Method and device for estimating state of charge of power battery and vehicle

Abstract

The invention discloses a method and device for estimating the state of charge of a power battery and a vehicle. The method comprises the steps that the real-time state of charge of the power battery is obtained, and standing time source information of the power battery is determined; correcting the open-circuit voltage based on the standing time source information to determine a maximum state of charge and a minimum state of charge; determining a target maximum state of charge and a target minimum state of charge based on the real-time state of charge, the maximum state of charge and the minimum state of charge; a target state of charge is determined based on the target maximum state of charge and the target minimum state of charge. According to the estimation method, the charge state of the power battery can be accurately estimated, the calculation workload is small, and the efficiency is high.

Description

Technical Field

[0001] The present application relates to the technical field of power batteries, and particularly to a method for estimating the state of charge of a power battery, an apparatus for estimating the state of charge of a power battery, and a vehicle. Background Art

[0002] With the gradual development of new energy technologies, new energy vehicles are becoming increasingly popular. During the process of driving a new energy vehicle, users have put forward higher and higher requirements for the accuracy of the available power of the new energy vehicle.

[0003] SOC (State of Charge) is the state of charge of the battery, which is used to characterize the percentage of the stored energy in the battery. Accurately estimating the SOC is of great significance for the remaining driving range of new energy vehicles. For SOC calculation, there are various algorithms in the industry, such as the open circuit voltage method, the ampere-hour integration method, the Kalman filter method, and the neural network method. For the charging process and the discharging process, some use the monomer battery cell with the highest power during charging as the charging SOC, and the monomer battery cell with the lowest power during discharging as the discharging SOC; some use the highest and lowest monomer battery cells added together in a certain proportion to obtain the final SOC.

[0004] For the OCV (Open Circuit Voltage Method), when the positive and negative electrodes of the battery are in an open circuit state and stand still for a certain period of time, the open circuit voltage of the positive and negative electrodes of the battery is measured to estimate the SOC of the battery. This method requires the standing time required for the battery to stand still, and the battery cannot be charged or discharged during the standing period. The advantage of this method is that it is relatively accurate. After correctly measuring the corresponding relationship between the open circuit voltage of the battery and the SOC, the SOC of the battery can be accurately calculated through this relationship. However, the disadvantages of this method are that the required standing time is long and inaccurate at low temperatures, and it is necessary to require that the battery cannot be charged or discharged during the standing period.

[0005] The ampere-hour integration method is to integrate the charging and discharging current of the battery over a period of time, and then calculate the SOC that changes during this period. The advantages of this method are simple calculation and adaptation to most scenarios; the disadvantages of this method are that it depends on the accuracy of the initial SOC, and is affected by the sampling accuracy and sampling frequency of the current sensor, and is also sensitive to the total battery capacity.

[0006] The Kalman filter method estimates the battery SOC by establishing a linear system or converting a non-linear system into a linear system to establish a battery model. Its advantage is that the error is considered in the calculation; its disadvantage is that it is more dependent on the accuracy of the battery model, and the calculation amount is large.

[0007] The neural network method estimates the SOC by learning and integrating a large amount of data, autonomously summarizing the internal laws of the battery system, and then estimating the SOC. Its advantages are that it does not require in-depth understanding of the internal battery model and only summarizes through data; its disadvantages are that it requires a huge amount of data samples and a large amount of computational work, and cloud computing is needed. Summary of the Invention

[0008] This application aims to solve at least one of the technical problems in the related art to some extent. To this end, the first object of this application is to propose an estimation method for the state of charge of a power battery, obtain the real-time state of charge of the power battery and determine the source information of the static time of the power battery, correct the open-circuit voltage based on the source information of the static time to determine the maximum state of charge and the minimum state of charge, determine the target maximum state of charge and the target minimum state of charge based on the real-time state of charge, the maximum state of charge and the minimum state of charge, and determine the target state of charge based on the target maximum state of charge and the target minimum state of charge. Thus, the state of charge of the power battery can be accurately estimated, with a small amount of computational work and high efficiency.

[0009] The second object of this application is to propose an estimation device for the state of charge of a power battery.

[0010] The third object of this application is to propose a vehicle.

[0011] To achieve the above object, an embodiment of the first aspect of this application proposes an estimation method for the state of charge of a power battery, the method includes: obtaining the real-time state of charge of the power battery and determining the source information of the static time of the power battery; correcting the open-circuit voltage based on the source information of the static time to determine the maximum state of charge and the minimum state of charge; determining the target maximum state of charge and the target minimum state of charge based on the real-time state of charge, the maximum state of charge and the minimum state of charge; determining the target state of charge based on the target maximum state of charge and the target minimum state of charge.

[0012] According to the estimation method for the state of charge of a power battery in the embodiment of this application, the real-time state of charge of the power battery is obtained and the source information of the static time of the power battery is determined, the open-circuit voltage is corrected based on the source information of the static time to determine the maximum state of charge and the minimum state of charge, the target maximum state of charge and the target minimum state of charge are determined based on the real-time state of charge, the maximum state of charge and the minimum state of charge, and the target state of charge is determined based on the target maximum state of charge and the target minimum state of charge. Thus, this method can accurately estimate the state of charge of the power battery, with a small amount of computational work and high efficiency.

[0013] In addition, the estimation method for the state of charge of a power battery according to the above embodiment of this application may also have the following additional technical features:

[0014] According to an embodiment of the present application, the static time source information includes the internal static time obtained by an internal timer of the power battery. Correcting the open-circuit voltage based on the static time source information includes: when the static time source is the internal static time, if the open-circuit voltage correction condition is satisfied, taking the state of charge corresponding to the maximum cell voltage as the maximum state of charge of the current power battery, and taking the state of charge corresponding to the minimum cell voltage as the minimum state of charge of the current power battery; if the open-circuit voltage correction condition is not satisfied, when there is a difference retention flag for the maximum state of charge of the power battery, adding the difference between the initial maximum state of charge and the initial minimum state of charge to the minimum state of charge of the power battery as the maximum state of charge of the current power battery, when there is a difference retention flag for the minimum state of charge of the power battery, subtracting the difference between the initial maximum state of charge and the initial minimum state of charge from the maximum state of charge of the power battery as the minimum state of charge of the current power battery, when there is no difference retention flag for the maximum state of charge of the power battery, taking the initial maximum state of charge as the maximum state of charge of the current power battery, and when there is no difference retention flag for the minimum state of charge of the power battery, taking the initial minimum state of charge as the minimum state of charge of the current power battery.

[0015] According to an embodiment of the present application, the static time source information includes the external static time obtained by the external TBOX of the power battery. Based on the static time source information, the open-circuit voltage is corrected, including: when the static time source is the external static time, if the open-circuit voltage correction condition is satisfied, the state of charge corresponding to the maximum cell voltage minus the state of charge consumption value is used as the current maximum state of charge of the power battery, and the state of charge corresponding to the minimum cell voltage minus the state of charge consumption value is used as the current minimum state of charge of the power battery, where the state of charge consumption value is the state of charge consumption value from the relay closing to the correction moment; if the open-circuit voltage correction condition is not satisfied, when there is a difference retention flag for the maximum state of charge of the power battery, the maximum state of charge of the power battery minus the difference between the initial maximum state of charge and the initial minimum state of charge and then minus the state of charge consumption value is used as the current maximum state of charge of the power battery, when there is a difference retention flag for the minimum state of charge of the power battery, the minimum state of charge of the power battery plus the difference between the initial maximum state of charge and the initial minimum state of charge and then minus the state of charge consumption value is used as the current minimum state of charge of the power battery, when there is no difference retention flag for the maximum state of charge of the power battery, the initial maximum state of charge minus the state of charge consumption value is used as the current maximum state of charge of the power battery, and when there is no difference retention flag for the minimum state of charge of the power battery, the initial minimum state of charge minus the state of charge consumption value is used as the current minimum state of charge of the power battery.

[0016] According to an embodiment of the present application, the open-circuit voltage correction condition includes: the voltage of the power battery is within a preset voltage range; when an effective voltage value is obtained after the power battery is static, the maximum state of charge corresponding to the maximum voltage and the minimum state of charge corresponding to the minimum voltage are outside the plateau period, where the plateau period is the position in the relationship curve between voltage and state of charge where the voltage change amount is less than the preset change threshold and the state of charge change amount is greater than the preset change threshold; the static time of the power battery reaches the preset static duration, where the static time includes the internal static time and the external static time.

[0017] According to an embodiment of the present application, determining the target maximum state of charge and the target minimum state of charge based on the real-time state of charge, the maximum state of charge, and the minimum state of charge includes: when the preset conditions are not met, determining an initial state-of-charge difference based on the difference between the maximum state of charge and the minimum state of charge, determining the target maximum state of charge according to the difference between the maximum state of charge and the real-time state of charge, and determining the target minimum state of charge according to the difference between the minimum state of charge and the real-time state of charge; wherein, the preset conditions include: the difference between the maximum state of charge and the real-time state of charge is greater than the full charge threshold, the minimum state of charge is greater than or equal to the minimum allowable discharge state and the difference between the minimum state of charge and the real-time state of charge is less than the minimum allowable discharge state, the minimum state of charge is less than the minimum allowable discharge state and the discharge condition lock is not triggered, the minimum state of charge is less than the minimum allowable discharge state and the discharge condition lock is triggered.

[0018] According to an embodiment of the present application, the method further includes: when the difference between the maximum state of charge and the real-time state of charge in the preset conditions is greater than the full charge threshold, determining the target maximum state of charge as the full charge threshold, and determining the target minimum state of charge according to the difference between the full charge threshold and the initial state of charge; when the minimum state of charge in the preset conditions is greater than or equal to the minimum allowable discharge state and the difference between the minimum state of charge and the real-time state of charge is less than the minimum allowable discharge state, or when the minimum state of charge is less than the minimum allowable discharge state and the discharge condition lock is not triggered, determining the target maximum state of charge according to the sum of the difference between the minimum allowable discharge state and the initial state of charge, and taking the minimum allowable discharge state as the target minimum state of charge; when the minimum state of charge in the preset conditions is less than the minimum allowable discharge state and the discharge condition lock is triggered, if the difference between the minimum state of charge and the real-time state of charge is less than zero, determining the target maximum state of charge according to the sum of the difference between the minimum allowable discharge state and the initial state of charge, and determining the target minimum state of charge to be zero.

[0019] According to an embodiment of the present application, the method further includes: when the maximum single-cell voltage in the power battery is valid and greater than or equal to the corresponding preset full-charge voltage, the charging current of the power battery is less than or equal to the preset maximum allowable current, and the minimum temperature of the single cells in the power battery is greater than the preset minimum allowable temperature, taking the full-charge threshold as the target maximum state of charge, determining the target minimum state of charge as the difference between the full-charge threshold and the initial state of charge difference, and setting the full-charge correction flag to 1; when the minimum temperature of the single cells in the power battery is greater than the preset temperature, the minimum single-cell voltage in the power battery is less than the discharge cut-off voltage threshold at the corresponding temperature, and the discharge current of the power battery is less than the discharge current threshold at the corresponding temperature, taking the initial state of charge difference as the target maximum state of charge, determining the target minimum state of charge as zero, and setting the discharge cut-off correction flag to 1.

[0020] According to an embodiment of the present application, determining the target state of charge based on the target maximum state of charge and the target minimum state of charge includes: obtaining a preset maximum state of charge coefficient and a preset minimum state of charge coefficient; determining a first product based on the product of the target maximum state of charge and the preset maximum state of charge coefficient, and determining a second product based on the product of the target minimum state of charge and the preset minimum state of charge coefficient; determining the target state of charge based on the sum of the first product and the second product, where the sum of the preset maximum state of charge coefficient and the preset minimum state of charge coefficient is 1.

[0021] According to an embodiment of the present application, obtaining the preset maximum state of charge coefficient includes: when the target maximum state of charge is less than the high state of charge preset threshold and the target minimum state of charge is greater than the low state of charge preset threshold, obtaining a first result by subtracting the product of the low state of charge preset threshold and the target maximum state of charge from the product of the high state of charge preset threshold and the target minimum state of charge, and obtaining a second result by adding the difference between the high state of charge preset threshold and the low state of charge preset threshold to the difference between the target minimum state of charge and the target maximum state of charge; determining the preset maximum state of charge coefficient based on the ratio of the first result to the second result; when the target maximum state of charge is greater than or equal to the high state of charge preset threshold, the preset maximum state of charge coefficient is 1; when the target minimum state of charge is less than or equal to the low state of charge preset threshold, the preset maximum state of charge coefficient is 0.

[0022] According to an embodiment of the present application, the method further includes: when the target state of charge is less than or equal to a preset minimum mapping threshold, the target indicated state of charge is zero; when the target state of charge is greater than or equal to a preset maximum mapping threshold, the target indicated state of charge is the full charge threshold; when the target state of charge is greater than the preset minimum mapping threshold and less than the preset maximum mapping threshold, the target indicated state of charge is determined according to the ratio of the target state of charge minus the preset minimum mapping threshold to the preset maximum mapping threshold minus the preset minimum mapping threshold.

[0023] According to an embodiment of the present application, the method further includes: when the target indicated state of charge is different from the actual indicated state of charge, adding the product of the real-time state of charge and a preset indicated state update coefficient to the target indicated state of charge as the actual indicated state of charge, where the preset indicated state update coefficient is less than 1 when the actual indicated state of charge is greater than the target indicated state of charge, the preset indicated state update coefficient is greater than 1 when the actual indicated state of charge is less than the target indicated state of charge, and the preset indicated state update coefficient when the target indicated state of charge is less than a preset difference is determined based on the difference between the target indicated state of charge and the actual indicated state of charge, where the preset indicated state update coefficient is positively correlated with the difference.

[0024] To achieve the above object, an embodiment of the second aspect of the present application provides an estimation device for the state of charge of a power battery, where the device includes: an acquisition module, configured to acquire the real-time state of charge of the power battery and determine the source information of the static time of the power battery; a first determination module, configured to correct the open-circuit voltage based on the source information of the static time to determine the maximum state of charge and the minimum state of charge; a second determination module, configured to determine a target maximum state of charge and a target minimum state of charge based on the real-time state of charge, the maximum state of charge, and the minimum state of charge; and a third determination module, configured to determine the target state of charge based on the target maximum state of charge and the target minimum state of charge.

[0025] For the estimation device of the state of charge of a power battery according to an embodiment of the present application, the acquisition module is configured to acquire the real-time state of charge of the power battery and determine the source information of the static time of the power battery, the first determination module is configured to correct the open-circuit voltage based on the source information of the static time to determine the maximum state of charge and the minimum state of charge, the second determination module is configured to determine the target maximum state of charge and the target minimum state of charge based on the real-time state of charge, the maximum state of charge, and the minimum state of charge, and the third determination module is configured to determine the target state of charge based on the target maximum state of charge and the target minimum state of charge. Thus, the device can accurately estimate the state of charge of the power battery, with a small amount of calculation work and high efficiency.

[0026] To achieve the above object, a vehicle proposed in the third aspect embodiment of the present application includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the above method for estimating the state of charge of the power battery is implemented.

[0027] According to the vehicle of the embodiment of the present application, by executing the above method for estimating the state of charge of the power battery, the state of charge of the power battery can be accurately estimated, with a small amount of calculation work and high efficiency.

[0028] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flowchart of a method for estimating the state of charge of a power battery according to an embodiment of the present application;

[0030] Figure 2 is a flowchart of a method for estimating the state of charge of a power battery according to a specific example of the present application;

[0031] Figure 3 is a block diagram of an apparatus for estimating the state of charge of a power battery according to an embodiment of the present application;

[0032] Figure 4 is a block diagram of a vehicle according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, and should not be construed as limiting the present application.

[0034] The method for estimating the state of charge of a power battery, the apparatus for estimating the state of charge of a power battery, and the vehicle proposed in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0035] Figure 1 is a flowchart of a method for estimating the state of charge of a power battery according to an embodiment of the present application.

[0036] As Figure 1 shown, the method for estimating the state of charge of a power battery according to the embodiment of the present application may include the following steps:

[0037] S1, obtain the real-time state of charge of the power battery and determine the source information of the static time of the power battery.

[0038] S2. Correct the open-circuit voltage based on the static time source information to determine the maximum state of charge and the minimum state of charge.

[0039] S3. Determine the target maximum state of charge and the target minimum state of charge based on the real-time state of charge, the maximum state of charge, and the minimum state of charge.

[0040] S4. Determine the target state of charge based on the target maximum state of charge and the target minimum state of charge.

[0041] Specifically, first obtain the real-time state of charge of the power battery. The real-time state of charge is the actual state of charge of the current power battery and can be obtained through real-time monitoring by the battery management system. The real-time state of charge of the power battery can be estimated by various methods, such as the ampere-hour integration method, the Kalman filtering method, etc. For example, the real-time state of charge of the power battery can be determined by the formula where t is the starting program step of the accumulation, t + n is the ending program step, I SOC is the real-time current corresponding to each program step, t cycle is the time consumed by a single program step, Ah Cap is the ampere-hour capacity of the current battery, and SOC Realtime is the real-time state of charge of the power battery. In addition, since the SOC Realtime may cause precision loss due to too small a value when the current is small, the following two methods are used to select the number of program steps n during accumulation: the method of accumulating the real-time state of charge number reaching the threshold, that is, the real-time cumulative calculation of SOC Realtime in the program, and at the same time setting a fixed accumulation threshold SOC RtLmt . When the accumulated SOC Realtime ≥SOC RtLmt , trigger an update and output the accumulated result within the above program step once. Or, the method of fixed-time update, that is, setting a fixed accumulation program step n RtLmt . When the program step n≥n RtLmt , trigger an update and output the accumulated result within the n RtLmt program steps once. Combining the above two methods, when the conditions are not met, the real-time state of charge SOC Realtime is output as 0; when the current value is large, the first method is faster to meet, and at this time, the SOC Realtime can be updated faster; when the current value is small, the second method is triggered after the cumulative time n RtL,t ×t cycle . It can avoid precision loss under small currents and update the SOC Realtime once at an appropriate time, avoiding no change in the SOC Realti,e for a long time.

[0042] The source for determining the battery's static time can be the internal static time or the external static time. The static time can be obtained through the real-time clock (RTC) timer inside the battery or the real-time time provided by an external device (such as a TBOX). After determining the source information of the static time, the open-circuit voltage can be corrected based on this information to determine the maximum state of charge and the minimum state of charge. For example, for the internal static time, when the open-circuit voltage correction conditions are met, such as after the static time reaches 30 minutes, the state of charge corresponding to the maximum cell voltage can be used as the current maximum state of charge, and the state of charge corresponding to the minimum cell voltage can be used as the current minimum state of charge. Since it takes a certain amount of time for the TBOX to obtain real-time time synchronization and it is necessary to wait for the TBOX initialization to end before outputting the corresponding time, the consumption value of the state of charge during this initialization process can be determined. Thus, the state of charge corresponding to the maximum cell voltage minus the consumption value of the state of charge can be used as the current maximum state of charge, and the state of charge corresponding to the minimum cell voltage minus the consumption value of the state of charge can be used as the current minimum state of charge.

[0043] After determining the maximum state of charge and the minimum state of charge, the target maximum state of charge and the target minimum state of charge can be determined based on the real-time state of charge, the maximum state of charge, and the minimum state of charge. This process is an important part of the state-of-charge estimation algorithm and is used to ensure the accuracy and stability of the state of charge. For example, the target maximum state of charge and the target minimum state of charge can be determined through a pre-set corresponding relationship. For example, the relationships between the real-time state of charge, the maximum state of charge, the minimum state of charge, and the target maximum state of charge and the target minimum state of charge are determined in advance. After the real-time state of charge, the maximum state of charge, and the minimum state of charge are determined, the corresponding relationship can be directly called to obtain the target maximum state of charge and the target minimum state of charge.

[0044] After the target maximum state of charge and the target minimum state of charge are determined, the target state of charge can be determined based on the target maximum state of charge and the target minimum state of charge. For example, it can be determined according to a certain ratio, such as the sum of the product of a preset ratio and the target maximum state of charge plus the product of another preset ratio and the target minimum state of charge. The target state of charge can be the state of charge displayed on the meter for showing to the user. Thus, in this way, the actual state of the battery can be better reflected, the performance of the battery management system can be optimized, the battery life can be extended, and the user experience can be improved. This method is particularly applicable to new energy vehicles and can effectively solve the problems of the accuracy and smoothness of the state-of-charge display.

[0045] According to an embodiment of the present application, the static time source information includes the internal static time obtained by the internal timer of the power battery. Correcting the open-circuit voltage based on the static time source information includes: when the static time source is the internal static time, if the open-circuit voltage correction condition is satisfied, the state of charge corresponding to the maximum cell voltage is used as the maximum state of charge of the current power battery, and the state of charge corresponding to the minimum cell voltage is used as the minimum state of charge of the current power battery; if the open-circuit voltage correction condition is not satisfied, when there is a difference retention flag for the maximum state of charge of the power battery, the minimum state of charge of the power battery plus the difference between the initial maximum state of charge and the initial minimum state of charge is used as the maximum state of charge of the current power battery. When there is a difference retention flag for the minimum state of charge of the power battery, the maximum state of charge of the power battery minus the difference between the initial maximum state of charge and the initial minimum state of charge is used as the minimum state of charge of the current power battery. When there is no difference retention flag for the maximum state of charge of the power battery, the initial maximum state of charge is used as the maximum state of charge of the current power battery. When there is no difference retention flag for the minimum state of charge of the power battery, the initial minimum state of charge is used as the minimum state of charge of the current power battery.

[0046] Specifically, the static time source information may include the internal static time obtained by the internal timer of the power battery. When the open-circuit voltage correction condition is satisfied, the maximum state of charge and the minimum state of charge can be processed separately according to the static time source. If the static time source is the internal static time, the state of charge corresponding to the maximum cell voltage is used as the maximum state of charge of the current power battery, and the state of charge corresponding to the minimum cell voltage is used as the minimum state of charge of the current power battery;

[0047] When the open-circuit voltage correction condition is not satisfied, the maximum state of charge and the minimum state of charge can be processed separately according to the source of the static time and the state of the difference retention flag. If the current static time source is the internal static time, when there is a difference retention flag for the maximum state of charge of the power battery, the minimum state of charge of the power battery plus the difference between the initial maximum state of charge and the initial minimum state of charge can be used as the maximum state of charge of the current power battery. When there is a difference retention flag for the minimum state of charge of the power battery, the maximum state of charge of the power battery minus the difference between the initial maximum state of charge and the initial minimum state of charge is used as the minimum state of charge of the current power battery. When there is no difference retention flag for the maximum state of charge of the power battery, the initial maximum state of charge is used as the maximum state of charge of the current power battery. When there is no difference retention flag for the minimum state of charge of the power battery, the initial minimum state of charge is used as the minimum state of charge of the current power battery.

[0048] For example, the initial maximum state of charge = 98%, the initial minimum state of charge = 95%, the difference between the initial maximum state of charge and the initial minimum state of charge = 3%, the state of charge corresponding to the maximum cell voltage = 97%, the state of charge corresponding to the minimum cell voltage = 96%. When the open-circuit voltage correction condition is met and the source of the static time is the internal static time, it is determined that the maximum state of charge = 97% and the minimum state of charge = 96%. When the open-circuit voltage correction condition is not met and the source of the static time is the internal static time, if there is a difference retention flag for the maximum state of charge, it can be determined that the maximum state of charge = 95% + 3% = 98%. If there is a difference retention flag for the minimum state of charge, it can be determined that the minimum state of charge = 98% - 3% = 95%. If there is no difference retention flag for the maximum state of charge, it can be determined that the maximum state of charge = 98%. If there is no difference retention flag for the minimum state of charge, it can be determined that the minimum state of charge = 95%. Thus, by considering the source of the static time and the state of the difference retention flag, the maximum state of charge and the minimum state of charge of the current power battery are dynamically adjusted. This method ensures more accurate and reliable state of charge estimation under different working conditions (such as internal static time). Especially for new energy vehicles, this correction logic can effectively optimize the performance of the battery management system, extend the battery life, and improve the user experience.

[0049] According to an embodiment of the present application, the source information of the static time includes the external static time obtained by the external TBOX of the power battery. Correcting the open-circuit voltage based on the source information of the static time includes: when the source of the static time is the external static time, if the open-circuit voltage correction condition is met, then subtract the state of charge consumption value from the state of charge corresponding to the maximum cell voltage as the maximum state of charge of the current power battery, and subtract the state of charge consumption value from the state of charge corresponding to the minimum cell voltage as the minimum state of charge of the current power battery, where the state of charge consumption value is the state of charge consumption value from the relay closing to the correction moment; if the open-circuit voltage correction condition is not met, then when there is a difference retention flag for the maximum state of charge of the power battery, subtract the difference between the initial maximum state of charge and the initial minimum state of charge and the state of charge consumption value from the maximum state of charge of the power battery as the maximum state of charge of the current power battery. When there is a difference retention flag for the minimum state of charge of the power battery, add the difference between the initial maximum state of charge and the initial minimum state of charge and subtract the state of charge consumption value from the minimum state of charge of the power battery as the minimum state of charge of the current power battery. When there is no difference retention flag for the maximum state of charge of the power battery, subtract the state of charge consumption value from the initial maximum state of charge as the maximum state of charge of the current power battery. When there is no difference retention flag for the minimum state of charge of the power battery, subtract the state of charge consumption value from the initial minimum state of charge as the minimum state of charge of the current power battery.

[0050] Specifically, the source information of the static time may include the external static time obtained by the external TBOX of the power battery. When the open-circuit voltage correction condition is met, the maximum state of charge and the minimum state of charge can be processed separately according to the source of the static time. If the source of the static time is the external static time, that is, when the static time is given by the TBOX, since the TBOX initialization takes time, the consumption value of the state of charge from the relay closing to the correction moment needs to be increased to compensate for the possible change in the state of charge during the external static time. Then, the state of charge corresponding to the maximum single-cell voltage minus the consumption value of the state of charge can be used as the current maximum state of charge of the power battery, and the state of charge corresponding to the minimum single-cell voltage minus the consumption value of the state of charge can be used as the current minimum state of charge of the power battery.

[0051] When the open-circuit voltage correction condition is not met, the maximum state of charge and the minimum state of charge can be processed separately according to the source of the static time and the state of the difference retention flag. If the source of the static time is the external static time, it is determined whether the current power battery has a difference retention flag. When there is a difference retention flag in the maximum state of charge of the power battery, the maximum state of charge of the power battery minus the difference between the initial maximum state of charge and the initial minimum state of charge and then minus the consumption value of the state of charge is used as the current maximum state of charge of the power battery, that is, the maximum state of charge = the maximum state of charge - the difference between the initial maximum state of charge and the initial minimum state of charge - the consumption value of the state of charge. When there is a difference retention flag in the minimum state of charge of the power battery, the minimum state of charge of the power battery plus the difference between the initial maximum state of charge and the initial minimum state of charge and then minus the consumption value of the state of charge is used as the current minimum state of charge of the power battery, that is, the current minimum state of charge of the power battery = the minimum state of charge of the power battery (determined according to the state of charge corresponding to the minimum single-cell voltage) + the difference between the initial maximum state of charge and the initial minimum state of charge - the consumption value of the state of charge. When there is no difference retention flag in the maximum state of charge of the power battery, the initial maximum state of charge minus the consumption value of the state of charge is used as the current maximum state of charge of the power battery. When there is no difference retention flag in the minimum state of charge of the power battery, the initial minimum state of charge minus the consumption value of the state of charge is used as the current minimum state of charge of the power battery.

[0052] For example, the initial maximum state of charge = 98%, the initial minimum state of charge = 95%, the difference between the initial maximum state of charge and the initial minimum state of charge = 3%, the state of charge consumption value = 2%, the state of charge corresponding to the maximum cell voltage = 97%, the state of charge corresponding to the minimum cell voltage = 96%. When the open-circuit voltage correction condition is met, if the source of the standing time is the external standing time, then it is determined that the maximum state of charge = 97% - 2% = 95%, and the minimum state of charge = 96% - 2% = 94%. When the open-circuit voltage correction condition is not met, if the source of the standing time is the external standing time, and there is a difference retention flag for the maximum state of charge, it can be determined that the maximum state of charge = 98% - 3% - 2% = 93%. When there is a difference retention flag for the minimum state of charge, it can be determined that the minimum state of charge = 95% + 3% - 2% = 96%. When there is no difference retention flag for the maximum state of charge, it can be determined that the maximum state of charge = 98% - 2% = 96%. When there is no difference retention flag for the minimum state of charge, it can be determined that the minimum state of charge = 95% - 2% = 93%.

[0053] Thus, by considering the source of the standing time and the state of the difference retention flag, the maximum state of charge and the minimum state of charge of the current power battery are dynamically adjusted. This method ensures that the state of charge estimation is more accurate and reliable under different working conditions (such as external standing time). Especially for new energy vehicles, this correction logic can effectively optimize the performance of the battery management system, extend the battery life, and improve the user experience.

[0054] According to an embodiment of the present application, the open-circuit voltage correction condition includes: the voltage of the power battery is within a preset voltage range; when an effective voltage value is obtained after the power battery stands still, the maximum state of charge corresponding to the maximum voltage and the minimum state of charge corresponding to the minimum voltage are outside the plateau period. Here, the plateau period is the position in the relationship curve between the voltage and the state of charge where the voltage change amount is less than the preset change threshold and the state of charge change amount is greater than the preset change threshold; the standing time of the power battery reaches the preset standing duration, where the standing time includes the internal standing time and the external standing time. The preset voltage range, the preset change threshold, and the preset standing duration can be determined according to the actual situation.

[0055] Specifically, open-circuit voltage correction is a method of estimating the state of charge by measuring the open-circuit voltage of the battery in a stationary state. However, this method requires a series of conditions to ensure the accuracy and reliability of the correction. That is, the voltage of the power battery is within a preset voltage range, which is a set voltage interval, usually determined according to the characteristics of the battery (such as chemical composition and operating temperature). For example, for a lithium iron phosphate battery, the preset voltage range may be from 1V to 4V. That is, to ensure that the battery voltage is within the normal operating range and exclude abnormal voltages (too high or too low), which may affect the accuracy of the relationship between open-circuit voltage correction and the state of charge.

[0056] After the power battery is stationary and an effective voltage value is obtained, the maximum state of charge corresponding to the maximum voltage and the minimum state of charge corresponding to the minimum voltage are outside the plateau period. Here, the plateau period is defined as the region in the relationship curve between voltage and state of charge where the change in voltage is less than a preset change threshold (e.g., 10 mV), but the change in state of charge is greater than a preset change threshold (e.g., 5%). The plateau period usually appears in the middle part of the state of charge curve, where the voltage is insensitive to changes in the state of charge. That is to say, open-circuit voltage correction needs to be carried out in the region where the voltage is sensitive to changes in the state of charge to ensure that the change in the state of charge can be accurately reflected by voltage measurement. If the state of charge corresponding to the maximum or minimum voltage is in the plateau period, the voltage change is not sufficient to accurately estimate the state of charge, so the plateau period needs to be excluded. Among them, the effective voltage value, that is, the voltage value obtained by the voltage sensor after the power battery is stationary, must be effective, that is, it meets the conditions of the voltage range and the non-plateau period.

[0057] The stationary time of the power battery reaches the preset stationary duration, which is a set time value used to ensure that the battery has enough stationary time before measuring the open-circuit voltage correction to reach a stable voltage state. The stationary time may vary depending on the battery type and temperature. The types of stationary time include internal stationary time, that is, the stationary time measured by the real-time clock (RTC) timer inside the battery. External stationary time, that is, the stationary time measured by the real-time time provided by an external device (such as TBOX, a vehicle communication module). To ensure that the battery has been fully stationary before measuring the open-circuit voltage correction to reduce the influence of current charge and discharge on the voltage, thereby improving the accuracy of the open-circuit voltage correction measurement.

[0058] Assume the preset voltage range: 1V to 4V, the definition of the plateau period: the voltage change < 10mV, the state of charge change > 5%, the preset static time: 60 minutes, the current maximum voltage: 3.5V, the corresponding state of charge is 99%, the current minimum voltage: 3.2V, the corresponding state of charge is 20%, the current static time: 65 minutes (internal static time), that is, perform a voltage range check: both the maximum voltage 3.5V and the minimum voltage 3.2V are within the preset voltage range (1V to 4V), the condition is met, and perform a plateau period check: assume that during the plateau period, the state of charge range with a voltage change less than 10mV is 30% to 90%, both the maximum state of charge (99%) and the minimum state of charge (20%) are not within the plateau period (30% to 90%), the condition is met, and perform a static time check: the internal static time is 65 minutes, which is greater than the preset static time of 60 minutes, the condition is met. All conditions are met, and the open-circuit voltage correction can be performed.

[0059] Thus, the open-circuit voltage correction conditions ensure that when performing the open-circuit voltage correction, the battery is in a suitable static state, and the relationship between the voltage and the state of charge meets the expectations. These conditions improve the accuracy and reliability of the state of charge estimation by excluding abnormal voltages, plateau periods, and insufficient static times. This method is particularly applicable to new energy vehicles, which can effectively optimize the performance of the battery management system, extend the battery life, and improve the user experience.

[0060] According to an embodiment of the present application, determining the target maximum state of charge and the target minimum state of charge based on the real-time state of charge, the maximum state of charge, and the minimum state of charge includes: in the case of not meeting the preset conditions, determining the initial state of charge difference based on the difference between the maximum state of charge and the minimum state of charge, and determining the target maximum state of charge according to the difference between the maximum state of charge and the real-time state of charge, and determining the target minimum state of charge according to the difference between the minimum state of charge and the real-time state of charge; wherein, the preset conditions include: the difference between the maximum state of charge and the real-time state of charge is greater than the full charge threshold, the minimum state of charge is greater than or equal to the minimum allowable discharge state and the difference between the minimum state of charge and the real-time state of charge is less than the minimum allowable discharge state, the minimum state of charge is less than the minimum allowable discharge state and the discharge condition lock is not triggered, the minimum state of charge is less than the minimum allowable discharge state and the discharge condition lock is triggered.

[0061] Specifically, when determining the target maximum state of charge (SOC) and the target minimum SOC based on the real-time SOC, the maximum SOC, and the minimum SOC, it is possible to determine whether the current situation meets a preset condition. If the preset condition is not met, the initial SOC difference can be determined based on the difference between the maximum SOC and the minimum SOC, the target maximum SOC can be determined based on the difference between the maximum SOC and the real-time SOC, and the target minimum SOC can be determined based on the difference between the minimum SOC and the real-time SOC. Among them, the preset condition is used to determine whether the current battery state meets specific full charge or discharge conditions. These conditions include: The difference between the maximum SOC and the real-time SOC is greater than the full charge threshold: indicating that the battery is close to the full charge state. The minimum SOC is greater than or equal to the minimum allowable discharge state and the difference between the minimum SOC and the real-time SOC is less than the minimum allowable discharge state: indicating that the battery is close to the discharged state but has not reached the lowest allowable discharge state. The minimum SOC is less than the minimum allowable discharge state and the discharge condition lock is not triggered: indicating that the battery has fallen below the lowest allowable discharge state but the discharge lock has not been triggered. The minimum SOC is less than the minimum allowable discharge state and the discharge condition lock is triggered: indicating that the battery has fallen below the lowest allowable discharge state and the discharge lock has been triggered.

[0062] That is, when the preset condition is not met, the calculation of the target maximum SOC and the target minimum SOC is based on the differences between the maximum SOC, the minimum SOC, and the real-time SOC. For example, the initial SOC difference = maximum SOC - minimum SOC, the target maximum SOC = maximum SOC - real-time SOC, and the target minimum SOC = minimum SOC - real-time SOC.

[0063] According to an embodiment of the present application, the method for estimating the SOC of a power battery further includes: when the difference between the maximum SOC and the real-time SOC in the preset condition is greater than the full charge threshold, determining the target maximum SOC as the full charge threshold and determining the target minimum SOC based on the difference between the full charge threshold and the initial SOC; when the minimum SOC is greater than or equal to the minimum allowable discharge state and the difference between the minimum SOC and the real-time SOC is less than the minimum allowable discharge state, or when the minimum SOC is less than the minimum allowable discharge state and the discharge condition lock is not triggered, determining the target maximum SOC based on the sum of the minimum allowable discharge state and the initial SOC difference and taking the minimum allowable discharge state as the target minimum SOC; when the minimum SOC is less than the minimum allowable discharge state and the discharge condition lock is triggered, if the difference between the minimum SOC and the real-time SOC is less than zero, determining the target maximum SOC based on the sum of the minimum allowable discharge state and the initial SOC difference and determining the target minimum SOC as zero.

[0064] Specifically, when the difference between the maximum state of charge and the real-time state of charge in the preset conditions is greater than the full charge threshold, the target maximum state of charge can be determined as the full charge threshold, and the target minimum state of charge can be determined as the difference between the full charge threshold and the initial state of charge. When the minimum state of charge in the preset conditions is greater than or equal to the minimum allowable discharge state and the difference between the minimum state of charge and the real-time state of charge is less than the minimum allowable discharge state, the target maximum state of charge can be determined according to the sum of the difference between the minimum allowable discharge state and the initial state of charge, that is, the target maximum state of charge = the minimum allowable discharge state + the difference of the initial state of charge, and the minimum allowable discharge state is used as the target minimum state of charge. Alternatively, when the minimum state of charge in the preset conditions is less than the minimum allowable discharge state and the emptying condition lock is not triggered, the target maximum state of charge can be determined according to the sum of the difference between the minimum allowable discharge state and the initial state of charge, that is, the target maximum state of charge = the minimum allowable discharge state + the difference of the initial state of charge, and the minimum allowable discharge state is used as the target minimum state of charge.

[0065] When the minimum state of charge in the preset conditions is less than the minimum allowable discharge state and the emptying condition lock is triggered, judge the magnitude relationship between the difference between the minimum state of charge and the real-time state of charge and zero. If the difference between the minimum state of charge and the real-time state of charge is less than zero, the target maximum state of charge can be determined according to the sum of the difference between the minimum allowable discharge state and the initial state of charge, that is, the target maximum state of charge = the minimum allowable discharge state + the difference of the initial state of charge, and the target minimum state of charge is determined as zero.

[0066] Thus, by dynamically adjusting the target maximum state of charge and the target minimum state of charge, it is ensured that the estimation of the state of charge of the battery is more accurate and reliable under different working conditions (such as approaching full charge or emptying). In addition, to maintain logical accuracy, it is necessary to determine that the target maximum state of charge is greater than or equal to the target minimum state of charge at any time. If the target maximum state of charge is less than the target minimum state of charge, the target minimum state of charge is used as the target maximum state of charge. And at any time, it is required that the difference between the target maximum state of charge and the target minimum state of charge remains unchanged. That is, the difference of the initial state of charge = the maximum state of charge - the minimum state of charge. If the current maximum state of charge - the minimum state of charge is not equal to the difference of the initial state of charge, then based on the minimum state of charge, the maximum state of charge = the minimum state of charge + the difference of the initial state of charge. If the current minimum state of charge + the difference of the initial state of charge is greater than the full charge threshold, then based on the maximum state of charge, the maximum state of charge is the full charge threshold, and the minimum state of charge is the full charge threshold - the difference of the initial state of charge.

[0067] According to an embodiment of the present application, the method for estimating the state of charge of a power battery further includes: when the maximum single-cell voltage in the power battery is valid and greater than or equal to the corresponding preset full-charge voltage, the charging current of the power battery is less than or equal to the preset maximum allowable current, and the minimum temperature of the single cells in the power battery is greater than the preset minimum allowable temperature, taking the full-charge threshold as the target maximum state of charge, determining the target minimum state of charge as the difference between the full-charge threshold and the initial state of charge difference, and setting the full-charge correction flag to 1; when the minimum temperature of the single cells in the power battery is greater than the preset temperature, the minimum single-cell voltage in the power battery is less than the discharge voltage threshold at the corresponding temperature, and the discharge current of the power battery is less than the discharge current threshold at the corresponding temperature, taking the initial state of charge difference as the target maximum state of charge, determining the target minimum state of charge as zero, and setting the discharge correction flag to 1.

[0068] Specifically, the purpose of full-charge correction is to accurately update the target maximum state of charge and the target minimum state of charge and set the full-charge correction flag when the power battery is approaching full charge. The full-charge correction conditions may include that the maximum single-cell voltage is valid and greater than or equal to the corresponding preset full-charge voltage, which means that the voltage of a certain single cell in the battery has reached or exceeded the voltage threshold of the full-charge state; the charging current of the power battery is less than or equal to the preset maximum allowable current, which means that the maximum-voltage single cell of the power battery has indeed reached the full-charge state, rather than a voltage spike caused by a large current; and the minimum temperature of the single cells in the power battery is greater than the preset minimum allowable temperature, which means that the polarization caused by the low temperature of the battery is small, ensuring that the maximum-voltage single cell has indeed reached the full-charge state. Thus, when the maximum single-cell voltage in the power battery is valid and greater than or equal to the corresponding preset full-charge voltage, the charging current of the power battery is less than or equal to the preset maximum allowable current, and the minimum temperature of the single cells in the power battery is greater than the preset minimum allowable temperature, the full-charge threshold (such as 100%) can be taken as the target maximum state of charge, the target minimum state of charge can be determined as the difference between the full-charge threshold and the initial state of charge difference, and the full-charge correction flag can be set to 1, indicating that the power battery is fully charged.

[0069] The purpose of the discharge correction is to accurately update the target maximum state of charge and the target minimum state of charge when the battery is approaching discharge, and set the discharge correction flag bit. The discharge correction conditions may include that the minimum temperature of the single cells in the power battery is greater than the preset temperature, which means that the polarization caused by the low temperature of the power battery is small, ensuring the effectiveness of the single cell voltage, and the minimum voltage single cell is indeed below the discharge voltage. The minimum single cell voltage in the power battery is less than the discharge voltage threshold at the corresponding temperature, which means that the voltage of a certain single cell in the battery has been lower than the voltage threshold of the discharge state. The discharge current of the power battery is less than the discharge current threshold at the corresponding temperature to avoid false triggering of the discharge correction caused by the voltage drop due to large current discharge. Thus, when the minimum temperature of the single cells in the power battery is greater than the preset temperature, the minimum single cell voltage in the power battery is less than the discharge voltage threshold at the corresponding temperature, and the discharge current of the power battery is less than the discharge current threshold at the corresponding temperature, the initial state of charge difference can be used as the target maximum state of charge, and the target minimum state of charge is determined to be zero, and the discharge correction flag bit is set to 1, indicating that the power battery has been discharged.

[0070] For example, the full charge threshold = 100%, the maximum state of charge = 98%, the minimum state of charge = 95%, and the initial state of charge difference = 98% - 95% = 3%. If the current maximum single cell voltage = 3.6V (greater than or equal to the preset full charge voltage = 3.6V), the charging current = -5A (less than or equal to the preset maximum allowable current = -10A), and the minimum temperature = 25°C (greater than or equal to the preset minimum allowable temperature = 15°C), the target maximum state of charge = 100% can be determined, the target minimum state of charge = 100% - 3% = 97%, and the full charge correction flag bit = 1. If the minimum temperature = 25°C (greater than or equal to the preset temperature = 15°C), the minimum single cell voltage = 2.5V (less than the discharge voltage threshold = 2.5V), and the discharge current = 5A (less than the discharge current threshold = 10A), the target maximum state of charge = 3% (the initial state of charge difference) can be determined, the target minimum state of charge = 0%, and the discharge correction flag bit = 1. Thus, under specific conditions, the target maximum state of charge and the target minimum state of charge are updated, and the corresponding correction flag bits are set to ensure more accurate and reliable estimation of the state of charge of the power battery. The full charge correction and the discharge correction are triggered when the battery is approaching full charge and discharge respectively, avoiding the problems of undercharging or over-discharging caused by inaccurate estimation of the state of charge, and improving the safety and service life of the battery.

[0071] According to an embodiment of the present application, determining the target state of charge based on the target maximum state of charge and the target minimum state of charge includes: obtaining a preset maximum state of charge coefficient and a preset minimum state of charge coefficient; determining a first product based on the product of the target maximum state of charge and the preset maximum state of charge coefficient, and determining a second product based on the product of the target minimum state of charge and the preset minimum state of charge coefficient; determining the target state of charge based on the sum of the first product and the second product, where the sum of the preset maximum state of charge coefficient and the preset minimum state of charge coefficient is 1.

[0072] Specifically, when determining the target state of charge according to the target maximum state of charge and the target minimum state of charge, the target state of charge is obtained by adding the target maximum state of charge and the target minimum state of charge with certain weights. First, obtain the preset maximum state of charge coefficient and the preset minimum state of charge coefficient, then determine the first product according to the product of the target maximum state of charge and the preset maximum state of charge coefficient, and determine the second product according to the product of the target minimum state of charge and the preset minimum state of charge coefficient. Then, determine the target state of charge according to the sum of the first product and the second product, that is, the target state of charge = target maximum state of charge * preset maximum state of charge coefficient + target minimum state of charge * preset minimum state of charge coefficient, where the sum of the preset maximum state of charge coefficient and the preset minimum state of charge coefficient is 1.

[0073] Further, according to an embodiment of the present application, obtaining the preset maximum state of charge coefficient includes: in the case where the target maximum state of charge is less than the high state of charge preset threshold and the target minimum state of charge is greater than the low state of charge preset threshold, obtaining a first result by subtracting the product of the low state of charge preset threshold and the target maximum state of charge from the product of the high state of charge preset threshold and the target minimum state of charge, and obtaining a second result by adding the difference between the high state of charge preset threshold and the low state of charge preset threshold to the difference between the target minimum state of charge and the target maximum state of charge; determining the preset maximum state of charge coefficient based on the ratio of the first result to the second result; in the case where the target maximum state of charge is greater than or equal to the high state of charge preset threshold, the preset maximum state of charge coefficient is 1; in the case where the target minimum state of charge is less than or equal to the low state of charge preset threshold, the preset maximum state of charge coefficient is 0. Wherein, the high state of charge preset threshold and the low state of charge preset threshold can be determined according to the actual situation.

[0074] Specifically, the magnitude relationship between the target maximum state of charge and the high state-of-charge preset threshold and the low state-of-charge preset threshold can be judged. When the target maximum state of charge is less than the high state-of-charge preset threshold and the target minimum state of charge is greater than the low state-of-charge preset threshold, a preset maximum state-of-charge coefficient can be obtained. For example, by subtracting the product of the low state-of-charge preset threshold and the target maximum state of charge from the product of the high state-of-charge preset threshold and the target minimum state of charge to obtain a first result, and adding the difference between the high state-of-charge preset threshold and the low state-of-charge preset threshold to the difference between the target minimum state of charge and the target maximum state of charge to obtain a second result; based on the ratio of the first result to the second result, the preset maximum state-of-charge coefficient is determined. For example, through the formula preset maximum state-of-charge coefficient = (high state-of-charge preset threshold * target minimum state of charge) - (low state-of-charge preset threshold * target maximum state of charge) / (high state-of-charge preset threshold - low state-of-charge preset threshold) + (target minimum state of charge - target maximum state of charge).

[0075] When the target maximum state of charge is greater than or equal to the high state-of-charge preset threshold, it indicates that the power battery is in a state close to full charge, and some full-charge related logics may need to be enabled, such as stopping charging, displaying the full-charge state, etc. The preset maximum state-of-charge coefficient can be determined to be 1, and the charging termination logic can be triggered. When the target minimum state of charge is less than or equal to the low state-of-charge preset threshold, it indicates that the power battery is in a state close to being discharged, and the preset maximum state-of-charge coefficient can be determined to be 0, which can trigger a low-battery warning or limit some high-power operations to avoid over-discharging the battery. Thus, the charging and discharging processes of the battery can be ensured to be safe, reasonable, and the user experience can be optimized.

[0076] According to an embodiment of the present application, the method for estimating the state of charge of the power battery further includes: when the target state of charge is less than or equal to the preset minimum mapping threshold, the target displayed state of charge is zero; when the target state of charge is greater than or equal to the preset maximum mapping threshold, the target displayed state of charge is the full-charge threshold; when the target state of charge is greater than the preset minimum mapping threshold and less than the preset maximum mapping threshold, the target displayed state of charge is determined according to the ratio of the target state of charge minus the preset minimum mapping threshold to the preset maximum mapping threshold minus the preset minimum mapping threshold. Among them, the preset minimum mapping threshold and the preset maximum mapping threshold can be determined according to the actual situation.

[0077] Specifically, the preset minimum mapping threshold is a set threshold used to determine that when the actual displayed state of charge is lower than this value, the target displayed state of charge should be displayed as 0. For example, when the actual displayed state of charge is lower than 3%, the target displayed state of charge is directly displayed as 0 to remind the user that the battery power is insufficient. The preset maximum mapping threshold is a set threshold used to determine that when the actual displayed state of charge is higher than this value, the target displayed state of charge is displayed as the full charge threshold (usually 100%). For example, after charging reaches full charge, when the actual displayed state of charge is higher than 99.5%, the target displayed state of charge is displayed as 100% to avoid a small amount of power consumption of the whole vehicle after full charge and the user's misunderstanding that the battery is not fully charged because the displayed state of charge is less than 100%. That is, the size relationship between the target state of charge and the preset minimum mapping threshold can be compared. When the target state of charge is less than or equal to the preset minimum mapping threshold, the target displayed state of charge is zero, which helps to clearly inform the user that the battery is about to run out and needs to be charged as soon as possible when the battery power is extremely low. The size relationship between the target state of charge and the preset maximum mapping threshold is compared. When the target state of charge is greater than or equal to the preset maximum mapping threshold, the target displayed state of charge is the full charge threshold to avoid the problem that the user misunderstands that the battery is not fully charged due to a small amount of power consumption of the whole vehicle after full charge and the displayed state of charge is less than 100%.

[0078] When the target state of charge is greater than the preset minimum mapping threshold and less than the preset maximum mapping threshold, the target displayed state of charge can be determined according to the ratio of the target state of charge minus the preset minimum mapping threshold to the preset maximum mapping threshold minus the preset minimum mapping threshold. That is, it can be determined by the formula target displayed state of charge = (target state of charge - preset minimum mapping threshold) / (preset maximum mapping threshold - preset minimum mapping threshold) * 100%, that is, in this case, the target displayed state of charge is calculated by a linear mapping method. When the target state of charge is between the preset minimum mapping threshold and the preset maximum mapping threshold, the target displayed state of charge changes linearly according to the position of the target state of charge, from 0 to 100%. Among them, the preset minimum mapping threshold can be set to a fixed value greater than 0 or a dynamic value according to the minimum battery temperature, which changes as the battery temperature decreases, so that the initial displayed state of charge reaches 0 faster at low temperatures, urging the user to charge as soon as possible, and also conforming to the characteristic of the battery capacity decreasing at low temperatures. The preset maximum mapping threshold can be set to 100 or a value close to 100 to ensure that the initial displayed state of charge does not immediately drop below 100 after charging ends, avoiding the user thinking that the battery is not fully charged.

[0079] Assume that the preset minimum mapping threshold = 3%, the preset maximum mapping threshold = 99.5%, the full charge threshold = 100%. When the target state of charge is 2%, since 2% ≤ 3%, it can be determined that the displayed state of charge is directly displayed as 0. When the target state of charge is 99.8%, since 99.8% ≥ 99.5%, it can be determined that the displayed state of charge is directly displayed as 100%. When the target state of charge is 50%, the displayed state of charge = (50% - 3%) / (99.5% - 3%) * 100% ≈ 49%. Thus, this method for estimating the state of charge of a power battery maps the true state of charge value to the displayed state of charge value by setting the preset minimum mapping threshold and the preset maximum mapping threshold, optimizing the display effect and improving the user experience. This method is particularly suitable for new energy vehicles and can effectively solve the problems of the accuracy and smoothness of the state of charge display.

[0080] According to an embodiment of the present application, the method for estimating the state of charge of a power battery further includes: when the target displayed state of charge is not the same as the actual displayed state of charge, adding the product of the target displayed state of charge and the preset display update coefficient to the real-time state of charge as the actual displayed state of charge, where the preset display update coefficient is less than 1 when the actual displayed state of charge is greater than the target displayed state of charge, the preset display update coefficient is greater than 1 when the actual displayed state of charge is less than the target displayed state of charge, and the preset display update coefficient when the target displayed state of charge is less than the preset difference is determined based on the difference between the target displayed state of charge and the actual displayed state of charge, where the preset display update coefficient has a positive correlation with the difference. Among them, the preset display update coefficient and the preset difference can be determined according to the actual situation.

[0081] Specifically, when the target displayed state of charge and the actual displayed state of charge are not equal, the preset display update coefficient can be used to catch up or wait to update the target displayed state of charge. That is to say, the target displayed state of charge is the ideal display state of charge value calculated according to the actual operating state of the vehicle, which reflects the theoretical remaining power of the battery in the current state. The actual displayed state of charge is the state of charge value actually displayed to the user on the vehicle dashboard or other display devices, which is updated by accumulating the real-time state of charge and should be equal to the target displayed state of charge.

[0082] Judge the magnitude relationship between the target apparent state of charge and the actual apparent state of charge. When the target apparent state of charge is different from the actual apparent state of charge, the actual apparent state of charge can be obtained by adding the product of the real-time state of charge and the preset apparent update coefficient to the target apparent state of charge, that is, it can be determined by the formula: actual apparent state of charge = target apparent state of charge + real-time state of charge * preset apparent update coefficient. Among them, the preset apparent update coefficient is a dynamically adjusted parameter, which is used to control the speed at which the actual apparent state of charge transitions to the target apparent state of charge. Its value is dynamically adjusted according to the relative magnitude between the actual apparent state of charge and the target apparent state of charge and the magnitude of the target apparent state of charge. For example, in the case of discharging when the actual apparent state of charge is greater than the target apparent state of charge, the preset apparent update coefficient can be taken to be greater than 1 (such as 1.2), and the actual apparent state of charge will quickly approach the target apparent state of charge, ensuring that the apparent state of charge can promptly reflect the increase in battery power. In the case of discharging when the actual apparent state of charge is less than the target apparent state of charge, the preset apparent update coefficient can be taken to be less than 1 (such as 0.8), and the actual apparent state of charge will decrease slowly to wait for the target apparent state of charge until the two are finally equal.

[0083] The preset apparent update coefficient when the target apparent state of charge is less than the preset difference is determined based on the difference between the target apparent state of charge and the actual apparent state of charge. That is to say, when the target apparent state of charge is close to 0, the preset apparent update coefficient is dynamically adjusted based on the difference between the target apparent state of charge and the actual apparent state of charge, and the preset apparent update coefficient has a positive correlation with the difference, that is, the larger the difference, the larger the preset apparent update coefficient, so as to accelerate the update speed of the apparent state of charge and ensure that when the target apparent state of charge is close to 0, the actual apparent state of charge can catch up in time, avoiding the situation where the actual apparent state of charge does not reach 0% when the discharge condition is reached. Thus, this method optimizes the update process of the apparent state of charge by dynamically adjusting the preset apparent update coefficient, improves the user experience, and at the same time ensures the accuracy and reliability of the apparent state of charge. This update mechanism is especially suitable for new energy vehicles and can effectively solve the problems of smoothness and accuracy of the state of charge display.

[0084] In addition, in an embodiment of the present application, when the power battery is in a discharge current state, the actual displayed state of charge is not allowed to increase, that is, it is not allowed to be greater than the value at the previous moment; when the power battery is in a charging state (including during energy recovery), the actual displayed state of charge is not allowed to decrease, that is, it is not allowed to be less than the value at the previous moment. Moreover, when in a charging state and both the actual displayed state of charge and the target displayed state of charge reach 99, the actual displayed state of charge is locked until the full charge condition is triggered, and the actual displayed state of charge is no longer locked. When the full charge correction flag bit is 1, it is considered that the battery is fully charged, and at this time, the actual displayed state of charge is set to the full charge threshold (such as 100). When the full discharge correction flag bit is 1, it is considered that the battery is fully discharged, and at this time, the actual displayed state of charge is set to 0.

[0085] In addition, in an embodiment of the present application, after the vehicle is powered on, relevant data can also be initialized. For example, at the first moment of power-on, the data stored during the previous power-off is read from the EEPROM (hereinafter referred to as EE) that stores the data for this calculation, which should include: the maximum SOC EEMax , the minimum SOC EEMin , the true SOC EEReal , the displayed SOC EEDisp , the time before power-off (year T Year , month T Month , day T Day , hour T Hour , minute T Minute , second T Second ), the time when the last OCV was executed (year T OCVYear , month T OCVMonth , day T OCVDay , hour T OCVHour , minute T OCVMinute , second T OCVSecond ), the difference retention flag bit Flg Diff , the cumulative discharge ampere-hour charge Ah after OCV OCVDChg . After the data is read, the validity of the data needs to be checked. For the state of charge data, it is required that the read data range is between 0 and 100 (including both ends). For the time data, it is required to be within its own time range. For example, the month data T Month should be 1 - 12, and the minute data T Minute should be 0 - 59. If the data exceeds the range, the data is considered invalid and is assigned a default value of 0.

[0086] Since the automotive power battery is divided into a low-voltage part and a high-voltage part, when the low-voltage vehicle is powered on, the battery high-voltage relay has not closed yet, and there is no current output at this time. It is necessary to filter the current value at this time, so it is necessary to judge the input current data. Only when it is confirmed that the relay is closed and the vehicle is in a high-voltage state, is the current value allowed to be input for calculation, I SOC= Input value, other case I SOC Is 0. The current sensor should output a current timeout signal. If no current data is received from the sensor after the set time T, it is considered that the current signal has timed out, and the current value I SOC Is set to 0. Also, according to the performance of the power battery, the maximum allowable discharge current and the maximum allowable charging current can be set. When the input current signal value is not within the range, it is considered that the current value is invalid and 0 is output. Since the battery capacity is affected by temperature, first, according to the current minimum temperature Temp Min Check the Temp-Capacity data table of the temperature-capacity relationship to obtain the current battery capacity value, and then multiply it by the SOH value to obtain the current battery capacity Ah Cap , where SOH (State of Health) is an index to measure the health of the battery and is usually expressed as a percentage value. It reflects the capacity retention degree of the battery relative to its initial state (usually the state when it is a new battery).

[0087] Since the current sensor sampling takes time and the default value before initialization needs to be filtered, it is necessary to judge the validity of the voltage value. According to the voltage characteristics of lithium iron phosphate batteries, it is required that the input voltage range is within 1V to 4V. If it is not within this range, it is considered that the voltage validity U vld Is invalid. And to avoid the influence of voltage spikes caused by abnormal sampling of the voltage sensor on the actual data, it is required that the voltage change value ≤ 10mV within a short number of program cycles (such as 5 program cycles). When this condition is met and the voltage range condition is met for a certain number of program cycles (such as 10 program cycles), the voltage validity U vld Outputs valid. Also, according to the voltage characteristics of the power battery after standing still, different standing still times are selected for different temperatures. According to the average temperature Temp of the battery Avg Query the Temp-Hour data table of the standing still time as the required standing still time T OCV . According to the internal RTC timer of the battery to judge the standing still time. When the EE value has not expired, calculate the difference between the RTC real-time time and the standing still time before power-off. When the standing still time ≥ T OCV Then output that the standing still time is satisfied. If the internal RTC time is accidentally reset, then judge the standing still time according to the external TBOX time. When the EE value has not expired, calculate the difference between the TBOX real-time time and the standing still time before power-off. When the standing still time ≥ T OCV Then output that the standing still time is satisfied. Since it takes a certain amount of time for the TBOX to obtain real-time timing, it is necessary to wait for the TBOX initialization to end and output the normal value.

[0088] The difference retention flag is used for difference retention during OCV execution, indicating the accuracy of the state of charge during correction to a certain extent. However, the correction value gradually becomes inaccurate over time, so the flag needs to be cleared according to time. When the RTC time is valid, calculate the difference between the RTC time and the time of the last OCV execution. After the difference ≥ the clearing days, clear the difference retention flag. When the RTC time is invalid, calculate the difference between the TBOX time and the time of the last OCV execution using the TBOX time. After the difference ≥ the clearing days, clear the difference retention flag. When the real-time discharged electricity is the cumulative discharged ampere-hour Ah after OCV Dchg and the cumulative discharged ampere-hour Ah after the last OCV OCVDchg After the difference exceeds the set threshold, clear the difference retention flag. At the first valid moment of the voltage after power-on, according to the maximum cell voltage U Max and the minimum cell voltage U Min , query the corresponding maximum SOC value SOC OCVMax and the minimum SOC value SOC OCVMin from the OCV-Temp-SOC table. And, according to the EE validity and the validity of the maximum and minimum cell voltages, select an appropriate state of charge value as the initial value. When the EE data validity check is normal, select the maximum SOC value SOC EEMax and the minimum SOC value SOC EEMin stored in the EE as the initial maximum SOC value SOC InitMax and the minimum SOC value SOC InitMin . If the EE data validity is invalid and the voltage validity is valid, select the maximum SOC value SOC OCVMax and the minimum SOC value SOC OCVMin corresponding to the maximum and minimum cell voltages queried from the OCV-Temp-SOC table as the initial maximum SOC value SOC InitMax and the minimum SOC value SOC InitMin .

[0089] The following combines Figure 2 to describe the method of this application.

[0090] As a specific example, the method for estimating the state of charge of the power battery of this application may include the following steps:

[0091] S101, obtain the real-time state of charge of the power battery and determine the source information of the static time of the power battery.

[0092] S102. Determine whether the voltage of the power battery is within the preset voltage range. After the power battery stands still, when an effective voltage value is obtained, determine whether the maximum state of charge corresponding to the maximum voltage and the minimum state of charge corresponding to the minimum voltage are outside the plateau period, and whether the standing time of the power battery reaches the preset standing duration. If yes, execute step S103; if no, execute step S107.

[0093] S103. Determine whether the source of the standing time is the internal standing time. If yes, execute step S104; if no, execute step S105.

[0094] S104. Take the state of charge corresponding to the maximum single - cell voltage as the maximum state of charge of the current power battery, take the state of charge corresponding to the minimum single - cell voltage as the minimum state of charge of the current power battery, and enter step S115.

[0095] S105. Determine whether the source of the standing time is the external standing time. If yes, execute step S106; if no, execute step S101.

[0096] S106. Subtract the state - of - charge consumption value from the state of charge corresponding to the maximum single - cell voltage as the maximum state of charge of the current power battery, subtract the state - of - charge consumption value from the state of charge corresponding to the minimum single - cell voltage as the minimum state of charge of the current power battery, and enter step S115.

[0097] S107. Determine whether the source of the standing time is the internal standing time. If yes, execute step S108; if no, execute step S111.

[0098] S108. Determine whether there is a difference - keeping flag for the maximum state of charge and the minimum state of charge of the power battery. If yes, execute step S109; if no, execute step S110.

[0099] S109. Add the difference between the initial maximum state of charge and the initial minimum state of charge to the minimum state of charge of the power battery as the maximum state of charge of the current power battery, subtract the difference between the initial maximum state of charge and the initial minimum state of charge from the maximum state of charge of the power battery as the minimum state of charge of the current power battery, and enter step S115.

[0100] S110. Take the initial maximum state of charge as the maximum state of charge of the current power battery, take the initial minimum state of charge as the minimum state of charge of the current power battery, and enter step S115.

[0101] S111. Determine whether the source of the standing time is the external standing time. If yes, execute step S112; if no, execute step S101.

[0102] S112. Determine whether there is a difference retention flag for the maximum state of charge (SOC) and the minimum SOC of the power battery. If so, execute step S113; if not, execute step S114.

[0103] S113. Subtract the difference between the initial maximum SOC and the initial minimum SOC and the SOC consumption value from the maximum SOC of the power battery to obtain the current maximum SOC of the power battery, and add the difference between the initial maximum SOC and the initial minimum SOC and subtract the SOC consumption value from the minimum SOC of the power battery to obtain the current minimum SOC of the power battery.

[0104] S114. Subtract the SOC consumption value from the initial maximum SOC to obtain the current maximum SOC of the power battery, and subtract the SOC consumption value from the initial minimum SOC to obtain the current minimum SOC of the power battery.

[0105] S115. Determine the target maximum SOC and the target minimum SOC based on the real-time SOC, the maximum SOC, and the minimum SOC.

[0106] S116. Obtain the preset maximum SOC coefficient and the preset minimum SOC coefficient, determine the first product based on the product of the target maximum SOC and the preset maximum SOC coefficient, determine the second product based on the product of the target minimum SOC and the preset minimum SOC coefficient, and determine the target SOC based on the sum of the first product and the second product.

[0107] In summary, according to the method for estimating the SOC of the power battery in the embodiments of the present application, the real-time SOC of the power battery is obtained, the source information of the static time of the power battery is determined, the open-circuit voltage is corrected based on the source information of the static time to determine the maximum SOC and the minimum SOC, the target maximum SOC and the target minimum SOC are determined based on the real-time SOC, the maximum SOC, and the minimum SOC, and the target SOC is determined based on the target maximum SOC and the target minimum SOC. Thus, the method can accurately estimate the SOC of the power battery, with a small amount of calculation work and high efficiency.

[0108] Corresponding to the above embodiments, the present application also proposes an apparatus for estimating the SOC of a power battery.

[0109] As Figure 3 shown, the apparatus 100 for estimating the SOC of the power battery in the embodiments of the present application includes: an acquisition module 110, a first determination module 120, a second determination module 130, and a third determination module 140.

[0110] Among them, the acquisition module 110 is used to acquire the real-time state of charge of the power battery and determine the source information of the static time of the power battery. The first determination module 120 is used to correct the open-circuit voltage based on the static time source information to determine the maximum state of charge and the minimum state of charge. The second determination module 130 is used to determine the target maximum state of charge and the target minimum state of charge based on the real-time state of charge, the maximum state of charge and the minimum state of charge. The third determination module 140 is used to determine the target state of charge based on the target maximum state of charge and the target minimum state of charge.

[0111] According to an embodiment of the present application, the static time source information includes the internal static time obtained by the internal timer of the power battery. The first determination module 120 corrects the open-circuit voltage based on the static time source information, and specifically is used for: when the static time source is the internal static time, if the open-circuit voltage correction condition is satisfied, the state of charge corresponding to the maximum cell voltage is used as the maximum state of charge of the current power battery, and the state of charge corresponding to the minimum cell voltage is used as the minimum state of charge of the current power battery; if the open-circuit voltage correction condition is not satisfied, when there is a difference retention flag for the maximum state of charge of the power battery, the minimum state of charge of the power battery plus the difference between the initial maximum state of charge and the initial minimum state of charge is used as the maximum state of charge of the current power battery, when there is a difference retention flag for the minimum state of charge of the power battery, the maximum state of charge of the power battery minus the difference between the initial maximum state of charge and the initial minimum state of charge is used as the minimum state of charge of the current power battery, when there is no difference retention flag for the maximum state of charge of the power battery, the initial maximum state of charge is used as the maximum state of charge of the current power battery, and when there is no difference retention flag for the minimum state of charge of the power battery, the initial minimum state of charge is used as the minimum state of charge of the current power battery.

[0112] According to an embodiment of the present application, the static time source information includes the external static time obtained by the external TBOX of the power battery. The first determination module 120 corrects the open-circuit voltage based on the static time source information, specifically: when the static time source is the external static time, if the open-circuit voltage correction condition is satisfied, the state of charge corresponding to the maximum cell voltage minus the state of charge consumption value is used as the maximum state of charge of the current power battery, and the state of charge corresponding to the minimum cell voltage minus the state of charge consumption value is used as the minimum state of charge of the current power battery, where the state of charge consumption value is the state of charge consumption value from the relay closing to the correction moment; if the open-circuit voltage correction condition is not satisfied, when there is a difference retention flag for the maximum state of charge of the power battery, the maximum state of charge of the power battery minus the difference between the initial maximum state of charge and the initial minimum state of charge and then minus the state of charge consumption value is used as the maximum state of charge of the current power battery. When there is a difference retention flag for the minimum state of charge of the power battery, the minimum state of charge of the power battery plus the difference between the initial maximum state of charge and the initial minimum state of charge and then minus the state of charge consumption value is used as the minimum state of charge of the current power battery. When there is no difference retention flag for the maximum state of charge of the power battery, the initial maximum state of charge minus the state of charge consumption value is used as the maximum state of charge of the current power battery. When there is no difference retention flag for the minimum state of charge of the power battery, the initial minimum state of charge minus the state of charge consumption value is used as the minimum state of charge of the current power battery.

[0113] According to an embodiment of the present application, the open-circuit voltage correction condition includes: the voltage of the power battery is within a preset voltage range; when an effective voltage value is obtained after the power battery is static, the maximum state of charge corresponding to the maximum voltage and the minimum state of charge corresponding to the minimum voltage are outside the plateau period, where the plateau period is the position in the relationship curve between voltage and state of charge where the voltage change amount is less than the preset change threshold and the state of charge change amount is greater than the preset change threshold; the static time of the power battery reaches the preset static duration, where the static time includes the internal static time and the external static time.

[0114] According to an embodiment of the present application, the second determination module 130 determines a target maximum state of charge and a target minimum state of charge based on the real-time state of charge, the maximum state of charge, and the minimum state of charge, and specifically is used for: when a preset condition is not satisfied, determining an initial state-of-charge difference based on the difference between the maximum state of charge and the minimum state of charge, determining the target maximum state of charge according to the difference between the maximum state of charge and the real-time state of charge, and determining the target minimum state of charge according to the difference between the minimum state of charge and the real-time state of charge; wherein, the preset condition includes: the difference between the maximum state of charge and the real-time state of charge is greater than the full-charge threshold, the minimum state of charge is greater than or equal to the minimum allowable discharge state and the difference between the minimum state of charge and the real-time state of charge is less than the minimum allowable discharge state, the minimum state of charge is less than the minimum allowable discharge state and the discharge condition lock is not triggered, the minimum state of charge is less than the minimum allowable discharge state and the discharge condition lock is triggered.

[0115] According to an embodiment of the present application, the second determination module 130 is further used for: when the difference between the maximum state of charge and the real-time state of charge in the preset condition is greater than the full-charge threshold, determining the target maximum state of charge as the full-charge threshold, and determining the target minimum state of charge according to the difference between the full-charge threshold and the initial state of charge; when the minimum state of charge is greater than or equal to the minimum allowable discharge state and the difference between the minimum state of charge and the real-time state of charge is less than the minimum allowable discharge state, or when the minimum state of charge is less than the minimum allowable discharge state and the discharge condition lock is not triggered, determining the target maximum state of charge according to the sum of the difference between the minimum allowable discharge state and the initial state of charge, and taking the minimum allowable discharge state as the target minimum state of charge; when the minimum state of charge is less than the minimum allowable discharge state and the discharge condition lock is triggered, if the difference between the minimum state of charge and the real-time state of charge is less than zero, determining the target maximum state of charge according to the sum of the difference between the minimum allowable discharge state and the initial state of charge, and determining the target minimum state of charge as zero.

[0116] According to an embodiment of the present application, the second determination module 130 is further configured to: when the maximum single cell voltage in the power battery is valid and greater than or equal to the corresponding preset full charge voltage, the charging current of the power battery is less than or equal to the preset maximum allowable current, and the minimum temperature of the single cells in the power battery is greater than the preset minimum allowable temperature, use the full charge threshold as the target maximum state of charge, determine the target minimum state of charge as the difference between the full charge threshold and the initial state of charge difference, and set the full charge correction flag to 1; when the minimum temperature of the single cells in the power battery is greater than the preset temperature, the minimum single cell voltage in the power battery is less than the discharge cut-off voltage threshold at the corresponding temperature, and the discharge current of the power battery is less than the discharge current threshold at the corresponding temperature, use the initial state of charge difference as the target maximum state of charge, determine the target minimum state of charge as zero, and set the discharge cut-off correction flag to 1.

[0117] According to an embodiment of the present application, the third determination module 140 determines the target state of charge based on the target maximum state of charge and the target minimum state of charge. Specifically, it is configured to: obtain a preset maximum state of charge coefficient and a preset minimum state of charge coefficient; determine a first product based on the product of the target maximum state of charge and the preset maximum state of charge coefficient, and determine a second product based on the product of the target minimum state of charge and the preset minimum state of charge coefficient; determine the target state of charge based on the sum of the first product and the second product, where the sum of the preset maximum state of charge coefficient and the preset minimum state of charge coefficient is 1.

[0118] According to an embodiment of the present application, the third determination module 140 obtains the preset maximum state of charge coefficient. Specifically, it is configured to: when the target maximum state of charge is less than the high state of charge preset threshold and the target minimum state of charge is greater than the low state of charge preset threshold, obtain a first result by subtracting the product of the low state of charge preset threshold and the target maximum state of charge from the product of the high state of charge preset threshold and the target minimum state of charge, and obtain a second result by adding the difference between the high state of charge preset threshold and the low state of charge preset threshold to the difference between the target minimum state of charge and the target maximum state of charge; determine the preset maximum state of charge coefficient based on the ratio of the first result to the second result; when the target maximum state of charge is greater than or equal to the high state of charge preset threshold, the preset maximum state of charge coefficient is 1; when the target minimum state of charge is less than or equal to the low state of charge preset threshold, the preset maximum state of charge coefficient is 0.

[0119] According to an embodiment of the present application, the third determination module 140 is further configured to: when the target state of charge is less than or equal to the preset minimum mapping threshold, the target displayed state of charge is zero; when the target state of charge is greater than or equal to the preset maximum mapping threshold, the target displayed state of charge is the full charge threshold; when the target state of charge is greater than the preset minimum mapping threshold and less than the preset maximum mapping threshold, determine the target displayed state of charge according to the ratio of the target state of charge minus the preset minimum mapping threshold to the preset maximum mapping threshold minus the preset minimum mapping threshold.

[0120] According to an embodiment of the present application, the third determination module 140 is further configured to: when the target displayed state of charge is different from the actual displayed state of charge, add the product of the real-time state of charge and the preset display update coefficient to the target displayed state of charge as the actual displayed state of charge, where the preset display update coefficient is less than 1 when the actual displayed state of charge is greater than the target displayed state of charge, the preset display update coefficient is greater than 1 when the actual displayed state of charge is less than the target displayed state of charge, and the preset display update coefficient when the target displayed state of charge is less than the preset difference is determined based on the difference between the target displayed state of charge and the actual displayed state of charge, where the preset display update coefficient is positively correlated with the difference.

[0121] It should be noted that for the details not disclosed in the estimation device for the state of charge of the power battery in the embodiments of the present application, please refer to the details disclosed in the estimation method for the state of charge of the power battery in the embodiments of the present application, and specific details will not be elaborated here.

[0122] The estimation device for the state of charge of the power battery according to the embodiment of the present application, the acquisition module is configured to acquire the real-time state of charge of the power battery and determine the source information of the static time of the power battery, the first determination module is configured to correct the open-circuit voltage based on the source information of the static time to determine the maximum state of charge and the minimum state of charge, the second determination module is configured to determine the target maximum state of charge and the target minimum state of charge based on the real-time state of charge, the maximum state of charge and the minimum state of charge, and the third determination module is configured to determine the target state of charge based on the target maximum state of charge and the target minimum state of charge. Thus, the device can accurately estimate the state of charge of the power battery, with small computational workload and high efficiency.

[0123] Corresponding to the above embodiment, the present application also proposes a vehicle.

[0124] As Figure 4 shown, the vehicle 200 according to the embodiment of the present application may include: a memory 210, a processor 220, and a program stored on the memory 210 and executable on the processor 220. When the processor 220 executes the program, the above-mentioned estimation method for the state of charge of the power battery is implemented.

[0125] According to the vehicle of the embodiment of the present application, by implementing the above-mentioned method for estimating the state of charge of the power battery, the state of charge of the power battery can be accurately estimated, with a small amount of calculation work and high efficiency.

[0126] It should be noted that the logic and / or steps represented in the flowchart or described in other ways herein, for example, can be considered as a definite sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or in combination with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or other suitable processing as necessary, and then stored in a computer memory.

[0127] It should be understood that each part of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiment, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0128] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0129] In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0130] In this application, unless otherwise clearly specified and limited, terms such as "install", "connect", "join", "fix", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0131] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for estimating the state of charge of a power battery, characterized in that: The method comprises: Acquire the real-time state of charge of the power battery and determine the source information of the rest time of the power battery; Correcting the open circuit voltage based on the rest time source information to determine a maximum state of charge and a minimum state of charge; determining a target maximum state of charge and a target minimum state of charge based on the real-time state of charge, the maximum state of charge, and the minimum state of charge; A target state of charge is determined based on the target maximum state of charge and the target minimum state of charge.

2. The method for estimating the state of charge of a power battery according to claim 1, characterized in that: The rest time source information includes the internal rest time acquired by the internal timer of the power battery, and the open circuit voltage is corrected based on the rest time source information, including: In the case where the rest time source is the internal rest time, if the open circuit voltage correction condition is met, the state of charge corresponding to the maximum cell voltage is used as the maximum state of charge of the current power battery, and the state of charge corresponding to the minimum cell voltage is used as the minimum state of charge of the current power battery; If the open circuit voltage correction condition is not met, then when the maximum state of charge of the power battery has a difference holding mark, the minimum state of charge of the power battery plus the difference between the initial maximum state of charge and the initial minimum state of charge is used as the current maximum state of charge of the power battery; when the minimum state of charge of the power battery has a difference holding mark, the maximum state of charge of the power battery minus the difference between the initial maximum state of charge and the initial minimum state of charge is used as the current minimum state of charge of the power battery; when the maximum state of charge of the power battery has no difference holding mark, the initial maximum state of charge is used as the current maximum state of charge of the power battery; when the minimum state of charge of the power battery has no difference holding mark, the initial minimum state of charge is used as the current minimum state of charge of the power battery.

3. The method for estimating the state of charge of a power battery according to claim 1, characterized in that: The rest time source information includes the external rest time acquired by the TBOX outside the power battery, and the open circuit voltage is corrected based on the rest time source information, including: In the case where the rest time source is the external rest time, if the open circuit voltage correction condition is met, the state of charge corresponding to the maximum cell voltage minus the state of charge consumption value is used as the current maximum state of charge of the power battery, and the state of charge corresponding to the minimum cell voltage minus the state of charge consumption value is used as the current minimum state of charge of the power battery, wherein the state of charge consumption value is the state of charge consumption value from the closing of the relay to the correction moment; If the open circuit voltage correction condition is not met, then when the maximum state of charge of the power battery has a difference holding mark, the maximum state of charge of the power battery minus the difference between the initial maximum state of charge and the initial minimum state of charge minus the state of charge consumption value is used as the current maximum state of charge of the power battery; when the minimum state of charge of the power battery has a difference holding mark, the minimum state of charge of the power battery plus the difference between the initial maximum state of charge and the initial minimum state of charge minus the state of charge consumption value is used as the current minimum state of charge of the power battery; when the maximum state of charge of the power battery does not have a difference holding mark, the initial maximum state of charge minus the state of charge consumption value is used as the current maximum state of charge of the power battery; when the minimum state of charge of the power battery does not have a difference holding mark, the initial minimum state of charge minus the state of charge consumption value is used as the current minimum state of charge of the power battery.

4. The method for estimating the state of charge of a power battery according to claim 2 or 3, characterized in that: The open circuit voltage correction condition includes: The voltage of the power battery is within a preset voltage range; After the power battery is at rest, when an effective voltage value is obtained, the maximum state of charge corresponding to the maximum voltage and the minimum state of charge corresponding to the minimum voltage are outside the plateau period, wherein the plateau period is a position in the relationship curve between voltage and state of charge where the voltage change is less than a preset change threshold and the state of charge change is greater than the preset change threshold; The rest time of the power battery reaches a preset rest time, wherein the rest time includes internal rest time and external rest time.

5. The method for estimating the state of charge of a power battery according to claim 1, characterized in that: The determining a target maximum state of charge and a target minimum state of charge based on the real-time state of charge, the maximum state of charge, and the minimum state of charge includes: If the preset condition is not met, determining an initial state of charge difference based on a difference between the maximum state of charge and the minimum state of charge, determining a target maximum state of charge based on a difference between the maximum state of charge and the real-time state of charge, and determining a target minimum state of charge based on a difference between the minimum state of charge and the real-time state of charge; Among them, the preset conditions include: the difference between the maximum state of charge and the real-time state of charge is greater than the full charge threshold, the minimum state of charge is greater than or equal to the minimum allowable discharge state and the difference between the minimum state of charge and the real-time state of charge is less than the minimum allowable discharge state, the minimum state of charge is less than the minimum allowable discharge state and the emptying condition lock is not triggered, and the minimum state of charge is less than the minimum allowable discharge state and the emptying condition lock is triggered.

6. The method for estimating the state of charge of a power battery according to claim 5, characterized in that: The method further comprises: In the case where the difference between the maximum state of charge and the real-time state of charge in the preset condition is greater than the full-charge threshold, determining the target maximum state of charge to be the full-charge threshold, and determining the target minimum state of charge according to the difference between the full-charge threshold and the initial state of charge; When the minimum state of charge in the preset condition is greater than or equal to the minimum allowable discharge state and the difference between the minimum state of charge and the real-time state of charge is less than the minimum allowable discharge state, or when the minimum state of charge is less than the minimum allowable discharge state and the emptying condition lock is not triggered, the target maximum state of charge is determined according to the sum of the difference between the minimum allowable discharge state and the initial state of charge, and the minimum allowable discharge state is used as the target minimum state of charge; When the minimum state of charge in the preset condition is satisfied and is less than the minimum allowable discharge state and the emptying condition lock is triggered, if the difference between the minimum state of charge and the real-time state of charge is less than zero, the target maximum state of charge is determined based on the sum of the difference between the minimum allowable discharge state and the initial state of charge, and the target minimum state of charge is determined to be zero.

7. The method for estimating the state of charge of a power battery according to claim 6, characterized in that: The method further comprises: In the case where the maximum single cell voltage in the power battery is valid and greater than or equal to the corresponding preset full charge voltage, the charging current of the power battery is less than or equal to the preset maximum allowable current, and the minimum temperature of the single cell in the power battery is greater than the preset minimum allowable temperature, the full charge threshold is used as the target maximum state of charge, and the target minimum state of charge is determined by the difference between the full charge threshold and the initial state of charge difference, and the full charge correction flag is set to 1; When the minimum temperature of the single cells in the power battery is greater than the preset temperature, the minimum single cell voltage in the power battery is less than the emptying voltage threshold at the corresponding temperature, and the discharge current of the power battery is less than the discharge current threshold at the corresponding temperature, the initial state of charge difference is used as the target maximum state of charge, the target minimum state of charge is determined to be zero, and the emptying correction flag is set to 1.

8. The method for estimating the state of charge of a power battery according to claim 1, characterized in that: The determining a target state of charge based on the target maximum state of charge and the target minimum state of charge includes: Obtaining a preset maximum state of charge coefficient and a preset minimum state of charge coefficient; Determining a first product based on a product of the target maximum state of charge and the preset maximum state of charge coefficient, and determining a second product based on a product of the target minimum state of charge and the preset minimum state of charge coefficient; The target state of charge is determined based on a sum of the first product and the second product, wherein a sum of the preset maximum state of charge coefficient and the preset minimum state of charge coefficient is 1.

9. The method for estimating the state of charge of a power battery according to claim 8, characterized in that: The obtaining of the preset maximum state of charge coefficient includes: In the case where the target maximum state of charge is less than the high charge preset threshold and the target minimum state of charge is greater than the low charge preset threshold, a first result is obtained by subtracting the product of the low charge preset threshold and the target maximum state of charge from the product of the high charge preset threshold and the target minimum state of charge, and a second result is obtained by adding the difference between the high charge preset threshold and the low charge preset threshold and the difference between the target minimum state of charge and the target maximum state of charge; Determining the preset maximum state of charge coefficient based on a ratio of the first result to the second result; When the target maximum state of charge is greater than or equal to the high charge preset threshold, the preset maximum state of charge coefficient is 1; When the target minimum state of charge is less than or equal to the low charge preset threshold, the preset maximum state of charge coefficient is 0.

10. The method for estimating the state of charge of a power battery according to claim 1, characterized in that: The method further comprises: When the target state of charge is less than or equal to a preset minimum mapping threshold, the target displayed state of charge is zero; When the target state of charge is greater than or equal to a preset maximum mapping threshold, the target displayed state of charge is a full charge threshold; When the target state of charge is greater than the preset minimum mapping threshold and less than the preset maximum mapping threshold, the target displayed state of charge is determined according to the ratio of the target state of charge minus the preset minimum mapping threshold to the preset maximum mapping threshold minus the preset minimum mapping threshold.

11. The method for estimating the state of charge of a power battery according to claim 10, characterized in that: The method further comprises: In the case that the target displayed state of charge is different from the actual displayed state of charge, the product of the target displayed state of charge plus the real-time state of charge and a preset displayed update coefficient is taken as the actual displayed state of charge, wherein the preset displayed update coefficient is less than 1 when the actual displayed state of charge is greater than the target displayed state of charge, and the preset displayed update coefficient is greater than 1 when the actual displayed state of charge is less than the target displayed state of charge, and the preset displayed update coefficient when the target displayed state of charge is less than the preset difference is determined based on the difference between the target displayed state of charge and the actual displayed state of charge, wherein the preset displayed update coefficient is positively correlated with the difference.

12. A vehicle, characterized in that: include: A memory, a processor, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for estimating the state of charge of a power battery according to any one of claims 1 to 11 is implemented.

13. A device for estimating the state of charge of a power battery, characterized in that: The device comprises: An acquisition module, used to acquire the real-time state of charge of the power battery and determine the source information of the rest time of the power battery; A first determination module, configured to correct the open circuit voltage based on the static time source information to determine a maximum state of charge and a minimum state of charge; a second determination module, configured to determine a target maximum state of charge and a target minimum state of charge based on the real-time state of charge, the maximum state of charge, and the minimum state of charge; The third determination module is configured to determine a target state of charge based on the target maximum state of charge and the target minimum state of charge.

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