SOC estimation method, electronic device, storage medium and vehicle

Abstract

The invention discloses an SOC estimation method, electronic equipment, a storage medium and a vehicle. The SOC estimation method comprises the following steps: acquiring battery cell parameters; obtaining the heat production quantity of the battery cell according to the battery cell parameters; determining the temperature of the battery cell according to the heat production amount and the conduction heat amount of the battery cell; determining the maximum available capacity of the battery cell according to the battery cell temperature; and determining the SOC value according to the maximum available capacity. According to the method, the maximum available capacity of the battery cell can be obtained through the temperature of the battery cell and the conduction heat, so that the SOC value is calculated, the maximum available capacity deviation of the battery cell caused by the temperature is reduced to a great extent, the accumulated error of the SOC value is reduced, and the estimation accuracy of the SOC value is improved.

Description

Technical Field

[0001] The present invention relates to the field of vehicles, and in particular to a SOC estimation method, an electronic device, a storage medium and a vehicle. Background Art

[0002] In the related art, the available capacity is currently obtained by looking up the table based on the battery pack temperature as the denominator for calculating the SOC (State of Charge) value. However, since there is a conductive material between the pack temperature and the battery cell temperature, there is a certain time delay. This will cause a difference in the available capacity obtained by looking up the table using the battery pack temperature as the battery cell temperature. In particular, when the high current charge and discharge is converted to a small current, when the battery cell heats up and is transferred to the battery pack, the battery pack temperature begins to rise and fails to drop in time, resulting in the selected available capacity not representing the battery cell capacity at that time. Selecting this capacity as the denominator obviously results in a large error, resulting in low accuracy in the SOC value calculation. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a method for estimating the state of charge (SOC). This method can obtain the maximum available capacity of a battery cell by using the battery cell temperature and heat conduction, thereby calculating the SOC value. This method can significantly reduce the deviation of the maximum available capacity of the battery cell caused by temperature, reduce the accumulated error of the SOC value, and improve the accuracy of the SOC value estimation.

[0004] A second object of the present invention is to provide an electronic device.

[0005] A third object of the present invention is to provide a computer-readable storage medium.

[0006] A fourth object of the present invention is to provide a vehicle.

[0007] In order to solve the above problems, an embodiment of the first aspect of the present invention provides an SOC estimation method, including: obtaining battery cell parameters; obtaining battery cell heat generation based on the battery cell parameters; determining the battery cell temperature based on the battery cell heat generation and conduction heat, wherein the conduction heat is the exchange heat between the battery cell and the battery pack; determining the maximum available capacity of the battery cell based on the battery cell temperature; and determining the SOC value based on the maximum available capacity.

[0008] According to the SOC estimation method of an embodiment of the present invention, when estimating the SOC value, the heat generation of the battery cell is first calculated based on the obtained battery cell parameters, and the heat conduction of the battery cell is obtained at the same time. The current battery cell temperature is obtained through the heat generation and heat conduction of the battery cell, and the maximum available capacity of the battery cell is obtained based on the current battery cell temperature, thereby calculating the SOC value, greatly reducing the maximum available capacity deviation of the battery cell caused by temperature, reducing the cumulative error of the SOC value, and improving the accuracy of the SOC value estimation.

[0009] In some embodiments, the battery cell parameters include the battery cell operating current and the battery cell initial temperature; obtaining the battery cell heat generation according to the battery cell parameters includes: determining the battery cell heat generation coefficient according to the battery cell operating current and the battery cell initial temperature; obtaining the battery cell heat generation according to the battery cell heat generation coefficient and the battery cell operating current.

[0010] In some embodiments, determining the battery cell temperature based on the heat generated by the battery cell and the heat conducted includes: obtaining the heat difference between the heat generated by the battery cell and the heat conducted; obtaining the battery cell temperature change based on the heat difference and the battery cell mass and the battery cell specific heat capacity; and determining the battery cell temperature based on the battery cell initial temperature and the battery cell temperature change.

[0011] In some embodiments, the SOC estimation method further includes: obtaining battery pack parameters, the battery pack parameters including the battery pack temperature; determining the conduction heat based on the battery pack parameters and the heat conduction parameters between the battery pack and the battery cell, wherein the heat conduction parameters include the conduction area of ​​heat exchange between the battery cell and the battery pack, the conduction coefficient of heat exchange between the battery cell and the battery pack, and the heat transfer length of heat exchange between the battery cell and the battery pack.

[0012] In some embodiments, the temperature change of the battery cell is obtained by the following formula: ; in, ; Among them, ∆t is the change in battery cell temperature before and after; Generates heat when the battery cell is working; is the current battery cell temperature; Indicates the battery pack temperature; λ Indicates the thermal conductivity of the battery cell; S Indicates the thermal conductivity area of ​​the battery cell and the battery pack; L indicates the thermal conductivity length of the battery cell and the battery pack; is the cell quality; is the specific heat capacity of the battery cell; is the heat generation coefficient of the battery cell; It is the working current of the battery cell.

[0013] In some embodiments, the SOC estimation method further includes: obtaining the rest time of the battery cell; when the rest time of the battery cell is greater than or equal to the rest time threshold, the initial temperature of the battery cell is the battery pack temperature; or, when the rest time of the battery cell is less than the rest time threshold, the initial temperature of the battery cell is the battery cell temperature of the previous estimation cycle saved.

[0014] In some embodiments, determining the SOC value according to the maximum available capacity includes: obtaining the SOC value by the following formula: ; Among them, SOC 初值 is the initial value of the battery state of charge, η is the efficiency coefficient at the current moment; is the maximum available capacity of the battery cell; is the working current.

[0015] A second aspect of the present invention provides an electronic device, comprising: at least one processor; a memory communicatively connected to the at least one processor; a computer program executable by the at least one processor is stored in the memory, and when the at least one processor executes the computer program, the SOC estimation method described in the above embodiment is implemented.

[0016] According to the electronic device of the embodiment of the present invention, the corresponding SOC estimation program can be stored in the memory. When the SOC estimation method is implemented, the maximum available capacity of the battery cell is obtained through the battery cell temperature and conductive heat, and the SOC value is calculated, which greatly reduces the maximum available capacity deviation of the battery cell caused by temperature, reduces the cumulative error of the SOC value, and improves the accuracy of the SOC value estimation.

[0017] A third aspect of the present invention provides a computer-readable storage medium, and when a computer program is executed, the SOC estimation method described in the above embodiment is implemented.

[0018] A fourth aspect of the present invention provides a vehicle, which includes the electronic device described in the above embodiment; or, the vehicle includes a battery pack and a controller, the battery pack includes at least one battery cell, and the controller is used to execute the SOC estimation method described in the above embodiment; the vehicle also includes a temperature sensor connected to the controller for detecting the battery pack temperature.

[0019] According to the vehicle of the embodiment of the present invention, when estimating the SOC value, the controller calculates the heat generated by the battery cells based on the battery cell parameters in the battery pack, and simultaneously obtains the heat conducted by the battery cells. The current battery cell temperature is obtained through the heat generated by the battery cells and the heat conducted, and the maximum available capacity of the battery cells is obtained based on the current battery cell temperature, thereby calculating the SOC value, thereby greatly reducing the maximum available capacity deviation of the battery cells caused by temperature, reducing the cumulative error of the SOC value, and improving the accuracy of the SOC value estimation.

[0020] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which: Figure 1 is a flow chart of a method for estimating SOC according to one embodiment of the present invention; Figure 2 is a schematic diagram of a battery model according to one embodiment of the present invention; Figure 3 is a flow chart of SOC estimation and processing according to one embodiment of the present invention; Figure 4 is a flow chart of SOC calculation according to one embodiment of the present invention; Figure 5 is a structural block diagram of an electronic device according to an embodiment of the present invention; Figure 6 is a structural block diagram of a vehicle according to one embodiment of the present invention; Figure 7 is a structural block diagram of a vehicle according to an embodiment of the present invention.

[0022] Reference numerals: Vehicle 200; Electronic device 100; battery pack 201; controller 202; temperature sensor 203; Processor 101; memory 102. DETAILED DESCRIPTION

[0023] The embodiments of the present invention will be described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention will be described in detail below.

[0024] In the prior art, the calculation of the battery SOC value can be achieved by the ampere-hour integration method. The formula for calculating the SOC value using the ampere-hour integration method is: ; In this formula, cap is the battery's available capacity. The battery's available capacity is used as the denominator, and its accuracy can greatly affect the SOC value. The battery's available capacity cap refers to the amount of charge that the battery can store under certain conditions, usually in ampere-hours (Ah), which represents the battery's total energy storage capacity.

[0025] The available capacity of the battery is related to the temperature of the battery cell, the charge and discharge current at the time, and the charge and discharge mode. The current technical solution is mainly based on the battery pack temperature. Through experimental test data tables, the corresponding available capacity cap of the battery at different temperatures is obtained by looking up the table, and this value is selected as the denominator to calculate the SOC. However, there is a conductive material between the battery pack temperature and the battery cell temperature, and there is a certain time delay. This will cause a difference in the available capacity obtained by looking up the table using the battery pack temperature as the battery cell temperature, resulting in low accuracy in the SOC value calculation.

[0026] In order to solve the above problems, an embodiment of the first aspect of the present invention provides an SOC estimation method, which can obtain the maximum available capacity of the battery cell through the battery cell temperature and conducted heat, thereby calculating the SOC value, greatly reducing the maximum available capacity deviation of the battery cell caused by temperature, reducing the cumulative error of the SOC value, and improving the accuracy of SOC value estimation.

[0027] Reference below Figure 1 A SOC estimation method according to an embodiment of the first aspect of the present invention is described. Figure 1 As shown, the method at least includes steps S1 to S5.

[0028] Step S1, obtaining battery cell parameters.

[0029] Specifically, when estimating the SOC value, it can be estimated by the Ampere-hour integration method. When estimating by the Ampere-hour integration method, it is necessary to look up the table based on the battery pack temperature and the experimental test data table to obtain the corresponding battery available capacity at different temperatures, so as to calculate the SOC value according to the formula. In order to reduce the calculated SOC value, the present invention uses the experimental test data table based on the battery cell temperature to look up the table to obtain the corresponding battery cell available capacity at different temperatures, so as to make the calculated SOC value more accurate. Therefore, when estimating the SOC value, it is necessary to first obtain the battery cell parameters. The battery cell parameters may include: physical size parameters such as battery cell length, width, thickness, and electrical parameters such as battery cell capacity, battery cell voltage, battery cell internal resistance and battery cell current.

[0030] Step S2: obtaining the heat generated by the battery cell according to the battery cell parameters.

[0031] Specifically, heat generation during battery cell operation is an inevitable phenomenon in the charging and discharging process. This heat generation is mainly caused by factors such as chemical reactions, resistance and current flow inside the battery cell. The heat generation power of high-energy-density batteries is usually higher. The greater the current density, the more intense the current flow inside the battery cell and the more heat is generated. The ambient temperature will affect the chemical reaction inside the battery cell. The higher the temperature, the faster the chemical reaction rate inside the battery cell, and the resistance may also change, resulting in increased heat generation. After obtaining the current battery cell parameters, the heat generation of the battery cell under the current working state is obtained by calculation.

[0032] Step S3: determining the cell temperature based on the heat generated and conducted by the cell.

[0033] Among them, the conducted heat is the heat exchanged between the battery cell and the battery pack.

[0034] Specifically, after calculating the heat generated by the battery cell under the current working state, it is necessary to consider the heat conduction of the battery cell. The battery cell will generate heat itself during operation, and the battery cell will also conduct heat with the battery pack. That is, the battery cell temperature is eventually exchanged with the ambient temperature through the battery pack. Therefore, after obtaining the heat generated by the battery cell, it is necessary to consider the heat exchange between the battery cell and the ambient temperature through the battery pack to finally obtain the battery cell temperature; if the battery cell temperature is greater than the ambient temperature, the current battery cell temperature is obtained by subtracting the heat dissipated by the battery cell to the environment from the heat generated by the battery cell; if the battery cell temperature is lower than the ambient temperature, the current battery cell temperature is obtained by adding the heat generated by the battery cell and the heat absorbed by the environment by the battery cell.

[0035] Step S4: determining the maximum available capacity of the battery cell according to the battery cell temperature.

[0036] Specifically, the maximum available capacity of a battery cell, commonly referred to as cell capacity, refers to the amount of energy that a battery or a single battery cell can store and is an important parameter for measuring battery performance. The material, design, structural dimensions, and manufacturing process of the battery cell will all affect its maximum available capacity, and will also affect the maximum available capacity of the battery cell at different temperatures. The same type of battery cell is used in the present invention, so the maximum available capacity of the battery cell is different at different temperatures. The maximum available capacity of the battery cell is usually determined through laboratory testing. In laboratory testing, the maximum available capacity of the battery cell is tested at different temperatures, and the data is recorded and summarized. After obtaining the battery cell temperature, the experimental test data table is searched to obtain the maximum available capacity of the battery cell at the current battery cell temperature.

[0037] Step S5: determining the SOC value according to the maximum available capacity.

[0038] Specifically, SOC is the state of charge of the battery, which indicates the percentage of the battery's current stored electricity relative to its maximum capacity. It is an important parameter in the battery management system, reflecting the remaining power and available status of the battery. When calculating the SOC value using the ampere-hour integration method, the battery's charge and discharge current is measured, and the current is integrated over time to calculate the amount of electricity charged or discharged from the battery, and then estimate the SOC. However, in actual applications, the maximum available capacity of the battery will change with changes in battery temperature. Therefore, to ensure the accuracy of the SOC estimation, when calculating the SOC value, the battery cell temperature is obtained in real time, and the experimental test data table is searched based on the battery cell temperature to obtain the maximum available capacity of the battery cell at the current battery cell temperature. The SOC value is then determined based on the maximum available capacity of the battery cell at the current temperature.

[0039] According to an embodiment of the present invention, when estimating the SOC value, the SOC value is estimated by first calculating the heat generated by the battery cell based on the obtained battery cell parameters, and simultaneously obtaining the heat conducted by the battery cell. The current battery cell temperature is obtained from the heat generated and conducted heat of the battery cell, and the maximum available capacity of the battery cell is obtained based on the current battery cell temperature, thereby calculating the SOC value. This method significantly reduces the deviation of the maximum available capacity of the battery cell caused by temperature, reduces the cumulative error of the SOC value, and improves the accuracy of the SOC value estimation. In some embodiments, the battery cell parameters include the battery cell operating current and the battery cell initial temperature; obtaining the battery cell heat generation based on the battery cell parameters includes: determining the battery cell heat generation coefficient based on the battery cell operating current and the battery cell initial temperature; and obtaining the battery cell heat generation based on the battery cell heat generation coefficient and the battery cell operating current.

[0040] Specifically, in order to calculate the heat generation of the battery cell, it is necessary to obtain the battery cell parameters, which include the battery cell operating current and the battery cell initial temperature; the battery cell operating current is the current when the battery cell is charging or discharging, and the battery cell heat generation coefficient can be determined based on the battery cell operating current and the battery cell initial temperature. The battery cell heat generation coefficient is affected by the battery cell material, the battery cell internal current, and the battery cell operating temperature. The battery cell heat generation coefficient corresponding to different battery cell operating currents and battery cell initial temperatures is different. Therefore, in order to accurately measure the battery cell heat generation coefficient, experimental tests are conducted on different battery cell operating currents and battery cell initial temperatures. The heat generation coefficient of the battery cell at the initial temperature is recorded. When calculating the heat generation of the battery cell, the initial temperature of the battery cell is determined. If the battery cell has been at rest for more than three hours, the initial temperature of the battery cell is equal to the detected battery pack temperature. If the battery cell has been at rest for less than three hours, the battery cell temperature may be different from the battery pack temperature. At this time, the initial temperature of the battery cell is the battery cell temperature stored at the previous moment. The heat generation coefficient of the battery cell is obtained by looking up the table based on the battery cell operating current and the initial temperature of the battery cell. The heat generation of the battery cell is calculated based on the heat generation coefficient and the battery cell operating current.

[0041] For example, when testing the heat generation coefficient of battery cells, they are grouped by their charge and discharge rates. The charge and discharge rate is a standardized value relative to the battery capacity, used to represent the current. A 1C charge or discharge current is used at the rated capacity of the battery. For example, if a battery has a rated capacity of 2000mAh (milliampere-hours), a 1C charge or discharge current is 2000mA (or 2A). A current of "0-0.3C" means the current can range from 0mA to 600mA.

[0042] The battery charge and discharge rates are divided into: 1 group 0-0.3C, 2 groups 0.3~0.5C, 3 groups 0.5C~0.8C, 4 groups 0.8C~1C... Under different battery charge and discharge rate groups, the battery cell heat generation coefficient is recorded at different temperatures. The battery cell heat generation coefficient record table is shown in the following table: Table 1 Heat generation coefficient of battery cells at different temperatures

[0043] Based on the experimental test data, the heat generation coefficients at different currents and temperatures are confirmed. The battery charge and discharge rates are divided into several groups, corresponding to several tables of battery cell heat generation coefficients at different temperatures.

[0044] In some embodiments, the battery cell temperature is determined based on the heat generated by the battery cell and the heat conducted, including: obtaining the heat difference between the heat generated by the battery cell and the heat conducted; obtaining the battery cell temperature change based on the heat difference and the battery cell mass and the battery cell specific heat capacity; and determining the battery cell temperature based on the battery cell initial temperature and the battery cell temperature change.

[0045] Specifically, the battery pack model is as follows: Figure 2 As shown, the battery cell is wrapped in a battery pack. To obtain the temperature of the battery cell, we cannot simply collect the temperature of the battery pack. We must consider the heat generated by the battery cell and the heat conducted. The heat conducted is the heat exchanged between the battery cell and the battery pack. The heat energy calculation formula is: ; in, is the total heat generated by the battery cell, m is the mass of the battery cell, C is the specific heat capacity of the battery cell, and ∆t is the change in the temperature of the battery cell before and after. By transforming the above formula, we can get the formula: ,and = Therefore, the cell temperature change can be calculated based on the heat difference, cell mass, and cell specific heat capacity. Among the cell module parameters, the cell specific heat capacity and cell mass can be measured and recorded in advance through experiments.

[0046] After calculating the heat generated by the battery cell, the temperature change of the battery cell is obtained. After the battery cell generates heat during operation, the battery cell will also exchange heat with the battery pack temperature. Therefore, after obtaining the heat generated by the battery cell, the temperature change of the battery cell is obtained, and the battery cell temperature is determined based on the initial temperature of the battery cell and the temperature change of the battery cell. If the battery cell temperature is greater than the battery pack temperature, the battery cell temperature is obtained by subtracting the temperature change of the battery cell from the heat generated by the battery cell. If the battery cell temperature is less than the battery pack temperature, the battery cell temperature is obtained by adding the temperature change of the battery cell to the heat generated by the battery cell.

[0047] In some embodiments, the SOC estimation method further includes: obtaining battery pack parameters, the battery pack parameters including the battery pack temperature; determining the conduction heat based on the battery pack parameters and the heat conduction parameters between the battery pack and the battery cell, wherein the heat conduction parameters include the conduction area of ​​heat exchange between the battery cell and the battery pack, the conduction coefficient of heat exchange between the battery cell and the battery pack, and the heat transfer length of heat exchange between the battery cell and the battery pack.

[0048] Specifically, the battery pack temperature refers to the temperature of the entire battery pack. The battery pack temperature is affected by many factors, including ambient temperature, battery pack heat dissipation design, battery charge and discharge status, etc. The estimation period can be a fixed time period, such as 1 minute or longer. During this period, the battery pack temperature may fluctuate due to various factors. In order to obtain a stable and representative temperature value, the average temperature of the battery pack during this period is calculated as the battery pack temperature.

[0049] After the battery cell is working, the temperature of the battery cell will also be exchanged with the battery pack temperature. Therefore, after obtaining the heat generated by the battery cell, the temperature change of the battery cell, that is, the conduction heat, is obtained. The battery cell temperature is determined according to the initial temperature of the battery cell and the conduction heat. After obtaining the battery pack parameters, the conduction heat is determined by calculating the battery pack parameters and the heat conduction parameters between the battery pack and the battery cell.

[0050] like Figure 2 As shown, there is a heat-conducting material between the battery cell and the battery pack. Therefore, the heat conduction parameters include the conduction area for heat exchange between the battery cell and the battery pack, and the heat transfer length for heat exchange between the battery cell and the battery pack. The heat conduction formula for the battery pack is: ; in, The heat conduction of the cell can be calculated according to the above formula: ∆T is the temperature difference of the cell, λ is the thermal conductivity coefficient of the cell, S is the thermal conduction area between the cell and the battery pack, and L is the thermal conduction length between the cell and the battery pack. The heat conduction parameters of the cell and the battery pack are calculated based on the battery pack design parameters and the laboratory experimental results to obtain the conduction area S (m2) between the cell and the battery pack. 2 ) and the thermal conduction length L(m) between the battery cell and the battery pack, and the conduction coefficient λ between the battery cell and the battery pack is measured experimentally.

[0051] In some embodiments, the temperature change of the battery cell is obtained by the following formula: ; in, ; Among them, ∆t is the change in battery cell temperature before and after; Generates heat when the battery cell is working; is the current battery cell temperature; Indicates the battery pack temperature; λ Indicates the thermal conductivity of the battery cell; S Indicates the thermal conductivity area of ​​the battery cell and the battery pack; L indicates the thermal conductivity length of the battery cell and the battery pack; is the cell quality; is the specific heat capacity of the battery cell; is the heat generation coefficient of the battery cell; It is the working current of the battery cell.

[0052] Specifically, according to the thermal energy calculation formula ,get ,and = Therefore, through the above formula and the battery pack heat conduction formula The formula for the change in cell temperature is obtained. Since the cell will exchange temperature with the battery pack, after obtaining the cell heat generation, the heat generated by the cell is subtracted from the heat conducted by the cell to obtain the total heat generated by the cell. The change in cell temperature before and after is then calculated to estimate the cell temperature. The cell temperature estimation formula is: ; in, The cell temperature at the next moment, The current cell temperature and ∆t are the changes in the cell temperature before and after. The change in the cell temperature ∆t is calculated based on the cell heat conduction Q, and the temperature difference is calculated to obtain the cell temperature at the next moment. , the temperature at the next moment is substituted into the current cell temperature to correct the current cell temperature Tcell, and the calculation is repeated according to the calculation cycle to obtain the accurate cell temperature. For example, the calculation cycle can be calculated once every 1 minute to change the cell temperature. The cycle can be adjusted according to the actual situation.

[0053] The present invention does not use the battery pack temperature as the basis for selecting the maximum available capacity. It directly uses heat changes to derive the temperature change value of the battery cell, calculates the battery cell temperature online, and selects the maximum available capacity of the battery cell based on the temperature. This can greatly reduce the delay problem caused by the battery pack temperature and reduce the SOC cumulative error.

[0054] In some embodiments, the SOC estimation method further includes: obtaining the rest time of the battery cell; when the rest time of the battery cell is greater than or equal to the rest time threshold, the initial temperature of the battery cell is the battery pack temperature; or, when the rest time of the battery cell is less than the rest time threshold, the initial temperature of the battery cell is the battery cell temperature of the previous estimation cycle saved.

[0055] Specifically, the battery cell generates heat when it is working. After the battery cell stops working and has been at rest for a period of time, the battery cell temperature can be consistent with the battery pack temperature. Therefore, when obtaining the battery cell temperature, it is necessary to determine the initial temperature of the battery cell based on the battery cell rest time. In order to determine the initial temperature of the battery cell, the battery cell rest time is judged. If the battery cell rest time is greater than or equal to the rest time threshold, the initial temperature of the battery cell is equal to the detected battery pack temperature. If the battery cell rest time is less than the rest time threshold, the battery cell rest time is short, and the battery cell temperature may be different from the battery pack temperature. At this time, the initial temperature of the battery cell is the battery cell temperature stored at the previous moment. The rest time threshold is obtained based on experiments. Based on the actual test results, the time required to confirm that the battery cell and the battery pack temperature are consistent is used as the rest time threshold.

[0056] For example, the rest time threshold can be set to 3 hours. If the cell rests for more than 3 hours and the vehicle is started, the battery pack and cell temperatures are assumed to be the same. If the cell rests for less than 3 hours, the temperature difference will be used, and the last stored cell temperature value will be used. At the end of a calculation cycle, the cell temperature for that estimation cycle is saved. If the cell stops working and the next time it is used, the cell rest time is less than 3 hours, and the current cell temperature is determined based on the cell temperature stored in the previous estimation cycle.

[0057] Reference below Figure 3 The SOC estimation step of the embodiment of the present invention is described with examples, and the specific contents are as follows.

[0058] Step S6: power on the vehicle.

[0059] Step S7: Check whether the standing time is greater than 3 hours. If yes, go to step S9; otherwise, go to step S10.

[0060] Step S8, calculating the calorific value of the battery cell during charging or discharging.

[0061] Step S9: The cell temperature is consistent with the battery temperature.

[0062] Step S10: using the last stored battery cell temperature.

[0063] Step S11: Calculate according to the heat generation formula: current cell temperature = initial cell temperature + ∆t. Store the current cell temperature when power is turned off.

[0064] Step S12: Look up the table to obtain the maximum available capacity of the battery cell according to the battery cell temperature.

[0065] Step S13: Calculate the SOC value at this time according to the SOC calculation formula.

[0066] Step S14: The vehicle is powered off and the corresponding SOC and battery cell temperature values ​​are stored.

[0067] In some embodiments, determining the SOC value according to the maximum available capacity includes: obtaining the SOC value by the following formula: ; Among them, SOC 初值 is the initial value of the battery state of charge, η is the efficiency coefficient at the current moment; is the maximum available capacity of the battery cell; For current.

[0068] Specifically, when using ampere-hour integration to calculate the SOC value, if the effect of the efficiency coefficient η on the SOC value is not considered, the SOC value calculation formula is: , the error of the calculated SOC value is too large; when calculating the SOC value, the present invention takes into account the influence of the efficiency coefficient η on the SOC value, and the efficiency coefficient η at different times is obtained through experiments to improve the accuracy of the SOC value calculation; after the whole vehicle is started, the SOC value at the current moment is obtained, that is, the initial SOC value, which can be the SOC value at the last power-off, and then according to the battery cell temperature, the maximum available capacity of the battery cell is obtained by looking up the table, and the current battery cell SOC value is calculated as the denominator and stored.

[0069] The present invention uses the heat generated by the basic battery cell after charging and discharging, combined with thermal diffusion and heat models, to perform a real-time online estimation of the battery cell temperature and adopts a related control strategy of the integral SOC calculation method.

[0070] For example, the maximum available capacity of a battery cell is different at different temperatures. The maximum available capacity of a battery cell is usually determined through laboratory testing. In the laboratory test, the maximum available capacity of the battery cell is tested at different temperatures and the data is recorded and summarized. After obtaining the battery cell temperature, the experimental test data table is searched to obtain the maximum available capacity of the battery cell at the current battery cell temperature. The maximum available capacity table of battery cells at different temperatures is shown in Table 2 below: Table 2 Maximum available capacity at different temperatures

[0071] Reference below Figure 4 The SOC calculation strategy of the embodiment of the present invention is described with examples, and the specific contents are as follows.

[0072] Step S15, input the required data, including: the specific heat capacity value Ccell of the battery cell; the heat conduction length between the battery cell and the battery pack; the heat conduction area between the battery cell and the battery pack; the battery pack temperature, which is the average temperature value within 1 minute; the battery cell temperature, which is the value stored in the memory; the charge and discharge current values, which are the absolute values ​​|i|; the battery cell rest time: Trest time, the rest parameter time; the SOC storage value, the SOC calculated value at each moment; the current integral efficiency η.

[0073] Step S16, if the rest time T is greater than or equal to the rest parameter time, then go to step S17, otherwise go to step S18.

[0074] Step S17: Initial value of battery cell temperature = average value of battery pack temperature.

[0075] Step S18: the initial value of the battery cell temperature = the battery cell temperature value at the last moment stored in the memory.

[0076] Step S19: Calculate the heat generated by the battery cell Q.

[0077] Step S20, ∆t calculation, which is performed once every 1 minute; Step S21: Calculate the cell temperature, which is calculated once every 1 minute (synchronized with the ∆t calculation).

[0078] Step S22: Look up the table to obtain the maximum available capacity Capcell of the battery cell.

[0079] Step S23, SOC calculation.

[0080] For example, when estimating SOC, after the vehicle is started, it is first confirmed whether the rest time of the battery cell is greater than or equal to the rest time threshold, and the current battery cell temperature is assigned according to the strategy. Then, the battery cell Q heat generation calculation is started (calculated in each cycle), the battery cell ∆t temperature difference calculation is calculated (calculated once every 1 minute), and the current battery cell temperature calculation is calculated (synchronously calculated once every 1 minute). The SOC calculation is performed by searching the maximum available capacity. After one cycle is completed, the timing is restarted for 1 minute and the next calculation is performed. The cycle is repeated to calculate Tcell_1, Tcell_2, etc.

[0081] The present invention primarily uses the heat generated by the battery cell during the charge and discharge process, along with physical properties such as the cell's specific heat, heat conduction area, and cell length, to calculate the actual temperature difference of the battery cell using a heat conduction formula. This allows the cell temperature to be calculated at that point. This temperature is then used to look up the maximum available capacity of the battery cell under those conditions, which is then used as the SOC denominator to more accurately calculate the SOC. Using the integral SOC calculation method, the delay caused by using temperature detection and calculation errors caused by temperature differences can be effectively reduced, improving SOC calculation accuracy and reducing SOC cumulative errors. Furthermore, this method redefines and arranges the battery pack temperature probe, allowing the cell temperature to be calculated after the temperature probe detects the battery pack temperature.

[0082] A second aspect of the present invention provides an electronic device, such as Figure 5 As shown, the electronic device 100 includes at least one processor 101 and a memory 102 .

[0083] Among them, at least one processor 101 is communicatively connected to the memory 102, and the memory 102 stores a computer program that can be executed by the at least one processor 101. When the at least one processor 101 executes the computer program, the SOC estimation method is implemented. The electronic device may include a battery manager, a vehicle controller or a domain controller in the vehicle, or other devices that can be used to estimate the SOC.

[0084] According to the electronic device of the embodiment of the present invention, the corresponding SOC estimation program can be stored in the memory. When the SOC estimation method is implemented, the maximum available capacity of the battery cell is obtained through the battery cell temperature and conductive heat, and the SOC value is calculated, which greatly reduces the maximum available capacity deviation of the battery cell caused by temperature, reduces the cumulative error of the SOC value, and improves the accuracy of the SOC value estimation.

[0085] A third aspect of the present invention provides a computer-readable storage medium, and when the computer program is executed, the SOC estimation method of the above embodiment is implemented.

[0086] A fourth aspect of the present invention provides a vehicle, such as Figure 6 As shown, the vehicle 200 includes: an electronic device 100, or Figure 7 As shown, vehicle 200 includes a battery pack 201 , a controller 202 and a temperature sensor 203 .

[0087] Among them, the battery pack 201 includes at least one battery cell, the controller 202 is used for the SOC estimation method, the temperature sensor 203 is connected to the controller 202, the temperature sensor 203 is used to detect the temperature of the battery pack 201 and send the detected temperature to the controller 202, and the controller 202 calculates the battery cell temperature based on the detected temperature of the battery pack 201.

[0088] According to the vehicle of the embodiment of the present invention, when estimating the SOC value, the controller calculates the heat generated by the battery cells based on the battery cell parameters in the battery pack, and simultaneously obtains the heat conducted by the battery cells. The current battery cell temperature is obtained through the heat generated by the battery cells and the heat conducted, and the maximum available capacity of the battery cells is obtained based on the current battery cell temperature, thereby calculating the SOC value, thereby greatly reducing the maximum available capacity deviation of the battery cells caused by temperature, reducing the cumulative error of the SOC value, and improving the accuracy of the SOC value estimation.

[0089] In the description of this specification, any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes additional implementations in which functions may be performed in a different order than shown or discussed, including performing functions in a substantially simultaneous manner or in a reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0090] The logic and / or steps represented in a flowchart or otherwise described herein, for example, can be considered a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" is any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (not exhaustive) of computer-readable media include: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in another suitable manner if necessary, and then storing it in a computer memory.

[0091] It should be understood that various components of the present invention may be implemented using hardware, software, firmware, or a combination thereof. In the aforementioned embodiments, multiple steps or methods may be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any of the following technologies known in the art, or a combination thereof, may be used: a discrete logic circuit having logic gates for implementing logic functions on data signals, an application-specific integrated circuit having suitable combinational logic gates, a programmable gate array (PGA), a field-programmable gate array (FPGA), etc.

[0092] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and 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 embodiment.

[0093] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing module, or each unit may exist physically separately, or two or more units may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or in the form of software functional modules. If the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they may also be stored in a computer-readable storage medium.

[0094] The storage medium mentioned above may be a read-only memory, a magnetic disk, or an optical disk, etc. Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and are not to be construed as limiting the present invention. Persons skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0095] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "example," "specific example," or "some examples" means that a specific feature, substrate, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, exemplary expressions of the above terms do not necessarily refer to the same embodiment or example.

[0096] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A SOC estimation method, characterized in that: include: Get battery cell parameters; Obtaining the heat generated by the battery cell according to the battery cell parameters; Determining the cell temperature based on the heat generated by the cell and the conducted heat, wherein the conducted heat is the exchange heat between the cell and the battery pack; determining the maximum available capacity of the battery cell according to the battery cell temperature; An SOC value is determined based on the maximum available capacity.

2. The SOC estimation method according to claim 1, characterized in that: The battery cell parameters include the battery cell operating current and the battery cell initial temperature; Obtaining the heat generated by the battery cell according to the battery cell parameters, including: Determining a heat generation coefficient of the battery cell according to the operating current of the battery cell and the initial temperature of the battery cell; The heat generation of the battery cell is obtained according to the heat generation coefficient of the battery cell and the operating current of the battery cell.

3. The SOC estimation method according to claim 2, characterized in that: Determining the battery cell temperature based on the heat generated and conducted heat of the battery cell includes: Obtaining a heat difference between the heat generated by the battery cell and the heat conducted; Obtaining a temperature change of the battery cell according to the heat difference, the mass of the battery cell, and the specific heat capacity of the battery cell; The battery cell temperature is determined according to the battery cell initial temperature and the battery cell temperature change.

4. The SOC estimation method according to claim 3, characterized in that: The SOC estimation method further includes: Acquire battery pack parameters, wherein the battery pack parameters include battery pack temperature; The conducted heat is determined based on the battery pack parameters and the heat conduction parameters between the battery pack and the battery cell, wherein the heat conduction parameters include the conduction area of ​​heat exchange between the battery cell and the battery pack, the conduction coefficient of heat exchange between the battery cell and the battery pack, and the heat transfer length of heat exchange between the battery cell and the battery pack.

5. The SOC estimation method according to claim 3, characterized in that: The cell temperature change is obtained by the following formula: ； in, ; Among them, ∆t is the change in battery cell temperature before and after; Generates heat when the battery cell is working; is the current battery cell temperature; Indicates the battery pack temperature; λ Indicates the thermal conductivity of the battery cell; S Indicates the thermal conductivity area of ​​the battery cell and the battery pack; L indicates the thermal conductivity length of the battery cell and the battery pack; is the cell quality; is the specific heat capacity of the battery cell; is the heat generation coefficient of the battery cell; It is the working current of the battery cell.

6. The SOC estimation method according to any one of claims 2 to 5, characterized in that: The SOC estimation method further includes: Get the battery cell idle time; When the rest time of the battery cell is greater than or equal to the rest time threshold, the initial temperature of the battery cell is the battery pack temperature; Alternatively, when the rest time of the battery cell is less than the rest time threshold, the initial battery cell temperature is the battery cell temperature of the last estimation cycle that is saved.

7. The SOC estimation method according to any one of claims 1 to 5, characterized in that: Determining an SOC value according to the maximum available capacity includes: The SOC value is obtained by the following formula: ; Among them, SOC 初值 is the initial value of the battery state of charge, η is the efficiency coefficient at the current moment; is the maximum available capacity of the battery cell; For current.

8. An electronic device, characterized in that: include: at least one processor; a memory communicatively coupled to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, and when the at least one processor executes the computer program, the SOC estimation method according to any one of claims 1 to 7 is implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed, the SOC estimation method according to any one of claims 1 to 7 is implemented.

10. A vehicle, characterized in that: The vehicle includes the electronic device according to claim 8, or the vehicle includes a battery pack and a controller, the battery pack includes at least one battery cell, and the controller is used to execute the SOC estimation method according to any one of claims 1 to 7; The vehicle also includes a temperature sensor connected to the controller for detecting the temperature of the battery pack.

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