Power battery equalization method and device

Abstract

The invention provides a power battery equalization method and device, and effectively solves the problem that a current BMS equalization scheme cannot provide an equalization capability index requirement for a power battery of an electric vehicle. The method comprises the steps that when it is determined that a power battery of the electric vehicle is in an uncharged state, the battery cell static time and the remaining electric quantity of each battery cell are obtained, and a remaining electric quantity comparison threshold value and a balanced electric quantity threshold value are calculated based on the remaining electric quantity; determining an error between the residual electric quantity comparison threshold value and the residual electric quantity of each battery cell, and determining an equilibrium state of each battery cell based on the error, the equilibrium electric quantity threshold value, the residual electric quantity comparison threshold value and the residual electric quantity; calculating the equalization time of the target battery cell based on the target battery cell of which the equalization state is determined so as to update the equalization time of the target battery cell to obtain the updated equalization time; and balancing the corresponding target battery cell based on the updated balancing time to obtain the balanced power battery.

Description

Technical Field

[0001] The present application relates to the technical field of battery balancing, and in particular to a power battery balancing method and device. Background Art

[0002] In order to improve the life and performance of power batteries and ensure the safety and reliability of electric vehicles, balancing technologies and solutions for power batteries have gradually been developed.

[0003] The current mainstream BMS balancing solution for power batteries of electric vehicles is to balance only during the charging process. For power batteries, balancing only during the charging process will also lead to the consistency of multiple cells in the power battery becoming worse and worse during the life cycle of the vehicle, and the available battery capacity of the power battery will also become lower and lower; for the whole vehicle, the actual cruising range of the vehicle will decrease with the increase of usage time. When the rate of decline exceeds the normal capacity decay rate of the power battery, this will increase customers' anxiety and even concerns about the driving range. Some serious vehicles need to return to the 4S shop for separate balancing maintenance of the power battery, which greatly increases the vehicle maintenance cost. Therefore, the current BMS balancing solution cannot meet the requirements of the power battery for the balancing capacity index. Summary of the invention

[0004] In view of this, the purpose of the present application is to provide a power battery balancing method and device, which effectively solves the problem that the current BMS balancing solution cannot provide the power battery of the electric vehicle with a balancing capacity index that meets the balancing capacity index requirements.

[0005] In a first aspect, an embodiment of the present application provides a power battery balancing method, which is applicable to an electric vehicle, wherein the electric vehicle includes a power battery and a BMS module and an RTC module corresponding to the power battery, and the method includes:

[0006] When it is determined that the power battery of the electric vehicle is in an uncharged state, the cell rest time and the remaining power of each cell in the power battery are obtained through the BMS module and the RTC module, so as to calculate the remaining power comparison threshold and the equalization power threshold of each cell based on the remaining power of each cell;

[0007] Determine the error between the remaining power comparison threshold and the remaining power of each battery cell by calculating the battery cell rest time of each battery cell, so as to determine the balancing state of each battery cell based on the error, the balancing power threshold, the remaining power comparison threshold and the remaining power;

[0008] Calculating the balancing time of the target battery cell based on the determined balancing state of the target battery cell, and updating the balancing time of the target battery cell with the calculated balancing time to obtain an updated balancing time;

[0009] Based on the updated balancing time, the corresponding target battery cells are balanced until all the battery cells are balanced to obtain a balanced power battery.

[0010] In combination with the first aspect, the embodiment of the present application provides a first possible implementation of the first aspect, wherein the power battery balancing method further includes:

[0011] When it is determined that the power battery of the electric vehicle is in a charging state, the minimum temperature of each battery cell and the maximum temperature difference of the battery cell are obtained through the BMS module, so as to obtain the charging current and duration of the battery based on the minimum temperature and the maximum temperature difference, so as to determine the remaining power of each battery cell in the battery;

[0012] The balancing time of the target battery cell is obtained based on the remaining power of each battery cell, and the power battery in a charging state is balanced based on the balancing time to obtain a balanced power battery.

[0013] In combination with the first aspect, an embodiment of the present application provides a second possible implementation of the first aspect, wherein obtaining the balancing time of the target battery cell based on the remaining power of each battery cell includes:

[0014] Calculate a remaining power comparison threshold and a balancing power threshold of each battery cell based on the remaining power of each battery cell during charging;

[0015] Determine the balancing state of each battery cell when the battery is in a charging state by using the relationship between the remaining power comparison threshold, the balancing power threshold, the remaining power of the battery cell when charging, and the error of the remaining power comparison threshold;

[0016] The balancing time of the target battery cell is calculated based on the determined balancing state of each battery cell.

[0017] In combination with the first aspect, an embodiment of the present application provides a third possible implementation of the first aspect, wherein the calculating the remaining power comparison threshold based on the remaining power of each battery cell includes:

[0018] Calculating an average value and a minimum value of the remaining power based on the remaining power of each battery cell;

[0019] The calculated average and minimum values ​​of the remaining power are processed to obtain a comparison threshold value of the remaining power of each battery cell.

[0020] In combination with the first aspect, an embodiment of the present application provides a fourth possible implementation of the first aspect, wherein the step of calculating the equalization power threshold of each battery cell based on the remaining power of each battery cell includes:

[0021] Inputting the calculated remaining power of each battery cell into a preset equalization power threshold calculation model;

[0022] The equalization power threshold calculation model calculates the remaining power of each battery cell to obtain the equalization power threshold of each battery cell.

[0023] In combination with the first aspect, an embodiment of the present application provides a fifth possible implementation of the first aspect, wherein the determining the balancing state of each battery cell based on the error, the balancing power threshold, the remaining power comparison threshold, and the remaining power includes:

[0024] Calculate the difference between the remaining power of each battery cell and the corresponding remaining power comparison threshold, and calculate the sum of the equalization power threshold and the error of each battery cell;

[0025] The calculated difference value and the calculated sum value are compared to obtain a comparison result, so as to determine the balance state of the corresponding battery cell based on the comparison result.

[0026] In combination with the first aspect, an embodiment of the present application provides a sixth possible implementation of the first aspect, wherein the calculating the balancing time of the battery cell based on the determined balancing state of the battery cell, and updating the balancing time of the target battery cell with the calculated balancing time, includes:

[0027] After the determined balanced state of the battery cell, the remaining power of the target battery cell, the remaining power comparison threshold and the error are calculated to obtain the balanced time of the target battery cell;

[0028] The last balancing time of the target cell is replaced based on the obtained balancing time of the target cell, so that the target cell is balanced based on the calculated balancing time.

[0029] In combination with the first aspect, the embodiment of the present application provides a seventh possible implementation of the first aspect, wherein the step of obtaining the balancing time of the battery cell according to calculation after determining the balancing state of the battery cell comprises:

[0030] Obtain the capacity and balancing current of the target battery cell and input them into the preset balancing time calculation model;

[0031] The balancing time calculation model calls the remaining power of the target battery cell, the remaining power comparison threshold and the error, and the capacity and balancing current of the target battery cell to calculate the balancing time of the target battery cell.

[0032] In combination with the first aspect, an embodiment of the present application provides an eighth possible implementation of the first aspect, wherein the balancing is performed based on the updated balancing time as the corresponding target battery cell until all the battery cells are balanced to obtain a balanced power battery, including:

[0033] Reading a cell balancing mode set for the power battery, so as to balance the target cell based on the cell balancing mode;

[0034] After determining that all target cells in the power battery have completed balancing, the BMS module identifies the power battery as a balanced power battery.

[0035] In a second aspect, an embodiment of the present application further provides a power battery balancing device, the device comprising:

[0036] an acquisition module, for acquiring, when it is determined that the power battery of the electric vehicle is in an uncharged state, a cell rest time and a remaining power of each cell in the power battery through the BMS module and the RTC module, so as to calculate a remaining power comparison threshold and a balanced power threshold of each cell based on the remaining power of each cell;

[0037] A determination module, configured to determine an error between a remaining power comparison threshold and the remaining power of each battery cell by calculating the battery cell rest time of each battery cell, so as to determine a balanced state of each battery cell based on the error, the balanced power threshold, the remaining power comparison threshold, and the remaining power;

[0038] An updating module, configured to calculate a balancing time of a target battery cell based on a target battery cell in a determined balancing state, and update the balancing time of the target battery cell with the calculated balancing time to obtain an updated balancing time;

[0039] The balancing module is used to balance the corresponding target cells based on the updated balancing time until all cells are balanced to obtain a balanced power battery.

[0040] A power battery balancing method provided in an embodiment of the present application is applicable to an electric vehicle, wherein the electric vehicle includes a power battery and a BMS module and an RTC module corresponding to the power battery. The method first obtains the cell rest time and the remaining power of each cell in the power battery through the BMS module and the RTC module when it is determined that the power battery of the electric vehicle is in an uncharged state, so as to calculate the remaining power comparison threshold and the balancing power threshold of each cell based on the remaining power of each cell; secondly, the error between the remaining power comparison threshold and the remaining power of each cell is determined by the calculated cell rest time of each cell, so as to calculate the remaining power comparison threshold and the balancing power threshold based on the error, the balancing power threshold, the remaining power comparison threshold and the remaining power determination threshold. Determine the balancing state of each battery cell; then calculate the balancing time of the target battery cell based on the target battery cell with the determined balancing state, update the balancing time of the target battery cell with the calculated balancing time, and obtain an updated balancing time; finally, balance the corresponding target battery cell based on the updated balancing time until all the batteries are balanced to obtain a balanced power battery, thereby achieving balancing for the power battery when the power battery is not in a charging state, avoiding the current BMS balancing solution that can only charge the power battery when it is charging and cannot provide the power battery of the electric vehicle with the balancing capacity index requirements, ensuring the balancing effect of the power battery, and then ensuring the life and performance of the power battery and the electric vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A schematic diagram showing a flow chart of a first power battery balancing method provided by the present invention is shown;

[0043] Figure 2 A schematic diagram of a process for determining a cell balancing state provided by the present invention is shown;

[0044] Figure 3 A schematic diagram showing a flow chart of a second power battery balancing method provided by the present invention is shown;

[0045] Figure 4 A schematic diagram of a process flow of a first power battery balancing device provided by the present invention is shown. DETAILED DESCRIPTION

[0046] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart under the guidance of the content of the present application, or remove one or more operations from the flowchart.

[0047] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0048] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0049] The current mainstream BMS balancing solution for power batteries of electric vehicles is to balance only during the charging process. This method will cause the consistency of multiple cells in the power battery to become worse and worse during the life cycle of the vehicle, and the available battery capacity of the power battery will become lower and lower; it will also cause the actual cruising range of the vehicle to decrease with the increase of usage time. When the rate of decrease exceeds the normal capacity decay rate of the power battery, it will increase customers' anxiety and even concerns about the driving range. Some serious vehicles need to return to the 4S shop for separate balancing maintenance of the power battery, which greatly increases the vehicle maintenance cost. Therefore, the current BMS balancing solution cannot meet the requirements of the power battery for the balancing capacity index.

[0050] Based on this, the embodiments of the present application provide a power battery balancing method and device, which are described below through embodiments.

[0051] Example 1

[0052] To facilitate understanding of this embodiment, a power battery balancing method disclosed in an embodiment of this application is first described in detail. Figure 1Flow chart of a power battery equalization method. A power battery equalization method provided by this application is applicable to electric vehicles. The electric vehicle includes a power battery and a BMS module and an RTC module corresponding to the power battery. The method includes:

[0053] S101. When it is determined that the power battery of the electric vehicle is in an uncharged state, the BMS module and the RTC module are used to obtain the cell rest time and the remaining power of each cell in the power battery, so as to calculate the remaining power comparison threshold and the equalization power threshold of each cell based on the remaining power of each cell;

[0054] S102. Determine the error between the remaining power comparison threshold and the remaining power of each cell through the calculated cell rest time of each cell, so as to determine the equalization state of each cell based on the error, the equalization power threshold, the remaining power comparison threshold, and the remaining power;

[0055] S103. Calculate the equalization time of the target cell based on the target cell whose equalization state is determined, and update the equalization time of the target cell with the calculated equalization time to obtain the updated equalization time;

[0056] S104. Equalize the corresponding target cell based on the updated equalization time until all cells are equalized, so as to obtain a power battery with equalization completed.

[0057] In step S101, it is determined whether the electric vehicle is charging by determining whether the charging gun on the electric vehicle is inserted into the charging port of the electric vehicle. If the charging gun is not inserted into the charging port, the BMS module and the RTC module set for the power battery on the electric vehicle start to work. The BMS module and the RTC module respectively combine the collected battery temperature data with the time information provided by the RTC module to calculate the rest time of multiple cells in the power battery. The battery data includes battery temperature data. The RTC module helps the BMS module record the start time and end time of the cell's static state by providing accurate time information. When the cell rest time T < T1 (the default value is 14 min, to be determined, can be calibrated, where TBD is the specific value of T1 and can be determined according to the actual situation), the BMS module reads the previous equalization time set for the power battery and does not need to change the read previous equalization time, that is, does not update the equalization time. When the electric vehicle is just powered on, the BMS module determines that the minimum temperature Tmin of the cell in the battery temperature data ≤ T0 (the default value is 0 °C, calibration value), and does not update the equalization time, that is, does not change the previous equalization time; when the cell rest time T of each cell in the power battery ≥ T1, then each cell is retested by the open circuit voltage test method OCV to obtain the remaining power SOC of each celli , the remaining power SOC i It is obtained by looking up the table according to the temperature, and the remaining power of the power battery is not corrected. The open circuit voltage test method OCV is an existing mature test method, which will not be described in detail here. The remaining power comparison threshold SOC of each battery cell is calculated based on the remaining power SOC of each battery cell. 阀值 and balancing power threshold Where i is the number of battery cells, which is used to determine the specific situation of the remaining power of each battery cell.

[0058] In the specific implementation process of step S101, there is an embodiment in which the calculation of the remaining power comparison threshold based on the remaining power of each battery cell includes:

[0059] S10111. Calculate an average value and a minimum value of the remaining power based on the remaining power of each battery cell;

[0060] S10112. Process the calculated average value and minimum value of the remaining power to obtain a comparison threshold value of the remaining power of each battery cell.

[0061] In steps S10111-S10112, the BMS module tests the remaining power SOC of each cell in the power battery obtained by the open circuit voltage test method OCV. i Add and divide by the number of cells in the power battery to obtain the remaining power SOC of the cells in the power battery. i The average SOC 平均 The BMS module measures the remaining capacity SOC of each cell in the power battery obtained by the open circuit voltage test method OCV. i Sorting can be done in ascending or descending order, and the remaining power SOC i Select the minimum SOC min , then formula (1) is based on the remaining power SOC i The average SOC 平均 and remaining charge SOC i Minimum SOC min Obtain the remaining power comparison threshold SOC 阈值 :

[0062]

[0063] Among them, for PHEV, the remaining power comparison threshold SOC 阀值 The rebound voltage needs to be considered. If the voltage rebounds particularly slowly, the pure electric error will increase. It is necessary to supplement the rebound data of the battery cell after low-temperature and low-capacity charging and discharging to compensate for the pure electric error.

[0064] In the specific implementation process of step S101, there is also an embodiment: calculating the equalization power threshold of each battery cell based on the remaining power of each battery cell, including:

[0065] S10121. Input the calculated remaining power of each battery cell into a preset equalization power threshold calculation model;

[0066] S10122. The equalization power threshold calculation model calculates the equalization power threshold of each battery cell based on the remaining power of each battery cell.

[0067] In steps S10121 - S10122, the BMS module uses the remaining power SOC of each battery cell in the power battery obtained by the open - circuit voltage test method OCV i , and based on the remaining power SOC of each battery cell i , the corresponding relationship between the size of the remaining power SOC and the equalization power threshold is SOC[100 - 0%], corresponding to (default value [2% - 5%], can be calibrated), then input the remaining power SOC of each battery cell i into the preset equalization power threshold calculation model in formulas (2) - (3), and obtain the equalization power threshold according to formulas (2) - (3)

[0068]

[0069] S102. The BMS module determines the error between the corresponding remaining power comparison threshold SOC 阈值 and the remaining power SOC i according to the calculated static time T of each battery cell. The error is the maximum error value obtained through a large number of experimental data, and can also be set according to the actual situation. When the static time T is in different stages, the corresponding error values are also different. When the static time of the battery cell is T1 <= T < T2 (default value T1 = 14min, T2 = 26min, TBD, can be calibrated), the error at this time is buff1; when the static time of the battery cell is T2 <= T <= T3 (default value T2 = 26min, T3 = 45min, TBD, can be calibrated), the error at this time is buff2; when the static time of the battery cell is T3 < T < T4 (T3 default 45min, T4 default 60min, TBD, can be calibrated), the error at this time is buff3; when the static time of the battery cell is T >= T4 (T4 default 60min, TBD, can be calibrated), the error at this time is buff4; thus, based on the remaining power comparison threshold SOC 阈值 and the remaining power SOC iDetermine the equalization state of each battery cell based on the error, equalization power threshold, remaining power comparison threshold, and the relationship between the remaining powers. The equalization state of each battery cell refers to two states: whether each battery cell needs equalization or not.

[0070] In the specific implementation process of step S102, as Figure 2 shown, there is an implementation method: determining the equalization state of each battery cell based on the error, equalization power threshold, remaining power comparison threshold, and remaining power includes:

[0071] S1021. Calculate the difference between the remaining power of each battery cell and the corresponding remaining power comparison threshold, and at the same time calculate the sum of the equalization power threshold of each battery cell and the error;

[0072] S1022. Compare the calculated difference and the sum to obtain a comparison result, and determine the equalization state of the corresponding battery cell based on the comparison result.

[0073] In steps S1021 - S1022, the judgment of the size of the difference between the remaining power of each battery cell and the corresponding remaining power comparison threshold and the sum of the equalization power threshold of each battery cell and the error is represented by formulas (4) - (5):

[0074]

[0075] For example, when the static time of the battery cell is T1 <= T < T2, if the size of the difference between the remaining power of each battery cell and the corresponding remaining power comparison threshold and the sum of the equalization power threshold of each battery cell and the error satisfies formula (4), the comparison result is that the difference exceeds the sum. At this time, the equalization state of the battery cell is that equalization is required, and the battery cell that requires equalization at this time is the target battery cell. When the size of the difference between the remaining power of each battery cell and the corresponding remaining power comparison threshold and the sum of the equalization power threshold of each battery cell and the error satisfies formula (5), the comparison result is that the difference is less than the sum. At this time, the equalization state of the battery cell is that equalization is not required; and so on. When the static time of the battery cell is T2 <= T <= T3, the static time of the battery cell is T3 < T < T4, and the static time of the battery cell is T >= T4, they are also judged by using formulas (4) and (5) respectively, and only the error needs to be replaced with the error corresponding to the static time T. The default values of buff1 - 4 are 0 and can be calibrated.

[0076] In step S103, the BMS module calculates for the target battery cell in the power battery that is determined to require equalization, based on multiple parameters of the target battery cell such as the remaining power comparison threshold SOC 阈值, remaining power and remaining power comparison threshold SOC corresponding to the stationary time 阈值 The error between the target battery cell and the remaining power can also be obtained, and other parameters of the target battery cell can be obtained to calculate the balancing time of the target battery cell, and the balancing time of the target battery cell is updated with the calculated balancing time to obtain the updated balancing time, so that the BMS module does not balance the target battery cell with the previous balancing time, but uses the updated balancing time to balance the target battery cell.

[0077] In the specific implementation process of step S103, there is an embodiment in which: the calculating the balancing time of the battery cell based on the determined balancing state of the battery cell, and updating the balancing time of the target battery cell with the calculated balancing time, includes:

[0078] S1031, calculating the remaining power of the target battery cell, the remaining power comparison threshold and the error according to the determined balanced state of the battery cell, to obtain the balanced time of the target battery cell;

[0079] S1032: Replace the last balancing time of the target cell with the read time based on the obtained balancing time of the target cell, so that the target cell is balanced based on the calculated balancing time.

[0080] In steps S1031-S1032, the BMS module calculates the error and the balanced power threshold. Remaining power comparison threshold SOC 阈值 , remaining power SOC i The target cell that needs to be balanced is determined in each cell of the determined power battery, and the target cell is compared with the threshold SOC based on the remaining power 阈值 , remaining power and remaining power comparison threshold SOC corresponding to the stationary time 阈值 The balancing time of the target cell is calculated based on the error between the remaining power and the remaining power and other parameters of the target cell, and the last balancing time for the target cell read by the BMS module is replaced by the balancing time of the target cell based on the calculated balancing time of the target cell.

[0081] In the specific implementation process of step S1031, there is an embodiment in which: obtaining the balancing time of the battery cell according to calculation after determining the balancing state of the battery cell includes:

[0082] S10311, obtaining the capacity and balancing current of the target battery cell, and inputting them into a preset balancing time calculation model;

[0083] S10312. The balancing time calculation model calls the remaining power of the target battery cell, the remaining power comparison threshold and the error, and the capacity and balancing current of the target battery cell to calculate the balancing time of the target battery cell.

[0084] In steps S10311 - S10312, obtain the capacity Sys of the target battery cell AH and the equalization current I balance . The capacity of the target battery cell is preset in the BMS module and can be called by the BMS module when calculating the equalization time of the target battery cell. The equalization current can be set by the BMS module according to the capacity and remaining capacity of the target battery cell, or can be based on the current during the equalization process in the historical equalization process. For example, when the rest time of the battery cell is T1 <= T < T2, at this time, the error between the remaining power comparison threshold SOC 阈值 and the remaining power is buff1, and input the capacity and equalization current of the target battery cell into formula (6):

[0085] T(i) balance =[SOC i - SOC 阈值 - buff1]*Sys AH / I balance (6)

[0086] When equalization is not required, the corresponding equalization time T(i) balance = 0; and so on. When the rest time of the battery cell is T2 <= T <= T3, the rest time of the battery cell is T3 < T < T4, and the rest time of the battery cell is T >= T4, the equalization time is also calculated using formula (6), and only the error needs to be replaced with the error corresponding to the rest time T

[0087] In step S104, after obtaining the calculated equalization time of the target battery cell, the BMS module equalizes the target battery cell using the calculated equalization time and equalization current of the target battery cell. During the equalization process, the BMS module continuously monitors the state of the target battery cell by continuously monitoring key parameters such as the voltage and temperature of the target battery cell, and adjusts the equalization strategy as needed. Once the battery cell reaches the equalized state, stop the equalization operation for the target battery cell, equalize the corresponding target battery cell based on the updated equalization time until all the battery cells are equalized, and verify whether all the battery cells have reached the equalized state to obtain the power battery with equalization completed, and restore the power battery to the normal power supply state

[0088] In the specific implementation process of step S104, there is an embodiment: equalizing the corresponding target battery cell based on the updated equalization time until all the battery cells are equalized to obtain the power battery with equalization completed, including:

[0089] S1041. Read the battery cell equalization mode set for the power battery to equalize the target battery cell based on the battery cell equalization mode

[0090] S1042: After determining that all target cells in the power battery have completed balancing, the BMS module identifies the power battery as a balanced power battery.

[0091] In steps S1041-S1042, the BMS module reads the cell balancing mode set for the power battery. In order to reduce the overall balancing time of the power battery, the present application controls all target cells that need to be balanced in the power battery to be balanced at the same time until all target cells have reached the balancing time and completed the balancing. The BMS module determines that the power battery has completed the balancing. At this time, the power battery has completed the balancing in the non-charging process, thereby ensuring the life and performance of the power battery.

[0092] Example 2

[0093] There is another embodiment of the power battery balancing method provided in the present application, such as Figure 3 As shown, the embodiment includes:

[0094] S201, when it is determined that the power battery of the electric vehicle is in a charging state, obtaining the minimum temperature of each battery cell and the maximum temperature difference of the battery cell through the BMS module, so as to obtain the charging current and duration of the battery based on the minimum temperature and the maximum temperature difference, so as to determine the remaining power of each battery cell in the battery;

[0095] S202: obtaining a balancing time of a target battery cell based on the remaining power of each battery cell, and balancing the power batteries in a charging state based on the balancing time to obtain a balanced power battery.

[0096] In step S201, it is determined whether the electric vehicle is charging by determining whether the charging gun on the electric vehicle is inserted into the charging port of the electric vehicle. If the charging gun is inserted into the charging port, the electric vehicle is charging. The BMS module detects the temperature of each battery cell in the power battery, and obtains the minimum temperature Tmin and the maximum temperature difference of the battery cell in the power battery based on the detected temperature of each battery cell, that is, the difference Tmax-Tmin between the maximum temperature and the minimum temperature. When the BMS module determines that the minimum temperature Tmin of the battery cell is less than the standard temperature T0 or the maximum temperature difference Tmax-Tmin is greater than the standard temperature difference T_differ, where the default value of the standard temperature T0 is 0°C, which is a calibration value, and the default value of the standard temperature difference T_differ is 5°C, which is a calibration value, there is no need to balance the power battery, and at this time, there is no need to obtain the charging current and the duration of the charging current of the power battery. When the charging current of the power battery obtained by the BMS module is less than or equal to the charging current threshold T_Charge_Cur, and the duration of the charging current of the power battery less than or equal to the charging current threshold T_Charge_Cur reaches the standard charging time T_Charge_balacne, the remaining power SOC of each cell in the power battery is measured using the open circuit voltage test method. i , the remaining power SOC i It is obtained by looking up the table according to the temperature, and the remaining power of the power battery is not corrected. The default value of the charging current threshold T_Charge_Cur is 0.1C, which is a calibration value, and the default value of the standard charging time T_Charge_balacne is 10s, which is a calibration value.

[0097] In step S202, the BMS module determines the remaining power SOC of each battery cell based on the remaining power SOC of each battery cell. i Calculate and obtain multiple parameters about each battery cell, such as the equalization power threshold Remaining power comparison threshold SOC 阈值 , remaining power SOC i Compare the remaining power to the SOC threshold 阈值The error buff5 between them is determined based on multiple parameters of each battery cell, and the balancing time of the target battery cell is calculated based on the target battery cell, and each target battery cell that needs to be balanced is balanced based on the balancing time. If there are multiple target batteries that need to be balanced at the same time, the BMS module controls all the target batteries to be balanced at the same time, and monitors the state data of the target batteries during the balancing process, such as temperature, to ensure the safety during the balancing process, and determines that the power battery in the charging state has been balanced and balanced after all the target batteries that need to be balanced have completed balancing, and verifies whether all the batteries have reached a balanced state, so as to obtain a balanced power battery, and obtain a balanced power battery.

[0098] In the specific implementation process of step S202, there is an embodiment of obtaining the balancing time of the target battery cell based on the remaining power of each battery cell, including:

[0099] S2021, calculating a remaining power comparison threshold and a balanced power threshold of each battery cell based on the remaining power of each battery cell during charging;

[0100] S2022, determining a balanced state of each battery cell when the battery is in a charging state by using a relationship between a remaining power comparison threshold, a balanced power threshold, the remaining power of the battery cell when charging, and an error of the remaining power comparison threshold;

[0101] S2023: Calculate the balancing time of the target battery cell based on the determined balancing state of each battery cell.

[0102] In step S2021, similar to steps S10111-S10112, the BMS module calculates the remaining power SOC of each battery cell. i Get the remaining power SOC of the battery cell in the power battery i The average SOC 平均 , the minimum remaining power SOC min , and the same processing method as formula (1) is used to calculate the remaining power SOC i The average SOC 平均 and remaining charge SOC i Minimum SOC min Processing remaining power comparison threshold SOC 阈值 , and in a manner similar to steps S10121-S10122, the remaining power SOC of each battery cell of the BMS module i The corresponding relationship between the balanced power threshold is SOC[100~0%], corresponding to (Default value [2%~5%], calibrable), then the remaining power SOC of each battery celli Input into the preset equalization power threshold calculation model in formula (2)-(3), and obtain the equalization power threshold according to formula (2)-(3)

[0103] In step S2022, formulas (7)-(8) similar to formulas (4)-(5) are used to compare the remaining power comparison threshold, the balancing power threshold, and the The remaining power SOC of the battery cell during charging i The relationship between the error of the battery cell during charging, the equalization power threshold, the remaining power of the battery cell during charging and the error of the battery cell during charging are used to make the judgment, wherein the default value of buff5 is 0, which can be calibrated:

[0104]

[0105] In step S2023, if formula (7) is satisfied, it is determined that the battery cell needs to be balanced. If formula (8) is satisfied, it is determined that the battery cell does not need to be balanced. Since balancing is not required, T(i) balance =0; therefore, the cell to be balanced is the target cell, and the balancing time of the target cell is calculated using formula (9):

[0106] T(i) balance =[SOC i -SOC 阀值 -buff5]*Sys AH / I balance (9)

[0107] Based on the balancing time of the target battery cell obtained by formula (9), the target battery cells are balanced according to the balancing time of the target battery cell calculated until all the target battery cells are balanced to obtain a balanced power battery.

[0108] Example 3

[0109] The present application also provides a power battery balancing device, such as Figure 4 The block diagram of a power battery balancing device is shown. The functions implemented by the power battery balancing device correspond to the steps of executing the power battery balancing method on the terminal device. The device can be understood as a component of a server including a processor, and the device includes:

[0110] The acquisition module 401 is used for acquiring the cell rest time and the remaining power of each cell in the power battery through the BMS module and the RTC module when it is determined that the power battery of the electric vehicle is in an uncharged state, so as to calculate the remaining power comparison threshold and the equalization power threshold of each cell based on the remaining power of each cell;

[0111] A determination module 402 is used to determine the error between the remaining power comparison threshold and the remaining power of each battery cell through the calculated battery cell rest time of each battery cell, so as to determine the balancing state of each battery cell based on the error, the balancing power threshold, the remaining power comparison threshold and the remaining power;

[0112] An updating module 403 is used to calculate the balancing time of the target battery cell based on the target battery cell in the determined balancing state, and update the balancing time of the target battery cell with the calculated balancing time to obtain an updated balancing time;

[0113] The balancing module 404 is used to balance the corresponding target battery cells based on the updated balancing time until all the battery cells are balanced to obtain a balanced power battery.

[0114] In a feasible implementation manner, the device further includes:

[0115] a second acquisition module, for, when it is determined that the power battery of the electric vehicle is in a charging state, acquiring the minimum temperature of each battery cell and the maximum temperature difference of the battery cell through the BMS module, so as to acquire the charging current and duration of the battery based on the minimum temperature and the maximum temperature difference, so as to determine the remaining power of each battery cell in the battery;

[0116] The second balancing module is used to obtain a balancing time of a target battery cell based on the remaining power of each battery cell, and balance the power battery in a charging state based on the balancing time to obtain a balanced power battery.

[0117] In a feasible implementation manner, the second balancing module includes:

[0118] A first calculation module, used to calculate a remaining power comparison threshold and a balanced power threshold of each battery cell based on the remaining power of each battery cell during charging;

[0119] A second determination module, used to determine the balanced state of each battery cell when the battery is in a charging state through a relationship between a remaining power comparison threshold, a balanced power threshold, the remaining power of the battery cell when charging, and an error between the remaining power comparison threshold;

[0120] The second calculation module is used to calculate the balancing time of the target battery cell based on the determined balancing state of each battery cell.

[0121] In a feasible implementation, the acquisition module includes:

[0122] A third calculation module, used to calculate the average value and the minimum value of the remaining power based on the remaining power of each battery cell;

[0123] The processing module is used to process the calculated average value and minimum value of the remaining power to obtain a comparison threshold value of the remaining power of each battery cell.

[0124] In a feasible implementation manner, the acquisition module further includes:

[0125] An input module, used to input the calculated remaining power of each battery cell into a preset equalization power threshold calculation model;

[0126] The fourth calculation module is used to calculate the remaining power of each battery cell using the equalization power threshold calculation model to obtain the equalization power threshold of each battery cell.

[0127] In a feasible implementation manner, the determination module includes:

[0128] A fifth calculation module, used to calculate the difference between the remaining power of each battery cell and the corresponding remaining power comparison threshold, and simultaneously calculate the sum of the equalization power threshold of each battery cell and the error;

[0129] A comparison module is used to compare the calculated difference value and the calculated sum value to obtain a comparison result, so as to determine the balance state of the corresponding battery cell based on the comparison result.

[0130] In a feasible implementation, the update module includes:

[0131] a sixth calculation module, configured to calculate the remaining power of the target battery cell, the remaining power comparison threshold and the error according to the determined balanced state of the battery cell, and obtain the balanced time of the target battery cell;

[0132] The replacement module is used to replace the last balancing time of the read target battery cell based on the obtained balancing time of the target battery cell, so that the target battery cell is balanced based on the calculated balancing time.

[0133] In a feasible implementation manner, the update module further includes:

[0134] A third acquisition module is used to acquire the capacity and balancing current of the target battery cell and input them into a preset balancing time calculation model;

[0135] The seventh calculation module is used for the balancing time calculation model to call the remaining power of the target battery cell, the remaining power comparison threshold and the error and the capacity and balancing current of the target battery cell to calculate the balancing time of the target battery cell.

[0136] In a feasible implementation manner, the balancing module includes:

[0137] Reading a cell balancing mode set for the power battery, so as to balance the target cell based on the cell balancing mode;

[0138] After determining that all target cells in the power battery have completed balancing, the BMS module identifies the power battery as a balanced power battery.

[0139] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the method embodiment, and will not be repeated in this application. In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0140] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0141] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0142] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a platform server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard drives, ROM, RAM, magnetic disks, or optical disks.

[0143] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A power battery balancing method, characterized in that: Applicable to an electric vehicle, the electric vehicle includes a power battery and a BMS module and an RTC module corresponding to the power battery, the method includes: When it is determined that the power battery of the electric vehicle is in an uncharged state, the cell rest time and the remaining power of each cell in the power battery are obtained through the BMS module and the RTC module, so as to calculate the remaining power comparison threshold and the equalization power threshold of each cell based on the remaining power of each cell; Determine the error between the remaining power comparison threshold and the remaining power of each battery cell by calculating the battery cell rest time of each battery cell, so as to determine the balancing state of each battery cell based on the error, the balancing power threshold, the remaining power comparison threshold and the remaining power; Calculating the balancing time of the target battery cell based on the determined balancing state of the target battery cell, and updating the balancing time of the target battery cell with the calculated balancing time to obtain an updated balancing time; Based on the updated balancing time, the corresponding target battery cells are balanced until all the battery cells are balanced to obtain a balanced power battery.

2. The method according to claim 1, characterized in that The power battery balancing method further includes: When it is determined that the power battery of the electric vehicle is in a charging state, the minimum temperature of each battery cell and the maximum temperature difference of the battery cell are obtained through the BMS module, so as to obtain the charging current and duration of the battery based on the minimum temperature and the maximum temperature difference, so as to determine the remaining power of each battery cell in the battery; The balancing time of the target battery cell is obtained based on the remaining power of each battery cell, and the power battery in a charging state is balanced based on the balancing time to obtain a balanced power battery.

3. The method according to claim 2, characterized in that Obtaining the balancing time of the target battery cell based on the remaining power of each battery cell includes: Calculate a remaining power comparison threshold and a balancing power threshold of each battery cell based on the remaining power of each battery cell during charging; Determine the balancing state of each battery cell when the battery is in a charging state by using the relationship between the remaining power comparison threshold, the balancing power threshold, the remaining power of the battery cell when charging, and the error of the remaining power comparison threshold; The balancing time of the target battery cell is calculated based on the determined balancing state of each battery cell.

4. The method according to claim 1, characterized in that The calculating the remaining power comparison threshold based on the remaining power of each battery cell includes: Calculating an average value and a minimum value of the remaining power based on the remaining power of each battery cell; The calculated average and minimum values ​​of the remaining power are processed to obtain a comparison threshold value of the remaining power of each battery cell.

5. The method according to claim 1, characterized in that The step of calculating the equalization power threshold of each battery cell based on the remaining power of each battery cell includes: Inputting the calculated remaining power of each battery cell into a preset equalization power threshold calculation model; The equalization power threshold calculation model calculates the remaining power of each battery cell to obtain the equalization power threshold of each battery cell.

6. The method according to claim 1, characterized in that The step of determining the balancing state of each battery cell based on the error, the balancing power threshold, the remaining power comparison threshold, and the remaining power includes: Calculate the difference between the remaining power of each battery cell and the corresponding remaining power comparison threshold, and calculate the sum of the equalization power threshold and the error of each battery cell; The calculated difference value and the calculated sum value are compared to obtain a comparison result, so as to determine the balance state of the corresponding battery cell based on the comparison result.

7. The method according to claim 1, characterized in that The calculating the balancing time of the battery cell based on the determined balancing state of the battery cell, and updating the balancing time of the target battery cell with the calculated balancing time, includes: After the determined balanced state of the battery cell, the remaining power of the target battery cell, the remaining power comparison threshold and the error are calculated to obtain the balanced time of the target battery cell; The last balancing time of the target cell is replaced based on the obtained balancing time of the target cell, so that the target cell is balanced based on the calculated balancing time.

8. The method according to claim 7, characterized in that The step of obtaining the balancing time of the battery cell by calculation after determining the balancing state of the battery cell comprises: Obtain the capacity and balancing current of the target battery cell and input them into the preset balancing time calculation model; The balancing time calculation model calls the remaining power of the target battery cell, the remaining power comparison threshold and the error, and the capacity and balancing current of the target battery cell to calculate the balancing time of the target battery cell.

9. The method according to claim 1, characterized in that: The method of performing balancing based on the updated balancing time as the corresponding target battery cell until all the battery cells are balanced to obtain a balanced power battery includes: Reading a cell balancing mode set for the power battery, so as to balance the target cell based on the cell balancing mode; After determining that all target cells in the power battery have completed balancing, the BMS module identifies the power battery as a balanced power battery.

10. A power battery equalization device, characterized in that: The device comprises: an acquisition module, for acquiring, when it is determined that the power battery of the electric vehicle is in an uncharged state, a cell rest time and a remaining power of each cell in the power battery through the BMS module and the RTC module, so as to calculate a remaining power comparison threshold and a balanced power threshold of each cell based on the remaining power of each cell; A determination module, configured to determine an error between a remaining power comparison threshold and the remaining power of each battery cell by calculating the battery cell rest time of each battery cell, so as to determine a balanced state of each battery cell based on the error, the balanced power threshold, the remaining power comparison threshold, and the remaining power; An updating module, configured to calculate a balancing time of a target battery cell based on a target battery cell in a determined balancing state, and update the balancing time of the target battery cell with the calculated balancing time to obtain an updated balancing time; The balancing module is used to balance the corresponding target cells based on the updated balancing time until all cells are balanced to obtain a balanced power battery.

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