Battery system and method for determining compensation voltage and initial SOC (State of Charge) during startup of battery system

Abstract

The invention relates to the technical field of energy storage, in particular to a battery system and a method for determining the compensation voltage and the initial SOC of the battery system when the battery system is started. The method comprises the following steps: acquiring the standing duration from the time when the battery system is turned on to the time when the battery system is turned off last time, and judging whether the standing duration does not reach a preset duration or not; if not, the compensation voltage is 0; if yes, acquiring a voltage state, a battery temperature, an equivalent circuit model of the battery and model parameters of the battery in the battery system in a standing state after the battery is started; according to the standing duration, the battery temperature, the voltage state, the equivalent circuit model and the model parameters, the compensation voltage is calculated, the accurate compensation voltage when the battery system is started can be obtained, then the accurate open-circuit voltage can be obtained, the accurate initial SOC of the battery system can be further obtained by inquiring an OCV-SOC table, and the accuracy of the battery system is improved. And the monitoring accuracy of the battery management system and the reliability and safety of the battery system are improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a battery system, and a method for determining a compensation voltage and an initial SOC when the battery is powered on. Background Art

[0002] The state of charge (SOC) of the battery system is the research focus and difficulty in the field of battery system state estimation, and is also the monitoring focus of the battery management system BMS (Battery Management System) in the battery system. SOC reflects the current remaining power of the battery system as a proportion of the total capacity, which is crucial to ensure the safety and efficient operation of the battery.

[0003] In SOC estimation, Ampere-Hour Counting (Ah Counting) is one of the most widely used methods. This method estimates SOC by accumulating the current during the battery charging and discharging process. However, the Ampere-Hour Counting method is very dependent on the accuracy of the initial SOC value. If the initial SOC value is inaccurate, all subsequent calculations will be affected, and the error of the initial SOC will gradually accumulate over time, resulting in a large deviation in the final SOC estimate. Therefore, improving the accuracy of the initial SOC at startup can greatly reduce the SOC estimation error after startup.

[0004] In order to obtain an accurate SOC of the battery system, it is necessary to accurately determine the initial SOC of the battery system when it is turned on. In the prior art, there are mainly two methods for determining the initial SOC of the battery system when it is turned on.

[0005] One is to maintain the SOC recorded at the last shutdown. This method is simple and easy to use, but it has significant defects. Since the battery will self-discharge during the period of inactivity, there is a large difference between the actual remaining capacity and the recorded SOC value. Therefore, the initial SOC recorded by this method is often inaccurate.

[0006] The second method is to obtain the initial SOC by querying the OCV-SOC table (Open Circuit Voltage - State of Charge) based on the open circuit voltage when the battery system is turned on. The effectiveness of this method depends on the battery system being stationary for a long enough time (usually more than 30 minutes) before turning on to ensure that the chemical reaction inside the battery reaches a state of equilibrium; if the on-off interval is short, this method will introduce a large error. On the other hand, due to the existence of compensation voltage (i.e., voltage changes caused by battery system temperature, self-discharge, etc. during the battery system sampling process), the actual measured open circuit voltage may not be accurate. In order to obtain an accurate open circuit voltage, these voltage changes need to be accurately measured and compensated. Summary of the invention

[0007] In view of the above problems, the present application provides a battery system and a method for determining the compensation voltage and initial SOC when the battery is powered on, which overcomes the above problems or at least partially solves the technical problem of obtaining an accurate compensation voltage.

[0008] According to one aspect of the present application, a method for determining a compensation voltage of a battery system is provided, the method comprising: obtaining a static time length from the time the battery system was powered on to the time it was last powered off, and determining whether the static time length does not reach a preset time length; if not, the compensation voltage is 0; if so, obtaining a voltage state of a battery in the battery system in a static state after powering on, a battery temperature, an equivalent circuit model of the battery and model parameters; and calculating the compensation voltage based on the static time length, the battery temperature, the voltage state and the equivalent circuit model and model parameters.

[0009] In an optional manner, the calculation of the compensation voltage based on the standing time, the battery temperature, the voltage state, and the equivalent circuit model and model parameters includes: when the voltage state is a boost state, the compensation voltage is calculated based on the standing time, the battery temperature, the equivalent circuit model and model parameters; when the voltage state is a step-down state, the step-down speed is obtained, and it is determined whether the step-down speed is greater than a preset speed; if so, the compensation voltage is calculated based on the standing time, the battery temperature, the equivalent circuit model and model parameters; if not, the compensation voltage is 0; when the voltage state is a stable state, the compensation voltage is 0.

[0010] In an optional manner, calculating the compensation voltage based on the standing time, the battery temperature, the equivalent circuit model and the model parameters includes: determining whether the battery temperature is greater than a preset temperature; if so, calculating the compensation voltage based on the standing time, the equivalent circuit model and the model parameters; if not, calculating the compensation voltage based on the standing time, the battery temperature, the preset temperature, the equivalent circuit model and the model parameters.

[0011] In an optional manner, the calculating the compensation voltage according to the static time, the equivalent circuit model and the model parameters includes: when the equivalent circuit model is a second-order RC model, the formula for calculating the compensation voltage is formula A1, and the formula A1 is: ; Said is the compensation voltage, V 1 is the first parameter, V 2 is the second parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, R 2 is the concentration difference polarization resistance, C 2 is the concentration difference polarization capacitance.

[0012] In an optional manner, the calculating the compensation voltage according to the static time, the equivalent circuit model and the model parameters includes: when the equivalent circuit model is the Thevenin model, the formula for calculating the compensation voltage is formula A2, and the formula A2 is:

[0013] Said is the compensation voltage, V 1 is the first parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is the electrochemical polarization capacitance.

[0014] In an optional manner, the calculating the compensation voltage according to the static time, the equivalent circuit model and the model parameters includes: when the equivalent circuit model is a PNGV model, the formula for calculating the compensation voltage is formula A3, and the formula A3 is:

[0015] Among them, the is the compensation voltage, V1 is the first parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, V 3 is the third parameter.

[0016] In an optional manner, the calculating the compensation voltage according to the static time, the equivalent circuit model and the model parameters includes: when the equivalent circuit model is a GNL model, the formula for calculating the compensation voltage is formula A4, and the formula A4 is:

[0017] Among them, the is the compensation voltage, V 1 is the first parameter, V 2 is the second parameter, V 3 is the third parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, R 2 is the concentration difference polarization resistance, C 2 is the concentration difference polarization capacitance.

[0018] In an optional manner, the formula for calculating the compensation voltage according to the rest time, the battery temperature, the preset temperature, the equivalent circuit model and the model parameters is:

[0019] Among them, the is the compensation voltage when the battery temperature is not greater than the preset temperature. Kb is the temperature correction factor, M is the preset temperature, T is the battery temperature, It is the compensation voltage when the battery temperature is greater than the preset temperature.

[0020] In an optional manner, the value of the first parameter is 0.02, the value of the second parameter is 0.16, and the value of the third parameter is 0.01.

[0021] According to one aspect of the present application, a method for determining an initial SOC of a battery system is provided, wherein the battery system comprises a plurality of battery cell units, and the method comprises: obtaining voltages of the respective battery cell units to obtain a plurality of cell voltages, and obtaining a maximum voltage and a minimum voltage among the plurality of cell voltages; correcting the maximum voltage according to a compensation voltage to obtain a first corrected voltage, and correcting the minimum voltage to obtain a second corrected voltage, wherein the compensation voltages are calculated by the above method; taking the first corrected voltage and the second corrected voltage as open circuit voltages, respectively, querying an OCV-SOC table to obtain a maximum SOC and a minimum SOC; and determining the initial SOC of the battery system according to the maximum SOC and the minimum SOC.

[0022] In an optional manner, the step of correcting the maximum voltage to obtain a first corrected voltage and correcting the minimum voltage to obtain a second corrected voltage based on the compensation voltage includes: when the voltage state is a boost state, the first corrected voltage is the sum of the maximum voltage and the compensation voltage, and the second corrected voltage is the sum of the minimum voltage and the compensation voltage; when the voltage state is a step-down state, the first corrected voltage is the difference between the maximum voltage and the compensation voltage, and the second corrected voltage is the difference between the minimum voltage and the compensation voltage; when the voltage state is a stable state, the first corrected voltage is the maximum voltage, and the second corrected voltage is the minimum voltage.

[0023] In an optional manner, the step of determining the initial SOC of the battery system based on the maximum SOC value and the minimum SOC value includes: obtaining the terminal SOC of the battery system when it was last shut down; determining whether the terminal SOC is within the range defined by the maximum SOC value and the minimum SOC value; if so, determining the terminal SOC as the initial SOC of the battery system; if not, when the terminal SOC is greater than the maximum SOC value, determining the maximum SOC value as the initial SOC of the battery system; when the terminal SOC is less than the minimum SOC value, determining the minimum SOC value as the initial SOC of the battery system.

[0024] In an optional manner, the step of using the first corrected voltage and the second corrected voltage as open circuit voltages, querying the OCV-SOC table, and obtaining the maximum SOC value and the minimum SOC value includes: using the first corrected voltage and the second corrected voltage as open circuit voltages, querying the T-OCV-SOC table according to the temperature of the battery system, and obtaining the maximum SOC value and the minimum SOC value.

[0025] According to one aspect of an embodiment of the present application, a battery system is provided, which includes: at least one processor, and a memory, wherein the memory is communicatively connected to the at least one processor, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method as described above.

[0026] According to one aspect of an embodiment of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of the above method.

[0027] The beneficial effects of the present application include: by using the method for determining the compensation voltage when the battery system is turned on, an accurate compensation voltage when the battery system is turned on can be obtained, and then an accurate open circuit voltage can be obtained, and the accurate initial SOC of the battery system can be further obtained by querying the OCV-SOC table, thereby improving the monitoring accuracy of the battery management system and the reliability and safety of the battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0029] Figure 1 is a schematic diagram of a battery system provided in an embodiment of the present application; Figure 2 Schematic diagram of the hardware structure of the BMS module provided in the embodiment of the present application; Figure 3 It is a flow chart of a method for determining a compensation voltage when a battery system is powered on provided in an embodiment of the present application; Figure 4 is a voltage response diagram of a battery system provided in an embodiment of the present application under pulse discharge conditions; Figure 5 is a schematic diagram of a second-order RC model provided in an embodiment of the present application; Figure 6 is a schematic diagram of the Thevenin model provided in the embodiments of the present application; Figure 7 is a schematic diagram of a PNGV model provided in an embodiment of the present application; Figure 8 is a schematic diagram of a GNL model provided in an embodiment of the present application; Fig. 9 is a schematic diagram of a flow chart of calculating a compensation voltage provided in an embodiment of the present application; Fig.10 It is a flowchart of a method for determining an initial SOC when a battery system is powered on provided in an embodiment of the present application; Fig.11 is a schematic diagram of a process for determining the SOC of a battery system provided in an embodiment of the present application; Fig.12 is a schematic diagram of a device for determining a compensation voltage when a battery system is powered on, provided in an embodiment of the present application; Fig.13 Schematic diagram of a device for determining an initial SOC when a battery system is powered on, provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field belong to the scope of protection of this application.

[0031] In addition, the technical features involved in the embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0032] See also Figure 1 , Figure 1 1 is a schematic diagram of a system provided in an embodiment of the present application, which is applicable to the battery system, a method for determining a compensation voltage when the battery system is powered on, and a method for determining an initial SOC when the battery system is powered on. The battery system includes a battery 100 and a BMS module 200. The battery 100 may be configured in a variety of ways, not limited to Figure 1 The situation shown.

[0033] The battery 100 includes a plurality of battery cells 10, and the plurality of battery cells 10 are connected in series to form the battery 100. Each battery cell 10 may be composed of one battery cell or a plurality of battery cells connected in parallel.

[0034] The battery 100 may be a lithium-ion battery, which mainly includes consumer batteries, power batteries and energy storage batteries. Among them, the consumer batteries usually require small size, light weight, high energy density and long cycle life, and are widely used in personal electronic devices such as mobile phones, laptops, tablet computers, digital cameras and portable music players. Among them, the power battery is mainly used in transportation tools such as new energy vehicles, electric bicycles, electric trains, etc., to provide the instantaneous high power output required by the vehicle to support operations such as acceleration and climbing. Among them, the energy storage battery is mostly used as a battery energy storage system for renewable energy such as solar energy, wind power, hydropower, etc., as well as in power grid peak and frequency regulation, backup power supply, microgrid and other occasions, mainly used for long-term storage and stable release of energy.

[0035] It is understandable that, in some embodiments, the battery system further includes a BMS (Battery Management System) module 200, which is responsible for monitoring the operating status of the battery cell unit 10 to ensure safe and reliable operation of the battery cell unit 10. The BMS module 200 can actually monitor and collect the state parameters of the battery cell unit 10 (including but not limited to the voltage, current, temperature, insulation resistance, etc. of the battery cell 10), and perform necessary analysis and calculation on the relevant state parameters to obtain more state evaluation parameters, and realize effective control of the battery cell unit 10 according to a specific protection control strategy to ensure the safe and reliable operation of the entire battery cell unit 10. At the same time, the BMS module 200 can exchange information with other external devices 300 (PCS, EMS, fire protection system, etc.) through its own communication interface and analog / digital input interface to form a linkage control to ensure the safe, reliable and efficient operation of the battery cell unit 10.

[0036] Embodiment 1 Before introducing in detail the method for determining the compensation voltage of the battery system, the hardware structure of the BMS module 200 provided in the embodiment of the present application is described.

[0037] See also Figure 2 , Figure 2 : is a hardware structure diagram of the BMS module 200 provided in an embodiment of the present application, which can execute the method for determining the compensation voltage of the battery system and the method for determining the initial SOC of the battery system. The BMS module 200 includes: At least one processor 21 and memory 22 (communicatively connected Figure 2 A bus connection and a processor are used as an example). A person skilled in the art can understand that Figure 2 The structure shown is only for illustration and does not limit the structure of the BMS module 200. For example, the BMS module 200 may also include Figure 2More or fewer components as shown, or with Figure 2 Different configurations are shown.

[0038] The processor 21 is used to provide computing and control capabilities, and control the BMS module 200 to execute any method provided in the following application embodiments, thereby managing the battery cell 10 accordingly.

[0039] It can be understood that the processor 21 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0040] The memory 22, as a non-transient computer-readable storage medium, can be used to store non-transient software programs, non-transient computer executable programs and modules, such as program instructions / modules corresponding to the various calculation methods in the embodiments of the present application. The processor 21 can implement the various calculation methods in any of the following method embodiments by running the non-transient software programs, instructions and modules stored in the memory 22. The memory 22 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device or other non-transient solid-state storage device. In some embodiments, the memory 22 may also include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0041] Embodiment 2 An embodiment of the present application also provides a non-volatile computer-readable storage medium, which stores computer-executable instructions, and the computer-executable instructions are executed by the battery system to perform various calculation methods in any of the following method embodiments.

[0042] An embodiment of the present application provides a computer program product, including a computing program stored on a non-volatile computer-readable storage medium, wherein the computer program includes program instructions, and when the program instructions are executed by a computer, the computer executes each computing method in any of the following method embodiments.

[0043] Through the description of the above implementation methods, ordinary technicians in this field can clearly understand that each implementation method can be implemented by means of software plus a general hardware platform, and of course it can also be implemented by hardware. Ordinary technicians in this field can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0044] Embodiment 3 The following is a discussion of a method for determining a compensation voltage when a battery system is powered on, provided in an embodiment of the present application. Figure 3 , Figure 3 : is a flow chart of a method for determining a compensation voltage when a battery system is powered on provided in an embodiment of the present application, the method comprising the following steps: Step S10, obtaining the idle time length from the time when the battery system was powered on to the time when it was last powered off, and determining whether the idle time length does not reach a preset time length.

[0045] The idle time refers to the time the battery system has been idle since it was turned on this time and the time it was last turned off.

[0046] The static state is divided into two sections. One section is the state of the battery system from the last shutdown to the current startup. The other section is the state of the battery neither charging nor discharging after the current startup until the first charge / discharge.

[0047] The static time may be obtained through a hardware clock inside the battery system and / or a network time protocol.

[0048] Step S20: if not, the compensation voltage is 0.

[0049] If the static time length of the battery system in the static state reaches the preset time length, it is determined that the compensation voltage is zero.

[0050] In some embodiments, when the battery system is not charged, discharged or any other operation that may significantly affect the state of the battery system for a period of time exceeding a preset threshold (e.g., 5 minutes), the battery system is deemed to be in a static state, and the static time of the battery system in the static state is accumulated. When the static time is greater than the preset time (e.g., 30 minutes), it is determined that the battery system is not affected by the compensation voltage, that is, the compensation voltage is determined to be zero, and the initial SOC of the battery system can be directly obtained by querying the OCV-SOC table based on the open circuit voltage of the battery system.

[0051] Step S30: If yes, then obtain the voltage state of the battery in the battery system in a static state after startup, the battery temperature, the equivalent circuit model of the battery and the model parameters.

[0052] When the standing time does not reach the preset time, it means that the chemical reaction inside the battery has not reached a state of equilibrium, so it is necessary to obtain various state parameters of the battery, including: voltage state, battery temperature, and battery equivalent circuit model and model parameters, so as to accurately determine the compensation voltage of the battery system for different voltage states.

[0053] The voltage state of the battery can be a boost state, a buck state, or a stable state. The boost state is a state where the battery voltage continues to increase, the buck state is a state where the battery voltage continues to decrease, and the stable state is a state where the battery is stable at a certain voltage value or has only slight fluctuations.

[0054] See also Figure 4 , Figure 4 This is a voltage response diagram of the battery provided in the embodiment of the present application under pulse discharge conditions. Among them, the AB segment is the voltage jump segment when the current is loaded; the BC segment is the voltage slowly changing segment after the current is loaded; the CD segment is the voltage jump segment after the current is unloaded; and the DE segment is the voltage slowly changing segment after the current is unloaded. The battery system enters a static state after the discharge is completed, for example Figure 4 The DE section, the static state in the DE section is the research focus of the embodiments of the present application, the DF section therein is a boost state where the voltage rebounds, and the FE section therein is a stable state of the voltage.

[0055] Similarly, when charging is completed and the battery enters the static state, the voltage will rebound in the initial stage of the static state, that is, it will enter the voltage reduction state and then enter the stable state.

[0056] The battery temperature of the battery system may be obtained by using a temperature sensor built into the battery system, or by using a temperature testing circuit.

[0057] The battery equivalent circuit model is designed to simulate the electrical characteristics of the battery by simplifying the circuit, so as to facilitate the analysis and prediction of battery performance. These models can help us understand the behavior of the battery in different operating scenarios, such as key indicators such as voltage, current, output power and efficiency. Common battery equivalent circuit models include the Rint model (internal resistance model), the Thevenin model (Thevenin model, also known as the first-order RC (Resistance-Capacitance, resistance-capacitance) model), the second-order RC model, the PNGV model (Partnership for a New Generation of Vehicles, new generation of automobile partnership program model), the GNL model (Generalized Nonlinear, nonlinear equivalent model), etc. Among them, the second-order RC model can better balance the model accuracy and model complexity, and has won wide recognition and adoption in the industry, becoming the preferred solution in the field of battery management system (BMS) design and performance optimization. Such as Figure 5 , 6 , 7 and 8 are second-order RC model, Thevenin model, PNGV model and GNL model respectively. Among them, U oc is the open circuit voltage, U L is the battery terminal voltage, and the resistance, capacitance and other parameters of each model are as follows: R 0 is the ohmic internal resistance, R1 is the electrochemical polarization internal resistance, C1 is the electrochemical polarization capacitance, R2 is the concentration difference polarization resistance, C2 is the concentration difference polarization capacitance, C q is the equivalent capacitance, R S is the self-discharge resistor.

[0058] When the battery system is in a static state (i.e., neither charging nor discharging) but has not yet reached a state of equilibrium, the battery system will exhibit characteristics including electrochemical polarization and concentration difference polarization. Electrochemical polarization refers to the change in potential difference caused by electrochemical reactions during the charging or discharging process of the battery system, while concentration difference polarization refers to the change in potential difference caused by the uneven concentration of the electrolyte inside the battery system. Based on the electrochemical polarity exhibited by the battery system, the electrochemical polarization internal resistance and electrochemical polarization capacitance of the battery system can be obtained; based on the concentration difference polarity exhibited by the battery system, the concentration difference polarization resistance and concentration difference polarization capacitance of the battery system can be obtained.

[0059] The identification (obtaining) of parameters such as resistance and capacitance in each model can be carried out through existing common experimental methods. For example: 1) Constant current charge and discharge test: Charge and discharge the battery at a constant current and record the voltage change over time. By analyzing the charge and discharge curves, the battery's ohmic internal resistance and electrochemical polarization resistance can be estimated.

[0060] 2) Pulse test: Apply a short current pulse to the battery and measure the instantaneous change in voltage before and after the pulse. This method can be used to estimate the dynamic internal resistance of the battery, including fast and slow response RC links.

[0061] 3) AC impedance spectroscopy: Apply a small amplitude AC signal (usually at the millivolt level) and measure the impedance of the battery over a wide frequency range. It can provide impedance information of the battery at different time scales, thereby identifying the parameters of the RC link.

[0062] 4) Step response test: Apply a step change in voltage or current to observe the dynamic response of the battery voltage. The step response can reveal the transient characteristics of the battery and help identify the RC time constant.

[0063] 5) Hybrid Pulse Power Characterization (HPPC) test: As a comprehensive dynamic test method, especially combining the features of pulse test and step response test, it includes a series of pulse charge and discharge of the battery at different states of charge (SOC) of the battery, while also considering the regeneration ability of the battery, providing a more comprehensive view of battery performance.

[0064] For example, the electrochemical polarization internal resistance can be obtained by measuring the relationship between the voltage and current of the battery system at different discharge depths and calculating the internal resistance using Ohm's law.

[0065] The electrochemical polarization capacitance can be obtained by applying a small-amplitude AC sinusoidal voltage to the battery system, measuring the AC impedance of the battery system, and obtaining the electrochemical polarization capacitance through AC impedance spectrum analysis.

[0066] The method for obtaining the concentration difference polarization resistance can be to measure the change relationship between the voltage and current of the battery system during the discharge or charging process of the battery system, calculate the voltage change caused by the current change, and thus obtain the concentration difference polarization resistance.

[0067] The concentration difference polarization capacitance can be obtained by performing an AC impedance test on the battery system, analyzing the frequency range related to the concentration difference polarization in the AC impedance spectrum, and calculating the concentration difference polarization capacitance.

[0068] Step S40, calculating the compensation voltage according to the rest time, the battery temperature, the voltage state, and the equivalent circuit model and model parameters.

[0069] When the voltage state is a boost state, the compensation voltage is calculated according to the rest time, the battery temperature, the equivalent circuit model and the model parameters.

[0070] When the voltage state is in a step-down state, the step-down speed is obtained to determine whether the step-down speed is greater than a preset speed; if so, the compensation voltage is calculated based on the standing time, the battery temperature, and the equivalent circuit model and model parameters; if not, the compensation voltage is 0.

[0071] The voltage reduction speed of the battery system can be calculated by measuring the voltage change of the battery system within a specific time, and then dividing it by the time period, and the quotient obtained is the voltage reduction speed. Specifically, a time window can be set, such as 10 seconds, and the voltage change of the battery system within these 10 seconds can be measured, and then the voltage change can be divided by 10 seconds, and the value obtained is the current voltage reduction speed.

[0072] When the voltage reduction speed is greater than the preset speed, it is considered that the battery is not in a stable state. Otherwise, it is considered that the battery is in a stable state, and at this time, the compensation voltage is determined to be zero.

[0073] The preset speed may be determined based on actual experience, for example, may be 4mV / 1000s.

[0074] When the voltage state is a stable state, the compensation voltage is 0.

[0075] In summary, when the voltage state is a boost state or a fast voltage drop state, the compensation voltage is calculated according to the rest time, the battery temperature, and the equivalent circuit model and model parameters. Fig. 9 , the specific steps are as follows: S41. Determine whether the battery temperature is greater than a preset temperature.

[0076] The preset temperature is usually room temperature, which may be 20 degrees Celsius.

[0077] S42. If yes, the compensation voltage is calculated according to the static time, the equivalent circuit model and the model parameters (Formula A).

[0078] Depending on the equivalent circuit model and model parameters, the calculation method of the compensation voltage is also different. The details are as follows: S421. When the equivalent circuit model is a second-order RC model, the formula for calculating the compensation voltage is formula A1, and the formula A1 is:

[0079] Said is the compensation voltage, V 1 is the first parameter, V 2 is the second parameter, tis the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, R 2 is the concentration difference polarization resistance, C 2 is the concentration difference polarization capacitance.

[0080] S422. When the equivalent circuit model is the Thevenin model, the formula for calculating the compensation voltage is formula A2, and the formula A2 is:

[0081] Said is the compensation voltage, V 1 is the first parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is the electrochemical polarization capacitance.

[0082] S423. When the equivalent circuit model is a PNGV model, the formula for calculating the compensation voltage is formula A3, and the formula A3 is:

[0083] Among them, the is the compensation voltage, the V 1 is the first parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, V 3 is the third parameter.

[0084] S424. When the equivalent circuit model is a GNL model, the formula for calculating the compensation voltage is formula A4, which is:

[0085] Among them, the is the compensation voltage, V 1 is the first parameter, V 2 is the second parameter, V 3 is the third parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, R 2 is the concentration difference polarization resistance, C 2 is the concentration difference polarization capacitance.

[0086] The unit of measurement for the static time in steps S421-S424 may be seconds; the first parameter V 1. Second parameter V 2. The third parameter V 3 Determined empirically, in some embodiments, the first parameter V The value of 1 is 0.02, and the second parameter V The value of 2 is 0.16, and the third parameter V The value of 3 is 0.01.

[0087] S43. If not, calculating the compensation voltage according to the rest time, the battery temperature, the preset temperature, the equivalent circuit model and model parameters (Formula B).

[0088] It is worth noting that the compensation voltage of the battery system is also affected by the temperature of the battery system. In some embodiments, the compensation voltage is calculated according to the following formula B: The formula B is:

[0089] Among them, the is the compensation voltage when the battery temperature is not greater than the preset temperature. Kb is the temperature correction factor, M is the preset temperature, T is the temperature of the battery system, It is the compensation voltage described in any one of steps S421-S424.

[0090] Among them, for the above temperature correction coefficient Kb , the acquisition method can be to obtain the ohmic internal resistance of the battery at different temperatures; the ohmic internal resistance at different temperatures divided by the ohmic internal resistance at room temperature is the temperature correction coefficient at different temperatures Kb .

[0091] The above formula B can be used to obtain the compensation voltage when the battery temperature is not greater than the preset temperature, thereby reducing the influence of temperature on the accuracy of the obtained compensation voltage.

[0092] In an embodiment of the present application, the static time length from the last shutdown of the battery system after startup is obtained, and it is determined whether the static time length does not reach the preset time length; if not, the compensation voltage is 0; if so, the voltage state of the battery in the static state after startup, the battery temperature, the equivalent circuit model and model parameters of the battery in the battery system are obtained; according to the static time length, the battery temperature, the voltage state and the equivalent circuit model and model parameters, the compensation voltage is calculated, and the accurate compensation voltage when the battery system is powered on can be obtained, and then the accurate open circuit voltage can be obtained, and the accurate initial SOC of the battery system can be further obtained by querying the OCV-SOC table, thereby improving the monitoring accuracy of the battery management system and the reliability and safety of the battery system.

[0093] Embodiment 4 The following is a discussion of the method for determining the initial SOC of the battery system provided in the embodiment of the present application. Fig.10 , Fig.10 1 is a flow chart of a method for determining an initial SOC of a battery system provided in an embodiment of the present application. The battery system includes a plurality of battery cells connected in series, and the method for determining an initial SOC of the battery system when it is powered on includes: Step S1, obtaining the voltage of each of the battery cells to obtain a plurality of cell voltages, and obtaining a maximum voltage and a minimum voltage among the plurality of cell voltages.

[0094] The battery system has a built-in BMS module, which can obtain the voltage of each of the battery cells, thereby obtaining multiple unit voltages, and further obtain the maximum voltage and the minimum voltage among the multiple unit voltages.

[0095] Step S2, according to the compensation voltage, correcting the maximum voltage to obtain a first correction voltage, and correcting the minimum voltage to obtain a second correction voltage, wherein the compensation voltage is calculated as described in the third embodiment.

[0096] In some embodiments, when the voltage state is a boost state, the first correction voltage is the sum of the maximum voltage and the compensation voltage, and the second correction voltage is the sum of the minimum voltage and the compensation voltage; when the voltage state is a step-down state, the first correction voltage is the difference between the maximum voltage and the compensation voltage, and the second correction voltage is the difference between the minimum voltage and the compensation voltage; when the voltage state is a stable state, the first correction voltage is the maximum voltage, and the second correction voltage is the minimum voltage.

[0097] Through the above method, according to the compensation voltage, the maximum voltage is corrected to obtain a first corrected voltage, and the minimum voltage is corrected to obtain a second corrected voltage, so that for different voltage states, such as a boost state, a buck state, and a stable state, there will be different methods of correcting the maximum voltage and the minimum voltage. The battery system can obtain an accurate open circuit voltage under different working conditions, thereby improving the accuracy of querying the OCV-SOC table based on the open circuit voltage and further determining the initial SOC of the battery system.

[0098] Step S3: taking the first corrected voltage and the second corrected voltage as open circuit voltages respectively, querying an OCV-SOC table to obtain a maximum SOC value and a minimum SOC value.

[0099] Among them, the OCV-SOC table is the open circuit voltage-state of charge table. When the battery system leaves the factory, the OCV and SOC corresponding relationship table is preset and stored in the BMS module. The corresponding state of charge can be queried by determining the open circuit voltage of the battery system.

[0100] In some embodiments, the step of using the first and second corrected voltages as open circuit voltages, querying the OCV-SOC table, and obtaining the maximum SOC value and the minimum SOC value, i.e., step S3, includes: using the first and second corrected voltages as open circuit voltages, querying the T-OCV-SOC table according to the temperature of the battery system, and obtaining the maximum SOC value and the minimum SOC value. That is, the influence of the temperature of the battery system on the SOC of the battery system is introduced, so that on the one hand, the accuracy of the obtained maximum SOC value and the minimum SOC value is high, and on the other hand, the operation stability and safety of the battery system can be guaranteed.

[0101] Step S4, determining the initial SOC of the battery system according to the maximum SOC value and the minimum SOC value.

[0102] There are many methods for determining the initial SOC of the battery system based on the maximum SOC value and the minimum SOC value, such as taking the average of the maximum SOC value and the minimum SOC value as the initial SOC of the battery system, or other methods may be used. Fig.11 The step of determining the initial SOC of the battery system according to the maximum SOC value and the minimum SOC value, i.e., step S4, includes: Step S401, obtaining the terminal SOC of the battery system when it was last shut down.

[0103] During the charging and discharging process of the battery system, the BMS module usually records the electrical parameters of the battery system, such as voltage, current and SOC at each stage, so as to obtain the terminal SOC of the battery system when it was last shut down.

[0104] It is worth noting that if the terminal SOC of the battery system at the last shutdown cannot be found, the preset SOC value is used as the terminal SOC at the last shutdown. The preset SOC value may be 50%.

[0105] Step S402, determining whether the terminal SOC is within the range defined by the maximum SOC value and the minimum SOC value, if so, executing step S403, if not, executing step S404.

[0106] Step S403: determining the terminal SOC as the initial SOC of the battery system.

[0107] Step S404, when the terminal SOC is greater than the maximum SOC value, the maximum SOC value is determined as the initial SOC of the battery system; when the terminal SOC is less than the minimum SOC value, the minimum SOC value is determined as the initial SOC of the battery system.

[0108] In order to facilitate readers to understand the inventive concept of the present application, the method for determining the initial SOC of the battery system of the present application is now verified in combination with experiments.

[0109] Experimental method: Take 5 battery systems, place them in an environmental chamber until they reach the test temperature (25°C for example), and verify the initial SOC of each battery system.

[0110] For any battery system, first charge / discharge the battery system to the test SOC value (taking the SOC value of 30% as an example), then manually modify the SOC to the wrong SOC (for example, 60%), and shut down the system; let the battery system stand for, for example, 1min, 10min, 20min, 30min (corresponding to the above-mentioned standing time), and 60min, and after powering on, observe whether the initial SOC of the battery system is corrected to the test SOC value (for example, the above-mentioned 30%).

[0111] In addition, modify the test temperature and test SOC value and repeat the above test.

[0112] When the method for determining the initial SOC of the battery system provided in the embodiment of the present application is used, the initial SOC of each battery system tested can be corrected to the test SOC value, indicating that the initial SOC determined by the method for determining the initial SOC of the battery system provided in the embodiment of the present application has high accuracy and good reliability.

[0113] In the embodiment of the present application, by obtaining the voltage of each of the battery cells, a plurality of cell voltages are obtained, and the maximum voltage and the minimum voltage among the plurality of cell voltages are obtained; according to the compensation voltage, the maximum voltage is corrected to obtain a first correction voltage, and the minimum voltage is corrected to obtain a second correction voltage, and the compensation voltage is calculated as described in the method of the third embodiment; the first correction voltage and the second correction voltage are respectively used as the open circuit voltage, and the OCV-SOC table is queried to obtain the maximum SOC and the minimum SOC; according to the maximum SOC and the minimum SOC, the initial SOC of the battery system is determined, and the initial SOC of the battery system can be accurately determined, thereby providing an accurate reference basis for subsequent charge and discharge management. In practical applications, this determination method can improve the use efficiency and life of the battery system, and reduce the degradation of the battery system performance caused by inaccurate initial SOC estimation of the battery system.

[0114] Embodiment 5 The following is a discussion of the device for determining the compensation voltage when the battery system is turned on provided in the embodiment of the present application. Fig.12 , Fig.12 It is a schematic diagram of a device for determining a compensation voltage when a battery system is powered on provided in an embodiment of the present application. The device 1 for determining a compensation voltage when a battery system is powered on includes a first judgment module 11, which is used to obtain the static time length from the time when the battery system is powered on to the time when it was last powered off, and to determine whether the static time length has not reached a preset time length. If not, a zeroing module 12 is entered; if so, a first acquisition module 13 is entered; the zeroing module 12 is used to set the compensation voltage to 0; the first acquisition module 13 is used to obtain the voltage state of the battery in the battery system in a static state after powering on, the battery temperature, the equivalent circuit model and model parameters of the battery; a first calculation module 14 is used to calculate the compensation voltage according to the static time length, the battery temperature, the voltage state and the equivalent circuit model and model parameters.

[0115] In some embodiments, the first calculation module 14 is used to calculate the compensation voltage according to the standing time, the battery temperature, and the equivalent circuit model and model parameters when the voltage state is a boost state; when the voltage state is a step-down state, obtain the step-down speed and determine whether the step-down speed is greater than a preset speed; if so, calculate the compensation voltage according to the standing time, the battery temperature, and the equivalent circuit model and model parameters; if not, the compensation voltage is 0; when the voltage state is a stable state, the compensation voltage is 0.

[0116] In some embodiments, the first calculation module 14 includes: a first judgment unit 141, used to judge whether the battery temperature is greater than a preset temperature; if so, execute the first calculation unit 142, if not, execute the second calculation unit 143; the first calculation unit 142, used to calculate the compensation voltage according to the standing time, the equivalent circuit model and model parameters; the second calculation unit 143, used to calculate the compensation voltage according to the standing time, the battery temperature, the preset temperature, the equivalent circuit model and model parameters.

[0117] In some embodiments, the first calculation unit 142 is specifically used for calculating the compensation voltage using the formula A1 when the equivalent circuit model is a second-order RC model. The formula A1 is: ; Said is the compensation voltage, V 1 is the first parameter, V 2 is the second parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, R 2 is the concentration difference polarization resistance, C 2 is the concentration difference polarization capacitance.

[0118] In some embodiments, the first calculation unit 142 is further configured to calculate the compensation voltage using the formula A2 when the equivalent circuit model is the Thevenin model. The formula A2 is:

[0119] Said is the compensation voltage, V 1 is the first parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is the electrochemical polarization capacitance.

[0120] In some embodiments, the first calculation unit 142 is further configured to calculate the compensation voltage using the formula A3 when the equivalent circuit model is a PNGV model. The formula A3 is:

[0121] Among them, the is the compensation voltage, V 1 is the first parameter, t is the standing time,R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, V 3 is the third parameter.

[0122] In some embodiments, the first calculation unit 142 is further configured to calculate the compensation voltage using the formula A4 when the equivalent circuit model is a GNL model. The formula A4 is:

[0123] Among them, the is the compensation voltage, V 1 is the first parameter, V 2 is the second parameter, V 3 is the third parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, R 2 is the concentration difference polarization resistance, C 2 is the concentration difference polarization capacitance.

[0124] In some embodiments, the formula of the second calculation unit 143 is:

[0125] Among them, the is the compensation voltage when the battery temperature is not greater than the preset temperature. Kb is the temperature correction factor, M is the preset temperature, T is the battery temperature, It is the compensation voltage when the battery temperature is greater than the preset temperature.

[0126] In some embodiments, the value of the first parameter is 0.02, the value of the second parameter is 0.16, and the value of the third parameter is 0.01.

[0127] In an embodiment of the present application, the first judgment module 11 obtains the static time length from the last shutdown after the battery system is turned on, and determines whether the static time length does not reach the preset time length. If not, enter the zeroing module 12; if so, enter the first acquisition module 13; the compensation voltage is set to 0 through the zeroing module 12; the voltage state of the battery in the static state after startup, the battery temperature, the equivalent circuit model and model parameters of the battery are obtained through the first acquisition module 13; the compensation voltage is calculated by the first calculation module 14 according to the static time length, the battery temperature, the voltage state and the equivalent circuit model and model parameters, so that an accurate compensation voltage can be obtained when the battery system is turned on, and then an accurate open circuit voltage can be obtained, and the accurate initial SOC of the battery system can be further obtained by querying the OCV-SOC table, thereby improving the monitoring accuracy of the battery system management system and the reliability and safety of the battery system.

[0128] Embodiment 6 The following is a discussion of the initial SOC determination device for the battery system when it is powered on provided in the embodiment of the present application. Fig.13 , Fig.13 : It is a schematic diagram of a device for determining the initial SOC of a battery system when it is powered on provided in an embodiment of the present application. The device 2 for determining the initial SOC of a battery system when it is powered on includes a first acquisition part 21, which is used to acquire the voltage of each of the battery cells, obtain multiple cell voltages, and obtain the maximum voltage and the minimum voltage among the multiple cell voltages; a correction part 22, which is used to correct the maximum voltage to obtain a first corrected voltage and correct the minimum voltage to obtain a second corrected voltage according to a compensation voltage, and the compensation voltage is calculated as described in Example 3; a query part 23, which is used to use the first corrected voltage and the second corrected voltage as open circuit voltages, respectively, to query the OCV-SOC table to obtain the maximum SOC and the minimum SOC; a determination part 24, which is used to determine the initial SOC of the battery system according to the maximum SOC and the minimum SOC.

[0129] In some embodiments, the correction part 22 is specifically used for when the voltage state is a boost state, the first correction voltage is the sum of the maximum voltage and the compensation voltage, and the second correction voltage is the sum of the minimum voltage and the compensation voltage; when the voltage state is a step-down state, the first correction voltage is the difference between the maximum voltage and the compensation voltage, and the second correction voltage is the difference between the minimum voltage and the compensation voltage; when the voltage state is a stable state, the first correction voltage is the maximum voltage, and the second correction voltage is the minimum voltage. In some embodiments, the determination part 24 includes: a first acquisition unit 241, used to obtain the terminal SOC of the battery system when it was last shut down; a first judgment unit 242, used to judge whether the terminal SOC is within the range defined by the maximum SOC value and the minimum SOC value, if so, enter the first determination unit 243, if not, enter the second determination unit 244; the first determination unit 243, used to determine the terminal SOC as the initial SOC of the battery system; the second determination unit 244, used to determine the maximum SOC value as the initial SOC of the battery system when the terminal SOC is greater than the maximum SOC value; when the terminal SOC is less than the minimum SOC value, determine the minimum SOC value as the initial SOC of the battery system.

[0130] In some embodiments, the query part 23 is specifically used to use the first corrected voltage and the second corrected voltage as open circuit voltages respectively, query the T-OCV-SOC table according to the temperature of the battery system, and obtain the maximum SOC value and the minimum SOC value.

[0131] In the embodiment of the present application, the voltage of each of the battery cells is obtained by the first acquisition part 21 to obtain multiple cell voltages, and the maximum voltage and the minimum voltage among the multiple cell voltages are obtained; the correction part 22 corrects the maximum voltage to obtain the first corrected voltage according to the compensation voltage, and corrects the minimum voltage to obtain the second corrected voltage, and the compensation voltage is calculated as described in the method of the third embodiment; the query part 23 uses the first corrected voltage and the second corrected voltage as the open circuit voltage, respectively, and queries the OCV-SOC table to obtain the maximum SOC and the minimum SOC; the determination part 24 determines the initial SOC of the battery system according to the maximum SOC and the minimum SOC, and the initial SOC of the battery system can be accurately determined, thereby providing an accurate reference basis for subsequent charge and discharge management. In practical applications, this determination method can improve the use efficiency and life of the battery system, and reduce the degradation of the battery system performance caused by inaccurate initial SOC estimation of the battery system.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for determining a compensation voltage when a battery system is turned on, characterized in that: The method comprises: Obtaining the static time length from the last time the battery system was turned on to the last time it was turned off, and determining whether the static time length does not reach a preset time length; If not, the compensation voltage is 0; If yes, then obtaining the voltage state of the battery in the battery system in a static state after startup, the battery temperature, the equivalent circuit model of the battery and the model parameters; The compensation voltage is calculated according to the rest time, the battery temperature, the voltage state, and the equivalent circuit model and model parameters.

2. The method according to claim 1, characterized in that The calculating the compensation voltage according to the rest time, the battery temperature, the voltage state, and the equivalent circuit model and model parameters includes: When the voltage state is a boost state, calculating the compensation voltage according to the rest time, the battery temperature, and the equivalent circuit model and model parameters; When the voltage state is in a step-down state, the step-down speed is obtained, and it is determined whether the step-down speed is greater than a preset speed; if so, the compensation voltage is calculated according to the rest time, the battery temperature, and the equivalent circuit model and model parameters; if not, the compensation voltage is 0; When the voltage state is a stable state, the compensation voltage is 0.

3. The method according to claim 2, characterized in that The calculating the compensation voltage according to the rest time, the battery temperature, and the equivalent circuit model and model parameters includes: Determining whether the battery temperature is greater than a preset temperature; If yes, calculating the compensation voltage according to the static time, the equivalent circuit model and the model parameters; If not, the compensation voltage is calculated according to the rest time, the battery temperature, the preset temperature, the equivalent circuit model and model parameters.

4. The method according to claim 3, characterized in that The calculating the compensation voltage according to the static time, the equivalent circuit model and the model parameters comprises: When the equivalent circuit model is a second-order RC model, the formula for calculating the compensation voltage is formula A1, and the formula A1 is: Said is the compensation voltage, V 1 is the first parameter, V 2 is the second parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, R 2 is the concentration difference polarization resistance, C 2 is the concentration difference polarization capacitance.

5. The method according to claim 3, characterized in that: The calculating the compensation voltage according to the static time, the equivalent circuit model and the model parameters comprises: When the equivalent circuit model is the Thevenin model, the formula for calculating the compensation voltage is formula A2, and the formula A2 is: Said is the compensation voltage, V 1 is the first parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is the electrochemical polarization capacitance.

6. The method according to claim 3, characterized in that The calculating the compensation voltage according to the static time, the equivalent circuit model and the model parameters comprises: When the equivalent circuit model is a PNGV model, the formula for calculating the compensation voltage is formula A3, and the formula A3 is: Among them, the is the compensation voltage, V 1 is the first parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, V 3 is the third parameter.

7. The method according to claim 3, characterized in that The calculating the compensation voltage according to the static time, the equivalent circuit model and the model parameters comprises: When the equivalent circuit model is a GNL model, the formula for calculating the compensation voltage is formula A4, which is: Among them, the is the compensation voltage, the V 1 is the first parameter, V 2 is the second parameter, V 3 is the third parameter, t is the standing time, R 1 is the electrochemical polarization internal resistance, C 1 is an electrochemical polarization capacitor, R 2 is the concentration difference polarization resistance, C 2 is the concentration difference polarization capacitance.

8. The method according to any one of claims 4 to 7, characterized in that: The formula for calculating the compensation voltage according to the rest time, the battery temperature, the preset temperature, the equivalent circuit model and the model parameters is: Among them, the is the compensation voltage when the battery temperature is not greater than the preset temperature, Kb is the temperature correction factor, M is the preset temperature, T is the battery temperature, It is the compensation voltage when the battery temperature is greater than the preset temperature.

9. The method according to claim 8, characterized in that The value of the first parameter is 0.02, the value of the second parameter is 0.16, and the value of the third parameter is 0.

01.

10. A method for determining the initial SOC of a battery system when it is turned on, characterized in that: The battery system includes a plurality of battery cells connected in series, and the method includes: Obtaining the voltage of each of the battery cells to obtain a plurality of cell voltages, and obtaining a maximum voltage and a minimum voltage among the plurality of cell voltages; According to the compensation voltage, the maximum value of the voltage is corrected to obtain a first correction voltage, and the minimum value of the voltage is corrected to obtain a second correction voltage, wherein the compensation voltage is calculated according to the method described in any one of claims 1 to 9; Taking the first corrected voltage and the second corrected voltage as open circuit voltages respectively, querying an OCV-SOC table to obtain a maximum SOC value and a minimum SOC value; An initial SOC of the battery system is determined according to the maximum SOC value and the minimum SOC value.

11. The method according to claim 10, characterized in that The step of correcting the maximum voltage to obtain a first corrected voltage and correcting the minimum voltage to obtain a second corrected voltage according to the compensation voltage includes: When the voltage state is a boost state, the first correction voltage is the sum of the maximum voltage and the compensation voltage, and the second correction voltage is the sum of the minimum voltage and the compensation voltage; When the voltage state is a step-down state, the first correction voltage is the difference between the maximum voltage and the compensation voltage, and the second correction voltage is the difference between the minimum voltage and the compensation voltage; When the voltage state is a stable state, the first correction voltage is the maximum voltage value, and the second correction voltage is the minimum voltage value.

12. The method according to claim 11, characterized in that The step of determining the initial SOC of the battery system according to the maximum SOC value and the minimum SOC value comprises: Obtaining the terminal SOC of the battery system when it was last shut down; Determining whether the terminal SOC is within a range defined by the maximum SOC value and the minimum SOC value; If yes, the terminal SOC is determined as the initial SOC of the battery system; If not, when the terminal SOC is greater than the maximum SOC value, the maximum SOC value is determined as the initial SOC of the battery system; when the terminal SOC is less than the minimum SOC value, the minimum SOC value is determined as the initial SOC of the battery system.

13. The method according to claim 10, characterized in that The step of taking the first corrected voltage and the second corrected voltage as open circuit voltages, querying an OCV-SOC table, and obtaining a maximum SOC value and a minimum SOC value comprises: The first corrected voltage and the second corrected voltage are respectively used as open circuit voltages, and a T-OCV-SOC table is queried according to the temperature of the battery system to obtain the maximum SOC value and the minimum SOC value.

14. A battery system, characterized in that: include: at least one processor; as well as A memory, wherein the memory is communicatively connected to the at least one processor, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method according to any one of claims 1 to 13.

15. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of the method according to any one of claims 1 to 13.

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