Method, device and electronic device for estimating energy efficiency of a battery pack

Abstract

The application discloses a kind of estimation methods of battery pack energy efficiency, the method comprises: based on the influence factor of the energy loss of battery pack caused in integrated process, the first actual available energy of battery pack is calculated, integrated process is the process of single cell integration into battery pack, and the influence factor at least includes one of series connection cell energy deviation, battery pack SOC usable interval, cell SOC difference in battery pack, sensor accuracy and battery pack internal resistance;Based on the energy loss caused by the difference of battery pack working temperature environment and the energy loss caused by storage discharge, the first actual available energy is adjusted, and the second actual available energy of battery pack is obtained;The ratio of second actual available energy and battery pack theoretical energy is calculated to obtain the energy efficiency of battery pack.The technical scheme provided by the application further improves the accuracy of battery pack energy efficiency estimation.

Description

Technical Field

[0001] This invention relates to the field of new energy lithium batteries, and specifically to a method, apparatus, and electronic device for estimating the energy efficiency of a battery pack. Background Technology

[0002] With the large-scale application of lithium batteries, especially the vigorous promotion of new energy vehicles, raw material costs have risen sharply, putting increasing cost pressure on enterprises and placing higher and higher demands on the integration efficiency from cell to battery pack. Integration efficiency includes mass energy density efficiency, volumetric energy density efficiency, energy efficiency, and capacity efficiency. Among these, energy efficiency is particularly important because it directly affects the system cost and the vehicle's driving range (energy efficiency is the ratio between the remaining energy of the entire battery pack after the cells are integrated into the battery pack, excluding energy losses, and the theoretical energy). Therefore, accurately estimating the energy efficiency of the battery pack is of great significance to battery manufacturers.

[0003] However, existing technologies for estimating battery energy efficiency or capacity efficiency still focus on the period after battery packing, failing to consider energy fluctuations that occur during battery pack manufacturing. For example, patent document (CN110031769A) discloses a method for estimating capacity loss based on temperature and pressure differences within the battery pack after packing. Therefore, how to further improve the accuracy of battery pack energy efficiency estimation is an urgent problem to be solved. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a method, apparatus and electronic device for estimating battery pack energy efficiency, thereby further improving the accuracy of battery pack energy efficiency estimation.

[0005] According to a first aspect, embodiments of the present invention provide a method for estimating the energy efficiency of a battery pack. The method includes: calculating a first actual usable energy of the battery pack based on factors affecting energy loss in the integration process, wherein the integration process is the process of integrating individual battery cells into the battery pack, and the factors affecting energy loss include at least one of series-connected cell energy deviation, usable SOC range of the battery pack, SOC difference of cells within the battery pack, sensor accuracy, and internal resistance of the battery pack; adjusting the first actual usable energy based on energy loss caused by differences in the operating temperature environment of the battery pack and energy loss caused by storage discharge to obtain a second actual usable energy of the battery pack, wherein the differences in the operating temperature environment are the differences between the operating temperature environment of the cells in the battery pack and the operating temperature environment of individual battery cells; and calculating the ratio of the second actual usable energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.

[0006] Optionally, calculating the first actual usable energy of the battery pack based on the influencing factors causing energy loss in the integrated process includes: calculating the theoretical energy of the battery pack based on the cell integration structure; calculating the corresponding energy loss value of the battery pack or the proportion coefficient of the remaining energy of the battery pack after energy loss through the influencing factors; and determining the first actual usable energy from the theoretical energy of the battery pack through the proportion coefficient and the energy loss value.

[0007] Optionally, the step of calculating the theoretical energy of the battery pack based on the cell integration structure includes: obtaining the number of cells connected in series and in parallel within the battery pack according to the cell integration structure; and obtaining the theoretical energy of the battery pack by multiplying the number of cells connected in series, the number of cells connected in parallel, the nominal capacity of a single cell, and the nominal voltage of a single cell.

[0008] Optionally, calculating the proportion of remaining energy of the battery pack after energy loss using the influencing factors includes: calculating a first ratio of the minimum energy of a single cell in the battery pack to the nominal energy of a single cell, obtaining a first proportion coefficient characterizing the energy deviation of the series-connected cells; calculating the difference between the upper and lower limits of the battery pack's State of Charge (SOC), obtaining a second proportion coefficient characterizing the usable range of the battery pack's SOC; calculating a second ratio of the cell energy difference to the minimum energy of a single cell, and calculating the product of the second ratio and the square root of the number of parallel cells, then inverting the calculation result within a percentage range to obtain a proportion coefficient characterizing the remaining energy of the battery pack. A third proportional coefficient is used to characterize the SOC difference of the cells within the battery pack. The cell energy difference includes the energy difference between cells caused by the accuracy difference of the capacity grading equipment and the energy difference caused by the self-discharge difference between cells during the integration process. The sampling energy loss of the sensor error is obtained, and a third ratio of the sampling energy loss to the energy of the smallest single cell is calculated. Then, the third ratio is inverted within a percentage range to obtain a fourth proportional coefficient used to characterize the accuracy of the sensor. The first proportional coefficient, the second proportional coefficient, the third proportional coefficient, and the fourth proportional coefficient are all attributed to the proportional coefficient.

[0009] Optionally, calculating the corresponding energy loss value of the battery pack through the influencing factors includes: calculating the energy consumption of the electrical connection mechanism inside the battery pack based on the product of the square of the nominal current of the battery pack and the internal resistance of the battery pack, and using the energy consumption of the electrical connection mechanism inside the battery pack as the energy loss value of the battery pack.

[0010] Optionally, determining the first actual usable energy from the theoretical energy of the battery pack using the proportionality coefficient and the energy loss value includes: calculating the product of the theoretical energy of the battery pack with the first proportionality coefficient, the second proportionality coefficient, the third proportionality coefficient, and the fourth proportionality coefficient to obtain an intermediate amount of remaining energy; and calculating the difference between the intermediate amount of remaining energy and the energy consumption of the electrical connection mechanism within the battery pack to obtain the first actual usable energy.

[0011] Optionally, the method further includes: calculating the ratio of the second actual available energy to the nominal voltage of the individual cell and the number of cells connected in series to obtain the actual capacity of the battery pack; and calculating the ratio of the actual capacity of the battery pack to the nominal capacity of the individual cell and the number of cells connected in parallel to obtain the capacity efficiency of the battery pack.

[0012] According to a second aspect, embodiments of the present invention provide a battery pack energy efficiency estimation device, the device comprising: a first loss unit, configured to calculate a first actual usable energy of the battery pack based on influencing factors causing energy loss in the integration process, wherein the integration process is the process of integrating individual cells into the battery pack, and the influencing factors include at least one of series cell energy deviation, usable range of battery pack SOC, SOC difference of cells within the battery pack, sensor accuracy, and battery pack internal resistance; a second loss unit, configured to adjust the first actual usable energy based on energy loss caused by differences in the operating temperature environment of the battery pack and energy loss caused by storage discharge, to obtain a second actual usable energy of the battery pack, wherein the differences in the operating temperature environment are the differences between the operating temperature environment of the cells in the battery pack and the operating temperature environment of individual cells; and an energy efficiency unit, configured to calculate the ratio of the second actual usable energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.

[0013] According to a third aspect, embodiments of the present invention provide an electronic device, including: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the method described in the first aspect, or any optional embodiment of the first aspect.

[0014] According to a fourth aspect, embodiments of the present invention provide a computer-readable storage medium storing computer instructions for causing the computer to perform the method described in the first aspect, or any alternative embodiment of the first aspect.

[0015] The technical solution provided in this application has the following advantages:

[0016] The technical solution provided in this application estimates the energy loss of a battery pack through three main stages: the cell-to-pack integration stage, the difference in the battery pack's operating temperature environment, and the battery pack assembly to battery system storage stage. Compared with existing technologies, it fully considers the impact of differences in assembly time from cell to system, differences in system topology connection structure, and differences in internal electrical design of the battery system on energy efficiency. This improves the accuracy of battery pack energy efficiency estimation. In the embodiments of this invention, factors affecting battery pack energy loss in the integration process are specifically introduced. These factors include at least one of the following: series cell energy deviation, usable range of battery pack SOC, SOC difference of cells within the battery pack, sensor accuracy, and battery pack internal resistance. This comprehensive consideration of energy loss factors allows for the determination of the first actual usable energy from the theoretical energy of the battery pack. Subsequently, the energy loss caused by the difference between the operating temperature environment of the cells in the battery pack and the operating temperature environment of individual cells, as well as the energy loss caused by self-discharge during battery pack storage, are also considered. Furthermore, the remaining energy of the battery pack is re-determined from the first actual usable energy to obtain the second actual usable energy. Finally, the energy efficiency of the battery pack can be obtained by calculating the ratio of the second actual available energy to the theoretical energy of the battery pack, which further improves the accuracy of the battery pack energy efficiency estimation. Attached Figure Description

[0017] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0018] Figure 1 A schematic diagram illustrating the steps of a method for estimating the energy efficiency of a battery pack according to one embodiment of the present invention is shown.

[0019] Figure 2 A schematic diagram of a battery pack energy efficiency estimation device according to one embodiment of the present invention is shown;

[0020] Figure 3 A schematic diagram of an electronic device according to one embodiment of the present invention is shown. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1In one embodiment, a method for estimating the energy efficiency of a battery pack specifically includes the following steps:

[0023] Step S101: Based on the factors affecting energy loss in the battery pack during the integration process, calculate the first actual usable energy of the battery pack. The integration process is the process of integrating individual cells into the battery pack. The influencing factors include at least one of the following: energy deviation of series cells, usable range of battery pack SOC, SOC difference of cells in the battery pack, sensor accuracy, and internal resistance of the battery pack.

[0024] Step S102: Based on the energy loss caused by the difference in the working temperature environment of the battery pack and the energy loss caused by storage discharge, the first actual usable energy is adjusted to obtain the second actual usable energy of the battery pack, wherein the difference in the working temperature environment is the difference between the working temperature environment of the cells in the battery pack and the working temperature environment of the individual cells.

[0025] Step S103: Calculate the ratio of the second actual available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.

[0026] Specifically, in estimating the energy efficiency of the battery pack according to this embodiment of the invention, the impact of differences in assembly time from the cells to the system, differences in system topology, and differences in internal electrical design of the battery system on energy efficiency is fully considered. This introduces factors influencing energy loss in the integration process, including at least one of the following: energy deviation of series-connected cells, usable SOC range of the battery pack, SOC differences among cells within the battery pack, sensor accuracy, and internal resistance of the battery pack. After determining the energy loss from the theoretical energy of the battery pack based on these factors, the remaining first actual usable energy of the battery pack is obtained during the integration stage. After the battery pack is completed, energy losses caused by the difference between the operating temperature environment of the cells in the battery pack and the operating temperature environment of individual cells, as well as energy losses caused by self-discharge during battery pack storage, are also considered. The remaining energy of the battery pack is then recalculated from the first actual usable energy to obtain the second actual usable energy. Finally, the ratio of the second actual usable energy to the theoretical energy of the battery pack is calculated to obtain the energy efficiency of the battery pack. Compared with existing technologies, this method more fully considers energy losses caused by the integration process during energy efficiency estimation, thereby further improving the accuracy of battery pack energy efficiency estimation.

[0027] Specifically, the influencing factors mentioned above are explained as follows:

[0028] The battery pack follows the principle of "connecting cells of the same capacity in series keeps the battery pack capacity unchanged, connecting cells in parallel increases the battery pack capacity, and connecting cells of different capacities in series reduces the battery pack capacity by the smaller value." Because the series connection structure of the cells within the battery pack can lead to energy deviations between them, these deviations correspond to unusable portions in actual use—in other words, energy losses. Therefore, in this embodiment, a portion of the energy loss is calculated using the energy deviation of the series-connected cells during battery production. Secondly, to ensure battery safety, battery manufacturers typically do not fully charge and discharge the batteries in real-world scenarios, thus defining a usable State of Charge (SOC) range. The unusable portions result in energy loss, and a portion of the energy loss is calculated based on this usable SOC range. Thirdly, due to the inherent differences between individual cells within the battery pack, their SOCs are not entirely identical, varying significantly. These SOC differences may result in cells that are not fully charged and those that are fully discharged being different cells, leading to energy losses. Therefore, this embodiment calculates a portion of the energy loss by calculating the SOC differences among the cells within the battery pack. Fourthly, during battery production, the sensors collecting parameters such as voltage, current, and resistance may have acquisition errors, which contribute to energy loss. This embodiment calculates a portion of the energy loss based on sensor accuracy, further improving the accuracy of subsequent energy efficiency estimation. Fifthly, after the battery pack is assembled, in addition to the internal resistance of individual cells, the battery pack itself has an additional internal resistance. This internal resistance often leads to heat dissipation and energy loss. Therefore, calculating energy loss based on the battery pack's internal resistance further improves the accuracy of energy efficiency estimation. In this embodiment, the specific algorithm for calculating the energy loss is the product of the square of the battery pack's nominal current and its internal resistance, multiplied by the discharge time, representing the energy consumption of the electrical connection mechanism within the battery pack.

[0029] Specifically, in one embodiment, step S101 above includes the following steps:

[0030] Step 1: Calculate the theoretical energy of the battery pack based on the cell integrated structure.

[0031] Step 2: Calculate the corresponding energy loss value of the battery pack or the proportion of the remaining energy of the battery pack after energy loss by considering the influencing factors.

[0032] Step 3: Determine the first actual usable energy from the theoretical energy of the battery pack using the proportionality coefficient and the energy loss value.

[0033] Specifically, after obtaining influencing factors such as "series cell energy deviation, usable SOC range of the battery pack, SOC difference of cells within the battery pack, sensor accuracy, and internal resistance of the battery pack," a proportionality coefficient related to these factors, representing the ratio of the remaining energy after energy loss to the theoretical energy, can be calculated. Alternatively, the energy loss directly caused by these factors can be calculated. Thus, the first actual usable energy can be determined from the theoretical energy of the battery pack using the proportionality coefficient and the lost energy value. Furthermore, in this embodiment, the theoretical energy of the battery pack varies due to differences in the battery pack integration structure (number of cells, series-parallel connection method). Therefore, it is necessary to calculate the accurate theoretical energy of the battery pack based on the integrated structure, thereby ensuring the accuracy of the first actual usable energy calculation result.

[0034] Specifically, in one embodiment, step one above includes the following steps:

[0035] Step 4: Obtain the number of cells connected in series and in parallel within the battery pack based on the cell integration structure.

[0036] Step 5: Obtain the theoretical energy of the battery pack by multiplying the number of cells in series, the number of cells in parallel, the nominal capacity of each cell, and the nominal voltage of each cell.

[0037] Specifically, in this embodiment, the number of series-connected cells and the number of parallel-connected cells in the battery pack are first obtained according to the cell integration structure in the battery pack integration process. Then, the theoretical energy value of a single cell is obtained by multiplying the nominal capacity and nominal voltage of a single cell. Finally, the product of the number of cells connected in series and the number of cells connected in parallel is calculated to obtain the maximum energy value that the entire battery pack can theoretically have, i.e., the theoretical energy of the battery pack.

[0038] Specifically, in one embodiment, step two above includes the following steps:

[0039] The aforementioned proportionality coefficients specifically include a first proportionality coefficient, a second proportionality coefficient, a third proportionality coefficient, and a fourth proportionality coefficient, which are calculated as follows:

[0040] 1. Calculate the first ratio of the minimum energy of a single cell in the battery pack to the nominal energy of a single cell, and obtain the first proportionality coefficient used to characterize the energy deviation of series-connected cells.

[0041] Specifically, f1=E min / E n E min This refers to the energy of the smallest cell used in a battery pack, E. n It is the nominal energy of a single battery cell. If the minimum energy of the battery cell is the nominal energy of the battery cell, then the value of the first proportional coefficient f1 is 1.

[0042] 2. Calculate the difference between the upper limit and the lower limit of the battery pack's SOC usage to obtain a second proportional coefficient used to characterize the usable range of the battery pack's SOC.

[0043] Specifically, in this embodiment, the usable range of the battery pack's State of Charge (SOC) is the difference between the upper and lower limits of battery usage preset by the battery manufacturer. This difference corresponds to a second proportional coefficient f2. Multiplying the theoretical energy of the battery pack by f2 yields the remaining usable energy value of the battery pack after energy loss caused by the unusable range of the battery pack's SOC.

[0044] 3. Calculate the second ratio of the cell energy difference to the minimum single cell energy, and calculate the product of the second ratio and the square root of the number of parallel cells. Then, invert the calculation result within the percentage range to obtain the third proportional coefficient used to characterize the SOC difference of cells in the battery pack. The cell energy difference includes the energy difference between cells caused by the difference in the accuracy of the capacity grading equipment and the energy difference caused by the difference in self-discharge between cells during the integration process.

[0045] Specifically, considering the differences in State of Charge (SOC) between individual cells within the battery pack, it's possible that fully charged and discharged cells may not be the same, resulting in energy loss. This energy loss can be calculated by statistically analyzing the differences in SOC among the individual cells. This can be achieved as follows: after cell capacity testing, the cells are stored according to a set storage time from cell to module assembly to obtain the battery pack. Then, each cell undergoes a standard discharge, and the SOC difference of each cell is obtained based on the discharge results, thereby calculating the energy difference. In this embodiment, to save on cell discharge steps and further improve the speed of energy loss estimation, an additional method for calculating energy loss based on the differences in SOC among individual cells is proposed: collecting the energy difference ΔE between cells caused by differences in the accuracy of the capacity testing equipment. eqi The study also collected data on the energy difference ΔE caused by the difference in self-discharge between battery cells during the period from when the cells rolled off the production line to when they were assembled into the module. sdc Then calculate the third proportionality coefficient f3 according to the following formula.

[0046]

[0047] In the formula, C min It is the minimum capacitance of a single cell within the battery pack, V. n It is the nominal voltage, C min *V n The value represents the minimum energy of a single battery cell, and P is the number of cells connected in parallel. In this embodiment, the value is obtained based on statistical experiments in battery production. The more cells connected in parallel, the greater the difference in SOC, and the more severe the energy loss. Thus, the above-mentioned third proportional coefficient expression is obtained.

[0048] 4. Obtain the sampling energy loss of the sensor error, and calculate the third ratio of the sampling energy loss to the minimum single cell energy. Then, invert the third ratio within the percentage range to obtain the fourth proportional coefficient used to characterize the sensor accuracy.

[0049] Specifically, the fourth proportionality coefficient f4, calculated from the sensor accuracy, is 1 - ΔE. sensor / (C min *V n The energy loss caused by sampling errors, resulting in incomplete charging and insufficient discharging to the true cutoff voltage, is represented by f4, which indicates the remaining energy percentage of a single cell after this energy loss. ΔE sensir This is the sampling energy loss caused by sensor error. This value can be obtained through high-precision measurement or theoretical analysis. min *V n This represents the minimum energy of a single battery cell. Here, the minimum energy of a single battery cell is used instead of the nominal energy of a single battery cell as the denominator. Referring to the bottleneck effect, the energy of the smallest cell determines the energy of the entire battery pack.

[0050] Specifically, in one embodiment, step three above includes the following steps:

[0051] Step 6: Calculate the product of the theoretical energy of the battery pack and the first proportional coefficient, the second proportional coefficient, the third proportional coefficient, and the fourth proportional coefficient to obtain the intermediate amount of remaining energy;

[0052] Step 7: Calculate the difference between the remaining intermediate energy and the energy consumption of the electrical connection mechanism in the battery pack to obtain the first actual usable energy.

[0053] Based on the above steps to obtain the proportional coefficient and energy loss value, the first actual usable energy, representing the remaining usable energy after energy loss during the battery pack production stage, can be accurately calculated. The formula is as follows:

[0054] E1 = E t *f1*f2*f3*f4-E sys

[0055] Where E1 is the first practically available energy, E t It is the theoretical energy of the battery pack, E sys It refers to the energy consumption of the electrical connection mechanism within the battery pack.

[0056] Specifically, in this embodiment of the invention, after the module is assembled into a battery pack, the irreversible energy loss caused by storage during the process from module assembly to battery system assembly is generally determined based on the storage performance characteristics of the battery cell. In this embodiment, the storage ratio coefficient determined based on storage discharge is f5. Because the heat dissipation boundaries of the battery system and individual cells differ during charging and discharging, the heat dissipation of the battery pack is poor, resulting in a difference between the operating temperature environment of the cells in the battery pack and the operating temperature environment of individual cells. This difference also affects the energy efficiency of the system. The temperature ratio coefficient obtained based on the energy retention capability of the cells in different temperature environments is f6, which can usually be obtained by looking up a table. f6 can be greater than 1 or less than 1. Based on this, after obtaining the first actual usable energy, the second actual usable energy E... real The calculation formula is as follows:

[0057] E real =E1*f5*f6

[0058] Specifically, in one embodiment, the battery pack energy efficiency estimation method provided by the present invention further includes the following steps:

[0059] Step 8: Calculate the ratio of the second actual usable energy to the nominal voltage and number of individual cells in series to obtain the actual capacity of the battery pack.

[0060] Step 9: Calculate the ratio of the actual capacity of the battery pack to the nominal capacity of each individual cell and the number of cells connected in parallel to obtain the capacity efficiency of the battery pack.

[0061] Specifically, based on the second actual usable energy calculated in the above steps, the capacity efficiency of the battery pack can also be calculated in this embodiment of the invention. Calculating the capacity efficiency using the more accurate second actual usable energy can further improve the accuracy of the capacity efficiency. The actual capacity C of the battery pack is then calculated. real As shown in the following formula

[0062] C real =E real / (V n *S).

[0063] In the formula, S is the number of cells connected in series in the battery pack, and V... n This refers to the nominal voltage of the battery cell. Since the capacity increases without increasing the voltage when cells are connected in parallel within the battery pack, and the capacity increases without increasing the capacity when cells are connected in series, the battery pack capacity is based on the minimum capacity of the series connection. Therefore, in a battery pack with both parallel and series structures, the capacity increase caused by parallel cells will be limited by the capacity of the series cells and will not increase the actual capacity of the battery pack. Thus, the actual usable capacity C of the battery pack can be obtained by calculating the ratio of the second actual usable energy to the nominal voltage of a single cell and the number of cells connected in series. realThen, the theoretical capacity of the battery pack is calculated by multiplying the nominal capacity of a single battery cell by the number of cells connected in parallel. Finally, the actual usable capacity C of the battery pack is calculated. real The capacity efficiency of a battery pack can be obtained by comparing its capacity with the theoretical capacity of the battery pack.

[0064] Specifically, in one embodiment, the battery pack energy efficiencies of the four systems are shown in the table below:

[0065] battery pack <![CDATA[E t .]]> f1 f2 f3 f4 Esys f5 f6 Energy efficiency A 34.61 1 1 0.9927 0.998 0.166 0.997 0.997 98.00％ B 66.56 1 1 0.9897 0.998 0.878 0.997 0.997 96.87％ C 75.37 1 1 0.995 0.998 0.603 0.9958 0.995 97.60％ D 63.59 1 1 0.995 0.998 0.572 0.9958 0.995 97.50％

[0066] Through the above steps, the technical solution provided in this application estimates the energy loss of the battery pack in two stages: the cell-to-pack integration stage and the battery pack-to-system storage stage. Compared with existing technologies, it fully considers the impact of differences in assembly time from cell to system, differences in system topology, and differences in internal electrical design of the battery system on energy efficiency. This improves the accuracy of battery pack energy efficiency estimation. In this embodiment of the invention, factors affecting battery pack energy loss in the integration process are specifically introduced. These factors include at least one of the following: series cell energy deviation, usable SOC range of the battery pack, SOC difference of cells within the battery pack, sensor accuracy, and battery pack internal resistance. This comprehensive consideration of energy loss factors allows for the determination of the first actual usable energy without loss from the theoretical energy of the battery pack. Furthermore, energy loss caused by the difference between the operating temperature environment of the cells in the battery pack and that of individual cells, as well as energy loss caused by self-discharge during battery pack storage, are also considered. The remaining energy of the battery pack is then recalculated from the first actual usable energy to obtain the second actual usable energy. Finally, the ratio of the second actual usable energy to the theoretical energy of the battery pack is calculated to obtain the energy efficiency of the battery pack, further improving the accuracy of battery pack energy efficiency estimation.

[0067] like Figure 2 As shown, this embodiment also provides a battery pack energy efficiency estimation device, which includes:

[0068] The first loss unit 101 is used to calculate the first actual usable energy of the battery pack based on the influencing factors that cause energy loss in the battery pack during the integration process. The integration process is the process of integrating individual battery cells into the battery pack. The influencing factors include at least one of the following: energy deviation of series-connected cells, usable SOC range of the battery pack, SOC difference of cells within the battery pack, sensor accuracy, and internal resistance of the battery pack. For details, please refer to the relevant description of step S101 in the above method embodiment, which will not be repeated here.

[0069] The second loss unit 102 adjusts the first actual usable energy based on the energy loss caused by ambient temperature and storage discharge during battery pack storage to obtain the second actual usable energy of the battery pack. For details, please refer to the relevant description of step S102 in the above method embodiments, which will not be repeated here.

[0070] Energy efficiency unit 103 calculates the ratio of the second actual usable energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack. For details, please refer to the relevant description of step S103 in the above method embodiment, which will not be repeated here.

[0071] The battery pack energy efficiency estimation device provided in this embodiment of the invention is used to execute the battery pack energy efficiency estimation method provided in the above embodiment. Its implementation method and principle are the same. For details, please refer to the relevant description of the above method embodiment, which will not be repeated here.

[0072] Through the collaborative efforts of the aforementioned components, the technical solution provided in this application estimates the energy loss of the battery pack in two stages: the cell-to-pack integration stage and the battery pack-to-system storage stage. Compared to existing technologies, it fully considers the impact of differences in assembly time from cell to system, differences in system topology, and differences in internal electrical design of the battery system on energy efficiency. This improves the accuracy of battery pack energy efficiency estimation. In this embodiment, the influencing factors of battery pack energy loss in the integration process are specifically introduced. These factors include at least one of the following: series cell energy deviation, usable SOC range of the battery pack, SOC difference of cells within the battery pack, sensor accuracy, and battery pack internal resistance. This comprehensive consideration of energy loss factors allows for the determination of the first actual usable energy without loss from the theoretical energy of the battery pack. Subsequently, the energy loss caused by the difference between the operating temperature environment of the cells in the battery pack and the operating temperature environment of individual cells, as well as the energy loss caused by self-discharge during battery pack storage, are also considered. Therefore, the remaining energy of the battery pack is re-determined from the first actual usable energy to obtain the second actual usable energy. Finally, the energy efficiency of the battery pack can be obtained by calculating the ratio of the second actual available energy to the theoretical energy of the battery pack, which further improves the accuracy of the battery pack energy efficiency estimation.

[0073] Figure 3 An electronic device according to an embodiment of the present invention is shown. The device includes a processor 901 and a memory 902, which can be connected via a bus or other means. Figure 3 Taking the example of a connection between China and Israel via a bus.

[0074] Processor 901 can be a Central Processing Unit (CPU). Processor 901 can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips.

[0075] The memory 902, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the methods in the above method embodiments. The processor 901 executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions, and modules stored in the memory 902, thereby implementing the methods in the above method embodiments.

[0076] The memory 902 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created by the processor 901, etc. Furthermore, the memory 902 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 902 may optionally include memory remotely located relative to the processor 901, and these remote memories may be connected to the processor 901 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0077] One or more modules are stored in memory 902, and when executed by processor 901, they perform the methods described in the above method embodiments.

[0078] The specific details of the aforementioned electronic device can be understood by referring to the relevant descriptions and effects in the above method embodiments, and will not be repeated here.

[0079] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The implemented program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.

[0080] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for estimating the energy efficiency of a battery pack, characterized in that, The method includes: The theoretical energy of the battery pack is calculated based on the cell integration structure; the corresponding energy loss value of the battery pack is calculated through influencing factors; a first ratio of the minimum energy of a single cell in the battery pack to the nominal energy of a single cell is calculated to obtain a first proportional coefficient used to characterize the energy deviation of series-connected cells; the difference between the upper and lower limits of the battery pack's State of Charge (SOC) is calculated to obtain a second proportional coefficient used to characterize the usable range of the battery pack's SOC; the second ratio of the cell energy difference to the minimum energy of a single cell is calculated, and the product of the second ratio and the square root of the number of parallel cells is calculated. The calculation result is then inverted within a percentage range to obtain a third proportional coefficient used to characterize the SOC difference of cells within the battery pack. The cell energy difference includes the energy difference between cells caused by differences in the accuracy of the capacity testing equipment and the energy difference caused by differences in self-discharge between cells during the integration process; the calculation formula for the third proportional coefficient is as follows: In the formula, This represents the third proportionality coefficient. It is the minimum capacity of a single cell within the battery pack. It is the nominal voltage. This represents the minimum energy of a single battery cell. P It refers to the number of battery cells connected in parallel. This indicates the energy difference between battery cells caused by variations in the precision of the capacity testing equipment. This refers to the energy difference caused by the difference in self-discharge between battery cells during the time from when the battery cell rolls off the production line to when it is assembled into a module. The sampling energy loss of the sensor error is obtained, and a third ratio of the sampling energy loss to the minimum single-cell energy is calculated. Then, the third ratio is inverted within a percentage range to obtain a fourth proportionality coefficient used to characterize the sensor accuracy. The formula for calculating the fourth proportionality coefficient is as follows: This represents the fourth proportionality coefficient. The sampling energy loss is due to sensor error. This represents the minimum energy of a single battery cell. The first proportional coefficient, the second proportional coefficient, the third proportional coefficient, and the fourth proportional coefficient all belong to the aforementioned proportional coefficients; The theoretical energy of the battery pack is calculated by multiplying it by the first proportional coefficient, the second proportional coefficient, the third proportional coefficient, and the fourth proportional coefficient to obtain the intermediate amount of remaining energy; the difference between the intermediate amount of remaining energy and the energy consumption of the electrical connection mechanism in the battery pack is calculated to obtain the first actual usable energy. Based on the energy loss caused by the difference in the working temperature environment of the battery pack and the energy loss caused by storage and discharge, the first actual usable energy is adjusted to obtain the second actual usable energy of the battery pack. The difference in the working temperature environment is the difference between the working temperature environment of the cells in the battery pack and the working temperature environment of the individual cells. The energy efficiency of the battery pack is obtained by calculating the ratio of the second actual available energy to the theoretical energy of the battery pack.

2. The method according to claim 1, characterized in that, The calculation of the theoretical energy of the battery pack based on the cell integrated structure includes: The number of cells connected in series and in parallel within the battery pack is obtained based on the cell integration structure. The theoretical energy of the battery pack is obtained by multiplying the number of cells connected in series, the number of cells connected in parallel, the nominal capacity of a single cell, and the nominal voltage of a single cell.

3. The method according to claim 1, characterized in that, The corresponding energy loss value of the battery pack is calculated based on influencing factors, including: The energy consumption of the electrical connection mechanism within the battery pack is calculated based on the product of the square of the nominal current of the battery pack and the internal resistance of the battery pack, and the energy consumption of the electrical connection mechanism within the battery pack is used as the energy loss value of the battery pack.

4. The method according to claim 2, characterized in that, The method further includes: The actual capacity of the battery pack is obtained by calculating the ratio of the second actual usable energy to the nominal voltage of the individual battery cell and the number of cells connected in series. The capacity efficiency of the battery pack is obtained by calculating the ratio of the actual capacity of the battery pack to the nominal capacity of the individual battery cells and the number of cells connected in parallel.

5. A device for estimating the energy efficiency of a battery pack, characterized in that, The device includes: The first loss unit is used to calculate the theoretical energy of the battery pack based on the cell integration structure; calculates a first ratio of the minimum energy of a single cell in the battery pack to the nominal energy of a single cell, obtaining a first proportional coefficient to characterize the energy deviation of series-connected cells; calculates the difference between the upper and lower limits of the battery pack's State of Charge (SOC), obtaining a second proportional coefficient to characterize the usable range of the battery pack's SOC; calculates a second ratio of the cell energy difference to the minimum energy of a single cell, and calculates the product of the second ratio and the square root of the number of parallel cells, then inverts the calculation result within a percentage range to obtain a third proportional coefficient to characterize the SOC difference of cells in the battery pack. The cell energy difference includes the energy difference between cells caused by the difference in the accuracy of the capacity testing equipment and the energy difference caused by the difference in self-discharge between cells during the integration process; the calculation formula for the third proportional coefficient is as follows: In the formula, This represents the third proportionality coefficient. It is the minimum capacity of a single cell within the battery pack. It is the nominal voltage. This represents the minimum energy of a single battery cell. P It refers to the number of battery cells connected in parallel. This indicates the energy difference between battery cells caused by variations in the precision of the capacity testing equipment. This refers to the energy difference caused by the difference in self-discharge between battery cells during the time from when the battery cell rolls off the production line to when it is assembled into a module. The sampling energy loss of the sensor error is obtained, and a third ratio of the sampling energy loss to the minimum single-cell energy is calculated. Then, the third ratio is inverted within a percentage range to obtain a fourth proportionality coefficient used to characterize the sensor accuracy. The formula for calculating the fourth proportionality coefficient is as follows: This represents the fourth proportionality coefficient. The sampling energy loss is due to sensor error. This represents the minimum energy of a single battery cell. The first proportional coefficient, the second proportional coefficient, the third proportional coefficient, and the fourth proportional coefficient all belong to the proportional coefficients; the theoretical energy of the battery pack is calculated by multiplying the theoretical energy of the battery pack by the first proportional coefficient, the second proportional coefficient, the third proportional coefficient, and the fourth proportional coefficient to obtain the intermediate amount of remaining energy; the difference between the intermediate amount of remaining energy and the energy consumption of the electrical connection mechanism in the battery pack is calculated to obtain the first actual usable energy; The second loss unit is used to adjust the first actual usable energy based on the energy loss caused by the difference in the working temperature environment of the battery pack and the energy loss caused by storage discharge, so as to obtain the second actual usable energy of the battery pack. The difference in the working temperature environment is the difference between the working temperature environment of the cells in the battery pack and the working temperature environment of the individual cells. The energy efficiency unit calculates the ratio of the second actual usable energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.

6. An electronic device, characterized in that, include: A memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, the processor executing the computer instructions to perform the method as described in any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the method as described in any one of claims 1-4.

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