Estimation Method, Device, Server and Storage Medium for Battery Cell Capacity

Abstract

The present application relates to the technical field of battery management systems, and particularly relates to a method, device, server, and storage medium for estimating the capacity of a battery cell. Among them, the method includes: obtaining the actual charging data of the battery cell within one or more state of charge (SOC) intervals; generating an actual charging voltage curve corresponding to each SOC interval according to the actual charging data within each SOC interval, and querying a pre-established voltage feature database with each SOC interval as an index to output a reference charging voltage curve for each SOC interval; calculating the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval. Thereby, problems such as the method for calculating the capacity of a battery cell in the related art being affected by the battery system and having low calculation accuracy are solved.

Description

Technical Field

[0001] The present application relates to the technical field of battery management systems, and particularly relates to a method, device, server, and storage medium for estimating the capacity of battery cells. Background Art

[0002] A battery pack generally contains dozens or even hundreds of battery cells. The capacity of the battery pack is determined by the capacities of individual battery cells. Accurately calculating the capacity of each battery cell can not only obtain the capacity degradation of each battery cell during use, but also calculate the current capacity of the battery pack based on the real-time calculated capacity of the battery cell, and further accurately calculate the SOH (State of Health) of the battery.

[0003] Since the battery pack is controlled by the highest voltage and the lowest voltage of the battery cells during charging / discharging, when the capacities and SOCs (State of Charge) of the battery cells in the battery pack are inconsistent, it is impossible to obtain the capacity of each battery cell through a simple charging / discharging method.

[0004] In related technologies, the corresponding relationship ΔV~ΔQ between voltage and capacity during constant current charging (discharging) is used to calculate the total capacity of the battery cells. However, this method is effective for battery systems such as NMC (ternary materials), but is not applicable to lithium iron phosphate (LiFePO4, LFP) battery systems. The voltage curve of the LFP battery system is very flat, which makes the relationship of ΔV~ΔQ in the voltage plateau region extremely sensitive. A small change in voltage will cause a significant change in capacity, resulting in a large estimation error of capacity. Summary of the Invention

[0005] The present application provides a method, device, server, and storage medium for estimating the capacity of battery cells to solve the problems that the method for calculating the capacity of battery cells in related technologies is affected by the battery system and the calculation accuracy is relatively low.

[0006] In a first aspect embodiment of the present application, a method for estimating the capacity of battery cells is provided. The method is applied to a server. The method includes the following steps: obtaining actual charging data of the battery cell within one or more State of Charge (SOC) intervals; generating an actual charging voltage curve corresponding to each SOC interval according to the actual charging data within each SOC interval, and querying a pre-established voltage feature database with each SOC interval as an index, and outputting a reference charging voltage curve for each SOC interval; calculating the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval.

[0007] According to the above technical means, the embodiments of the present application can accurately calculate the actual capacity of the battery cell by comparing the actual charging voltage curve of the battery cell with the corresponding reference charging voltage curve. Since the pre-calibrated standard reference charging voltage curve is utilized, the actual capacity of the battery cell can be accurately compared according to the voltage curve, avoiding the influence of the battery system on the estimation result, and being effectively applicable to multiple battery systems. At the same time, the estimation method of the embodiments of the present application can be deployed on the server, and the computing resources of the server are utilized to improve the computing efficiency.

[0008] Optionally, calculating the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval includes: calculating the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval, and determining an objective function according to the root mean square error; finding the optimal solution for the objective function by the least squares method to obtain the actual capacity of the battery cell.

[0009] According to the above technical means, the embodiments of the present application can calculate the root mean square error of the actual charging voltage curve and the reference charging voltage curve and use it to determine the objective function, and find the optimal solution by the least squares method to calculate the actual capacity of the battery cell.

[0010] Optionally, calculating the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval includes: dividing the total charging time of the reference battery cell into different charging stages; adding interval identifiers to the SOC intervals corresponding to each charging stage, and establishing a mathematical expression between the SOC interval, SOC, and capacity according to the interval identifiers; using the mathematical expression to extract the actual charging voltage curve and the corresponding reference charging voltage curve, and calculating the root mean square error of the battery cell according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve of each SOC interval.

[0011] According to the above technical means, the embodiments of the present application can divide the total charging time of the reference battery cell into different charging stages, set interval identifiers for the SOC intervals of different charging stages, establish mathematical expressions for different SOC intervals, further use the mathematical expressions to extract the actual charging voltage curve and the corresponding reference charging voltage curve, and calculate the root mean square error according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve of each SOC interval.

[0012] Optionally, before querying the pre-established voltage characteristic database, it further includes: constructing a charging test matrix of temperature and charging current; obtaining charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, and performing interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain a plurality of reference charging voltage curves; constructing the voltage characteristic database according to each SOC interval and the corresponding reference charging voltage curve.

[0013] According to the above technical means, the embodiment of the present application can construct a charging test matrix from two dimensions of temperature and charging current, perform interpolation processing on the charging voltage curves obtained at different charging temperatures and rates through the charging matrix to obtain a plurality of reference charging voltage curves, and use them and the SOC interval to construct a voltage characteristic database, so as to subsequently find the corresponding reference charging voltage curve according to the SOC interval.

[0014] Optionally, the performing interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain a plurality of reference charging voltage curves includes: calculating the maximum charging capacity corresponding to the charging voltage curves at all different rates; determining the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, and dividing the capacity interval into a plurality of grids according to the step size; calculating a first constant according to the voltage value of each grid, obtaining the charging voltage value at any charging current according to the first constant, and generating a plurality of reference charging voltage curves based on the charging voltage value at any charging current.

[0015] According to the above technical means, the embodiment of the present application can perform interpolation processing on the charging voltage curves at different charging rates, and calculate the reference charging voltage curve corresponding to the charging voltage value at any charging current through a formula.

[0016] Optionally, the performing interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain a plurality of reference charging voltage curves includes: calculating the maximum charging capacity corresponding to the charging voltage curves at all different temperatures; determining the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, and dividing the capacity interval into a plurality of grids according to the step size; calculating a second constant according to the voltage value of each grid, obtaining the voltage curve under any temperature condition according to the second constant, and obtaining a plurality of reference charging voltage curves based on the voltage curve under any temperature condition.

[0017] According to the above technical means, the embodiment of the present application can perform interpolation processing on the charging voltage curves at different temperatures, and calculate the reference charging voltage curve corresponding to the voltage curve under any temperature condition through a formula.

[0018] Optionally, obtaining the charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix includes: at a preset temperature, performing constant current discharge at a first preset current until a preset cut-off voltage, then switching to a second preset current for constant current discharge until the preset cut-off voltage, after standing for a first preset duration, performing constant current charge at a third preset current until the preset cut-off voltage, and recording the charging voltage curve at the current temperature and / or the current charging rate; after standing for a second preset duration, performing constant current discharge at a fourth preset current until the preset cut-off voltage, then switching to a fifth preset current for constant current discharge until the preset cut-off voltage, and after standing for a third preset duration, re-performing the charging test at other charging rates and / or other charging temperatures.

[0019] According to the above technical means, the embodiments of the present application can obtain the charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, so as to obtain the reference charging voltage curve according to the charging voltage curve subsequently.

[0020] The embodiments of the second aspect of the present application provide a method for estimating the capacity of an electric cell, and the method is applied to a server. Wherein, the method includes the following steps: constructing a charging test matrix of temperature and charging current; obtaining the charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, and performing interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain the reference charging voltage curve of each SOC interval; constructing a voltage feature database according to the reference charging voltage curve of each SOC interval, querying the reference charging voltage curve of each SOC interval by using the voltage feature database, and calculating the actual capacity of the electric cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval.

[0021] The embodiments of the third aspect of the present application provide an apparatus for estimating the capacity of an electric cell, and the apparatus is applied to a server. Wherein, the apparatus includes: obtaining the actual charging data of the electric cell within one or more state of charge (SOC) intervals; generating the actual charging voltage curve of the corresponding SOC interval according to the actual charging data within each SOC interval, and querying the pre-established voltage feature database with each SOC interval as an index to output the reference charging voltage curve of each SOC interval; calculating the actual capacity of the electric cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval.

[0022] Optionally, the first calculation module is further configured to: calculate the root mean square error of the electric cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval, and determine the objective function according to the root mean square error; find the optimal solution of the objective function by the least square method to obtain the actual capacity of the electric cell.

[0023] Optionally, the first calculation module is further configured to: divide the total charging time of the reference battery cell into different charging stages; add interval identifiers to the SOC intervals corresponding to each charging stage, and establish a mathematical expression between the SOC interval, SOC, and capacity according to the interval identifiers; use the mathematical expression to extract the actual charging voltage curve and the corresponding reference charging voltage curve, and calculate the root mean square error of the battery cell according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve in each SOC interval.

[0024] Optionally, it further includes: a processing module, configured to construct a charging test matrix of temperature and charging current before querying a pre-established voltage feature database; obtain charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, and perform interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain a plurality of reference charging voltage curves; construct the voltage feature database according to each SOC interval and the corresponding reference charging voltage curve.

[0025] Optionally, the processing module is further configured to: calculate the maximum charging capacity corresponding to the charging voltage curves at all different rates; determine the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, and divide the capacity interval into multiple grids according to the step size; calculate a first constant according to the voltage value of each grid, obtain the charging voltage value at any charging current according to the first constant, and generate a plurality of reference charging voltage curves based on the charging voltage value at any charging current.

[0026] Optionally, the processing module is further configured to: calculate the maximum charging capacity corresponding to the charging voltage curves at all different temperatures; determine the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, and divide the capacity interval into multiple grids according to the step size; calculate a second constant according to the voltage value of each grid, obtain the voltage curve under any temperature condition according to the second constant, and obtain a plurality of reference charging voltage curves based on the voltage curve under any temperature condition.

[0027] Optionally, the processing module is further configured to: perform constant current discharge at a first preset current until a preset cut-off voltage at a preset temperature, then switch to a second preset current for constant current discharge until the preset cut-off voltage, after standing for a first preset duration, perform constant current charge at a third preset current until the preset cut-off voltage, and record the charging voltage curve at the current temperature and / or the current charging rate; after standing for a second preset duration, perform constant current discharge at a fourth preset current until a preset cut-off voltage, then switch to a fifth preset current for constant current discharge until the preset cut-off voltage, and after standing for a third preset duration, re-perform the charging test at other charging rates and / or other charging temperatures.

[0028] An embodiment of the fourth aspect of the present application provides an estimation device for the capacity of an electric core. The device is applied to a server. Wherein, the device includes: a construction module, configured to construct a charging test matrix of temperature and charging current; an interpolation module, configured to obtain charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, and perform interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain reference charging voltage curves for each SOC interval; a second calculation module, configured to construct a voltage feature database according to the reference charging voltage curves for each SOC interval, query the reference charging voltage curves for each SOC interval by using the voltage feature database, and calculate the actual capacity of the electric core according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval.

[0029] An embodiment of the fifth aspect of the present application provides a server, including: a memory, a processor, and a computer program stored on the memory and executable on the processor. The processor executes the program to implement the method for estimating the capacity of an electric core as described in the above embodiments.

[0030] An embodiment of the sixth aspect of the present application provides a computer-readable storage medium, on which a computer program is stored, and the program is executed by a processor to be used for implementing the method for estimating the capacity of an electric core as described in the above embodiments.

[0031] Thus, the present application has at least the following beneficial effects:

[0032] (1) Embodiments of the present application can accurately calculate the actual capacity of the electric core by comparing the actual charging voltage curve of the electric core with the corresponding reference charging voltage curve. Since the pre-calibrated standard reference charging voltage curve is used, the actual capacity of the electric core can be accurately compared according to the voltage curve, avoiding the influence of the battery system on the estimation result, being effectively applicable to multiple battery systems. At the same time, the estimation method of the embodiments of the present application can be deployed on a server, and the computing resources of the server are utilized to improve the computing efficiency.

[0033] (2) In the embodiments of the present application, the root mean square error of the actual charging voltage curve and the reference charging voltage curve can be calculated, and the objective function can be determined by using it. The actual capacity of the battery cell can be calculated by optimization through the least squares method.

[0034] (3) In the embodiments of the present application, the total charging time of the reference battery cell can be divided into different charging stages, interval identifiers can be set for the SOC intervals of different charging stages, mathematical expressions for different SOC intervals can be established, and further, the actual charging voltage curve and the corresponding reference charging voltage curve can be extracted by using the mathematical expressions. The root mean square error can be calculated according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve for each SOC interval.

[0035] (4) In the embodiments of the present application, a charging test matrix can be constructed from two dimensions of temperature and charging current, interpolation processing can be performed on the charging voltage curves obtained at different charging temperatures and rates through the charging matrix to obtain multiple reference charging voltage curves, and a voltage feature database can be constructed by using them and the SOC intervals, so as to subsequently find the corresponding reference charging voltage curve according to the SOC interval.

[0036] (5) In the embodiments of the present application, interpolation processing can be performed on the charging voltage curves at different charging rates, and the reference charging voltage curve corresponding to the charging voltage value at any charging current can be calculated through a formula.

[0037] (6) In the embodiments of the present application, interpolation processing can be performed on the charging voltage curves at different temperatures, and the reference charging voltage curve corresponding to the voltage curve under any temperature condition can be calculated through a formula.

[0038] (7) In the embodiments of the present application, the charging voltage curves at different charging temperatures and / or different charging rates can be obtained according to the charging test matrix, so as to subsequently obtain the reference charging voltage curve according to the charging voltage curve.

[0039] Thus, the technical problems in the related art that the method for calculating the capacity of the battery cell is affected by the battery system and the calculation accuracy is relatively low are solved.

[0040] The additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and / or additional aspects and advantages of the present application will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0042] Figure 1 is a flowchart of a method for estimating the capacity of a battery cell according to an embodiment of the present application;

[0043] Figure 2Schematic diagram of charging interval division and interval identification provided according to an embodiment of the present application;

[0044] Figure 3 Flowchart of a method for estimating the capacity of an electric core provided according to an embodiment of the present application;

[0045] Figure 4 Schematic diagram of charging interval division and interval identification for any electric core in an LFP battery pack provided according to an embodiment of the present application;

[0046] Figure 5 Flowchart of a method for estimating the capacity of an electric core provided according to another embodiment of the present application;

[0047] Figure 6 Schematic diagram of an apparatus for estimating the capacity of an electric core provided according to an embodiment of the present application;

[0048] Figure 7 Schematic diagram of an apparatus for estimating the capacity of an electric core provided according to another embodiment of the present application;

[0049] Figure 8 Schematic diagram of the structure of a server provided according to an embodiment of the present application. Detailed implementation manners

[0050] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, and should not be construed as limiting the present application.

[0051] The method, apparatus, server, and storage medium for estimating the capacity of an electric core according to the embodiments of the present application will be described below with reference to the accompanying drawings. In the related art mentioned in the above background art, the corresponding relationship ΔV~ΔQ between voltage and capacity during constant current charging (discharging) is used to calculate the total capacity of the electric core. However, this method is effective for battery systems such as NMC, but not applicable to the LFP battery system, and the estimation error of the capacity is very large. The present application provides a method for estimating the capacity of an electric core. In this method, the actual capacity of the electric core is accurately calculated by comparing the actual charging voltage curve of the electric core with the corresponding reference charging voltage curve. Since the pre-calibrated standard reference charging voltage curve is used, the actual capacity of the electric core can be accurately compared according to the voltage curve, avoiding the influence of the battery system on the estimation result and being effectively applicable to multiple battery systems. Thus, the problems that the method for calculating the capacity of the electric core in the related art is affected by the battery system and the calculation accuracy is low are solved.

[0052] Specifically, Figure 1Schematic flow diagram of a method for estimating the capacity of an electric cell provided by an embodiment of the present application.

[0053] As Figure 1 shown, the method for estimating the capacity of the electric cell, which is applied to a server, includes the following steps:

[0054] In step S101, actual charging data of the electric cell within one or more state of charge (SOC) intervals is obtained.

[0055] Among them, the electric cell can be any electric cell, such as a certain electric cell in an LFP battery pack, a nickel-metal hydride battery cell, a lithium battery cell, etc.

[0056] In step S102, an actual charging voltage curve corresponding to each SOC interval is generated based on the actual charging data within each SOC interval, and with each SOC interval as an index, a pre-established voltage feature database is queried to output a reference charging voltage curve for each SOC interval.

[0057] Among them, the voltage feature database stores the relationship between the SOC interval and the reference charging voltage curve (i.e., the standard charging voltage curve). The specific establishment method will be described in the following embodiments and will not be elaborated here.

[0058] It can be understood that in the embodiment of the present application, an actual charging voltage curve corresponding to each SOC interval of the electric cell can be generated, the reference charging voltage curve corresponding to each SOC interval can be queried in the pre-established voltage feature database, and the required values can be calculated based on the actual charging voltage curve and the reference charging voltage curve subsequently.

[0059] In the embodiment of the present application, before querying the pre-established voltage feature database, it further includes: constructing a charging test matrix of temperature and charging current; obtaining charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, performing interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain multiple reference charging voltage curves; constructing a voltage feature database according to each SOC interval and the corresponding reference charging voltage curve.

[0060] It can be understood that in the embodiment of the present application, a charging test matrix can be constructed from two dimensions of temperature and charging current. As shown in Table 1, then charging voltage curves at different temperatures and charging rates are obtained according to the charging test matrix, interpolation processing is performed to obtain reference charging voltage curves, and finally a voltage feature database is constructed according to each SOC interval and the corresponding reference charging voltage curve. Among them, Table 1 is a charging test matrix table.

[0061] Table 1

[0062]

[0063] Further, in the embodiments of the present application, obtaining the charging voltage curve at different charging temperatures and / or different charging rates according to the charging test matrix includes: at a preset temperature, performing constant current discharge at a first preset current until a preset cut-off voltage, then switching to a second preset current for constant current discharge until the preset cut-off voltage, after standing for a first preset duration, performing constant current charge at a third preset current until the preset cut-off voltage, and recording the charging voltage curve at the current temperature and / or the current charging rate; after standing for a second preset duration, performing constant current discharge at a fourth preset current until the preset cut-off voltage, then switching to a fifth preset current for constant current discharge until the preset cut-off voltage, and after standing for a third preset duration, restarting the charging test at other charging rates and / or other charging temperatures.

[0064] Among them, the preset temperature can be set according to specific circumstances, which is the charge and discharge process under constant temperature conditions. The first preset current, the second preset current, the third preset current, the fourth preset current, and the fifth preset current can be set according to specific circumstances. The first preset duration, the second preset duration, and the third preset duration can be set according to specific circumstances, and no limitation is made thereto.

[0065] Taking the charging temperature as T1 and the charging rate as I 15 as an example, the method for obtaining the reference charging voltage curve is as follows:

[0066] 1. Perform constant current discharge at 0.3C until the preset cut-off voltage, switch to 0.05C and continue constant current discharge until the preset cut-off voltage, stand for 0.5 hours, and perform constant current charge at I 15 until the cut-off voltage, and record the voltage curve;

[0067] 2. Stand for 0.5 hours, perform constant current discharge at 0.3C until the cut-off voltage, switch to 0.05C and continue constant current discharge until the cut-off voltage, and stand for 0.5 hours. After completing the I 15 charging, restart the charging test at other rates.

[0068] In the embodiments of the present application, performing interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain multiple reference charging voltage curves includes: calculating the maximum charging capacity corresponding to the charging voltage curves at all different rates; determining the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, dividing the capacity interval into multiple grids according to the step size; calculating a first constant according to the voltage value of each grid, obtaining the charging voltage value at any charging current according to the first constant, and generating multiple reference charging voltage curves based on the charging voltage values at any charging current.

[0069] Specifically, in the embodiments of the present application, after obtaining the voltage curves at different temperatures and charging rates, interpolation processing needs to be performed. Taking the charging voltage curves at different rates at temperature T1 as an example, the interpolation method is as follows:

[0070] Calculate the maximum charging capacity Q corresponding to the charging voltage curves at all different rates max , divide the capacity intervals corresponding to all charging curves with Q max / 100 as the step size into 100 grids. In each grid, the following formula is satisfied:

[0071] AB = V, (1)

[0072] where A = (kb), V is the voltage value in the grid, solve the values of k and b in the above linear equation, and based on k and b, the charging voltage value at any charging current can be obtained.

[0073] In the embodiments of the present application, interpolation processing is performed on the charging voltage curves at different temperatures and / or different charging rates to obtain multiple reference charging voltage curves, including: calculating the maximum charging capacity corresponding to the charging voltage curves at all different temperatures; determining the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, dividing the capacity interval into multiple grids according to the step size; calculating the second constant according to the voltage value of each grid, obtaining the voltage curve under any temperature condition according to the second constant, and obtaining multiple reference charging voltage curves based on the voltage curve under any temperature condition.

[0074] Specifically, taking the charging voltage curve at the charging rate of I 11 as an example, multiple reference charging voltage curves under any temperature condition are obtained by the following method:

[0075] Calculate the maximum charging capacity Q corresponding to the charging voltage curves at all different temperatures max , divide the capacity intervals corresponding to all charging curves with Q max / 100 as the step size into 100 grids. In each grid, the following formula is satisfied:

[0076] V = ae c / T , (2)

[0077] Solve equation (2) to obtain the values of a and c, and the voltage curve under any temperature condition can be obtained through the values of a and c.

[0078] In step S103, calculate the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve in each SOC interval.

[0079] It can be understood that in the embodiments of the present application, by querying the reference charging voltage curve corresponding to each SOC interval in the pre-established voltage characteristic database, the actual capacity of the battery cell is calculated using the actual charging voltage curve and the reference charging voltage curve. The specific calculation method is described as follows.

[0080] In the embodiments of the present application, calculating the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval includes: calculating the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval, and determining the objective function according to the root mean square error; finding the optimal solution for the objective function by the least squares method to obtain the actual capacity of the battery cell.

[0081] Among them, calculating the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval includes: dividing the total charging time of the reference battery cell into different charging stages; adding interval identifiers to the SOC intervals corresponding to each charging stage, and establishing a mathematical expression between the SOC interval, SOC, and capacity according to the interval representation; using the mathematical expression to extract the actual charging voltage curve and the corresponding reference charging voltage curve, and calculating the root mean square error of the battery cell according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve of each SOC interval.

[0082] It can be understood that in the embodiments of the present application, the total charging time can be divided into different charging stages according to the numerical change of the actual charging current of the reference battery cell, the SOC intervals corresponding to each charging stage of the battery cell are marked, a mathematical expression of the SOC interval, SOC, and capacity is established according to the interval identifier, the mathematical expressions of the actual charging voltage curve and the corresponding reference charging voltage curve corresponding to the battery cell in the SOC interval are extracted according to the mathematical expression to calculate the root mean square error of the battery cell, the objective function is determined through the root mean square error, and the optimal solution of the objective function is found by the least squares method to obtain the actual capacity of the battery cell.

[0083] Specifically, in the embodiments of the present application, the entire charging process is divided into several intervals. Among them, t1 is in the first charging stage, and the corresponding charging SOC interval is denoted as θ1; t2 is in the second charging stage, and the charging voltage at the moment of t2 has tended to be stable; t3 is the moment when the second charging process is about to end, and the charging SOC interval corresponding to the moment from t2 to t3 is denoted as θ2; t4 is in the third charging stage, and the charging voltage curve at the moment of t4 has tended to be stable; t5 is the moment when the third charging process is about to end, and the charging SOC interval corresponding to the moment from t4 to t5 is denoted as θ3; the time interval division and the corresponding SOC interval division in other charging processes are similar, denoted as t6, t7, θ4; t8, t9, θ5... specifically as Figure 2 shown.

[0084] Establish the interval expressions for different SOC charging intervals θ1, θ2, θ3, θ4…, and denote the SOC at the starting moment of charging for the battery cell numbered i as The capacity is denoted as Then the expressions for different SOC intervals are respectively:

[0085]

[0086]

[0087]

[0088]

[0089] ……

[0090] Extract the actual charging voltage curves corresponding to different SOC intervals in the total charging voltage curve according to the interval identifier and the interval expression. As Figure 2 shown, extract the actual charging voltage curves corresponding to different charging stages, and denote them respectively as

[0091] Furthermore, after obtaining the actual charging voltage curve, according to the temperature and current values at different charging stages during the actual charging process, query the reference charging voltage curve (V(I, T, x)) in the voltage feature database, and calculate the root mean square error between the actual charging voltage curve of each battery cell and the reference charging voltage curve, and calculate the actual capacity of each battery cell based on the least squares method The calculation formula is as follows:

[0092]

[0093]

[0094] where K1, K2, K3, K4… are the weights during optimization for each charging stage.

[0095] Next, an estimation method for the SOC of the battery cell in the embodiment of the present application will be elaborated through a specific embodiment. As Figure 3 shown, the specific steps are as follows:

[0096] S1: Construct a feature database V = f(I, T, x) of the charging voltage - current - temperature - SOC of the LFP battery cell, that is, construct a feature database of the standard charging voltage curve (reference charging voltage curve) of the LFP battery cell;

[0097] 1. Construct an LFP charging test matrix

[0098] According to the performance parameter table of a certain LFP cell, a charging test matrix is constructed from two dimensions of temperature and charging current, as shown in Table 2. Among them, Table 2 is an example table of the charging test matrix.

[0099] Table 2

[0100]

[0101] 2. Obtain the standard charging voltage curve

[0102] Taking the charging temperature of 25°C and the charging rate of 1C as an example, the method for obtaining the reference charging voltage curve is as follows:

[0103] A. Perform constant current discharge at 0.3C until the preset cut-off voltage, switch to 0.05C and continue constant current discharge to the preset cut-off voltage, stand for 0.5 hours, charge at 1C constant current to the cut-off voltage, and record the voltage curve;

[0104] B. Stand for 0.5 hours, perform constant current discharge at 0.3C to the cut-off voltage, switch to 0.05C and continue constant current discharge to the cut-off voltage, stand for 0.5 hours.

[0105] C. After completing the 1C charging, restart the charging test at other rates.

[0106] 3. Construct the feature database

[0107] After obtaining the voltage curves at different temperatures and charging rates, interpolation processing is required to construct the voltage feature database.

[0108] Taking the charging voltage curves at different rates at 25°C as an example, the interpolation method is as follows:

[0109] Calculate the maximum charging capacity Q corresponding to the charging voltage curves at all different rates max = 100Ah. Divide the capacity intervals corresponding to all charging curves into 100 grids with a step of 1Ah. In each grid, the formula (1) is satisfied, and the linear equation (1) is solved to obtain the values of k and b. Based on k and b, the charging voltage values at any charging current can be obtained.

[0110] Taking the charging voltage curve at the charging rate of 0.1C as an example, the feature database in the temperature dimension can be obtained through the following method:

[0111] Calculate the maximum charging capacity Q corresponding to the charging voltage curves at all different temperatures max = 98Ah. Divide the capacity intervals corresponding to all charging curves into 100 grids with a step of 0.98Ah. In each grid, the formula (2) is satisfied, and the equation (2) is solved to obtain the values of a and c. Through the values of a and c, the voltage curves under any temperature conditions can be obtained.

[0112] S2. Divide the total charging time into different charging stages t1, t2, t3, t4… according to the numerical change of the actual charging current of the battery, and mark the SOC intervals corresponding to different charging stages of each battery cell as

[0113] Figure 4 is the actual charging curve of any battery cell i in a certain model of LFP battery pack. The entire charging process is divided into 7 SOC intervals, where The corresponding charging time is [0, t1], The corresponding charging time is [t2, t3], The corresponding charging time is [t4, t5], The corresponding charging time is [t6, t7], The corresponding charging time is [t8, t9], The corresponding charging time is [t 10 t 11 , The corresponding charging time is [t 12 t 13 , where the values of t1 to t 13 are shown in Table 3, with the unit of hour. Table 3 shows the time corresponding to different charging process divisions.

[0114] Table 3

[0115] <![CDATA[t1]]> <![CDATA[t2]]> <![CDATA[t3]]> <![CDATA[t4]]> <![CDATA[t5]]> <![CDATA[t6]]> <![CDATA[t7]]> <![CDATA[t8]]> <![CDATA[t9]]> <![CDATA[t 10 > <![CDATA[t 11 > <![CDATA[t 12 > <![CDATA[t 13 > 0.03 0.11 0.29 0.31 0.42 0.45 0.5 0.53 0.61 0.63 0.72 0.74 0.83

[0116] S3. Establish the interval expressions for different SOC intervals ;

[0117] The standard capacity of the selected LFP battery cell at a certain temperature is 90 Ah. The SOC (i.e., the initial SOC) at the starting moment of charging of the battery cell numbered i is denoted as The capacity is denoted as Then the expressions for different SOC intervals are respectively:

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125] S4. Extract the actual charging voltage curves corresponding to each battery cell (i) in different charging SOC intervals.

[0126] As Figure 4 shown, extract the actual charging voltage curves corresponding to different charging stages, and denote them respectively as

[0127] S5. Query the standard voltage curve through the feature database, and use the root mean square error between and the standard voltage curve as the objective function, and calculate the and initial of each battery cell through the least squares method.

[0128] According to the temperature and current values in different charging stages during the actual charging process, query the reference charging voltage curve (V(I, T, x)) in the voltage feature database, calculate the root mean square error between the actual charging voltage curve of each battery cell and the reference charging voltage curve, and calculate the actual capacity of each battery cell based on the least squares method The calculation formula is as follows:

[0129]

[0130] Among them, K1, K2, K3, K4, K5, K6, K7 are the weights during optimization for each charging stage. Calculate the actual capacity of each battery cell As shown in Table 4. Among them, Table 4 is the capacity of each battery cell in the LFP battery pack.

[0131] Table 4

[0132]

[0133]

[0134]

[0135] The method for estimating the cell capacity proposed according to the embodiments of the present application can accurately calculate the actual capacity of the cell by comparing the actual charging voltage curve of the cell with the corresponding reference charging voltage curve. Since the pre-calibrated standard reference charging voltage curve is utilized, the actual capacity of the cell can be accurately compared based on the voltage curve, avoiding the influence of the battery system on the estimation result and being effectively applicable to multiple battery systems. At the same time, the estimation method of the embodiments of the present application can be deployed on the server to improve the calculation efficiency by using the computing resources of the server; the root mean square error of the actual charging voltage curve and the reference charging voltage curve can be calculated and used to determine the objective function, and the actual capacity of the cell can be calculated by optimization using the least squares method; the total charging time of the reference cell can be divided into different charging stages, interval identifiers can be set for the SOC intervals of different charging stages, mathematical expressions for different SOC intervals can be established, and further, the actual charging voltage curve and the corresponding reference charging voltage curve can be extracted using the mathematical expressions, and the root mean square error can be calculated according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve of each SOC interval; a charging test matrix can be constructed from two dimensions of temperature and charging current, interpolation processing can be performed on the charging voltage curves obtained at different charging temperatures and rates through the charging matrix to obtain multiple reference charging voltage curves, and a voltage feature database can be constructed using them and the SOC intervals for subsequent searching of the corresponding reference charging voltage curve according to the SOC interval; interpolation processing can be performed on the charging voltage curves at different charging rates, and the reference charging voltage curve corresponding to the charging voltage value at any charging current can be calculated through a formula; interpolation processing can be performed on the charging voltage curves at different temperatures, and the reference charging voltage curve corresponding to the voltage curve under any temperature condition can be calculated through a formula.

[0136] Figure 5 It is a flowchart of another method for estimating the cell capacity according to the embodiments of the present application.

[0137] As Figure 5 shown, this method for estimating the cell capacity is applied to a server and includes the following steps:

[0138] In step S201, a charging test matrix of temperature and charging current is constructed.

[0139] Among them, the construction method of the charging test matrix has been described in the above embodiments and will not be elaborated here.

[0140] In step S202, charging voltage curves at different charging temperatures and / or different charging rates are obtained according to the charging test matrix, and interpolation processing is performed on the charging voltage curves at different temperatures and / or different charging rates to obtain the reference charging voltage curve of each SOC interval.

[0141] It can be understood that the embodiments of the present application can obtain the charging voltage curves at different charging temperatures and charging rates according to the charging test matrix, and then perform interpolation processing to obtain the reference charging voltage curves for each SOC interval. The method of interpolation processing has been described in the above embodiments and will not be elaborated here.

[0142] In step S203, a voltage feature database is constructed according to the reference charging voltage curves for each SOC interval, the reference charging voltage curves for each SOC interval are queried using the voltage feature database, and the actual capacity of the battery cell is calculated based on the actual charging voltage curve and the reference charging voltage curve for each SOC interval.

[0143] Among them, the voltage feature database stores the relationship between the SOC interval and the reference charging voltage curve, and the reference charging voltage curve corresponding to the SOC interval can be queried using the voltage feature database.

[0144] It can be understood that the embodiments of the present application can query the reference charging voltage curves for each SOC interval using the voltage feature database, calculate the actual capacity and the initial SOC of the battery cell based on the actual charging voltage curve and the corresponding reference charging voltage curve for each SOC interval, and calculate the actual SOC corresponding to the battery cell during the charging process using the actual capacity and the initial SOC. The specific calculation method has been described in the above embodiments and will not be elaborated here.

[0145] According to the method for estimating the capacity of a battery cell proposed by the embodiments of the present application, by constructing a charging test matrix from two dimensions of temperature and charging current, obtaining the charging voltage curves at different charging temperatures and charging rates, performing interpolation processing on the charging voltage curves to obtain the reference charging voltage curves, calculating the actual capacity of the battery cell based on the actual charging voltage curve and the reference charging voltage curve for each SOC interval of the battery cell, and deploying this calculation method on a server, it is not affected by the battery system and can accurately calculate the capacity of each battery cell in the battery pack.

[0146] Next, a device for estimating the capacity of a battery cell proposed according to the embodiments of the present application will be described with reference to the accompanying drawings.

[0147] Figure 6 It is a block diagram of the device for estimating the capacity of a battery cell according to the embodiments of the present application.

[0148] As Figure 6 shown, the device 10 for estimating the capacity of a battery cell includes: an acquisition module 101, an output module 102, and a first calculation module 103.

[0149] Among them, the acquisition module 101 is used to acquire the actual charging data of the battery cell within one or more state of charge (SOC) intervals; the output module 102 is used to generate the actual charging voltage curve corresponding to each SOC interval according to the actual charging data within each SOC interval, generate the actual charging voltage curve corresponding to the SOC interval according to the actual charging data, and query the pre-established voltage characteristic database with each SOC interval as the index, and output the reference charging voltage curve of each SOC interval; the first calculation module 103 is used to calculate the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval.

[0150] In the embodiment of the present application, the first calculation module 103 is further configured to: calculate the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval, and determine the objective function according to the root mean square error; find the optimal solution for the objective function by the least squares method to obtain the actual capacity of the battery cell.

[0151] In the embodiment of the present application, the first calculation module 103 is further configured to: calculate the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of each SOC interval, and determine the objective function according to the root mean square error; find the optimal solution for the objective function by the least squares method to obtain the actual capacity of the battery cell.

[0152] In the embodiment of the present application, the device 10 of the present application further includes: a processing module.

[0153] Among them, the processing module is used to construct a charging test matrix of temperature and charging current before querying the pre-established voltage characteristic database; obtain the charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, and perform interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain multiple reference charging voltage curves; construct a voltage characteristic database according to each SOC interval and the corresponding reference charging voltage curve.

[0154] In the embodiment of the present application, the processing module is further configured to: calculate the maximum charging capacity corresponding to the charging voltage curves at all different rates; determine the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, and divide the capacity interval into multiple grids according to the step size; calculate the first constant according to the voltage value of each grid, obtain the charging voltage value at any charging current according to the first constant, and generate multiple reference charging voltage curves based on the charging voltage value at any charging current.

[0155] In an embodiment of the present application, the processing module is further configured to: calculate the maximum charging capacity corresponding to the charging voltage curves at all different temperatures; determine the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, and divide the capacity interval into multiple grids according to the step size; calculate a second constant according to the voltage value of each grid, obtain the voltage curve under any temperature condition according to the second constant, and obtain a plurality of reference charging voltage curves based on the voltage curve under any temperature condition.

[0156] In an embodiment of the present application, the processing module is further configured to: at a preset temperature, perform constant current discharge at a first preset current until a preset cut-off voltage, then switch to a second preset current for constant current discharge until the preset cut-off voltage, after standing for a first preset duration, perform constant current charging at a third preset current until the preset cut-off voltage, and record the charging voltage curve at the current temperature and / or the current charging rate; after standing for a second preset duration, perform constant current discharge at a fourth preset current until the preset cut-off voltage, then switch to a fifth preset current for constant current discharge until the preset cut-off voltage, and re-perform the charging test at other charging rates and / or other charging temperatures after standing for a third preset duration.

[0157] It should be noted that the foregoing explanation of the embodiment of the method for estimating the cell capacity is also applicable to the cell capacity estimation device of this embodiment, and will not be elaborated here.

[0158] The estimation device for the cell capacity proposed in the embodiments of the present application can accurately calculate the actual capacity of the cell by comparing the actual charging voltage curve of the cell with the corresponding reference charging voltage curve. Since the pre-calibrated standard reference charging voltage curve is utilized, the actual capacity of the cell can be accurately compared based on the voltage curve, avoiding the influence of the battery system on the estimation result and being effectively applicable to multiple battery systems. At the same time, the estimation method in the embodiments of the present application can be deployed on the server to improve the calculation efficiency by utilizing the computing resources of the server; the root mean square error of the actual charging voltage curve and the reference charging voltage curve can be calculated and used to determine the objective function, and the actual capacity of the cell can be calculated by optimization using the least squares method; the total charging time of the reference cell can be divided into different charging stages, interval identifiers can be set for the SOC intervals in different charging stages, mathematical expressions for different SOC intervals can be established, and further the actual charging voltage curve and the corresponding reference charging voltage curve can be extracted using the mathematical expressions, and the root mean square error can be calculated according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve in each SOC interval; a charging test matrix can be constructed from two dimensions of temperature and charging current, interpolation processing can be performed on the charging voltage curves obtained at different charging temperatures and rates through the charging matrix to obtain multiple reference charging voltage curves, and a voltage feature database can be constructed using them and the SOC intervals for subsequent searching for the corresponding reference charging voltage curve according to the SOC interval; interpolation processing can be performed on the charging voltage curves at different charging rates, and the reference charging voltage curve corresponding to the charging voltage value at any charging current can be calculated through a formula; interpolation processing can be performed on the charging voltage curves at different temperatures, and the reference charging voltage curve corresponding to the voltage curve under any temperature condition can be calculated through a formula.

[0159] Figure 7 It is a block diagram of the estimation device for the cell capacity in another embodiment of the present application.

[0160] As Figure 7 shown, the estimation device 20 for the cell capacity is applied to the server and includes: a construction module 201, an interpolation module 202, and a second calculation module 203.

[0161] Among them, the construction module 201 is used to construct a charging test matrix of temperature and charging current; the interpolation module 202 is used to obtain the charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, and perform interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain the reference charging voltage curve for each SOC interval; the second calculation module 203 is used to construct a voltage feature database according to the reference charging voltage curve for each SOC interval, query the reference charging voltage curve for each SOC interval using the voltage feature database, and calculate the actual capacity of the cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval

[0162] It should be noted that the foregoing explanation of the embodiments of the method for estimating the capacity of the battery cell also applies to the device for estimating the capacity of the battery cell in this embodiment, and will not be elaborated here.

[0163] It should be noted that the foregoing explanation of the embodiments of the method for estimating the capacity of the battery cell also applies to the device for estimating the capacity of the battery cell in this embodiment, and will not be elaborated here.

[0164] The device for estimating the capacity of the battery cell according to the embodiment of the present application constructs a charging test matrix from two dimensions of temperature and charging current, obtains charging voltage curves at different charging temperatures and charging rates, performs interpolation processing on the charging voltage curves to obtain a reference charging voltage curve, calculates the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve of the battery cell in each SOC interval, and deploys this calculation method on the server, which is not affected by the battery system and can accurately calculate the capacity of each battery cell in the battery pack.

[0165] Figure 8 It is a schematic structural diagram of the server provided by the embodiment of the present application. The server may include:

[0166] A memory 801, a processor 802, and a computer program stored on the memory 801 and executable on the processor 802.

[0167] When the processor 802 executes the program, it implements the method for estimating the capacity of the battery cell provided in the foregoing embodiment.

[0168] Further, the server further includes:

[0169] A communication interface 803 for communication between the memory 801 and the processor 802.

[0170] The memory 801 is used to store a computer program executable on the processor 802.

[0171] The memory 801 may include a high-speed RAM (Random Access Memory) memory, and may also include a non-volatile memory, such as at least one disk memory.

[0172] If the memory 801, the processor 802, and the communication interface 803 are implemented independently, the communication interface 803, the memory 801, and the processor 802 can be interconnected via a bus and communicate with each other. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, an EISA (Extended Industry Standard Architecture) bus, or the like. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 8 only a thick line is used to represent it in Figure 8 , but it does not mean that there is only one bus or one type of bus.

[0173] Optionally, in specific implementation, if the memory 801, the processor 802, and the communication interface 803 are integrated on a chip, the memory 801, the processor 802, and the communication interface 803 can communicate with each other through an internal interface.

[0174] The processor 802 may be a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present application.

[0175] The embodiments of the present application further provide a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the method for estimating the core capacity as described above is implemented.

[0176] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, without conflict, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0177] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "N" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0178] Any process or method description, whether in a flowchart or otherwise described herein, can be understood to represent a module, segment, or portion of code that includes one or N executable instructions for implementing a customized logical function or process. The scope of the preferred embodiments of the present application includes additional implementations, where the functions may be performed in a substantially simultaneous manner or in a reverse order according to the involved functions, rather than in the order shown or discussed. This should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0179] It should be understood that various parts of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits with logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits with appropriate combinational logic gate circuits, programmable gate arrays, field-programmable gate arrays, etc.

[0180] Those of ordinary skill in the art of the present technology can understand that all or part of the steps carried by the methods of the above embodiments can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

Claims

1. A method for estimating the capacity of an electric cell, characterized in that, The method is applied to a server, and the method includes the following steps: Obtain the actual charging data of the battery cell within one or more state of charge (SOC) intervals; Generate an actual charging voltage curve for each SOC interval based on the actual charging data within each SOC interval, and query a pre-established voltage characteristic database with each SOC interval as an index, and output a reference charging voltage curve for each SOC interval; Calculate the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval; The calculating the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval includes: Calculate the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval, and determine an objective function according to the root mean square error; Find the optimal solution for the objective function by the least squares method to obtain the actual capacity of the battery cell; The calculating the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval includes: Divide the total charging time of the reference battery cell into different charging stages; Add interval identifiers to the SOC intervals corresponding to each charging stage, and establish a mathematical expression among the SOC intervals, SOC, and capacity according to the interval identifiers; Use the mathematical expression to extract the actual charging voltage curve and the corresponding reference charging voltage curve, and calculate the root mean square error of the battery cell according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve for each SOC interval.

2. The method for estimating the cell capacity according to claim 1, wherein Before querying the pre-established voltage characteristic database, it further includes: Construct a charging test matrix of temperature and charging current; Obtain charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, and perform interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain multiple reference charging voltage curves; Construct the voltage characteristic database according to each SOC interval and the corresponding reference charging voltage curve.

3. The method for estimating the cell capacity according to claim 2, wherein The performing interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain multiple reference charging voltage curves includes: Calculate the maximum charging capacity corresponding to the charging voltage curves at all different rates; Determine the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, and divide the capacity interval into multiple grids according to the step size; Calculate a first constant according to the voltage value of each grid, obtain the charging voltage value at any charging current according to the first constant, and generate multiple reference charging voltage curves based on the charging voltage value at any charging current.

4. The method for estimating the cell capacity according to claim 2, wherein The performing interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain multiple reference charging voltage curves includes: Calculate the maximum charging capacity corresponding to the charging voltage curves at all different temperatures; Determine the step size of the capacity interval corresponding to each charging voltage curve according to the maximum charging capacity, and divide the capacity interval into multiple grids according to the step size; Calculate a second constant according to each grid voltage value, obtain a voltage curve under any temperature condition according to the second constant, and obtain a plurality of reference charging voltage curves based on the voltage curve under any temperature condition.

5. The method for estimating the capacity of an electric cell according to claim 2, wherein The obtaining of the charging voltage curve at different charging temperatures and / or different charging rates according to the charging test matrix includes: At a preset temperature, perform constant current discharge at a first preset current until a preset cut-off voltage, then switch to a second preset current for constant current discharge until the preset cut-off voltage. After standing for a first preset duration, perform constant current charge at a third preset current until the preset cut-off voltage, and record the charging voltage curve at the current temperature and / or current charging rate. After standing for a second preset duration, perform constant current discharge at a fourth preset current until a preset cut-off voltage, then switch to a fifth preset current for constant current discharge until the preset cut-off voltage, and re-perform the charging test at other charging rates and / or other charging temperatures after standing for a third preset duration.

6. A method for estimating the capacity of an electric core, characterized in that, The method is applied to a server, and the method includes the following steps: Construct a charging test matrix of temperature and charging current; Obtain the charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, and perform interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain the reference charging voltage curves for each SOC interval. Construct a voltage feature database according to the reference charging voltage curves for each SOC interval, query the reference charging voltage curves for each SOC interval by using the voltage feature database, and calculate the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval. The calculating of the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval includes: Calculate the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval, and determine an objective function according to the root mean square error. Find the optimal solution for the objective function by the least squares method to obtain the actual capacity of the battery cell. The calculating of the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval includes: Divide the total charging time of the reference battery cell into different charging stages; Add interval identifiers to the SOC intervals corresponding to each charging stage, and establish a mathematical expression between the SOC interval, SOC, and capacity according to the interval identifiers. Use the mathematical expression to extract the actual charging voltage curve and the corresponding reference charging voltage curve, and calculate the root mean square error of the battery cell according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve for each SOC interval.

7. An estimation device for the capacity of an electric cell, characterized in that, The device is applied to a server, and the device includes: An acquisition module, configured to acquire the actual charging data of the battery cell within one or more state of charge (SOC) intervals. An output module, configured to generate an actual charging voltage curve for each SOC interval based on the actual charging data within each SOC interval, generate the actual charging voltage curve corresponding to the SOC interval according to the actual charging data, and use each SOC interval of the SOC interval as an index to query a pre-established voltage feature database, and output the reference charging voltage curve for each SOC interval; A first calculation module, configured to calculate the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval; The calculating the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval includes: Calculating the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval, and determining an objective function according to the root mean square error; Finding an optimal solution for the objective function by the least squares method to obtain the actual capacity of the battery cell; The calculating the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval includes: Dividing the total charging time of the reference battery cell into different charging stages; Adding interval identifiers to the SOC intervals corresponding to each charging stage, and establishing a mathematical expression between the SOC interval, SOC, and capacity according to the interval identifiers; Extracting the actual charging voltage curve and the corresponding reference charging voltage curve by using the mathematical expression, and calculating the root mean square error of the battery cell according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve for each SOC interval.

8. An estimating device for the capacity of an electric cell, characterized in that, The device is applied to a server, where the device includes: A construction module, configured to construct a charging test matrix of temperature and charging current; An interpolation module, configured to obtain charging voltage curves at different charging temperatures and / or different charging rates according to the charging test matrix, and perform interpolation processing on the charging voltage curves at different temperatures and / or different charging rates to obtain the reference charging voltage curve for each SOC interval; A second calculation module, configured to construct a voltage feature database according to the reference charging voltage curve for each SOC interval, query the reference charging voltage curve for each SOC interval by using the voltage feature database, and calculate the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval; The calculating the actual capacity of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval includes: Calculating the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval, and determining an objective function according to the root mean square error; Finding an optimal solution for the objective function by the least squares method to obtain the actual capacity of the battery cell; The calculating the root mean square error of the battery cell according to the actual charging voltage curve and the reference charging voltage curve for each SOC interval includes: Dividing the total charging time of the reference battery cell into different charging stages; Add interval identifiers to the SOC intervals corresponding to each charging stage, and establish mathematical expressions among the SOC intervals, SOC, and capacity according to the interval identifiers; Extract the actual charging voltage curve and the corresponding reference charging voltage curve by using the mathematical expressions, and calculate the root mean square error of the battery cell according to the mathematical expressions of the actual charging voltage curve and the reference charging voltage curve in each SOC interval respectively.

9. A server, characterized in that, It includes: A memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the program to implement the method for estimating the capacity of the battery cell according to any one of claims 1-6.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to be used for implementing the method for estimating the capacity of the battery cell according to any one of claims 1-6.

Images