirement, this means that the cycle life of the battery pack in the actual test exceeds the number of cycles required for the vehicle to meet its driving requirements. Therefore, the battery pack can be safely and effectively used in the vehicle to provide the required power support for the vehicle.

[0150] The method for estimating the life attenuation of a battery pack provided in an embodiment of the present application first calculates the service life correction factor of the battery pack by obtaining the first charge and discharge cycle number of the battery cell when the capacity decays to a preset ratio, the capacity retention rate change rate of the battery cell and the battery pack, and the internal resistance change rate of the battery pack, and then uses the correction factor to adjust the first charge and discharge cycle number to obtain the second charge and discharge cycle number of the battery pack at the same capacity decay ratio. Next, based on the vehicle's mileage requirements, unit mileage power consumption and battery pack capacity, the required number of charge and discharge cycles required for the vehicle is determined. Finally, the second charge and discharge cycle number is compared with the required value. If the former is greater than the latter, it is determined that the battery pack meets the vehicle performance requirements. This method solves the problem of evaluating the number of cycles of power battery packs through time-consuming cyclic charge and discharge tests in the prior art by comprehensively considering the performance differences and internal resistance changes between the battery cell and the battery pack, significantly shortens the research and development cycle of the power battery pack, and meets the urgent development time requirements of the project.

[0151] Figure 3 A schematic diagram of the structure of the battery pack life attenuation estimation device provided in this application, such as Figure 3 As shown, the battery pack life attenuation estimation device 300 provided in this embodiment includes:

[0152] An acquisition module 301 is used to acquire the first charge and discharge cycle number of a cell when the capacity decays to a preset ratio, the capacity retention rate change rate of the cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack;

[0153] A determination module 302, configured to determine a service life correction factor of the battery pack based on a capacity retention rate change rate of the battery cell, a capacity retention rate change rate of the battery pack, and an internal resistance change rate of the battery pack;

[0154] The determination module 302 is further configured to determine, based on the first charge-discharge cycle number and the service life correction factor, a second charge-discharge cycle number of the battery pack when the capacity decays to the preset ratio.

[0155] In a possible implementation manner, the determination module 302 is further configured to determine a first ratio of a capacity retention rate change rate of the battery pack to a capacity retention rate change rate of the battery cell;

[0156] The determination module 302 is specifically configured to multiply the first ratio by the internal resistance change rate of the battery pack to obtain a service life correction factor of the battery pack.

[0157] In a possible implementation, the determination module 302 is specifically configured to multiply the first charge and discharge cycle number by the service life correction factor to obtain a second charge and discharge cycle number of the battery pack when the capacity decays to the preset ratio.

[0158] In a possible implementation manner, the acquisition module 301 is further used to acquire the first capacity of the battery cell after each charge-discharge cycle in the process in which the capacity of the battery cell decays to the preset ratio;

[0159] The determination module 302 is specifically used to determine the capacity retention rate of the battery cell in each charge and discharge cycle based on the first capacity after each charge and discharge cycle and the initial capacity of the battery cell;

[0160] The determination module 302 is specifically configured to determine a capacity retention rate change rate of the battery cell based on the capacity retention rate of the battery cell in each charge and discharge cycle.

[0161] In a possible implementation, the device further includes: a circulation module 303;

[0162] The cycle module 303 is used to perform a first number of charge and discharge cycles on the battery pack;

[0163] The acquisition module 301 is further used to acquire the second capacity after each charge and discharge cycle;

[0164] The determination module 302 is further configured to determine a capacity retention rate of the battery pack in each charge and discharge cycle based on the second capacity after each charge and discharge cycle and the initial capacity of the battery pack;

[0165] The determination module 302 is specifically configured to determine a capacity retention rate change rate of the battery pack based on the capacity retention rate of the battery pack in each charge and discharge cycle.

[0166] In a possible implementation manner, the acquisition module 301 is further configured to acquire the internal resistance of the battery pack after each second number of charge and discharge cycles are performed during the process of performing the first number of charge and discharge cycles on the battery pack;

[0167] The determination module 302 is specifically configured to determine a change rate of the internal resistance of the battery pack based on the internal resistance of the battery pack obtained multiple times.

[0168] In a possible implementation manner, the determination module 302 is further configured to determine a required value of the number of charge and discharge cycles of the vehicle based on the required mileage of the vehicle, the power consumption per unit mileage, and the capacity of the battery pack;

[0169] The determination module 302 is further configured to determine that the battery pack meets the performance requirement of the vehicle when the second number of charge and discharge cycles is greater than the required number of charge and discharge cycles.

[0170] The battery pack life attenuation estimation device provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and this embodiment will not be described in detail here.

[0171] Figure 4 This is a schematic diagram of the structure of the battery pack life attenuation estimation device provided in this application. Figure 4 As shown, the electronic device 400 provided in this embodiment includes: at least one processor 401 and a memory 402. Optionally, the device 400 also includes a communication component 403. The processor 401, the memory 402 and the communication component 403 are connected via a bus 404.

[0172] In a specific implementation process, at least one processor 401 executes the computer-executable instructions stored in the memory 402, so that at least one processor 401 executes the above method.

[0173] The specific implementation process of the processor 401 can be found in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0174] In the above embodiments, it should be understood that the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the invention can be directly implemented as a hardware processor, or can be implemented by a combination of hardware and software modules in the processor.

[0175] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (NVM), such as at least one disk storage.

[0176] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of this application is not limited to only one bus or one type of bus.

[0177] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0178] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0179] The above-mentioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0180] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as: ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0181] The division of units is only a logical function division, and there may be other divisions in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0182] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0183] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0184] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0185] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0186] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for estimating the life attenuation of a battery pack, characterized in that: include: Obtaining the first charge and discharge cycle number of the battery cell when the capacity decays to a preset ratio, the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack; Determining a service life correction factor of the battery pack based on the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack; Based on the first charge and discharge cycle number and the service life correction factor, a second charge and discharge cycle number of the battery pack when the capacity decays to the preset ratio is determined.

2. The method according to claim 1, characterized in that The determining of the service life correction factor of the battery pack based on the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack and the internal resistance change rate of the battery pack includes: Determine a first ratio of a capacity retention rate change rate of the battery pack to a capacity retention rate change rate of the battery cell; The first ratio is multiplied by the internal resistance change rate of the battery pack to obtain a service life correction factor of the battery pack.

3. The method according to claim 1, characterized in that The determining, based on the first charge-discharge cycle number and the service life correction factor, a second charge-discharge cycle number of the battery pack when the capacity decays to the preset ratio includes: The first charge-discharge cycle number is multiplied by the service life correction factor to obtain a second charge-discharge cycle number of the battery pack when the capacity decays to the preset ratio.

4. The method according to any one of claims 1 to 3, characterized in that Obtaining the capacity retention rate change rate of the battery cell monomer includes: Acquire the first capacity of the battery cell after each charge-discharge cycle in the process in which the capacity of the battery cell decays to the preset ratio; Determining the capacity retention rate of the battery cell in each charge and discharge cycle based on the first capacity after each charge and discharge cycle and the initial capacity of the battery cell; Based on the capacity retention rate of the battery cell in each charge and discharge cycle, the capacity retention rate change rate of the battery cell is determined.

5. The method according to any one of claims 1 to 3, characterized in that: Obtaining the capacity retention rate change rate of the battery pack, including: Performing a first number of charge-discharge cycles on the battery pack, and obtaining a second capacity after each charge-discharge cycle; Determining a capacity retention rate of the battery pack during each charge and discharge cycle based on the second capacity after each charge and discharge cycle and the initial capacity of the battery pack; Based on the capacity retention rate of the battery pack during each charge and discharge cycle, a capacity retention rate change rate of the battery pack is determined.

6. The method according to claim 5, characterized in that Obtaining the internal resistance change rate of the battery pack, including: In the process of performing a first number of charge-discharge cycles on the battery pack, after each second number of charge-discharge cycles, obtaining an internal resistance of the battery pack; Based on the internal resistance of the battery pack acquired multiple times, a change rate of the internal resistance of the battery pack is determined.

7. The method according to any one of claims 1 to 3, characterized in that Also includes: Determining a required number of charge and discharge cycles of the vehicle based on the vehicle's mileage requirement, the power consumption per unit mileage, and the capacity of the battery pack; When the second number of charge and discharge cycles is greater than the required value of the charge and discharge cycles, it is determined that the battery pack meets the performance requirement of the vehicle.

8. A battery pack life attenuation estimation device, characterized in that: include: An acquisition module, used to acquire the first charge and discharge cycle number of the battery cell when the capacity decays to a preset ratio, the capacity retention rate change rate of the battery cell, the capacity retention rate change rate of the battery pack, and the internal resistance change rate of the battery pack; A determination module, configured to determine a service life correction factor of the battery pack based on a capacity retention rate change rate of the battery cell, a capacity retention rate change rate of the battery pack, and an internal resistance change rate of the battery pack; The determination module is further configured to determine, based on the first charge-discharge cycle number and the service life correction factor, a second charge-discharge cycle number of the battery pack when the capacity decays to the preset ratio.

9. A battery pack life attenuation estimation device, characterized in that: include: Memory, processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory, so that the processor performs the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 7 when executed by a processor.

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