A state of charge calculation method and device, a storage medium and a battery management system

Abstract

This application belongs to the field of battery technology, and particularly relates to a method, apparatus, computer-readable storage medium, and battery management system for calculating the state of charge (SOC). The SOC calculation method may include: determining the temperature-equivalent internal resistance related to the battery's temperature and SOC; adding the temperature-equivalent internal resistance as a correction factor to a preset first battery model to obtain a corrected second battery model; and calculating the battery's SOC using a Kalman filter algorithm based on the second battery model. This application can effectively reduce calculation errors caused by temperature differences, improve the accuracy of SOC calculation, reduce battery overcharging and over-discharging, and improve battery safety and lifespan.

Description

Technical Field

[0001] This application belongs to the field of battery technology, and in particular relates to a method, apparatus, computer-readable storage medium, and battery management system for calculating state of charge. Background Technology

[0002] With the development of battery technology, electric vehicles replacing gasoline vehicles has become a trend in the automotive industry. The State of Charge (SOC) of an electric vehicle represents the remaining charge of the battery. Timely and accurate monitoring of the battery's SOC is crucial for the safe use of electric vehicles.

[0003] In existing technologies, the main methods for calculating battery SOC include the ampere-hour integration method, the open-circuit voltage method, and the Kalman filter algorithm. However, these methods all have large calculation errors, resulting in low accuracy of the calculated SOC. This can easily lead to overcharging and over-discharging of the battery, reducing its safety and lifespan. Summary of the Invention

[0004] In view of this, embodiments of this application provide a SOC calculation method, apparatus, computer-readable storage medium, and battery management system to solve the problem of large calculation errors in existing SOC calculation methods.

[0005] A first aspect of this application provides a SOC calculation method, which may include:

[0006] Determine the temperature-equivalent internal resistance related to the battery's temperature and SOC;

[0007] The temperature equivalent internal resistance is added as a correction factor to the preset first battery model to obtain the corrected second battery model.

[0008] Based on the second battery model, the SOC of the battery is calculated using the Kalman filter algorithm.

[0009] In one specific implementation of the first aspect, determining the temperature-equivalent internal resistance related to the battery's temperature and SOC may include:

[0010] Obtain the relationship between battery operating voltage and temperature at a specified SOC;

[0011] Determine the temperature-dependent internal resistance of the battery at a specified SOC based on the corresponding relationship.

[0012] In one specific implementation of the first aspect, determining the temperature-equivalent internal resistance of the battery at a specified SOC based on the corresponding relationship may include:

[0013] The first operating voltage is determined according to the corresponding relationship; wherein, the first operating voltage is the operating voltage of the battery at a specified temperature;

[0014] Calculate the voltage difference between the first operating voltage and the second operating voltage; wherein the second operating voltage is the operating voltage of the battery at a preset reference temperature;

[0015] The temperature equivalent internal resistance of the battery at a specified temperature is determined based on the voltage difference.

[0016] In one specific implementation of the first aspect, determining the temperature equivalent internal resistance of the battery at a specified temperature based on the voltage difference may include:

[0017] The ratio of the voltage difference to the current charge / discharge rate of the battery is determined as the temperature equivalent internal resistance of the battery at a specified temperature.

[0018] In one specific implementation of the first aspect, after determining the temperature-equivalent internal resistance of the battery at a specified SOC based on the corresponding relationship, the SOC calculation method may further include:

[0019] Data fitting is performed on the temperature-dependent equivalent internal resistance at a specified SOC to obtain the fitting equation and the fitted temperature-dependent internal resistance at the specified SOC.

[0020] In one specific implementation of the first aspect, after performing data fitting on the temperature-dependent equivalent internal resistance at a specified SOC to obtain the fitting equation and the fitted temperature-dependent equivalent internal resistance at the specified SOC, the SOC calculation method may further include:

[0021] The fitting equations for other SOCs are determined based on the fitting equations under the specified SOC; wherein the coefficients of the fitting equations under other SOCs are obtained by interpolating the coefficients of the fitting equations under the specified SOC.

[0022] In one specific implementation of the first aspect, in the second battery model, the open-circuit voltage is the sum of the measured voltage, the battery model equivalent voltage, and the temperature equivalent voltage; wherein, the temperature equivalent voltage is the product of the temperature equivalent internal resistance and the load current.

[0023] A second aspect of this application provides a SOC computing device, which may include:

[0024] Temperature equivalent internal resistance determination module, used to determine the temperature equivalent internal resistance related to the battery temperature and SOC;

[0025] The battery model correction module is used to add the temperature equivalent internal resistance as a correction amount to the preset first battery model to obtain the corrected second battery model.

[0026] The Kalman filter calculation module is used to calculate the state of charge (SOC) of the battery based on the second battery model using the Kalman filter algorithm.

[0027] In one specific implementation of the second aspect, the temperature equivalent internal resistance determination module may include:

[0028] The correspondence acquisition submodule is used to obtain the correspondence between the battery's operating voltage and temperature at a specified SOC.

[0029] The temperature equivalent internal resistance determination submodule is used to determine the temperature equivalent internal resistance of the battery at a specified SOC based on the corresponding relationship.

[0030] In one specific implementation of the second aspect, the temperature equivalent internal resistance determination submodule may include:

[0031] The operating voltage determination unit is used to determine the first operating voltage according to the corresponding relationship; wherein, the first operating voltage is the operating voltage of the battery at a specified temperature;

[0032] A voltage difference calculation unit is used to calculate the voltage difference between a first operating voltage and a second operating voltage; wherein the second operating voltage is the operating voltage of the battery at a preset reference temperature;

[0033] The temperature equivalent internal resistance determination unit is used to determine the temperature equivalent internal resistance of the battery at a specified temperature based on the voltage difference.

[0034] In one specific implementation of the second aspect, the temperature equivalent internal resistance determination unit can be specifically used to: determine the ratio of the voltage difference to the current charge / discharge rate of the battery as the temperature equivalent internal resistance of the battery at a specified temperature.

[0035] In one specific implementation of the second aspect, the temperature equivalent internal resistance determination module may further include:

[0036] The data fitting submodule is used to perform data fitting on the temperature equivalent internal resistance related to temperature at a specified SOC, and obtain the fitting equation and the fitted temperature equivalent internal resistance at the specified SOC.

[0037] In one specific implementation of the second aspect, the temperature equivalent internal resistance determination module may further include:

[0038] The coefficient difference submodule is used to determine the fitting equations for other SOCs based on the fitting equations for a specified SOC; wherein the coefficients of the fitting equations for other SOCs are obtained by interpolating the coefficients of the fitting equations for the specified SOC.

[0039] In one specific implementation of the second aspect, in the second battery model, the open-circuit voltage is the sum of the measured voltage, the battery model equivalent voltage, and the temperature equivalent voltage; wherein, the temperature equivalent voltage is the product of the temperature equivalent internal resistance and the load current.

[0040] A third aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of any of the above-described SOC computing methods.

[0041] A fourth aspect of this application provides a battery management system, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of any of the above-described SOC calculation methods.

[0042] The fifth aspect of this application provides a computer program product that, when run on a battery management system, causes the battery management system to execute the steps of any of the above-described SOC calculation methods.

[0043] The beneficial effects of this application embodiment compared with the prior art are as follows: In this application embodiment, the temperature equivalent internal resistance is used to characterize the error influence of temperature on SOC calculation. The temperature equivalent internal resistance is used as a correction amount to correct the existing battery model, and Kalman filtering is performed based on the corrected battery model to obtain the battery SOC. This can effectively reduce the calculation error caused by temperature difference, improve the SOC calculation accuracy, reduce battery overcharging and over-discharging, and improve battery safety and service life. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a flowchart of one embodiment of a SOC calculation method in this application.

[0046] Figure 2 This is a schematic diagram of the battery's discharge curves at different temperatures;

[0047] Figure 3 A schematic flowchart for determining the temperature-dependent internal resistance of a battery at a specified SOC.

[0048] Figure 4 This is a schematic diagram of a second-order RC model;

[0049] Figure 5 A schematic diagram of the battery model obtained by modifying the second-order RC model;

[0050] Figure 6 A comparative diagram of SOC calculation results;

[0051] Figure 7 This is a structural diagram of one embodiment of a SOC computing device according to the present application.

[0052] Figure 8 This is a schematic block diagram of a battery management system according to an embodiment of this application. Detailed Implementation

[0053] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0055] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0056] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0057] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrases "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0058] Furthermore, in the description of this application, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0059] This application provides a SOC calculation method, apparatus, computer-readable storage medium, and battery management system, applicable to various scenarios involving SOC calculation during actual battery use. For example, it addresses the specific application scenario of calculating the SOC of an electric vehicle battery during driving or charging.

[0060] To better understand the embodiments of this application, the concepts of state of charge, charge / discharge rate, open circuit voltage, health state, and discharge curve appearing in the embodiments of this application will be explained in detail here.

[0061] (1) State of Charge (SOC), which is the ratio of the battery's remaining charge to its rated capacity. The SOC of a battery is 0 when it is fully discharged and 1 when it is fully charged.

[0062] State of Charge (SOC) is one of the important parameters of the Battery Management System (BMS), and it is also the basis for the charging and discharging control strategy and battery balancing of the entire electric vehicle. However, due to the complexity of the battery structure, SOC cannot be obtained by direct measurement. It can only be estimated by using relevant calculation methods based on certain external characteristics of the battery, such as internal resistance and current.

[0063] (2) Charge / discharge rate (C) is a measure of how fast a charge / discharge occurs.

[0064] Charge / discharge rate = charge / discharge current / rated capacity. For example, a battery with a rated capacity of 100 ampere-hours (Ah) discharged at a current of 20 amperes (A) has a discharge rate of 0.2C. If the battery is completely discharged in 1 hour, it is called a 1C discharge; if it is completely discharged in 2 hours, it is called a 1 / 2 = 0.5C discharge; and so on.

[0065] (3) Open Circuit Voltage (OCV) is the voltage measured from the two ends of the battery after the battery has been left to stand for a period of time. In other words, the potential difference between the positive and negative terminals of the battery is called OCV.

[0066] In existing technologies, obtaining OCV requires the battery to be left idle for a period of time. It is not possible to obtain OCV during normal driving or while the battery is continuously charging and discharging.

[0067] (4) State of Health (SOH), which is the ratio of the battery's current actual capacity to its rated capacity. As the battery ages, the SOH will continuously decrease.

[0068] (5) Discharge curve, which is a curve plotted with the battery's operating voltage on the ordinate and discharge time, discharge amount, and SOC or DOD on the abscissa. During battery discharge, its operating voltage constantly changes over time; a flat curve indicates stable battery operating voltage. Measuring the battery's discharge curve is one of the fundamental methods for studying battery performance. Based on the discharge curve, one can determine whether the battery's operating performance is stable and the maximum allowable current when the battery is operating stably.

[0069] To better understand the embodiments of this application, the SOC calculation method, apparatus, computer-readable storage medium, and battery management system provided according to the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0070] The SOC calculation method provided in this application can be implemented by a battery management system (BMS) of an electric vehicle. The BMS can use temperature equivalent internal resistance (TEIR) to characterize the impact of temperature on SOC calculation errors. By using TEIR as a correction factor to adjust the existing battery model, and then performing Kalman filtering based on the adjusted model, the battery SOC can be obtained. This effectively reduces calculation errors caused by temperature differences, improves SOC calculation accuracy, reduces battery overcharging and over-discharging, and enhances battery safety and lifespan.

[0071] Please see Figure 1 One embodiment of a SOC calculation method in this application may include:

[0072] Step S101: Determine the temperature-equivalent internal resistance related to the battery's temperature and SOC.

[0073] In one specific implementation of this application, the correspondence between the battery's operating voltage and temperature at a specified SOC can be obtained first.

[0074] Figure 2 The figure shows a discharge curve obtained from an actual test of a battery. It illustrates the discharge curves of the battery at 0.33C discharge at various specified temperatures: 55°C, 25°C, 0°C, -10°C, -20°C, and -30°C. The horizontal axis represents the State of Charge (SOC), and for simplicity, the percentage signs are omitted; for example, a value of 10 indicates an SOC of 10%. The vertical axis represents the operating voltage in volts (V). As can be seen from the figure, there are significant differences in the operating voltage at different temperatures. This is because the temperature difference causes changes in the battery's internal resistance.

[0075] The relationship between operating voltage and temperature at various specified SOCs (State of Charge) of 0, 5, 10, 15, 20, ..., 90, 95, and 100 is shown in the table below:

[0076]

[0077] For example, when the SOC is specified as 5, the operating voltage corresponding to 55℃ is 3.359V, the operating voltage corresponding to 25℃ is 3.367V, the operating voltage corresponding to 0℃ is 3.247V, the operating voltage corresponding to -10℃ is 3.110V, the operating voltage corresponding to -20℃ is 3.027V, and the operating voltage corresponding to -30℃ is 3.008V.

[0078] Given this correspondence, the temperature-dependent equivalent internal resistance of the battery at a specified SOC can be determined. For example... Figure 3 As shown, taking any given SOC as an example, the specific process for determining the temperature equivalent internal resistance may include the following steps:

[0079] Step S1011: Determine the first working voltage according to the corresponding relationship.

[0080] The first operating voltage is the operating voltage of the battery at a specified temperature.

[0081] Step S1012: Calculate the voltage difference between the first working voltage and the second working voltage.

[0082] The second operating voltage is the operating voltage of the battery at a preset reference temperature. In this embodiment, 25°C can be used as the reference temperature.

[0083] Step S1013: Determine the temperature equivalent internal resistance of the battery at a specified temperature based on the voltage difference.

[0084] Specifically, the ratio of the voltage difference to the current charge / discharge rate of the battery can be determined as the temperature equivalent internal resistance of the battery at a specified temperature.

[0085] For any given State of Charge (SOC), the above process can determine the battery's equivalent internal resistance at various specified temperatures, including 55°C, 25°C, 0°C, -10°C, -20°C, and -30°C. By fitting these equivalent internal resistances to the data, a fitting equation for that given SOC can be obtained. The specific form of the fitting equation can be set according to actual conditions, and this application does not impose specific limitations on this.

[0086] In one specific implementation of this application, the following quadratic fitting equation can be used:

[0087] RT =T a (T-25) 2 +T b (T-25)

[0088] Where T is temperature, R T Temperature equivalent internal resistance, in ohms (Ω), T a and T b These are the equation coefficients, and both of these equation coefficients are related to SOC.

[0089] The equivalent internal resistance at various specified temperatures, fitted under a given SOC, is shown in the table below:

[0090]

[0091]

[0092] For example, when the specified SOC is 5, the temperature equivalent internal resistance corresponding to 55℃ is -0.0242Ω, the temperature equivalent internal resistance corresponding to 25℃ is 0Ω, the temperature equivalent internal resistance corresponding to 0℃ is 0.3641Ω, the temperature equivalent internal resistance corresponding to -10℃ is 0.7770Ω, the temperature equivalent internal resistance corresponding to -20℃ is 1.0303Ω, and the temperature equivalent internal resistance corresponding to -30℃ is 1.0860Ω.

[0093] After obtaining the fitting equation for a specified SOC, any temperature (including temperatures other than the specified temperatures) can be substituted into the fitting equation to obtain the temperature equivalent internal resistance at that temperature.

[0094] After obtaining the fitting equations for each specified SOC, the fitting equations for other SOCs can be determined based on the fitting equations for the specified SOCs. The coefficients of the fitting equations for other SOCs can be obtained by interpolating the coefficients of the fitting equations for the specified SOCs.

[0095] For example, when the SOC is specified as 5, the coefficients of the fitted equation are denoted as T. a (5) and T b (5) When the SOC is specified as 10, the coefficients of the fitted equation are denoted as T. a (10) and T b (10) For any SOC between 5 and 10, the quadratic coefficients of its fitting equation can be obtained by adjusting T. a (5) and T a (10) Interpolation is performed to obtain the first-order coefficients, which can be obtained by interpolating T. b (5) and T b (10) Interpolation is performed to obtain the result.

[0096] Through the above fitting and interpolation process, the temperature equivalent internal resistance corresponding to any SOC and any temperature can be derived based on the finite specified SOC and temperature equivalent internal resistance corresponding to the specified temperature.

[0097] In one specific implementation of this application, considering that when the battery temperature is high (greater than 25°C), the effect of temperature on internal resistance is small and can even be ignored, the temperature equivalent internal resistance corresponding to temperatures below 25°C can be calculated only, thereby reducing the amount of calculation.

[0098] Step S102: Add the temperature equivalent internal resistance as a correction factor to the preset first battery model to obtain the corrected second battery model.

[0099] The first battery model can be any battery model in the prior art, including but not limited to first-order RC model, second-order RC model and other battery models.

[0100] For ease of explanation, here we will use Figure 4 The second-order RC model shown is used as an example for illustration. As shown in the figure, the second-order RC model consists of two RC network structures and a resistor connected in series, U OC Let R0 represent the battery's open-circuit voltage, R1 and R2 represent the battery's polarization resistance, C1 and C2 represent the battery's polarization capacitance, R1 and C1 connected in parallel form an RC network, R2 and C2 connected in parallel form an RC network, I represent the load current, and V0 represent the battery's measured voltage, i.e., the directly measured battery port voltage. Then, the following second-order RC model equation can be established:

[0101] V0 = U OC -U1-U2-IR0

[0102] Where U1 and U2 represent the voltages of the two RC network structures.

[0103] Adding the temperature-equivalent internal resistance as a correction factor to the second-order RC model yields the following: Figure 5 The modified battery model shown is the second battery model. As shown in the figure, R... T This is the temperature-equivalent internal resistance. By connecting it in series with two RC network structures and an ohmic resistor, we can establish the following modified battery model equation:

[0104] V0 = U OC -U1-U2-IR0-IR T

[0105] Extending the second-order RC model to other battery models, we can obtain the following general second battery model equation:

[0106] V0 = U OC -V RC -IR T

[0107] Among them, V RC Let V be the equivalent voltage of the battery model. Different battery models correspond to different equivalent voltages. For the second-order RC model, we have: V RC =U1+U2+IR0.

[0108] As can be seen from the above equations, in the second battery model, the open-circuit voltage is the sum of the measured voltage, the battery model equivalent voltage, and the temperature equivalent voltage. The temperature equivalent voltage is the product of the temperature equivalent internal resistance and the load current.

[0109] Step S103: Based on the second battery model, calculate the battery's SOC using the Kalman filter algorithm.

[0110] In one specific implementation of this application, the state equation used in the Kalman filter algorithm can be determined according to the ampere-hour integration method:

[0111]

[0112] Where K is the sequence number of the Kalman filter algorithm iteration, and SOC K-1 The SOC is the value obtained from the (K-1)th calculation. K Let SOC be the value obtained from the Kth calculation, Δt be the time interval between the two calculations, Ca be the rated capacity of the battery, SOH be the state of health of the battery, and k be the value of the battery. t is the preset temperature coefficient, and w is the error of the state equation.

[0113] Based on the second battery model, the measurement equations used in the Kalman filter algorithm can be determined:

[0114] V0(K)=U OC (SOC K )-V RC -IR T +v

[0115] Where V0(K) is the measured voltage during the Kth calculation, U OC (SOC K ) is SOC K The corresponding open-circuit voltage, v is the measurement equation error.

[0116] Once the state equation and measurement equation are determined, the Kalman filter algorithm can be used to calculate the battery's SOC. The specific calculation method of the Kalman filter algorithm can be found in any existing Kalman filter algorithm, and will not be elaborated further in this embodiment.

[0117] Figure 6 The diagram shows a comparison of the SOC calculation results. The diagram shows the discharge curve at a reference temperature of 25°C (curve 1), the actual discharge curve at -20°C (curve 2), the discharge curve at -20°C obtained by SOC calculation using the prior art method (curve 3), and the discharge curve at -20°C obtained by SOC calculation using the method in this embodiment (curve 4). It can be seen that the SOC calculation method in this embodiment effectively reduces the calculation error caused by temperature differences compared to the SOC calculation method in the prior art.

[0118] In summary, in this embodiment, the temperature equivalent internal resistance is used to characterize the error impact of temperature on SOC calculation. The temperature equivalent internal resistance is used as a correction factor to correct the existing battery model, and Kalman filtering is performed based on the corrected battery model to obtain the battery SOC. This can effectively reduce the calculation error caused by temperature differences, improve the accuracy of SOC calculation, reduce battery overcharging and over-discharging, and improve battery safety and service life.

[0119] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0120] Corresponding to the SOC calculation method provided in the above embodiment, Figure 7 This illustration shows a structural diagram of an embodiment of a SOC computing device provided in this application.

[0121] In this embodiment, a SOC computing device may include:

[0122] Temperature equivalent internal resistance determination module 701 is used to determine the temperature equivalent internal resistance related to the battery temperature and SOC.

[0123] The battery model correction module 702 is used to add the temperature equivalent internal resistance as a correction amount to the preset first battery model to obtain the corrected second battery model.

[0124] The Kalman filter calculation module 703 is used to calculate the SOC of the battery based on the second battery model using the Kalman filter algorithm.

[0125] In one specific implementation of this application embodiment, the temperature equivalent internal resistance determination module may include:

[0126] The correspondence acquisition submodule is used to obtain the correspondence between the battery's operating voltage and temperature at a specified SOC.

[0127] The temperature equivalent internal resistance determination submodule is used to determine the temperature equivalent internal resistance of the battery at a specified SOC based on the corresponding relationship.

[0128] In one specific implementation of this application embodiment, the temperature equivalent internal resistance determination submodule may include:

[0129] The operating voltage determination unit is used to determine the first operating voltage according to the corresponding relationship; wherein, the first operating voltage is the operating voltage of the battery at a specified temperature;

[0130] A voltage difference calculation unit is used to calculate the voltage difference between a first operating voltage and a second operating voltage; wherein the second operating voltage is the operating voltage of the battery at a preset reference temperature;

[0131] The temperature equivalent internal resistance determination unit is used to determine the temperature equivalent internal resistance of the battery at a specified temperature based on the voltage difference.

[0132] In one specific implementation of this application, the temperature equivalent internal resistance determination unit can be specifically used to: determine the ratio of the voltage difference to the current charge / discharge rate of the battery as the temperature equivalent internal resistance of the battery at a specified temperature.

[0133] In one specific implementation of this application embodiment, the temperature equivalent internal resistance determination module may further include:

[0134] The data fitting submodule is used to perform data fitting on the temperature equivalent internal resistance related to temperature at a specified SOC, and obtain the fitting equation and the fitted temperature equivalent internal resistance at the specified SOC.

[0135] In one specific implementation of this application embodiment, the temperature equivalent internal resistance determination module may further include:

[0136] The coefficient difference submodule is used to determine the fitting equations for other SOCs based on the fitting equations for a specified SOC; wherein the coefficients of the fitting equations for other SOCs are obtained by interpolating the coefficients of the fitting equations for the specified SOC.

[0137] In one specific implementation of this application, in the second battery model, the open-circuit voltage is the sum of the measured voltage, the battery model equivalent voltage, and the temperature equivalent voltage; wherein, the temperature equivalent voltage is the product of the temperature equivalent internal resistance and the load current.

[0138] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0139] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0140] Figure 8 A schematic block diagram of a battery management system provided in an embodiment of this application is shown. For ease of explanation, only the parts related to the embodiment of this application are shown.

[0141] like Figure 8 As shown, the battery management system 8 of this embodiment includes: a processor 80, a memory 81, and a computer program 82 stored in the memory 81 and executable on the processor 80. When the processor 80 executes the computer program 82, it implements the steps described in the various SOC computing method embodiments above, for example... Figure 1 Steps S101 to S103 are shown. Alternatively, when processor 80 executes computer program 82, it implements the functions of each module / unit in the above-described device embodiments, for example... Figure 7 The functions of modules 701 to 703 are shown.

[0142] For example, computer program 82 can be divided into one or more modules / units, one or more of which are stored in memory 81 and executed by processor 80 to complete this application. One or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 82 in battery management system 8.

[0143] Those skilled in the art will understand that Figure 8 This is merely an example of the battery management system 8 and does not constitute a limitation on the battery management system 8. It may include more or fewer components than shown, or combine certain components, or different components. For example, the battery management system 8 may also include input / output devices, network access devices, buses, etc.

[0144] The processor 80 can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0145] The memory 81 can be an internal storage unit of the battery management system 8, such as a hard disk or RAM within the battery management system 8. The memory 81 can also be an external storage device of the battery management system 8, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the battery management system 8. Furthermore, the memory 81 can include both internal storage units and external storage devices within the battery management system 8. The memory 81 is used to store computer programs and other programs and data required by the battery management system 8. The memory 81 can also be used to temporarily store data that has been output or will be output.

[0146] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0147] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0148] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0149] In the embodiments provided in this application, it should be understood that the disclosed device / battery management system and method can be implemented in other ways. For example, the device / battery management system embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0150] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0151] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0152] If an integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable storage medium can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable storage medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0153] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for calculating the state of charge, characterized in that, include: Determine the temperature equivalent internal resistance related to the battery's temperature and state of charge; the temperature equivalent internal resistance at a specified temperature is the ratio of the voltage difference between the operating voltage at the specified temperature and the operating voltage at a preset reference temperature to the current charge / discharge rate. Keeping the original ohmic resistance in the preset first battery model unchanged, the temperature equivalent internal resistance is used as a correction factor and connected in series with the original ohmic resistance in the first battery model to obtain the corrected second battery model. Based on the second battery model, the state of charge of the battery is calculated using the Kalman filter algorithm.

2. The method for calculating the state of charge according to claim 1, characterized in that, The determination of the temperature-equivalent internal resistance related to the battery's temperature and state of charge includes: Obtain the correspondence between the operating voltage and temperature of the battery under a specified state of charge; The temperature equivalent internal resistance of the battery in the specified state of charge is determined based on the correspondence.

3. The method for calculating the state of charge according to claim 2, characterized in that, Determining the temperature-equivalent internal resistance of the battery in the specified state of charge based on the correspondence includes: The first operating voltage is determined according to the correspondence; wherein, the first operating voltage is the operating voltage of the battery at a specified temperature; Calculate the voltage difference between the first operating voltage and the second operating voltage; wherein, the second operating voltage is the operating voltage of the battery at a preset reference temperature; The temperature equivalent internal resistance of the battery at the specified temperature is determined based on the voltage difference.

4. The method for calculating the state of charge according to claim 2, characterized in that, After determining the temperature-equivalent internal resistance of the battery in the specified state of charge based on the aforementioned correspondence, the method further includes: Data fitting is performed on the temperature equivalent internal resistance related to temperature under the specified charged state to obtain the fitting equation and the fitted temperature equivalent internal resistance under the specified charged state.

5. The method for calculating the state of charge according to claim 4, characterized in that, After performing data fitting on the temperature-equivalent internal resistance related to temperature under the specified charged state to obtain the fitting equation and the fitted temperature-equivalent internal resistance under the specified charged state, the method further includes: The fitting equations for other charging states are determined based on the fitting equation for the specified charging state; wherein the coefficients of the fitting equations for the other charging states are obtained by interpolation of the coefficients of the fitting equation for the specified charging state.

6. The method for calculating the state of charge according to any one of claims 1 to 5, characterized in that, In the second battery model, the open-circuit voltage is the sum of the measured voltage, the battery model equivalent voltage, and the temperature equivalent voltage; wherein, the temperature equivalent voltage is the product of the temperature equivalent internal resistance and the load current.

7. A state of charge calculation device, characterized in that, include: A temperature equivalent internal resistance determination module is used to determine the temperature equivalent internal resistance related to the battery's temperature and state of charge; the temperature equivalent internal resistance at a specified temperature is the ratio of the voltage difference between the operating voltage at the specified temperature and the operating voltage at a preset reference temperature to the current charge / discharge rate. The battery model correction module is used to keep the original ohmic resistance in the preset first battery model unchanged, and to connect the temperature equivalent internal resistance as a correction amount in series with the original ohmic resistance of the first battery model to obtain the corrected second battery model. The Kalman filter calculation module is used to calculate the state of charge of the battery based on the second battery model using the Kalman filter algorithm.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the state of charge calculation method as described in any one of claims 1 to 6.

9. A battery management system, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the state of charge calculation method as described in any one of claims 1 to 6.

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