Method and device for estimating state of charge

Abstract

The invention provides a state of charge estimation method and device. The efficiency of acquiring an SOC-OCV curve can be improved. The method comprises the following steps: acquiring test data of a battery, wherein the test data comprises test data for performing pulse discharging or pulse charging on the battery; fitting the test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC; obtaining an equilibrium potential corresponding to each SOC according to the fitting curve corresponding to each SOC; and obtaining an SOC-OCV curve of the battery according to the equilibrium potential corresponding to each SOC.

Description

Method and device for estimating state of charge Technical Field

[0001] The present application relates to the field of battery technology, and in particular, to a method and device for estimating a state of charge. Background Art

[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, when obtaining a battery's SOC-OCV curve, the battery voltage at each SOC is measured after a long rest period, such as more than two hours, to eliminate polarization. This significantly increases the time required to obtain the SOC-OCV curve. Therefore, improving the efficiency of obtaining SOC-OCV curves has become a challenge.

[0003] Summary of the Invention

[0004] The present application provides a method and apparatus for estimating the state of charge, which can improve the efficiency of obtaining the SOC-OCV curve.

[0005] In a first aspect, a method for estimating a state of charge is provided, comprising: obtaining test data of a battery, the test data comprising test data of pulse discharging or pulse charging 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 an equilibrium potential corresponding to each SOC based on the fitting curve corresponding to each SOC; and obtaining an SOC-OCV curve of the battery based on the equilibrium potential corresponding to each SOC.

[0006] In the embodiments of the present application, the SOC-OCV curve is obtained by fitting the test data corresponding to each SOC. In this way, the rest time for obtaining the test data can be set very short, which is equivalent to a very short relaxation period for the battery. Therefore, the technical solution of the embodiments of the present application shortens the test time, improves the test efficiency, and can quickly obtain the SOC-OCV curve of the battery. In addition, since the rest time can be set very short, the data sampling density can be increased, which is conducive to increasing the accuracy of the SOC-OCV curve.

[0007] In one implementation, fitting the test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC includes fitting the test data corresponding to each SOC according to the relaxation process of the battery to obtain a fitting curve corresponding to each SOC. Considering the characteristics of the battery relaxation process can facilitate obtaining a fitting result that meets error requirements and improve fitting efficiency.

[0008] In one implementation, fitting the test data corresponding to each SOC according to the battery's relaxation process to obtain a fitting curve corresponding to each SOC includes: fitting the test data corresponding to each SOC according to the battery's relaxation process to obtain a relaxation model that fits the test data corresponding to each SOC; and obtaining a fitting curve corresponding to each SOC based on the relaxation model. Once the relaxation model is obtained through fitting using the relaxation model, a complete fitting curve can be obtained.

[0009] In one implementation, fitting the test data corresponding to each SOC according to the battery's relaxation process to obtain a relaxation model that fits the test data corresponding to each SOC includes: obtaining an initial relaxation model according to the battery's relaxation process, the initial relaxation model including model parameters to be determined; and fitting the initial relaxation model to the test data corresponding to each SOC to determine the model parameters to obtain a relaxation model for the test data corresponding to each SOC. Utilizing an initial relaxation model that conforms to the battery's relaxation process allows for effective fitting and improves processing efficiency.

[0010] In one implementation, fitting the initial relaxation model to 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 from the fitting of 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 accuracy of the fitting.

[0011] In one implementation, the test data corresponding to each SOC includes N sampling points, and the kth data segment in the at least one data segment includes the kth to Nth sampling points, where N and k are positive integers, and k is less than N. This can make the test data more consistent with the relaxation model, thereby obtaining a more accurate fitting result.

[0012] In one implementation, obtaining an initial relaxation model based on the relaxation process of the battery includes: establishing a Nernst equation for representing the relationship between electrode potential and lithium ion concentration; converting the Nernst equation into a relationship between the electrode potential and the time based on the relationship between the current and the change in lithium ion concentration, and the relationship between the current and time, to obtain the initial relaxation model.

[0013] In one implementation, converting the Nernst equation into a relationship between the electrode potential and the time includes: determining a relationship between the current and the change in lithium ion concentration based on 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 a 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.

[0014] In one implementation, obtaining the relationship between the current and the time includes determining the relationship between the current and the time based on a relationship between the current and the change in lithium ion concentration and a relationship between the lithium ion concentration and the time.

[0015] In the above manner, a relaxation model with fewer variables that conforms to the relaxation process can be obtained, which is convenient for fitting operations.

[0016] In one implementation, obtaining the equilibrium potential corresponding to each SOC based on the fitting curve corresponding to each SOC includes: obtaining, based on the fitting curve corresponding to each SOC, the voltage of the fitting curve corresponding to each SOC at a time point that satisfies a preset condition after a test period, thereby obtaining the equilibrium potential corresponding to each SOC. In this way, the equilibrium potential can be obtained through the fitting curve without the need for testing.

[0017] In one implementation, the preset condition includes: the voltage difference between two adjacent time points is less than a preset threshold. The equilibrium potential thus obtained is substantially close to the actual equilibrium potential, thereby improving the accuracy of the SOC-OCV curve.

[0018] 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 rest 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 the resulting SOC-OCV curve can be smoother, thereby preserving the characteristics of the SOC-OCV curve.

[0019] In one implementation, 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 rest time, wherein the second discharge or charge rate is lower than the first discharge or charge rate, and the second discharge or charge time is longer than the first discharge or charge time. A more complete OCV range can be obtained by utilizing the second stage discharge or charge process.

[0020] In one implementation, the test data corresponding to each SOC is the test data within the static time corresponding to each SOC.

[0021] In one implementation, the method further includes: determining a discharge or charge state corresponding to the test data based on current data in the test data; and extracting test data corresponding to each SOC based on the discharge or charge state.

[0022] In one implementation, the test data corresponding to each SOC is extracted according to the discharge or charge state, including: in the case of the discharge state, extracting data within the time period when the current is 0 after each negative current; or in the case of the charging state, extracting data within the time period when the current is 0 after each positive current.

[0023] By extracting test data according to the charge and discharge status, the required data can be accurately extracted, thereby improving the accuracy of the results.

[0024] In one implementation, the method further includes: obtaining 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; obtaining 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.

[0025] In one implementation, the method further includes: in response to the export operation in the operating area, exporting 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.

[0026] In a second aspect, a device for estimating state of charge is provided, comprising a unit for implementing the method described in the first aspect or any implementation manner of the first aspect.

[0027] According to a third aspect, an electronic device is provided, comprising a memory and a processor, wherein the memory stores computer instructions, and the processor calls the computer instructions to enable the electronic device to implement the method according to the first aspect or any implementation manner of the first aspect.

[0028] In a fourth aspect, a computer-readable storage medium is provided for storing a computer program, which, when executed by a computing device, enables the computing device to implement the method according to the first aspect or any implementation manner of the first aspect.

[0029] In a fifth aspect, a computer program product is provided, comprising a computer-readable code, or a non-volatile computer-readable storage medium carrying a computer-readable code. When the computer-readable code runs in an electronic device, the processor in the electronic device executes the method described in the first aspect or any implementation of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0031] FIG1 is a schematic flowchart of a method for estimating a state of charge according to an embodiment of the present application.

[0032] FIG2 is a schematic diagram of a pulse discharge curve according to an embodiment of the present application.

[0033] FIG3 is a schematic diagram of a curve showing the relationship between time and voltage at a single SOC according to an embodiment of the present application.

[0034] FIG4 is a schematic diagram of an SOC-OCV curve of a battery according to an embodiment of the present application.

[0035] FIG5 is a schematic diagram showing the accuracy of the SOC-OCV curves obtained at different discharge times according to an embodiment of the present application.

[0036] 6-8 are schematic diagrams of the display interface of the embodiment of the present application.

[0037] FIG9 is a schematic block diagram of a device for estimating state of charge according to an embodiment of the present application.

[0038] FIG10 is a schematic block diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0041] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0042] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are for illustrative purposes only and do not constitute any limitation on this application.

[0043] A battery generally refers to a single physical module that includes one or more battery cells to provide a higher voltage and capacity. For example, a battery can include a battery module or a battery pack. Batteries typically also include a casing that encloses the battery cells. This casing prevents liquids and other foreign matter from affecting the charging or discharging of the battery cells.

[0044] In some embodiments, the battery cells may include lithium-ion batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., but this is not limited in the present embodiment. Generally, battery cells are also referred to as battery cells. Battery cells may be cylindrical, flat, rectangular, or other regular or irregular shapes. The technical solutions of the embodiments of the present application can be applied to battery cells of any shape.

[0045] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet comprises 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. The current collector uncoated with the positive active material layer protrudes from the current collector coated with the positive active material layer, and the current collector uncoated with the positive active material layer serves as the positive electrode tab. For lithium-ion batteries, for 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. The negative electrode sheet comprises 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. The current collector uncoated with the negative active material layer protrudes from the current collector coated with the negative active material layer, and the current collector uncoated with the negative active material layer serves as the negative electrode tab. The negative current collector can be made of copper, and the negative active material can be carbon or silicon, among others. In order to ensure that large currents can pass without melting, there are multiple positive electrode tabs and they are stacked together, and there are multiple negative electrode tabs and they are stacked together.

[0046] The SOC-OCV curve of a battery is the basis of battery testing. Usually, in the process of obtaining the SOC-OCV curve of a battery, when testing the voltage of the battery at each SOC, it is necessary to let it stand for a long time, such as more than 2 hours, to eliminate the polarization of the battery. For example, the battery is discharged at a constant current, and after each 10% SOC discharge, the current is cut off and the battery is left to stand for 2 hours to eliminate the polarization of the battery, and this cycle is repeated until the discharge is completed. The last voltage of the battery after each 2-hour relaxation is extracted as the equilibrium potential of the corresponding SOC. The SOC-OCV curve of the battery can be drawn based on multiple SOCs and their corresponding equilibrium potentials. Therefore, it takes a long time to obtain the SOC-OCV curve in this way. The entire process takes about 47 hours, and the number of voltage sampling points is relatively small. Since the voltage fluctuates greatly under high and low SOC states, the test error is also large.

[0047] To this end, the present application provides a method for estimating the state of charge, by fitting the test data corresponding to each SOC to obtain the equilibrium potential corresponding to each SOC, and then obtaining 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.

[0048] The battery in the embodiments of the present application may be a power battery, such as a lithium-ion battery, a lithium metal battery, a lead-acid battery, a nickel-cadmium battery, a nickel-metal hydride battery, a lithium-sulfur battery, a lithium-air battery, or a sodium-ion battery. For the sake of simplicity, the following description will take a lithium-ion battery as an example.

[0049] In terms of scale, the power battery can be a single battery cell, a battery module, or a battery pack, without limitation. In terms of application scenarios, the power battery can be used in power devices such as automobiles and ships. For example, it can be used in power vehicles to power the motor of the power vehicle and serve as the power source of the electric vehicle. The power battery can also power other electrical devices in the electric vehicle, such as the air conditioner and the car player.

[0050] Figure 1 shows a schematic flow chart of a method 100 for estimating the state of charge (SOC) according to an embodiment of the present application. Method 100 is used to obtain a battery's SOC-OCV curve. This SOC-OCV curve represents the relationship between the battery's voltage and SOC when the battery is not polarized. The battery's voltage when the battery is not polarized is also referred to as the battery's equilibrium potential. As shown in Figure 1, method 100 includes some or all of the following steps.

[0051] Step 110: Acquire test data of the battery, where the test data includes test data of pulse discharging or pulse charging of the battery.

[0052] Step 120 : Fit the test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC.

[0053] Step 130: Obtain the equilibrium potential corresponding to each SOC according to the fitting curve corresponding to each SOC.

[0054] Step 140: Obtain the SOC-OCV curve of the battery according to the equilibrium potential corresponding to each SOC.

[0055] In the embodiment of the present application, the test data used includes test data of pulse discharge or pulse charge of the battery. Pulse discharge or pulse charge means that after each discharge or charge for a period of time, it is left to stand for a period of time, and then discharge or charge is continued and then left to stand, and this cycle is repeated until the discharge or charge is completed. The test data includes data collected during the standing time after each discharge or charge. Each discharge or charge corresponds to an SOC. In this way, there are test data corresponding to multiple SOCs for multiple discharges, and the test data corresponding to each SOC is the data collected during the corresponding standing time. For each SOC, these data can be used to fit a complete fitting curve. The equilibrium potential corresponding to the SOC can be obtained using the fitting curve. In this way, the SOC-OCV curve of the battery can be obtained through the equilibrium potentials corresponding to multiple SOCs.

[0056] In the related art, the standing time after testing the voltage under each SOC is relatively long. Usually, the battery needs at least 2 hours of relaxation to eliminate polarization, and the equilibrium potential of the battery can be directly measured after the polarization is eliminated. In the embodiment of the present application, the SOC-OCV curve is obtained by fitting the test data corresponding to each SOC. In this way, the standing time for obtaining the test data can be set to be very short, which is equivalent to the battery undergoing a very short relaxation. Its purpose is not to eliminate the polarization of the battery, but to obtain the test data required for fitting. Therefore, the technical solution of the embodiment of the present application shortens the test time, improves the test efficiency, and can quickly obtain the SOC-OCV curve of the battery. In addition, since the standing time can be set to be very short, the sampling density of the data can be increased, which is conducive to increasing the accuracy of the SOC-OCV curve.

[0057] In the embodiment of the present application, the data of voltage variation over time can be collected by repeatedly "discharging + resting" or repeatedly "charging + resting". In the embodiment of the present application, the repeated "discharging + resting" method is used as an example to describe in detail how to collect data of voltage variation over time during the discharge process.

[0058] In an embodiment of the present application, optionally, 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 rest time. Optionally, the test data corresponding to each SOC is the test data within the rest time corresponding to each SOC.

[0059] Taking discharge as an example, in the first stage, the battery is controlled to perform constant current discharge with a first pulse current of a first discharge rate and a first discharge time. After discharge, it is allowed to stand for a first period of time, and test data is collected during the first period of standing time. In this way, test data of the battery under a SOC is obtained after each discharge.

[0060] When the number of discharges reaches a first number threshold or the voltage of the battery is less than a first voltage threshold, the battery is controlled to stop discharging.

[0061] The battery is repeatedly discharged at a first pulse current with a first discharge rate and a first discharge time, and is briefly rested after each discharge. The rest period is the battery's relaxation period, and the data collected during this period is used as test data for the battery at a single SOC. In this way, after multiple discharges and rest periods, test data for batteries at multiple SOCs can be obtained. To prevent over-discharge of the battery, a first count threshold or a first voltage threshold can be set. Discharge can be stopped as long as the discharge count reaches the first count threshold or the voltage is less than the first voltage threshold.

[0062] The first discharge rate can be, for example, 1C. The first duration can be set to a shorter value, such as 5 minutes, meaning only a short rest period is required after each discharge. The first count threshold is the threshold for the number of discharges based on the first pulse current, and can be set between 60 and 80, such as 70 times. The first voltage threshold is determined based on the electrode material, and can be set between 2V and 3V, for example, to prevent damage to the electrode material from over-discharge. For example, for a lithium iron phosphate battery, the first voltage threshold can be 2.0V, and for a ternary lithium battery, the first voltage threshold can be 2.8V.

[0063] The present embodiment utilizes test data from the rest period to fit the equilibrium potential. This eliminates the need for a long rest period after each discharge to eliminate polarization and obtain the equilibrium potential. Therefore, the rest period can be very short. Furthermore, the sampling density can be increased by increasing the number of discharges, obtaining more test data and making the resulting SOC-OCV curve smoother while preserving the characteristics of the SOC-OCV curve.

[0064] 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 rest 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. Optionally, the test data corresponding to each SOC is the test data within the rest time corresponding to each SOC.

[0065] For example, after the above-mentioned first stage, the battery is controlled to perform constant current discharge with a second pulse current of a second discharge rate and a second discharge time, wherein the second discharge rate is less than the first discharge rate, the second discharge time is longer than the first discharge time, and each discharge is followed by a second rest period of time, which may be equal to or different from the first period of time. Test data is collected during the rest period of the second period of time, so that test data of the battery under one SOC is obtained after each discharge.

[0066] When the number of discharges reaches a second number threshold or the voltage of the battery is less than a second voltage threshold, the battery is controlled to stop discharging.

[0067] To release more power and obtain a more complete OCV range, the battery can continue to discharge based on a second pulse current that is smaller than the first pulse current, and rest for a short period of time after each discharge. Similarly, to prevent over-discharge of the battery, a second count threshold or a second voltage threshold can be set. As long as the discharge count reaches the second count threshold or the voltage is less than the second voltage threshold, discharge can be stopped.

[0068] The second discharge rate is less than the first discharge rate. For example, when the first discharge rate is 1C, the second discharge rate is 0.2C. The second duration can be set to be smaller, for example, 5 minutes, that is, only a short rest time is required after each discharge. The second number threshold is the threshold of 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.

[0069] As an example, in the test process shown in Table 1, in steps 1 and 2, the battery is respectively charged with a constant current and constant voltage to the upper limit voltage, i.e., the full charge voltage, using a current of 1C; in step 3, the charge polarization is weakened after standing for 1H, and then steps 4 to 8 are entered. In steps 4 to 8, the battery is discharged for 60s each time based on a first pulse current, such as 1C, and is allowed to stand for a first time, such as 5 minutes, after each discharge. When the battery voltage is less than or equal to a first voltage threshold, such as 2.8V, or the number of discharges reaches a first threshold, such as 70 times, the discharge is stopped, and steps 9 to 13 are entered. In steps 9 to 13, the battery is discharged for 90s each time based on a second pulse current, such as 0.2C, and is allowed to stand for a second time, such as 5 minutes, after each discharge. When the battery voltage is less than or equal to a second voltage threshold, such as 2.8V, or the number of discharges reaches a second threshold, such as 30 times, the discharge is stopped, and step 14 is entered, and the test process ends.

[0070] Table 1

[0071] Based on the above test process, the pulse discharge curve shown in Figure 2 can be obtained. As shown in Figure 2, assuming that one voltage is collected every 1 second, the number of sampling points during the entire test process is 30,000. The number of sampling points during the rest period after each discharge (the battery relaxation period) is 300, which is equivalent to collecting 300 voltages at each SOC. In this way, by fitting the 300 sets of voltage and time test data collected at each SOC, the fitting curve corresponding to each SOC can be obtained.

[0072] For different batteries, test data can be obtained using the above method. 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, the column names and other related data structures of the test data of different batteries can be preset. After each test data import, the column names and other related data structures are compared. If there is a discrepancy, an error message will be displayed. When a match is found, the test data of the corresponding battery will be identified.

[0073] Since the test data may be test data of a discharge or charge state, the discharge or charge 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 charge state.

[0074] Optionally, in the case of a discharge state, data is extracted during a time period in which the current is zero after each negative current; or, in the case of a charge state, data is extracted during a time period in which the current is zero after each positive current.

[0075] In the embodiment of the present application, the test data corresponding to each SOC can optionally be fitted according to the relaxation process of the battery to obtain a fitting curve corresponding to each SOC. Taking into account the characteristics of the battery relaxation process can facilitate obtaining a fitting result that meets the error requirements and improve fitting efficiency.

[0076] Alternatively, the test data corresponding to each SOC can be fitted according to the battery's relaxation process to obtain a relaxation model that fits the test data corresponding to each SOC; and then, based on the relaxation model, a fitting curve corresponding to each SOC can be obtained. Once the relaxation model is obtained, a complete fitting curve can be obtained using the relaxation model fitting.

[0077] Optionally, an initial relaxation model can be obtained based on the relaxation process of the battery, wherein 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 to obtain a relaxation model for the test data corresponding to each SOC.

[0078] Specifically, based on the characteristics of the battery's relaxation process, an initial relaxation model can be established, where the model parameters are variables, i.e., quantities to be determined. Using the test data corresponding to the SOC for fitting, the model parameters can be determined, and then a relaxation model for the test data corresponding to each SOC can be obtained. In this way, using an initial relaxation model that conforms to the battery's relaxation process can effectively achieve fitting and improve processing efficiency.

[0079] In one implementation, the initial relaxation model may be:

[0080] in, is voltage, x is time, and a, b, c, and d are model parameters. This relaxation model can express the relationship between time x and voltage using only four parameters a, b, c, and d. The relationship between them is convenient for fitting operation, which is simple and accurate.

[0081] Optionally, a Nernst equation can be established to represent the relationship between electrode potential and lithium ion concentration; and then, based on the relationship between current and lithium ion concentration change, and the relationship between current and time, the Nernst equation is converted into a relationship between the electrode potential and the time to obtain the initial relaxation model.

[0082] Optionally, the Nernst equation may be converted into a relationship equation between the electrode potential and the time in the following manner: according to Fick's first law, a relationship equation between the current and the change in lithium ion concentration is determined; according to the relationship equation between the current and the change in lithium ion concentration, the Nernst equation is converted into a relationship equation between the electrode potential and the current; the relationship equation between the current and the time is obtained; and according to the relationship equation between the current and the time, the relationship equation between the electrode potential and the current is converted into a relationship equation between the electrode potential and the time.

[0083] Optionally, the relationship between the current and the time may be determined according to a relationship between the current and the change in lithium ion concentration, and a relationship between the lithium ion concentration and the time.

[0084] Hereinafter, how to establish the initial relaxation model is described in detail.

[0085] During the relaxation process of the 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 the condition of concentration polarization, it can be considered that the transfer of lithium ions is in equilibrium. Therefore, the electrode potential can be expressed by the Nernst equation, that is:

[0086] in, is the electrode potential; C0 is the concentration of the reactant on the electrode surface; C R is the concentration of the reaction product on the electrode surface; F is the Faraday constant, unit C / mol, its value is equal to the Avogadro constant NA = 6.02214×1023mol -1 The product of the elementary charge e = 1.602176 × 10-19 C, that 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, usually R = 8.314 J*K -1 *mol -1 .

[0087] The Nernst equation reflects the relationship between electrode potential and lithium ion concentration. The concentration difference is the main driving force for lithium ion diffusion. The Nernst equation calculates the electrode potential from the perspective of concentration change. However, since the essence of electrochemistry is the relationship between material change and charge transfer, it is necessary to establish the relationship between electrical signals such as current and concentration change. When the mass transfer process only considers diffusion mass transfer,

[0088] From this, we can get:

[0089] Where N is the number of moles of reactants, n is the number of electrons required for the reactants to react, F is the Faraday constant, Q is the total amount of reaction on the electrode surface, and m0 is the mass transfer coefficient. is the bulk reactant concentration, c0 is the reactant concentration on the electrode surface, and A is the reaction area.

[0090] When the dynamic process of electron transfer is fast enough, that is, C0=0, the reactants on the electrode surface are at the maximum rate under the mass transfer conditions, and the concentrations of reactants and products are in equilibrium at a certain potential. The above-mentioned Nernst equation can be linked. Assuming that when the initial concentration of the product is 0, that is, when the concentration of the bulk is 0,

[0091] when i=i lim / 2, according to formula (8):

[0092] At this time, it is not related to the substrate concentration, but is related to the mass transfer coefficient. lim Represents the limiting current, that is, the maximum current under the conditions when the electrode surface reaction is at the maximum rate under the changed mass transfer conditions; is the standard electrode potential; m R is the mass transfer coefficient of the reaction product on the electrode surface; m0 is the mass transfer coefficient of the reactant.

[0093] When only considering diffusion mass transfer, as the electrode reaction occurs, the diffusion layer thickness δ is proportional to t^(1 / 2), while the current is proportional to t^(-1 / 2). Assuming δ = δ(t), then:

[0094] According to the relationship between the approximate number of moles of reactants in the diffusion layer at any time t, we can obtain:

[0095] Differentiating both sides of formula (11) and substituting it into formula (10) yields:

[0096] Simplifying formula (12), we get:

[0097] Further, we obtain: dδ(t)δ(t)=2D0dt (14);

[0098] When t = 0, δ(t) = 0, integrate both ends of formula (14) and simplify it to obtain:

[0099] Substituting formula (15) into formula (10), we can obtain the relationship between current and concentration:

[0100] At this point, Fick's first law can be used to establish the relationship between current and one-dimensional changes in matter using flow as an intermediate quantity:

[0101] 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. is the concentration gradient.

[0102] In practice, the signals we can obtain are electrical signals, such as current (i). To facilitate actual testing, we hope to obtain the relationship between current and time. Therefore, based on formulas (17) and (18),

[0103] Where C0(x,t) is the concentration; is the initial concentration; n is the number of lithium ions transferred in the electrode reaction; A is the electrode area; F is the Faraday constant; Do is the diffusion coefficient; erf is the error function, and the current and time can be described as:

[0104] At this point, the description of the equilibrium potential and concentration, namely formula (2), the description of the concentration and current, namely formula (16), and the description of the current and time, namely formula (19), are completed.

[0105] Combining the above relationship and simplifying the parameters, we can obtain the initial relaxation model used to identify the relationship between equilibrium potential and time:

[0106] in, is the voltage, t is the time, and a, b, c and d are model parameters.

[0107] By using the test data corresponding to multiple SOCs and the initial relaxation model, the values ​​of the model parameters a, b, c, and d can be obtained. In 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 fitting can be used as the initial values ​​for the next fitting. Input t is different test time, input is the voltage at the corresponding time. After fitting calculation, the accurate a, b, c and d can be obtained.

[0108] Optionally, during fitting, at least one data segment from the test data corresponding to each SOC may be selected for fitting; and the model parameters obtained from the fitting of 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 kth data segment in the at least one data segment is the kth to Nth sampling points, where N and k are positive integers, and k is less than N.

[0109] Specifically, throughout the relaxation process, the electrode potential's evolution is influenced by ohmic polarization, electrochemical polarization, and concentration polarization. The impact of different polarization types varies across different SOCs, with the overall impact of ohmic and electrochemical polarization occurring between 0 and 15 seconds. Since the initial relaxation model only considers the influence of concentration polarization, to better fit the test data to the relaxation model and obtain more accurate fitting results, fitting can be performed on data from sampling points at different relaxation intervals. For example, assuming the relaxation process lasts 300 seconds, with a 1-second interval between adjacent sampling points (i.e., voltage acquisition every 1 second), fitting can be performed using data from 1 to 300 seconds, 2 to 300 seconds, 3 to 300 seconds, and finally 15 to 300 seconds. For example, using the curvefit function included in MATLAB, curve fitting is performed and the optimal fit, i.e., the one with the smallest error, is returned. The optimal fit is then selected as the values ​​for a, b, c, and d.

[0110] Once the model parameters are determined, the fitting curve corresponding to each SOC can be obtained, so that the equilibrium potential corresponding to each SOC can be obtained based on the fitting curve corresponding to each SOC.

[0111] Optionally, based on the fitting curve corresponding to each SOC, the voltage of the fitting curve corresponding to each SOC at a time point that satisfies a preset condition after the test period can be obtained to obtain the equilibrium potential corresponding to each SOC. For example, the preset condition may include: the difference between the voltages corresponding to two adjacent time points is less than a preset threshold. Optionally, the threshold is 0.000001V.

[0112] When the voltage does not change over time, it can be considered the equilibrium potential after the battery is depolarized. Therefore, a condition can be set that the difference between the voltages at two adjacent time points is less than a threshold to effectively control the voltage extension calculation. When the calculation result meets this condition, the calculation stops and the voltage calculated at this time is used as the equilibrium potential.

[0113] For example, as shown in Figure 3, the relationship between time and voltage at a single SOC, i.e., the fitted curve corresponding to the SOC, has time as the horizontal axis and voltage as the vertical axis. The solid line represents test data, i.e., voltage data collected during a relaxation period using the aforementioned pulse discharge method. Based on this test data, the model parameters of the relaxation model can be obtained. After determining the model parameters, the voltage extension calculation is performed using the relaxation model to obtain the voltage data shown in the dashed line. Given the boundary condition for voltage balance calculation that the difference between the voltages at two adjacent time points is less than 0.000001V, when the calculation reaches time T2, the voltage at that moment is 3.829V. The difference between the voltage value at the previous sampling time and the value is less than 0.000001V, so the equilibrium potential of the battery at this SOC can be considered to be 3.829V. The equilibrium potential obtained in this way is substantially close to the actual equilibrium potential, thereby improving the accuracy of the SOC-OCV curve.

[0114] According to the equilibrium potential of the battery under multiple SOCs, the SOC-OCV curve of the battery can be drawn as shown in Figure 4.

[0115] FIG5 shows the accuracy of the SOC-OCV curves obtained at different discharge times. It can be seen that the goodness of fit R2 of the SOC-OCV curves obtained using the method of the embodiment of the present application is above 0.99, which has high accuracy.

[0116] In an embodiment of the present application, test data can optionally be imported and processing results displayed through a display interface. Optionally, in one implementation, a display interface can be obtained, 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, 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 fitting curve corresponding to each SOC is displayed in the second sub-area. Based on the fitting 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 fitting curve corresponding to each SOC, and the SOC-OCV curve of the battery is exported to a target storage address.

[0117] As shown in FIG6 , a display interface 600 according to an embodiment of the present application is shown. The display interface 600 may include an operation area 610 and a result display area 620 . The result display area 620 includes a first sub-area 621 , a second sub-area 622 , and a third sub-area 623 .

[0118] Operations can be entered in the operation area 610, such as import, fit, and export. The import operation allows test data to be exported; the fit operation allows the test data to be fitted as described in the above embodiment, with the corresponding results displayed in the display area; and the export operation allows the corresponding results to be exported. Other operations can also be entered in the operation area 610, which are not limited in this embodiment.

[0119] For example, as shown in Figure 7, after the user enters the import operation, the import data page 640 may be displayed, where the user can import the corresponding test data. Optionally, the battery's original pulse discharge or pulse charge curve may also be displayed in the third sub-area 623. As shown in Figure 8, after the user enters the fit operation, data fitting is performed, and a processing progress window 650 is displayed. After processing is completed, the fitted curve corresponding to each SOC may be displayed in the second sub-area 622, and the battery's SOC-OCV curve may be displayed in the first sub-area 621.

[0120] Optionally, the display interface 600 further includes a parameter setting area 630. In response to a setting operation in the parameter setting area 630, the parameter setting may be obtained; accordingly, in response to the operation input and the parameter setting in the operation area 610, the SOC-OCV curve of the battery is displayed in the first sub-area 621, the fitting 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.

[0121] The parameter settings may include settings for at least one of the battery's electrode type, charge / discharge type, and electrode material. Examples of electrode types include two electrodes or three electrodes, charge / discharge types include charging or discharging, and electrode material parameters include, for example, electrode material particle size. The parameter settings may also include other settings, such as settings for a fitting algorithm and test conditions, which are not limited in the present embodiment.

[0122] For example, after the user imports the test data, the user can set the parameters in the parameter setting area 630 and then perform fitting to obtain the corresponding processing results.

[0123] The first sub-area 621 displays the SOC-OCV curve of the battery, such as the curve shown in Figure 4; the second sub-area 622 displays the fitting curve corresponding to each SOC, such as the curve shown in Figure 3; the third sub-area 623 displays the original pulse discharge or pulse charge curve of the battery, such as the curve shown in Figure 2.

[0124] Optionally, the result display area 620 may further include a display sub-area for displaying other results, that is, corresponding results may be displayed according to user needs. For example, the results shown in FIG. 5 may be displayed, and this embodiment of the present application is not limited thereto.

[0125] By using the above display interface, users can obtain desired results through simple operations, thereby improving user experience.

[0126] The above describes the method of the embodiment of the present application, and the following describes the device of the embodiment of the present application. It should be understood that the relevant descriptions in the following embodiments can refer to the previous embodiments, and for the sake of brevity, they are not repeated here.

[0127] FIG9 shows a schematic block diagram of a state of charge estimation apparatus 900 according to an embodiment of the present application. As shown in FIG9 , the apparatus 900 includes: an acquisition unit 910 and a processing unit 920 .

[0128] The acquisition unit 910 is used to acquire test data of the battery, where the test data includes test data of pulse discharging or pulse charging of the battery.

[0129] The processing unit 920 is used to fit the test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC; obtain the equilibrium potential corresponding to each SOC based on the fitting curve corresponding to each SOC; and obtain the SOC-open circuit voltage (OCV) curve of the battery based on the equilibrium potential corresponding to each SOC.

[0130] 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 fitting curve corresponding to each SOC.

[0131] Optionally, the processing unit 920 is used 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.

[0132] Optionally, the processing unit 920 is used 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, determine the model parameters, and obtain a relaxation model of the test data corresponding to each SOC.

[0133] Optionally, the processing unit 920 is used 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 with the smallest error in the fitting of the at least one data segment as the model parameters of the relaxation model.

[0134] Optionally, the test data corresponding to each SOC includes N sampling points, the kth data segment in the at least one data segment includes the kth to Nth sampling points, N and k are positive integers, and k is less than N.

[0135] Optionally, the processing unit 920 is configured to:

[0136] A Nernst equation is established to represent the relationship between the electrode potential and the lithium ion concentration; based on the relationship between the current and the change in lithium ion concentration, and the relationship between the current and time, the Nernst equation is converted into a relationship between the electrode potential and the time to obtain the initial relaxation model.

[0137] Optionally, the processing unit 920 is used to: determine the relationship between the current and the change in lithium ion concentration based on Fick's first law; convert 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; 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 based on the relationship between the current and the time.

[0138] Optionally, the processing unit 920 is configured to determine a relationship between the current and the time according to a relationship between the current and the change in lithium ion concentration, and a relationship between the lithium ion concentration and the time.

[0139] Optionally, the processing unit 920 is configured to: obtain, based on the fitting curve corresponding to each SOC, the voltage of the fitting curve corresponding to each SOC at a time point that meets a preset condition after a test period, and obtain the equilibrium potential corresponding to each SOC.

[0140] Optionally, the preset condition includes: a difference between voltages corresponding to two adjacent time points is less than a preset threshold.

[0141] Optionally, 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 rest time.

[0142] Optionally, the process of pulse discharging or pulse charging the battery also 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 standing 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.

[0143] Optionally, the test data corresponding to each SOC is the test data within the static time corresponding to each SOC.

[0144] Optionally, the processing unit 920 is configured to: determine a discharge or charge state corresponding to the test data based on current data in the test data; and extract test data corresponding to each SOC based on the discharge or charge state.

[0145] Optionally, the processing unit 920 is configured to: in the case of a discharge state, extract data within a time period when the current is zero after each negative current; or in the case of a charging state, extract data within a time period when the current is zero after each positive current.

[0146] Optionally, the processing unit 920 is configured to identify the test data according to the acquired data structure of the test data and a preset data structure.

[0147] Optionally, the device 900 also includes: a display unit, used to 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, the original pulse discharge or pulse charge curve of the battery is displayed in the third sub-area; in response to the fitting operation in the operation area, the processing unit 920 is used to 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, the equilibrium potential corresponding to each SOC is obtained; according to the equilibrium potential corresponding to each SOC, the SOC-OCV curve of the battery is displayed in the first sub-area.

[0148] Optionally, the processing unit 920 is used to: in response to the export operation in the operating 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.

[0149] Figure 10 shows a schematic block diagram of an electronic device 1000 according to an embodiment of the present application. As shown in Figure 10, 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 any of the above-mentioned methods.

[0150] The present application also provides a computer-readable storage medium for storing a computer program. When the computer program is executed by a computing device, the computing device implements the method in any of the above implementations.

[0151] The present application also provides a computer program product including computer-readable code, or a non-volatile computer-readable storage medium carrying computer-readable code. When the computer-readable code runs in an electronic device, the processor in the electronic device executes the method in any of the above implementations.

[0152] It should be noted that, under the premise of no conflict, the various embodiments and / or technical features in each embodiment described in this application can be arbitrarily combined with each other, and the technical solution obtained after the combination should also fall within the scope of protection of this application.

[0153] Those skilled in the art will appreciate that the units and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel 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.

[0154] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described systems, devices and units can refer to the corresponding processes in the above-described method embodiments and will not be repeated here.

[0155] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0156] The units described as separate components may or may not be physically separate, and 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 these units may be selected to achieve the purpose of this embodiment according to actual needs.

Claims

1. A method for estimating a state of charge, characterized in that: include: Acquiring test data of a battery, wherein the test data includes test data of pulse discharging or pulse charging of the battery; Fitting the test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC; According to the fitting curve corresponding to each SOC, the equilibrium potential corresponding to each SOC is obtained; According to the equilibrium potential corresponding to each SOC, the SOC-OCV curve of the battery is obtained.

2. The method according to claim 1, characterized in that The fitting of the test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC includes: The test data corresponding to each SOC is fitted according to the relaxation process of the battery to obtain a fitting curve corresponding to each SOC.

3. The method according to claim 2, characterized in that The step of fitting the test data corresponding to each SOC according to the relaxation process of the battery to obtain a fitting curve corresponding to each SOC includes: 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; According to the relaxation model, a fitting curve corresponding to each SOC is obtained.

4. The method according to claim 3, characterized in that The step of 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 includes: Acquiring an initial relaxation model according to the relaxation process of the battery, wherein the initial relaxation model includes model parameters to be determined; The initial relaxation model is fitted to the test data corresponding to each SOC, and the model parameters are determined to obtain a relaxation model of the test data corresponding to each SOC.

5. The method according to claim 4, characterized in that The step of fitting the initial relaxation model to the test data corresponding to each SOC to determine the model parameters includes: Selecting at least one data segment in the test data corresponding to each SOC for fitting; The model parameters obtained by fitting with the smallest error in the fitting of the at least one data segment are used as the model parameters of the relaxation model.

6. The method according to claim 5, characterized in that The test data corresponding to each SOC includes N sampling points, the kth data segment in the at least one data segment is the kth to Nth sampling points, N and k are positive integers, and k is less than N.

7. The method according to any one of claims 4 to 6, characterized in that The obtaining of an initial relaxation model according to the relaxation process of the battery comprises: Establish the Nernst equation for expressing the relationship between electrode potential and lithium ion concentration; According to the relationship between the current and the change of lithium ion concentration, and the relationship between the current and time, the Nernst equation is converted into a relationship between the electrode potential and the time to obtain the initial relaxation model.

8. The method according to claim 7, characterized in that The converting the Nernst equation into a relationship between the electrode potential and the time includes: According to Fick's first law, determining a relationship between the current and the change in lithium ion concentration; According to the relationship between the current and the change in the lithium ion concentration, converting the Nernst equation into a relationship between the electrode potential and the current; Obtaining a relationship between the current and the time; According to the relationship expression between the current and the time, the relationship expression between the electrode potential and the current is converted into the relationship expression between the electrode potential and the time.

9. The method according to claim 8, characterized in that The obtaining of the relationship between the current and the time includes: The relationship between the current and the time is determined according to the relationship between the current and the change in the lithium ion concentration and the relationship between the lithium ion concentration and the time.

10. The method according to any one of claims 1 to 9, characterized in that: The step of obtaining the equilibrium potential corresponding to each SOC according to the fitting curve corresponding to each SOC includes: According to the fitting curve corresponding to each SOC, the voltage of the fitting curve corresponding to each SOC at a time point that meets a preset condition after the test time period is obtained to obtain the equilibrium potential corresponding to each SOC.

11. The method according to claim 10, characterized in that The preset condition includes: the difference between voltages corresponding to two adjacent time points is less than a preset threshold.

12. The method according to any one of claims 1 to 11, characterized in that 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 rest time.

13. The method according to claim 12, characterized in that The process of pulse discharging or pulse charging the battery also 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 standing 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.

14. The method according to claim 12 or 13, characterized in that The test data corresponding to each SOC is the test data within the static time corresponding to each SOC.

15. The method according to any one of claims 1 to 14, characterized in that The method further comprises: Determining a discharge or charge state corresponding to the test data according to current data in the test data; According to the discharge or charge state, test data corresponding to each SOC is extracted.

16. The method according to claim 15, characterized in that The extracting test data corresponding to each SOC according to the discharge or charge state includes: In the case of a discharge state, extract the data in the time period when the current is zero after each negative current; or In the case of the charging state, data is extracted for a period of time in which the current is zero after each period of positive current.

17. The method according to any one of claims 1 to 16, characterized in that The method further comprises: Acquire a display interface, wherein the display interface includes an operation area and a display area, and the display area includes a first sub-area, a second sub-area, and a third sub-area; In response to the introduction operation in the operation area, displaying an 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, 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; According to the fitting curve corresponding to each SOC, the equilibrium potential corresponding to each SOC is obtained; The SOC-OCV curve of the battery is displayed in the first sub-area according to the equilibrium potential corresponding to each SOC.

18. The method according to claim 17, characterized in that The method further comprises: In response to the export operation in the operation area, 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 is exported to a target storage address.

19. A device for estimating state of charge, characterized in that: include: An acquisition unit, used for acquiring test data of a battery, wherein the test data includes test data of pulse discharging or pulse charging of the battery; A processing unit, configured to fit the test data corresponding to each SOC in the test data to obtain a fitting curve corresponding to each SOC; and obtain an equilibrium potential corresponding to each SOC according to the fitting curve corresponding to each SOC; According to the equilibrium potential corresponding to each SOC, the SOC-OCV curve of the battery is obtained.

20. An electronic device, characterized in that: The electronic device comprises a memory and a processor, wherein the memory stores computer instructions, and the processor calls the computer instructions to enable the electronic device to implement the method according to any one of claims 1 to 18.

21. A computer-readable storage medium, characterized in that: Used to store a computer program, which, when executed by a computing device, causes the computing device to implement the method according to any one of claims 1 to 18.

22. A computer program product, characterized in that The invention comprises a computer-readable code, or a non-volatile computer-readable storage medium carrying the computer-readable code, wherein when the computer-readable code is executed in an electronic device, a processor in the electronic device executes the method according to any one of claims 1 to 18.

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