Methods and apparatus for estimating state of charge

Abstract

This application provides a method and apparatus for estimating the state of charge (SOC) and improving the efficiency of obtaining SOC-OCV curves. The method includes: acquiring test data of a battery, including test data from pulse discharge or pulse charging of the battery; fitting the test data corresponding to each SOC in the test data to obtain a fitting curve for each SOC; obtaining the equilibrium potential corresponding to each SOC based on the fitting curve; and obtaining the SOC-OCV curve of the battery based on the equilibrium potential corresponding to each SOC.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method and apparatus for estimating the state of charge. Background Technology

[0002] The SOC-OCV curve, which represents the relationship between a battery's State of Charge (SOC) and Open-Circuit Voltage (OCV), is fundamental to battery testing. Typically, obtaining the SOC-OCV curve involves allowing the battery to rest for a considerable period, such as more than two hours, to eliminate battery polarization before testing the voltage at each SOC. This results in a lengthy acquisition process. Therefore, improving the efficiency of SOC-OCV curve acquisition is a problem that needs to be addressed. Summary of the Invention

[0003] This application provides a method and apparatus for estimating the state of charge, which can improve the efficiency of obtaining SOC-OCV curves.

[0004] In a first aspect, a method for estimating the state of charge (SOC) is provided, comprising: acquiring test data of a battery, the test data including test data of pulse discharge or pulse charge of the battery; fitting the test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC; obtaining the equilibrium potential corresponding to each SOC based on the fitting curve corresponding to each SOC; and obtaining the SOC-OCV curve of the battery based on the equilibrium potential corresponding to each SOC.

[0005] In this embodiment, the SOC-OCV curve is obtained by fitting the test data corresponding to each SOC. This allows for a very short resting time for acquiring the test data, essentially requiring only a short relaxation period for the battery. Therefore, the technical solution of this embodiment shortens the testing time, improves testing efficiency, and enables rapid acquisition of the battery's SOC-OCV curve. Furthermore, the short resting time increases the data sampling density, which is beneficial for improving the accuracy of the SOC-OCV curve.

[0006] In one implementation, fitting the test data corresponding to each SOC in the test data to obtain a fitting curve for each SOC includes: fitting the test data corresponding to each SOC based on the battery's relaxation process to obtain a fitting curve for each SOC. Considering the characteristics of the battery's relaxation process makes it easier to obtain fitting results that meet the error requirements, thus improving fitting efficiency.

[0007] In one implementation, fitting the test data corresponding to each SOC based on the battery's relaxation process to obtain a fitting curve for each SOC includes: fitting the test data corresponding to each SOC based on the battery's relaxation process to obtain a relaxation model that fits the test data corresponding to each SOC; and obtaining the fitting curve for each SOC based on the relaxation model. By fitting using the relaxation model, a complete fitting curve can be obtained after obtaining the relaxation model.

[0008] In one implementation, fitting the test data corresponding to each SOC based on the battery's relaxation process to obtain a relaxation model for the test data corresponding to each SOC includes: obtaining an initial relaxation model based on the battery's relaxation process, the initial relaxation model including model parameters to be determined; fitting the initial relaxation model and the test data corresponding to each SOC to determine the model parameters, thereby obtaining a relaxation model for the test data corresponding to each SOC. Using an initial relaxation model that conforms to the battery's relaxation process can effectively achieve fitting and improve processing efficiency.

[0009] In one implementation, the step of fitting the initial relaxation model and the test data corresponding to each SOC to determine the model parameters includes: selecting at least one data segment from the test data corresponding to each SOC for fitting; and using the model parameters obtained by fitting the at least one data segment with the smallest error as the model parameters of the relaxation model. By selecting at least one data segment from the test data for fitting, the fitting result with the smallest error can be selected, thereby improving the fitting accuracy.

[0010] In one implementation, the test data corresponding to each SOC includes N sampling points, where the k-th data segment in the at least one data segment is the sampling point from k to N, where N and k are positive integers, and k is less than N. This allows the test data to better fit the relaxation model, thereby obtaining more accurate fitting results.

[0011] In one implementation, obtaining the initial relaxation model based on the battery's relaxation process includes: establishing a Nernst equation to represent the relationship between electrode potential and lithium-ion concentration; and converting the Nernst equation into a relationship between electrode potential and time based on the relationship between current and lithium-ion concentration changes, and the relationship between current and time, to obtain the initial relaxation model.

[0012] In one implementation, converting the Nernst equation into a relationship between the electrode potential and time includes: determining the relationship between the current and the change in lithium ion concentration according to Fick's first law; converting the Nernst equation into a relationship between the electrode potential and the current based on the relationship between the current and the change in lithium ion concentration; obtaining the relationship between the current and the time; and converting the relationship between the electrode potential and the current into a relationship between the electrode potential and the time based on the relationship between the current and the time.

[0013] In one implementation, obtaining the relationship between the current and the time includes: determining the relationship between the current and the time based on the relationship between the current and the change in lithium ion concentration, and the relationship between the lithium ion concentration and the time.

[0014] The above method can yield a relaxation model with fewer variables that conforms to the relaxation process, making it easier to perform fitting calculations.

[0015] In one implementation, obtaining the equilibrium potential corresponding to each SOC based on its fitted curve includes: obtaining the voltage at a time point after a test period that satisfies a preset condition based on the fitted curve corresponding to each SOC, thus obtaining the equilibrium potential corresponding to each SOC. This allows the equilibrium potential to be obtained through the fitted curve, eliminating the need for testing.

[0016] In one implementation, the preset condition includes: the voltage difference between two adjacent time points is less than a preset threshold. This results in an equilibrium potential that is substantially close to the actual equilibrium potential, thereby improving the accuracy of the SOC-OCV curve.

[0017] In one implementation, the process of pulse discharging or pulse charging the battery includes a first stage, in which the battery is pulse-discharged or pulse-charged using a first discharge or charge rate, a first discharge or charge time, and a resting time. By setting the discharge or charge parameters of the first stage, the sampling density can be increased, more test data can be obtained, and thus the resulting SOC-OCV curve is smoother and can retain the characteristics of the SOC-OCV curve.

[0018] In one implementation, the process of pulse discharging or pulse charging the battery further includes a second stage. In this second stage, the battery is pulse-discharged or pulse-charged using a second discharge or charge rate, a second discharge or charge time, and the resting time. The second discharge or charge rate is less than the first discharge or charge rate, and the second discharge or charge time is longer than the first discharge or charge time. Utilizing this second-stage discharge or charge process allows for a more complete OCV (Optical Characteristic Value) range.

[0019] In one implementation, the test data corresponding to each SOC is the test data within the resting time corresponding to each SOC.

[0020] In one implementation, the method further includes: determining the discharge or charging state corresponding to the test data based on the current data in the test data; and extracting the test data corresponding to each SOC based on the discharge or charging state.

[0021] In one implementation, extracting test data corresponding to each SOC based on the discharge or charge state includes: in the discharge state, extracting data within a time period when the current is 0 after each negative current; or in the charge state, extracting data within a time period when the current is 0 after each positive current.

[0022] Extracting test data based on the charge / discharge state allows for accurate extraction of the required data, thereby improving the accuracy of the results.

[0023] In one implementation, the method further includes: acquiring a display interface, the display interface including an operation area and a display area, the display area including a first sub-area, a second sub-area, and a third sub-area; in response to an import operation in the operation area, displaying the original pulse discharge or pulse charge curve of the battery in the third sub-area; in response to a fitting operation in the operation area, fitting the test data corresponding to each SOC in the test data, and displaying the fitting curve corresponding to each SOC in the second sub-area; acquiring the equilibrium potential corresponding to each SOC based on the fitting curve corresponding to each SOC; and displaying the SOC-OCV curve of the battery in the first sub-area based on the equilibrium potential corresponding to each SOC. In this way, the user can obtain the desired results through simple operations, thereby improving the user experience.

[0024] In one implementation, the method further includes: in response to an export operation in the operating region, exporting at least one of the original pulse discharge or pulse charge curve of the battery, the fitted curve corresponding to each SOC, and the SOC-OCV curve of the battery to a target storage address.

[0025] In a second aspect, an apparatus for estimating the state of charge is provided, comprising units for implementing the method described in the first aspect or any implementation thereof.

[0026] Thirdly, an electronic device is provided, including a memory and a processor, the memory storing computer instructions, the processor invoking the computer instructions to cause the electronic device to perform the method according to the first aspect or any implementation thereof.

[0027] Fourthly, a computer-readable storage medium is provided for storing a computer program that, when executed by a computing device, causes the computing device to implement the method according to the first aspect or any implementation thereof.

[0028] Fifthly, a computer program product is provided that includes computer-readable code, or a non-volatile computer-readable storage medium carrying computer-readable code, wherein when the computer-readable code is run in an electronic device, a processor in the electronic device executes the method according to the first aspect or any implementation thereof. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0030] Figure 1 This is a schematic flowchart of a method for estimating the state of charge according to an embodiment of this application.

[0031] Figure 2 This is a schematic diagram of the pulse discharge curve of an embodiment of this application.

[0032] Figure 3 This is a schematic diagram of the relationship between time and voltage under a single SOC according to an embodiment of this application.

[0033] Figure 4 This is a schematic diagram of the SOC-OCV curve of the battery according to an embodiment of this application.

[0034] Figure 5 This is a schematic diagram showing the accuracy of the SOC-OCV curves obtained when the number of discharges is different according to the embodiments of this application.

[0035] Figures 6-8 This is a schematic diagram of the display interface according to an embodiment of this application.

[0036] Figure 9This is a schematic block diagram of a state-of-charge estimation apparatus according to an embodiment of this application.

[0037] Figure 10 This is a schematic block diagram of an electronic device according to an embodiment of this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0040] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0041] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0042] A battery typically refers to a single physical module comprising one or more individual battery cells to provide higher voltage and capacity. For example, a battery may include a battery module or a battery pack. Typically, a battery also includes a housing for encapsulating one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0043] In some embodiments, a battery cell may include a lithium-ion battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc., and this application embodiment is not limited thereto. Generally, a battery cell may also be referred to as a battery cell. A battery cell may be cylindrical, flat, cuboid, or other regular or irregular shapes. The technical solutions of the embodiments of this application can be applied to battery cells of any shape.

[0044] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrodes. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the uncoated current collector protrudes beyond the coated current collector, serving as the positive electrode tab. Taking a lithium-ion battery as an example, the positive current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the uncoated current collector protrudes beyond the coated current collector, serving as the negative electrode tab. The negative current collector can be made of copper, and the negative active material can be carbon or silicon, etc. To ensure that a large current can pass through without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together.

[0045] The SOC-OCV curve of a battery is fundamental to battery testing. Typically, when obtaining the SOC-OCV curve, a relatively long resting period, such as more than 2 hours, is required to eliminate battery polarization before testing the battery voltage at each SOC. For example, the battery is discharged at a constant current, with the current cut off and a 2-hour resting period after each 10% SOC discharge to eliminate battery polarization; this cycle is repeated until the discharge is complete. The last voltage after each 2-hour relaxation period is extracted as the equilibrium potential for the corresponding SOC. The SOC-OCV curve can be plotted based on multiple SOCs and their corresponding equilibrium potentials. Therefore, this method of obtaining the SOC-OCV curve is time-consuming, requiring approximately 47 hours overall, and involves a relatively small number of voltage sampling points. Furthermore, the significant voltage fluctuations between high and low SOC states lead to substantial testing errors.

[0046] To this end, this application provides a method for estimating the state of charge (SOC), which obtains the equilibrium potential corresponding to each SOC by fitting the test data corresponding to each SOC, and then obtains the SOC-OCV curve of the battery based on the equilibrium potentials corresponding to multiple SOCs, aiming to obtain the SOC-OCV curve accurately and efficiently.

[0047] The battery in this application embodiment can be a power battery, such as a lithium-ion battery, lithium metal battery, lead-acid battery, nickel-cadmium battery, nickel-metal hydride battery, lithium-sulfur battery, lithium-air battery, or sodium-ion battery. For simplicity, the following description uses a lithium-ion battery as an example.

[0048] In terms of scale, this power battery can be a single battery cell, or a battery module or battery pack; there are no specific limitations. In terms of application scenarios, this power battery can be used in power systems such as automobiles and ships. For example, it can be used in electric vehicles to power their motors, serving as a power source for electric vehicles. This power battery can also power other electrical components in electric vehicles, such as in-vehicle air conditioning and in-vehicle media players.

[0049] Figure 1 A schematic flowchart of a method 100 for estimating the state of charge (SOC) according to an embodiment of this application is shown. Method 100 is used to obtain the SOC-OCV curve of a battery. This SOC-OCV curve represents the relationship between the battery's voltage and SOC when it is unpolarized; the battery's voltage when it is unpolarized is also called the battery's equilibrium potential. Figure 1 As shown, method 100 includes some or all of the following steps.

[0050] Step 110: Obtain test data for the battery, including test data for pulse discharge or pulse charging of the battery.

[0051] Step 120: Fit the test data corresponding to each SOC in the test data to obtain the fitting curve corresponding to each SOC.

[0052] Step 130: Obtain the equilibrium potential corresponding to each SOC based on the fitting curve corresponding to each SOC.

[0053] Step 140: Obtain the SOC-OCV curve of the battery based on the equilibrium potential corresponding to each SOC.

[0054] In this embodiment, the test data used includes test data from pulse discharge or pulse charging of the battery. Pulse discharge or pulse charging involves discharging or charging for a period of time, then allowing it to rest for a period of time, then continuing to discharge or charge, and then resting again, repeating this cycle until the discharge or charging is complete. The test data includes data collected during the rest period after each discharge or charge. Each discharge or charge corresponds to a State of Charge (SOC), thus multiple discharges result in multiple SOCs with corresponding test data. The test data for each SOC is the data collected during the corresponding rest period. For each SOC, a complete fitting curve can be obtained using these data. The equilibrium potential corresponding to that SOC can be obtained using this fitting curve. Thus, the SOC-OCV curve of the battery can be obtained through the equilibrium potentials corresponding to multiple SOCs.

[0055] In related technologies, the resting time after testing the voltage at each SOC is relatively long, typically requiring at least two hours of relaxation for the battery to eliminate polarization. Once polarization is eliminated, the equilibrium potential is directly measured. However, in this embodiment, the SOC-OCV curve is obtained by fitting the test data corresponding to each SOC. This allows for a very short resting time for data acquisition, essentially requiring only a short relaxation period. The purpose is not to eliminate battery polarization, but rather to obtain the test data needed for fitting. Therefore, the technical solution of this embodiment shortens the testing time, improves testing efficiency, and enables rapid acquisition of the battery's SOC-OCV curve. Furthermore, the short resting time increases the data sampling density, which is beneficial for improving the accuracy of the SOC-OCV curve.

[0056] This application embodiment can collect voltage change data over time by repeatedly "discharging + resting" or repeatedly "charging + resting". This application embodiment takes the repeated "discharging + resting" method as an example to describe in detail how to collect voltage change data over time during the discharge process.

[0057] In this embodiment, optionally, the process of pulse discharging or pulse charging the battery includes a first stage, in which the battery is pulse-discharging or pulse-charging using a first discharge or charge rate, a first discharge or charge time, and a resting time. Optionally, the test data corresponding to each SOC is the test data within the resting time corresponding to each SOC.

[0058] Taking discharge as an example, in the first stage, the battery is controlled to perform constant current discharge using the first pulse current with the first discharge rate and the first discharge time. After discharge, the battery is left to stand for a first duration. During the first duration of standing, test data is collected. In this way, test data of the battery at one SOC is obtained after each discharge.

[0059] When the number of discharges reaches the first threshold or the battery voltage is less than the first voltage threshold, the battery is controlled to stop discharging.

[0060] The battery undergoes multiple constant-current discharges using a first pulse current at a first discharge rate and a first discharge time, with a short rest period after each discharge. The data collected during this rest period serves as the test data for a single battery at its state of charge (SOC). By performing multiple discharges and rest periods, test data for multiple SOCs can be obtained. To prevent over-discharge, a first discharge threshold or a first voltage threshold can be set. Discharge can be stopped once the discharge count reaches the first discharge threshold or the voltage falls below the first voltage threshold.

[0061] The first discharge rate can be, for example, equal to 1C; the first duration can be set relatively short, for example, 5 minutes, meaning only a short resting time is needed after each discharge; the first discharge threshold is a threshold for the number of discharges based on the first pulse current, for example, it can be set between 60 and 80, such as 70 times; the first voltage threshold is determined based on the electrode material, for example, it can be set between 2V and 3V to avoid over-discharge of the battery and damage to the electrode material. For example, for lithium iron phosphate batteries, the first voltage threshold can be 2.0V, and for ternary lithium batteries, the first voltage threshold can be 2.8V.

[0062] This embodiment of the application uses test data within a resting time to fit and obtain the equilibrium potential, without requiring a long resting time after each discharge to eliminate polarization and obtain the equilibrium potential. Therefore, the resting time can be very short. Furthermore, the sampling density can be increased by increasing the number of discharges, obtaining more test data, thus making the resulting SOC-OCV curve smoother and preserving the characteristics of the SOC-OCV curve.

[0063] Optionally, the process of pulse discharging or pulse charging the battery further includes a second stage, in which the battery is pulse-discharged or pulse-charged using a second discharge or charge rate, a second discharge or charge time, and the resting time. The second discharge or charge rate is less than the first discharge or charge rate, and the second discharge or charge time is longer than the first discharge or charge time. Optionally, the test data corresponding to each SOC is the test data within the resting time corresponding to each SOC.

[0064] For example, after the first stage mentioned above, the battery is controlled to perform constant current discharge using a second pulse current with a second discharge rate and a second discharge time. The second discharge rate is less than the first discharge rate, the second discharge time is longer than the first discharge time, and the battery is left to stand for a second duration after each discharge. The second duration may be equal to or different from the first duration. Test data is collected during the second duration of the standby time, so that test data of the battery at one SOC is obtained after each discharge.

[0065] When the number of discharges reaches the second threshold or the battery voltage is less than the second voltage threshold, the battery is controlled to stop discharging.

[0066] To release more charge and achieve a more complete OCV range, the battery can continue discharging based on a second pulse current less than the first pulse current, and then be briefly idle after each discharge. Similarly, to prevent over-discharge, a second count threshold or a second voltage threshold can be set. Discharging can be stopped as long as the condition of reaching the second count threshold or the condition of the voltage being less than the second voltage threshold is met.

[0067] The second discharge rate is less than the first discharge rate; for example, if the first discharge rate is 1C, the second discharge rate is 0.2C. The second duration can be set relatively short, for example, 5 minutes, meaning only a short resting time is needed after each discharge. The second threshold is a threshold for the number of discharges based on the second pulse current; for example, it can be set between 20 and 40, such as 30 times. The second voltage threshold is determined based on the electrode material; for example, it can be set between 2V and 3V to avoid over-discharge of the battery and damage to the electrode material. For example, for lithium iron phosphate batteries, the second voltage threshold can be 2.0V, and for ternary lithium batteries, the second voltage threshold can be 2.8V.

[0068] As an example, the test process shown in Table 1 involves the following steps: In steps 1 and 2, the battery is charged to its upper limit voltage (full charge voltage) using a 1C current. In step 3, the charging polarization is reduced after a 1H rest period, and then the process proceeds to steps 4 through 8. In steps 4 through 8, the battery discharges for 60 seconds each time based on a first pulse current (e.g., 1C), and is then allowed to rest for a first duration (e.g., 5 minutes) after each discharge. Discharge is stopped when the battery voltage is less than or equal to a first voltage threshold (e.g., 2.8V), or when the number of discharges reaches a first threshold (e.g., 70 times), and the process proceeds to steps 9 through 13. In steps 9 through 13, the battery discharges for 90 seconds each time based on a second pulse current (e.g., 0.2C), and is then allowed to rest for a second duration (e.g., 5 minutes) after each discharge. Discharge is stopped when the battery voltage is less than or equal to a second voltage threshold (e.g., 2.8V), or when the number of discharges reaches a second threshold (e.g., 30 times), and the process proceeds to step 14, ending the test process.

[0069] Table 1

[0070]

[0071]

[0072] Based on the above testing process, we can obtain Figure 2 The pulse discharge curve shown is as follows. Figure 2 As shown, assuming one voltage is collected every 1 second, the total number of sampling points during the entire test process is 30,000. The number of sampling points during the battery's relaxation period after each discharge is 300, which is equivalent to collecting 300 voltages at each State of Charge (SOC). Thus, by fitting the 300 sets of voltage and time test data collected at each SOC, a fitting curve corresponding to each SOC can be obtained.

[0073] For different batteries, test data can be obtained using the methods described above. Optionally, a preset data structure can be set for the test data of different batteries. This allows the test data to be identified based on the data structure of the acquired test data and the preset data structure. For example, preset data structures such as column names for test data of different batteries can be used. After each import of test data, the column names and other related data structures are compared. When differences are found, an error will be displayed. When a match is found, the data is identified as the test data of the corresponding battery.

[0074] Since the test data may be test data of discharge or charging states, the discharge or charging state corresponding to the test data can be determined based on the current data in the test data; and the test data corresponding to each SOC can be extracted based on the discharge or charging state.

[0075] Optionally, in the discharge state, data is extracted during the time period when the current is 0 after each negative current segment; or, in the charging state, data is extracted during the time period when the current is 0 after each positive current segment.

[0076] In this embodiment, optionally, the test data corresponding to each SOC can be fitted according to the battery's relaxation process to obtain a fitting curve for each SOC. Considering the characteristics of the battery's relaxation process, it is easier to obtain fitting results that meet the error requirements, thus improving fitting efficiency.

[0077] Optionally, the test data corresponding to each SOC can be fitted according to the battery relaxation process to obtain a relaxation model that fits the test data corresponding to each SOC; then, based on the relaxation model, a fitting curve corresponding to each SOC can be obtained. By fitting using the relaxation model, a complete fitting curve can be obtained after obtaining the relaxation model.

[0078] Optionally, an initial relaxation model can be obtained based on the battery's relaxation process. The initial relaxation model includes model parameters to be determined. The initial relaxation model and the test data corresponding to each SOC are fitted to determine the model parameters, so as to obtain the relaxation model of the test data corresponding to each SOC.

[0079] Specifically, based on the characteristics of the battery relaxation process, an initial relaxation model can be established, where the model parameters are variables, i.e., quantities to be determined. By fitting the model with test data corresponding to the State of Charge (SOC), the model parameters can be determined, thus obtaining the relaxation model for the test data corresponding to each SOC. In this way, using an initial relaxation model that conforms to the battery relaxation process can effectively achieve fitting and improve processing efficiency.

[0080] In one implementation, the initial relaxation model can be:

[0081]

[0082] in, Let x be voltage, c be time, and a, b, c, and d be model parameters. This relaxation model can represent the relationship between time x and voltage using only four parameters: a, b, c, and d. The relationship between them facilitates fitting calculations, which is simple and accurate.

[0083] Optionally, a Nernst equation can be established to represent the relationship between electrode potential and lithium ion concentration; then, based on the relationship between current and lithium ion concentration change, and the relationship between current and time, the Nernst equation can be converted into a relationship between electrode potential and time to obtain the initial relaxation model.

[0084] Optionally, the Nernst equation can be converted into a relationship between the electrode potential and the time as follows: Based on Fick's first law, determine the relationship between the current and the change in lithium ion concentration; based on the relationship between the current and the change in lithium ion concentration, convert the Nernst equation into a relationship between the electrode potential and the current; obtain the relationship between the current and the time; based on the relationship between the current and the time, convert the relationship between the electrode potential and the current into a relationship between the electrode potential and the time.

[0085] Optionally, the relationship between the current and the time can be determined based on the relationship between the current and the change in lithium ion concentration, and the relationship between the lithium ion concentration and the time.

[0086] The following describes in detail how to establish this initial relaxation model.

[0087] During the relaxation process of a battery, the equilibrium potential is mainly affected by the diffusion rate of lithium ions in the solid phase. The entire diffusion process is dominated by concentration polarization. Under concentration polarization conditions, the transfer of lithium ions can be considered to be in equilibrium. Therefore, the electrode potential can be expressed by the Nernst equation, i.e.:

[0088]

[0089] in, C is the electrode potential; C0 is the concentration of the reactant on the electrode surface; C R The concentration of the reaction products on the electrode surface is denoted by F; F is the Faraday constant, in units of C / mol, and its value is equal to Avogadro's constant NA = 6.02214 × 10²³ mol. -1 The product of the elementary charge e = 1.602176 × 10⁻¹⁹ C is 96485.33 ± 0.0083 C / mol; Ln is a logarithmic function; n is the number of lithium ions transferred in the electrode reaction; R is a constant term, typically R = 8.314 J*K. -1 *mol -1 .

[0090] The Nernst equation reflects the relationship between electrode potential and lithium-ion concentration; concentration difference is the primary driving force for lithium-ion diffusion. While the Nernst equation calculates electrode potential from the perspective of concentration change, since the essence of electrochemistry is the relationship between mass change and charge transfer, it is necessary to establish a relationship between electrical signals, such as current, and concentration change. When only diffusion mass transfer is considered in the mass transfer process...

[0091]

[0092]

[0093] Therefore, we can conclude that:

[0094]

[0095] Where N is the number of moles of reactants, n is the number of electrons required for the reaction, F is the Faraday constant, Q is the total amount of reaction on the electrode surface, and m0 is the mass transfer coefficient. c0 is the concentration of reactants in bulk, c0 is the concentration of reactants on the electrode surface, and A is the reaction area.

[0096] When the kinetics of electron transfer are fast enough, i.e., C0 = 0, the reactants on the electrode surface reach their maximum rate under these mass transfer conditions. The concentrations of reactants and products are in equilibrium at a given potential. This can be explained by referring to the Nernst equation mentioned above, assuming that the initial concentration of the product is 0, i.e., the bulk concentration is 0.

[0097]

[0098]

[0099]

[0100] when i=i lim When / 2, according to formula (8), we can obtain:

[0101]

[0102] At this point, it is independent of substrate concentration but related to the mass transfer coefficient. lim This represents the limiting current, which is the maximum current under the modified mass transfer conditions when the reaction at the electrode surface is at its maximum rate. This represents the standard electrode potential; m R is the mass transfer coefficient of the reaction products on the electrode surface; m0 is the mass transfer coefficient of the reactants.

[0103] Considering only diffusion mass transfer, as the electrode reaction occurs, the diffusion layer thickness δ is directly proportional to t^(1 / 2), while the current is proportional to t^(-1 / 2). Let δ = δ(t), then:

[0104]

[0105] Based on the approximate molar number relationship of reactants in the diffusion layer at any time t, we can obtain:

[0106]

[0107] Differentiating both sides of equation (11) and substituting them into equation (10), we get:

[0108]

[0109] Simplifying formula (12), we get:

[0110]

[0111] Furthermore, we obtain:

[0112] dδ(t)δ(t)=2D0dt(14);

[0113] When t = 0 and δ(t) = 0, integrating both sides of equation (14) and simplifying, we get:

[0114]

[0115] Substituting equation (15) into equation (10), we obtain the relationship between current and concentration:

[0116]

[0117] At this point, Fick's first law can be used, with flow rate as an intermediate quantity, to establish the relationship between electric current and one-dimensional changes in matter:

[0118]

[0119] Where j(0,t) is the flow rate, i.e., the diffusion flux; i(t) is the time; n is the number of lithium ions transferred in the electrode reaction; F is the Faraday constant; A is the electrode area; Do is the diffusion coefficient; x is the position relative to the electrode; and C0 is the concentration. For the concentration gradient.

[0120] In practice, the signals we can obtain are electrical signals, such as current (i). To facilitate actual testing, we want to obtain the relationship between current and time. Therefore, based on formulas (17) and (18),

[0121]

[0122] Where C0(x,t) is the concentration; Let be the initial concentration; n be the number of lithium ions transferred in the electrode reaction; A be the electrode area; F be the Faraday constant; Do be the diffusion coefficient; and erf be the error function. The current versus time description can be obtained as follows:

[0123]

[0124] Thus, the descriptions of equilibrium potential and concentration (equation (2), concentration and current (equation (16), and current and time (equation (19)) are completed.

[0125] Combining the above relationships and simplifying the parameters, we can obtain an initial relaxation model to characterize the relationship between equilibrium potential and time:

[0126]

[0127] in, Let t be voltage, t be time, and a, b, c, and d be model parameters.

[0128] Using test data from multiple SOCs and the initial relaxation model, the values ​​of model parameters a, b, c, and d can be obtained. During this process, the initial values ​​of a, b, c, and d can be set based on empirical data; for example, a can be set to the voltage value at the end of each rest period. Optionally, the values ​​of the model parameters obtained from the previous fit can be used as the initial values ​​for the next fitting. Input t represents different test times, and input... Given the voltage at the corresponding time, accurate values ​​a, b, c, and d can be obtained through fitting calculations.

[0129] Optionally, during fitting, at least one data segment from the test data corresponding to each SOC can be selected for fitting; and the model parameters obtained by fitting the at least one data segment with the smallest error are used as the model parameters of the relaxation model. Optionally, the test data corresponding to each SOC includes N sampling points, and the k-th data segment in the at least one data segment is the k-th to N-th sampling point, where N and k are positive integers, and k is less than N.

[0130] Specifically, during the entire relaxation process, the trend of electrode potential change will be affected by ohmic polarization, electrochemical polarization, and concentration polarization. The duration of influence of different types of polarization varies within different states of charge (SOC). The duration of influence of ohmic and electrochemical polarization is generally distributed within 0–15 s. Since the initial relaxation model only considered the influence of concentration polarization, to make the test data more closely fit the relaxation model and obtain more accurate fitting results, data from sampling points within different relaxation periods can be fitted. For example, assuming the entire relaxation process is 300 s, with a 1 s interval between adjacent sampling points (i.e., voltage is collected every 1 s), data from 1 s to 300 s, 2 s to 300 s, 3 s to 300 s, ..., 15 s to 300 s can be used for fitting. For example, the curvefit function in MATLAB can be used for curve fitting, and the optimal fitting result (i.e., the fitting result with the smallest error) can be returned. The optimal fitting result can then be selected as the values ​​of a, b, c, and d.

[0131] Once the model parameters are determined, the fitting curve for each SOC can be obtained. Based on the fitting curve for each SOC, the equilibrium potential for each SOC can be obtained.

[0132] Optionally, based on the fitted curve corresponding to each SOC, the voltage at a time point after the test period that meets a preset condition can be obtained, thus obtaining the equilibrium potential corresponding to each SOC. For example, the preset condition may include: the voltage difference between two adjacent time points is less than a preset threshold. Optionally, the threshold is 0.000001V.

[0133] When the voltage remains constant over time, it can be considered the equilibrium potential after battery depolarization. Therefore, a condition can be set where the voltage difference between two adjacent time points is less than a threshold to effectively control the extrapolation calculation of the voltage. The calculation stops when the condition is met, and the voltage calculated at this point is taken as the equilibrium potential.

[0134] For example, such as Figure 3The curve showing the relationship between time and voltage at a single SOC is the fitted curve corresponding to the SOC. The horizontal axis represents time, and the vertical axis represents voltage. The solid line represents the test data, specifically the voltage data collected during a relaxation period using the pulse discharge method described above. Based on this test data, the model parameters in the relaxation model can be obtained. Then, based on the determined model parameters, the voltage extrapolation calculation is performed using this relaxation model, resulting in the voltage data shown by the dashed line. The boundary condition for voltage balance calculation is that the voltage difference between two adjacent time points is less than 0.000001V. When the calculation reaches time T2, the voltage at that time is 3.829V. The difference between this voltage and the voltage value at the previous sampling time is less than 0.000001V, so the battery's equilibrium potential at this SOC can be considered to be 3.829V. This equilibrium potential is close to the actual equilibrium potential, thus improving the accuracy of the SOC-OCV curve.

[0135] Based on the battery's equilibrium potential at multiple SOCs, a graph can be drawn as follows: Figure 4 The SOC-OCV curve of the battery is shown.

[0136] Figure 5 The accuracy of the SOC-OCV curves obtained with different discharge cycles is shown. It can be seen that the goodness of fit R2 of the SOC-OCV curves obtained by the method of this application embodiment is all above 0.99, which shows high accuracy.

[0137] In this embodiment, optionally, test data and processing results can be imported and displayed through a display interface. Optionally, in one implementation, a display interface can be obtained, comprising an operation area and a display area, the display area including a first sub-area, a second sub-area, and a third sub-area; in response to an import operation in the operation area, the original pulse discharge or pulse charge curve of the battery is displayed in the third sub-area; in response to a fitting operation in the operation area, the test data corresponding to each SOC in the test data is fitted, and the fitted curve corresponding to each SOC is displayed in the second sub-area; based on the fitted curve corresponding to each SOC, the equilibrium potential corresponding to each SOC is obtained; based on the equilibrium potential corresponding to each SOC, the SOC-OCV curve of the battery is displayed in the first sub-area. Optionally, in response to an export operation in the operation area, at least one of the original pulse discharge or pulse charge curve of the battery, the fitted curve corresponding to each SOC, and the SOC-OCV curve of the battery is exported to a target storage address.

[0138] like Figure 6The diagram illustrates a display interface 600 according to an embodiment of this application. The display interface 600 may include an operation area 610 and a result display area 620, wherein the result display area 620 includes a first sub-area 621, a second sub-area 622, and a third sub-area 623.

[0139] The operation area 610 can be used to input operations, such as import, fit, and export. The import operation allows exporting test data; the fit operation allows fitting the test data as described in the above embodiments, and the corresponding results are displayed in the display area; the export operation allows exporting the corresponding results. Other operations can also be input in the operation area 610, but this embodiment does not limit the scope of these operations.

[0140] For example, such as Figure 7 As shown, after the user inputs the import operation, the import data page 640 can be displayed, where the user can import the corresponding test data. Optionally, the battery's original pulse discharge or pulse charge curve can also be displayed in the third sub-area 623. Figure 8 As shown, after the user inputs the fitting operation, data fitting is performed, and the processing progress window 650 is displayed simultaneously. After processing is complete, the fitting curve corresponding to each SOC can be displayed in the second sub-region 622, and the SOC-OCV curve of the battery can be displayed in the first sub-region 621.

[0141] Optionally, the display interface 600 further includes a parameter setting area 630. In response to a setting operation in the parameter setting area 630, parameter settings can be acquired; correspondingly, in response to the operation input in the operation area 610 and the parameter settings, the SOC-OCV curve of the battery is displayed in the first sub-area 621, the fitted curve corresponding to each SOC is displayed in the second sub-area 622, and the original pulse discharge or pulse charge curve of the battery is displayed in the third sub-area 623.

[0142] The parameter settings may include at least one of the following: battery electrode type, charge / discharge type, and electrode material. Electrode type may include, for example, two-electrode or three-electrode configurations; charge / discharge type may include, for example, charging or discharging; and electrode material parameters may include, for example, electrode material particle size. These parameter settings may also include other settings, such as settings for the fitting algorithm and test conditions, which are not limited in this application embodiment.

[0143] For example, after importing test data, users can set parameters in parameter setting area 630, and then perform fitting to obtain the corresponding processing results.

[0144] The first sub-region 621 displays the battery's SOC-OCV curve, for example... Figure 4The curve shown; the second sub-region 622 displays the fitted curve corresponding to each SOC, for example... Figure 3 The curve shown; the third sub-region 623 displays the battery's original pulse discharge or pulse charge curve, for example... Figure 2 The curve shown.

[0145] Optionally, the result display area 620 may also include a display sub-area for displaying other results; that is, corresponding results can be displayed according to the user's needs. For example, it may display... Figure 5 The results shown are not limited to the embodiments of this application.

[0146] With the above-described display interface, users can obtain the desired results through simple operations, thereby improving the user experience.

[0147] The methods of embodiments of this application have been described above, and the devices of embodiments of this application are described below. It should be understood that the relevant descriptions in the following embodiments can be referred to the foregoing embodiments, and for the sake of brevity, they will not be repeated.

[0148] Figure 9 A schematic block diagram of a state-of-charge estimation apparatus 900 according to an embodiment of this application is shown. Figure 9 As shown, the device 900 includes an acquisition unit 910 and a processing unit 920.

[0149] The acquisition unit 910 is used to acquire test data of the battery, including test data of pulse discharge or pulse charge of the battery.

[0150] The processing unit 920 is used to fit the test data corresponding to each SOC in the test data to obtain the fitting curve corresponding to each SOC; according to the fitting curve corresponding to each SOC, the equilibrium potential corresponding to each SOC is obtained; and according to the equilibrium potential corresponding to each SOC, the SOC-open circuit voltage OCV curve of the battery is obtained.

[0151] Optionally, the processing unit 920 is configured to: fit the test data corresponding to each SOC according to the relaxation process of the battery, and obtain the fitting curve corresponding to each SOC.

[0152] Optionally, the processing unit 920 is configured to: fit the test data corresponding to each SOC according to the relaxation process of the battery to obtain a relaxation model that fits the test data corresponding to each SOC; and obtain a fitting curve corresponding to each SOC according to the relaxation model.

[0153] Optionally, the processing unit 920 is configured to: obtain an initial relaxation model based on the relaxation process of the battery, the initial relaxation model including model parameters to be determined; fit the initial relaxation model and the test data corresponding to each SOC to determine the model parameters, so as to obtain a relaxation model for the test data corresponding to each SOC.

[0154] Optionally, the processing unit 920 is configured to: select at least one data segment from the test data corresponding to each SOC for fitting; and use the model parameters obtained by fitting the at least one data segment with the smallest error as the model parameters of the relaxation model.

[0155] Optionally, the test data corresponding to each SOC includes N sampling points, and the k-th data segment in the at least one data segment is the k-th to N-th sampling point, where N and k are positive integers and k is less than N.

[0156] Optionally, the processing unit 920 is used for:

[0157] A Nernst equation is established to represent the relationship between electrode potential and lithium ion concentration. Based on the relationship between current and lithium ion concentration change, and the relationship between current and time, the Nernst equation is transformed into a relationship between electrode potential and time to obtain the initial relaxation model.

[0158] Optionally, the processing unit 920 is configured to: determine the relationship between the current and the change in lithium ion concentration according to Fick's first law; convert the Nernst equation into a relationship between the electrode potential and the current according to the relationship between the current and the change in lithium ion concentration; obtain the relationship between the current and the time; and convert the relationship between the electrode potential and the current into a relationship between the electrode potential and the time according to the relationship between the current and the time.

[0159] Optionally, the processing unit 920 is configured to: determine the relationship between the current and the time based on the relationship between the current and the change in lithium ion concentration, and the relationship between the lithium ion concentration and the time.

[0160] Optionally, the processing unit 920 is used to: obtain the voltage at a time point after the test period that meets the preset conditions based on the fitting curve corresponding to each SOC, and obtain the equilibrium potential corresponding to each SOC.

[0161] Optionally, the preset condition includes: the voltage difference between two adjacent time points is less than a preset threshold.

[0162] Optionally, the process of pulse discharging or pulse charging the battery includes a first stage, in which the battery is pulsed discharged or pulse charged using a first discharge or charge rate, a first discharge or charge time, and a resting time.

[0163] Optionally, the process of pulse discharging or pulse charging the battery further includes a second stage, in which a second discharge or charge rate, a second discharge or charge time, and the resting time are used to pulse discharge or pulse charge the battery, wherein the second discharge or charge rate is less than the first discharge or charge rate, and the second discharge or charge time is longer than the first discharge or charge time.

[0164] Optionally, the test data corresponding to each SOC is the test data within the resting time corresponding to each SOC.

[0165] Optionally, the processing unit 920 is configured to: determine the discharge or charging state corresponding to the test data based on the current data in the test data; and extract the test data corresponding to each SOC based on the discharge or charging state.

[0166] Optionally, the processing unit 920 is configured to: extract data during a time period when the current is 0 after each negative current in a discharging state; or extract data during a time period when the current is 0 after each positive current in a charging state.

[0167] Optionally, the processing unit 920 is configured to: identify the test data according to the data structure of the acquired test data and a preset data structure.

[0168] Optionally, the device 900 further includes: a display unit for acquiring a display interface, the display interface including an operation area and a display area, the display area including a first sub-area, a second sub-area, and a third sub-area; in response to an import operation in the operation area, displaying the original pulse discharge or pulse charge curve of the battery in the third sub-area; in response to a fitting operation in the operation area, the processing unit 920 is configured to fit the test data corresponding to each SOC in the test data, display the fitting curve corresponding to each SOC in the second sub-area; acquire the equilibrium potential corresponding to each SOC based on the fitting curve corresponding to each SOC; and display the SOC-OCV curve of the battery in the first sub-area based on the equilibrium potential corresponding to each SOC.

[0169] Optionally, the processing unit 920 is configured to: in response to an export operation in the operating region, export at least one of the original pulse discharge or pulse charge curve of the battery, the fitted curve corresponding to each SOC, and the SOC-OCV curve of the battery to a target storage address.

[0170] Figure 10 A schematic block diagram of an electronic device 1000 according to an embodiment of this application is shown. Figure 10 As shown, the device 1000 includes a memory 1010 and a processor 1020. The memory 1010 stores computer instructions, and the processor 1020 invokes the computer instructions to enable the electronic device 1000 to implement the method in any of the above implementation methods.

[0171] This application also provides a computer-readable storage medium for storing a computer program that, when executed by a computing device, causes the computing device to implement the method in any of the above implementations.

[0172] This application also provides a computer program product including computer-readable code, or a non-volatile computer-readable storage medium carrying computer-readable code, wherein when the computer-readable code is run in an electronic device, the processor in the electronic device executes the method in any of the above implementations.

[0173] It should be noted that, without conflict, the various embodiments and / or technical features described in this application can be arbitrarily combined with each other, and the resulting technical solutions should also fall within the protection scope of this application.

[0174] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0175] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the above method embodiments, and will not be repeated here.

[0176] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0177] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

Claims

1. A method of state of charge estimation, characterized by, The method comprises the following steps: acquiring test data of a battery, wherein the test data comprises test data of pulse discharge or pulse charge of the battery; fitting test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC; acquiring a balance potential corresponding to each SOC according to the fitting curve corresponding to each SOC; obtaining an SOC-OCV curve of the battery according to the balance potential corresponding to each SOC; wherein the acquiring of the balance potential corresponding to each SOC according to the fitting curve corresponding to each SOC comprises: acquiring a voltage of the fitting curve corresponding to each SOC at a time point after a test time period and satisfying a preset condition to obtain the balance potential corresponding to each SOC.

2. The method of claim 1, wherein, The fitting of the test data corresponding to each SOC in the test data to obtain the fitting curve corresponding to each SOC comprises: fitting the test data corresponding to each SOC according to a relaxation process of the battery to obtain the fitting curve corresponding to each SOC.

3. The method of claim 2, wherein, The fitting of the test data corresponding to each SOC according to the relaxation process of the battery to obtain the fitting curve corresponding to each SOC comprises: fitting the test data corresponding to each SOC according to the relaxation process of the battery to obtain a relaxation model fitting the test data corresponding to each SOC; obtaining the fitting curve corresponding to each SOC according to the relaxation model.

4. The method of claim 3, wherein, The fitting of the test data corresponding to each SOC according to the relaxation process of the battery to obtain the fitting curve corresponding to each SOC comprises: acquiring an initial relaxation model according to the relaxation process of the battery, wherein the initial relaxation model comprises model parameters to be determined; fitting the initial relaxation model and the test data corresponding to each SOC to determine the model parameters to obtain the relaxation model of the test data corresponding to each SOC.

5. The method of claim 4, wherein, The fitting of the initial relaxation model and the test data corresponding to each SOC to determine the model parameters comprises: selecting at least one data segment in the test data corresponding to each SOC for fitting; selecting model parameters obtained by fitting with the minimum fitting error of the at least one data segment as the model parameters of the relaxation model.

6. The method of claim 5, wherein, Each test data corresponding to each SOC comprises N sampling points, and a kth data segment in the at least one data segment is from a kth sampling point to an Nth sampling point, wherein N and k are positive integers, and k is less than N.

7. The method of claim 4, wherein, The acquiring of the initial relaxation model according to the relaxation process of the battery comprises: establishing a Nernst equation for representing a relationship between an electrode potential and a lithium ion concentration; converting the Nernst equation into a relationship between the electrode potential and time according to a relationship between a current and a change in the lithium ion concentration and a relationship between the current and time to obtain the initial relaxation model.

8. The method of claim 7, wherein, The conversion of the Nernst equation into the relationship between the electrode potential and time comprises: determining a relationship between the current and the change in the lithium ion concentration according to Fick's first law; According to the relationship between the current and the lithium ion concentration change, the Nernst equation is converted into a relationship between the electrode potential and the current; Obtain the relationship between the current and the time; According to the relationship between the current and the time, the relationship between the electrode potential and the current is converted into a relationship between the electrode potential and the time.

9. The method of claim 8, wherein, The method further comprises: According to the relationship between the current and the lithium ion concentration change, and the relationship between the lithium ion concentration and the time, the relationship between the current and the time is determined.

10. The method of claim 9, wherein, The preset condition includes: the difference between the voltages corresponding to two adjacent time points is less than a preset threshold.

11. The method of claim 1, wherein, The process of pulse discharging or charging the battery includes a first stage, in which the battery is pulse discharged or charged using a first discharge or charge rate, a first discharge or charge time, and a resting time.

12. The method of claim 11, wherein, The process of pulse discharging or charging the battery also includes a second stage, in which the battery is pulse discharged or charged using a second discharge or charge rate, a second discharge or charge time, and the resting time, wherein the second discharge or charge rate is less than the first discharge or charge rate, and the second discharge or charge time is longer than the first discharge or charge time.

13. The method of claim 12, wherein, The test data corresponding to each SOC is the test data within the resting time corresponding to each SOC.

14. The method of claim 1, wherein, The method further comprises: According to the current data in the test data, determine the discharge or charge state corresponding to the test data; According to the discharge or charge state, extract the test data corresponding to each SOC.

15. The method of claim 14, wherein, The method further comprises: In the case of discharge state, extract the data within the time period when the current is 0 after each negative current segment; or In the case of charging state, extract the data within the time period when the current is 0 after each positive current segment.

16. The method according to any one of claims 1 to 15, characterized in that, The method further comprises: Obtain a display interface, the display interface includes an operation area and a display area, the display area includes a first sub-area, a second sub-area and a third sub-area; In response to the import operation in the operation area, display the original pulse discharge or pulse charge curve of the battery in the third sub-area; In response to the fitting operation in the operation area, fit the test data corresponding to each SOC in the test data, and display the fitting curve corresponding to each SOC in the second sub-area; According to the fitting curve corresponding to each SOC, obtain the equilibrium potential corresponding to each SOC; According to the equilibrium potential corresponding to each SOC, display the SOC-OCV curve of the battery in the first sub-area.

17. The method of claim 16, wherein, The method further comprises: In response to the export operation in the operation area, export at least one of the original pulse discharge or pulse charge curve of the battery, the fitting curve corresponding to each SOC, and the SOC-OCV curve of the battery to a target storage address.

18. An apparatus for state of charge estimation, the apparatus comprising: Comprise: An acquisition unit is configured to acquire test data of a battery, the test data including test data of pulse discharge or pulse charge of the battery; A processing unit is configured to fit test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC, acquire a balance potential corresponding to each SOC according to the fitting curve corresponding to each SOC, and obtain an SOC-OCV curve of the battery according to the balance potential corresponding to each SOC. The processing unit is further configured to acquire, according to the fitting curve corresponding to each SOC, a voltage of a time point after a test time period that satisfies a preset condition of the fitting curve corresponding to each SOC, and obtain the balance potential corresponding to each SOC.

19. An electronic device, comprising: An electronic device includes a memory storing computer instructions and a processor invoking the computer instructions to enable the electronic device to implement the method according to any one of claims 1 to 17.

20. A computer-readable storage medium, characterized in that, A computer program for storage, when executed by a computing device, enables the computing device to implement the method according to any one of claims 1 to 17.

21. A computer program product, characterised in that, A non-volatile computer readable storage medium including computer readable code or carrying computer readable code, when the computer readable code runs in an electronic device, a processor in the electronic device executes the method according to any one of claims 1 to 17.

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