Battery pack power balancing method and device

Abstract

The present application discloses a battery pack charge balancing method and device. The method includes: obtaining a first correspondence relationship of the battery pack upon completion of charging of the battery pack, obtaining a first temperature and a first voltage of each battery cell at the completion of charging; determining a first remaining charge capacity of each battery cell based on the first temperature, the first voltage, and the first correspondence relationship; determining the largest of multiple first remaining charge capacities as a target remaining charge capacity; for each battery cell, calculating the difference between the target remaining charge capacity and the first remaining charge capacity corresponding to the battery cell to obtain a first remaining charge capacity to be balanced for the battery cell; and, if the first remaining charge capacity to be balanced is greater than a preset threshold, balancing the charge of the battery cells based on the first remaining charge capacity to be balanced during the next discharge of the battery cells. This allows accurate charge balancing of the battery cells.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method and device for balancing the charge of a battery pack. Background Art

[0002] Electric vehicles are gradually replacing gasoline-powered vehicles in our daily lives. Battery packs are typically constructed from numerous battery cells connected in series and parallel to meet the range and energy requirements of electric vehicles. Although battery cell manufacturers rigorously screen and prioritize consistent cell capacities before assembly, variations in cell capacity persist, resulting in a lower capacity for the series-assembled battery pack than for a single cell.

[0003] To address the problem of poor charge consistency between battery cells, battery pack balancing can be used to achieve charge consistency. Currently, battery cell balancing is typically performed using a balancing algorithm based on the State of Charge (SOC).

[0004] However, the SOC-based balancing algorithm depends largely on the accuracy of the SOC, and the SOC value is generally difficult to accurately determine. Therefore, the SOC-based balancing algorithm is difficult to accurately balance the battery cells. Summary of the Invention

[0005] The embodiments of the present application provide a method and apparatus for balancing the power of a battery pack, which can determine the power to be balanced of a battery cell based on the remaining charge power of the battery cell, thereby accurately balancing the power of the battery cells.

[0006] In a first aspect, an embodiment of the present application provides a method for balancing a battery pack, the method comprising:

[0007] When charging of the battery pack is completed, obtaining a first correspondence relationship of the battery pack, and obtaining a first temperature and a first voltage of each battery cell at the end of charging, wherein the first correspondence relationship is a correspondence relationship between the temperature, voltage, and remaining charge of the battery cell during the charging process, and the battery pack includes multiple battery cells;

[0008] Determine a first remaining charge capacity of each battery cell according to the first temperature, the first voltage and the first corresponding relationship;

[0009] Determining a maximum of the plurality of first remaining charging capacities as a target remaining charging capacities;

[0010] For each of the plurality of battery cells, perform the following steps:

[0011] Calculating the difference between the target remaining charge capacity and the first remaining charge capacity corresponding to the battery cell to obtain a first to-be-balanced capacity of the battery cell;

[0012] When the first amount of electricity to be balanced is greater than a preset threshold, during the next discharge process of the battery cells, the electricity of the battery cells is balanced based on the first amount of electricity to be balanced.

[0013] In a second aspect, an embodiment of the present application provides a battery pack power balancing device, the device comprising:

[0014] a first acquiring module, configured to acquire, when charging of the battery pack is completed, a first corresponding relationship of the battery pack, and acquire a first temperature and a first voltage of each battery cell at the end of charging, wherein the first corresponding relationship is a corresponding relationship between the temperature, the voltage, and the remaining charge capacity of the battery cell during the charging process, and the battery pack includes a plurality of battery cells;

[0015] A first determining module, configured to determine a first remaining charge capacity of each battery cell according to the first temperature, the first voltage, and the first corresponding relationship;

[0016] a second determining module, configured to determine a maximum of the plurality of first remaining charging capacities as a target remaining charging capacities;

[0017] The first processing module is configured to perform the following steps for each battery cell of the plurality of battery cells:

[0018] Calculating the difference between the target remaining charge capacity and the first remaining charge capacity corresponding to the battery cell to obtain a first to-be-balanced capacity of the battery cell;

[0019] When the first amount of electricity to be balanced is greater than a preset threshold, during the next discharge process of the battery cells, the electricity of the battery cells is balanced based on the first amount of electricity to be balanced.

[0020] In a third aspect, an embodiment of the present application provides an electronic device, the device comprising: a processor and a memory storing computer program instructions,

[0021] When the processor executes the computer program instructions, the battery pack power balancing method as shown in any one of the embodiments of the first aspect is implemented.

[0022] In a fourth aspect, an embodiment of the present application provides a computer storage medium having computer program instructions stored thereon, and when the computer program instructions are executed by a processor, the battery pack power balancing method shown in any one of the embodiments of the first aspect is implemented.

[0023] In a fifth aspect, an embodiment of the present application provides a computer program product. When the instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes the battery pack power balancing method shown in any one of the embodiments of the first aspect.

[0024] The battery pack charge balancing method and device of the embodiment of the present application can obtain a first correspondence relationship of the battery pack and a first temperature and a first voltage of each battery cell at the end of charging when charging of the battery pack is completed. The first correspondence relationship is the correspondence relationship between the temperature, voltage, and remaining charge of the battery cell during the charging process. The first remaining charge of each battery cell is determined based on the first temperature, first voltage, and the first correspondence relationship, and the largest of multiple first remaining charge capacities is determined as the target remaining charge. Then, for each of the multiple battery cells, the difference between the target remaining charge and the first remaining charge corresponding to the battery cell is calculated to obtain the first charge to be balanced of the battery cell. Then, if the first charge to be balanced is greater than a preset threshold, the charge of the battery cell is balanced based on the first charge to be balanced during the next discharge of the battery cell. In this way, the charge to be balanced of the battery cell can be determined based on the remaining charge of the battery cell, thereby accurately balancing the battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] Figure 1 This is one of the flow charts of a battery pack power balancing method provided by one embodiment of the present application;

[0027] Figure 2 This is a schematic diagram of a curve showing the relationship between voltage and remaining charge capacity provided by an embodiment of the present application;

[0028] Figure 3 This is the second flow chart of a battery pack power balancing method provided by one embodiment of the present application;

[0029] Figure 4 This is a structural diagram of a power balancing device for a battery pack provided by one embodiment of the present application;

[0030] Figure 5 This is a schematic structural diagram of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0031] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating the examples of the present application.

[0032] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0033] As mentioned in the background, electric vehicles are gradually replacing gasoline-powered vehicles in our daily lives. Typically, battery packs consist of numerous battery cells connected in series and parallel to meet the range or energy requirements of electric vehicles. Although battery cell manufacturers rigorously screen and prioritize consistent cell capacities before grouping, variations in cell capacity persist, resulting in a battery pack capacity lower than the sum of the individual cell capacities.

[0034] To address the problem of poor power consistency between battery cells, a balancing function can be added to the Battery Management System (BMS) to enable balancing of the battery pack to achieve power consistency.

[0035] Balancing methods can be categorized as active and passive. Active balancing is relatively difficult to implement in both hardware and algorithmic terms, and its effect on improving battery pack capacity is limited. Passive balancing, on the other hand, requires only balancing resistors in hardware to enable energy-efficient balancing. With the appropriate balancing strategy, it can increase the battery pack's usable capacity and, when used in electric vehicles, improve range.

[0036] The most typical passive balancing method is to rely on balancing resistor discharge balancing. The balancing algorithm can be divided into balancing based on voltage, SOC or capacity.

[0037] Voltage estimation is relatively simple, but the voltage difference is more obvious only at the end of charging or discharging. The corresponding balancing start time is short, making it difficult to achieve consistency in the battery pack voltage in a timely and effective manner.

[0038] The SOC-based balancing algorithm depends largely on the accurate estimation of SOC, and the SOC-based balancing algorithm will cause repeated balancing to occur, so it is not the optimal method to enable balancing.

[0039] The capacity-based balancing algorithm is the most direct method to reflect the balancing effect. The essence of balancing is to make the battery pack capacity tend to be consistent. The balancing range is wide and the fault tolerance is large. However, there is little research on capacity-based balancing algorithms. Some of them still estimate the remaining power based on SOC and then start balancing. This type of balancing algorithm has large errors and is difficult to meet the needs of engineering implementation.

[0040] Based on this, an embodiment of the present application provides a method for balancing the power of a battery pack. The method for balancing the power of a battery pack provided by an embodiment of the present application is introduced below.

[0041] Figure 1 A flow chart of a battery pack power balancing method according to an embodiment of the present application is shown.

[0042] like Figure 1 As shown, the execution subject of the battery pack power balancing method may be a battery pack power balancing device, and the battery pack power balancing method may include the following steps:

[0043] S110, when charging of the battery pack is completed, obtaining a first corresponding relationship of the battery pack, and obtaining a first temperature and a first voltage of each battery cell when charging is completed;

[0044] S120, determining a first remaining charge capacity of each battery cell according to the first temperature, the first voltage, and the first corresponding relationship;

[0045] S130, determining the largest of the plurality of first remaining charging capacities as the target remaining charging capacities;

[0046] For each of the plurality of battery cells, perform the following steps:

[0047] S140, calculating the difference between the target remaining charge capacity and the first remaining charge capacity corresponding to the battery cell to obtain a first to-be-balanced capacity of the battery cell;

[0048] S150 , when the first amount of electricity to be balanced is greater than a preset threshold, during the next discharge process of the battery cells, the electricity of the battery cells is balanced based on the first amount of electricity to be balanced.

[0049] Thus, when charging of the battery pack is completed, a first correspondence of the battery pack can be obtained, as well as the first temperature and first voltage of each battery cell at the end of charging. The first correspondence is the correspondence between the temperature, voltage, and remaining charge of the battery cell during the charging process. The first remaining charge of each battery cell is determined based on the first temperature, first voltage, and first correspondence, and the largest of multiple first remaining charge capacities is determined as the target remaining charge. For each of the multiple battery cells, the difference between the target remaining charge and the first remaining charge corresponding to the battery cell is calculated to obtain the first charge to be balanced of the battery cell. Then, if the first charge to be balanced is greater than a preset threshold, the charge of the battery cell is balanced based on the first charge to be balanced during the next discharge of the battery cell. In this way, the charge to be balanced of the battery cell can be determined based on the remaining charge of the battery cell, thereby accurately balancing the charge of the battery cells.

[0050] Regarding S110 , the battery pack may include a plurality of battery cells.

[0051] For example, the battery pack can be a power battery, such as a lithium iron phosphate power battery. The lithium iron phosphate power battery has strong stability, high safety, and a relatively long life, and is very popular in power system fields such as vehicles, special aerospace, and electric tools.

[0052] The first corresponding relationship may be a corresponding relationship between the temperature, voltage and remaining charge capacity of the battery cell during the charging process.

[0053] Exemplarily, the first corresponding relationship may be a three-dimensional graph, or a plurality of relationship curves between voltage and remaining charge capacity, where different relationship curves correspond to different temperatures.

[0054] The battery pack can be charged to any state, which can be fully charged or not fully charged.

[0055] The first temperature may be the temperature of the battery cell at the end of charging of the battery pack. The temperatures of the multiple battery cells may be considered to be the same, and the temperature of the battery pack may be directly collected as the first temperature.

[0056] The first voltage may be the voltage of the battery cell at the time when charging of the battery pack is completed.

[0057] The remaining charge capacity may be the difference between the rated capacity of the battery cell and the current remaining energy.

[0058] In some embodiments, in order to obtain an accurate first correspondence, before obtaining the first correspondence of the battery pack, the method may further include:

[0059] The following steps are performed for each of a plurality of different temperatures to determine a corresponding relationship between the voltage and the remaining charge capacity at each temperature, thereby obtaining a first corresponding relationship:

[0060] When the battery pack is at temperature, charge the battery pack;

[0061] When the battery pack reaches a fully charged state, calibrating the initial remaining charge capacity of the first battery cell with the largest voltage to a first preset value;

[0062] discharging the battery pack, and determining a second remaining charge capacity of the first battery cell when the battery pack is discharged to a preset state;

[0063] charging the battery pack, and recording a plurality of voltages of the first battery cell and the remaining charge capacity corresponding to each voltage during a process in which the remaining charge capacity of the first battery cell decreases from a second remaining charge capacity to a second preset value;

[0064] A corresponding relationship between the voltage and the remaining charge capacity at a temperature is determined based on the plurality of voltages and the remaining charge capacity corresponding to each voltage.

[0065] Here, the first preset value and the second preset value can be set according to actual needs. For example, the first preset value and the second preset value can both be 0.

[0066] The preset state may be any state during the discharge process.

[0067] Specifically, the calibration process for the correspondence between voltage and remaining charge at each temperature can be as follows: while the battery pack is at the specified temperature, the battery pack is charged. When the battery pack reaches a fully charged state, the voltage of each battery cell is collected, the first battery cell with the highest voltage is determined, the sequence number of the first battery cell is recorded, and the current remaining charge of the first battery cell, i.e., the initial remaining charge, is calibrated to 0 Ah. The battery pack is then discharged. During the discharge process, the real-time remaining charge of the first battery cell can be estimated using the ampere-hour integration method and stored in real time. When the battery pack is discharged to a predetermined state, the remaining charge of the first battery cell at this time is determined as a second remaining charge. The battery pack is then charged again. As the remaining charge of the first battery cell decreases from the second remaining charge to 0 Ah, multiple voltages of the first battery cell and the remaining charge corresponding to each voltage are recorded. Based on the multiple voltages and the remaining charge corresponding to each voltage, the correspondence between voltage and remaining charge at the specified temperature can be determined.

[0068] Through the above process, the corresponding relationships between the voltages corresponding to the multiple temperatures and the remaining charge capacity can be determined, thereby obtaining a first corresponding relationship.

[0069] The first battery cell with the highest voltage may be the battery cell that first reaches the cut-off charging voltage during the charging process. For example, the cut-off charging voltage may be 3.65V.

[0070] The formula for the ampere-hour integration method can be:

[0071]

[0072] in, can be the second remaining charge capacity of the first battery cell, It can be the initial remaining charge capacity of the first battery cell, that is, can be equal to a first preset value, is the charging current, For charging time.

[0073] For example, in a lithium iron phosphate power battery pack, the relationship curve between the voltage and the remaining charge capacity of a battery cell with a capacity of 100Ah at a temperature of 25°C can be as follows: Figure 2 shown.

[0074] In this way, through the above process, the first corresponding relationship can be accurately calibrated, laying the foundation for power balancing.

[0075] Regarding S120 , the first remaining charge capacity may be the remaining charge capacity of the battery cell when charging of the battery pack is completed.

[0076] In order to accurately correct the remaining charge capacity of the battery cell when the battery pack is finished charging, the remaining charge capacity of the battery cell when the battery pack is finished charging may be corrected based on the first corresponding relationship.

[0077] Specifically, since the first correspondence is the correspondence between the temperature, voltage, and remaining charge of the battery cell during the charging process, the first remaining charge corresponding to the first temperature and the first voltage can be determined from the first correspondence, that is, the remaining charge of the battery cell at the end of charging the battery pack.

[0078] In the case where the first correspondence is a curve, the curve is composed of a plateau region and two slope regions. The voltage in the plateau region corresponds to a large error in the remaining charge capacity. Therefore, in some embodiments, to improve the accuracy of the first remaining charge capacity, S120 may include:

[0079] Determine a minimum target voltage among the plurality of first voltages and a target corresponding relationship corresponding to the first temperature in the first corresponding relationships;

[0080] When the target voltage is not in the plateau region in the target correspondence, for each battery cell, the remaining charge capacity corresponding to the first voltage is searched from the target correspondence to obtain a first remaining charge capacity of the battery cell.

[0081] Here, the target corresponding relationship may be a corresponding relationship between the voltage and the remaining charge capacity at the first temperature.

[0082] The change in the remaining charge power corresponding to the unit voltage change in the plateau area may be greater than the first threshold. For example, Figure 2 In the relationship curve shown, the line segment between the first point 210 and the second point 220 is a plateau area.

[0083] The first threshold value can be set according to actual needs. For example, the first threshold value can be 0.01.

[0084] Specifically, if the target voltage is in the plateau region, the first remaining charge capacity of the battery cell may be the remaining charge capacity corresponding to the first voltage in the target correspondence relationship.

[0085] In this way, the accuracy of the first remaining charge capacity can be improved through the above process.

[0086] In some embodiments, to improve the accuracy of the first remaining charge capacity, after determining the minimum target voltage among the plurality of first voltages, the method may further include:

[0087] When the target voltage is in the plateau region, the first remaining charge capacities of the plurality of battery cells are corrected to remaining charge capacities corresponding to the end points of the plateau region.

[0088] Here, the end point of the platform area can be the inflection point at the end of the platform area. Figure 2 In the relationship curve shown, the end point of the plateau region may be the first point 210 .

[0089] Specifically, if the target voltage is in the plateau region, the first remaining charge capacities of the plurality of battery cells may all be the remaining charge capacities corresponding to the end points of the plateau region in the target correspondence relationship.

[0090] For example, the target voltage is 3.38V, which is in the plateau region. Therefore, the first remaining charge capacity of the plurality of battery cells may be corrected to the remaining charge capacity of 10 Ah corresponding to the end point of the plateau region.

[0091] In this way, the accuracy of the first remaining charge capacity can be improved through the above process.

[0092] Regarding S130 , the battery cell with the largest first remaining charge capacity has the smallest remaining charge capacity. Therefore, when performing energy balancing, the battery cell with the largest first remaining charge capacity can be used as a reference for energy balancing of the other battery cells. Therefore, it is necessary to determine the largest of the multiple first remaining charge capacities, i.e., the target remaining charge capacity.

[0093] Regarding S140 , the first amount of electricity to be balanced may be the amount of electricity that needs to be balanced in the battery cells.

[0094] The first to-be-balanced power of each battery cell may be a difference between the target remaining charge power and the first remaining charge power corresponding to the battery cell.

[0095] In some embodiments, to avoid over-balancing due to errors in the amount of electricity to be balanced, S140 may include:

[0096] Calculating the difference between the target remaining charge capacity and the first remaining charge capacity corresponding to the battery cell to obtain a second remaining charge capacity to be balanced of the battery cell;

[0097] The product of the second power to be balanced and the first preset coefficient is determined as the first power to be balanced.

[0098] Here, the first preset coefficient may be a positive number less than 1. The specific value of the first preset coefficient may be set according to actual needs. For example, the first preset coefficient may be 0.8.

[0099] The second to-be-balanced capacity of each battery cell may be a difference between the target remaining charge capacity and the first remaining charge capacity corresponding to the battery cell.

[0100] If there is an error in the remaining charge of each battery cell, it will cause an error in the second charge to be balanced. Balancing based on the error in the second charge to be balanced will cause overbalancing. Therefore, the first charge to be balanced can be set to the theoretical charge to be balanced, that is, the product of the second charge to be balanced and the first preset coefficient.

[0101] For example, if the first preset coefficient is 0.8, the calculation formula for the first amount of electricity to be balanced may be:

[0102]

[0103] in, is the first amount of electricity to be balanced, The remaining charge capacity of the target, It is the first remaining charging capacity.

[0104] For example, the target remaining charge capacity is 10 Ah, and the first charge to be balanced is (10 Ah-0 Ah)×0.8=8 Ah.

[0105] In this way, by setting the first amount of electricity to be balanced to be the product of the second amount of electricity to be balanced and the first preset coefficient, and the first preset coefficient being a positive number less than 1, over-balancing due to errors in the amount of electricity to be balanced can be avoided.

[0106] Regarding S150 , the next discharge may be the next discharge closest to the current moment.

[0107] For each battery cell, during the next discharge process, the battery cell can be controlled to discharge more than the first amount of electricity to be balanced, thereby achieving electricity balance for the battery cell.

[0108] It can be set that the battery cell is only balanced when the first battery cell to be balanced is greater than a preset threshold. If the first battery cell to be balanced is not greater than the preset threshold, the battery cell is not balanced during the next discharge process.

[0109] The battery pack charge balancing method provided in the embodiment of the present application can perform charge balancing during the entire discharge process, greatly improving the balancing efficiency.

[0110] In some embodiments, to avoid repeated balancing, the preset threshold may be the product of the rated capacity of the battery cell and the second preset coefficient.

[0111] Here, since the capacities of different battery packs are different, the preset threshold value may be the product of the rated capacity of the battery cell and the second preset coefficient. The second preset coefficient may be set according to actual needs. For example, the second preset coefficient may be 0.5%.

[0112] For example, if the rated capacity of a battery cell is 100 Ah, the second preset coefficient is 0.5%, and the preset threshold is 0.5 Ah. Therefore, if the first charge to be balanced of a battery cell exceeds 0.5 Ah, the charge of that battery cell will be balanced based on the first charge to be balanced during the next discharge of the battery cell. If the first charge to be balanced of a battery cell does not exceed 0.5 Ah, the charge of that battery cell will not be balanced during the next discharge of the battery cell.

[0113] In this way, by setting the battery cells to perform power balancing only when the first power to be balanced is greater than a preset threshold, frequent power balancing can be avoided, thereby avoiding repeated balancing.

[0114] In some embodiments, in order to accurately perform balancing control, the method may further include:

[0115] In the process of balancing the electric quantity of the battery cells based on the first electric quantity to be balanced, obtaining the balancing current and the balancing time of the battery cells;

[0116] Determine the balanced capacity of the battery cells based on the balancing current and the balancing time;

[0117] Determine the remaining power to be balanced of the battery cell according to the first power to be balanced and the balanced power;

[0118] When the remaining power to be balanced of the battery cells is less than or equal to a third preset value, power balancing of the battery cells is stopped.

[0119] Here, the balancing current may be a discharge current value that needs to be increased between battery cells in order to perform charge balancing. For example, the balancing current may be between 10 mA and 200 mA.

[0120] The balancing current may be the current balancing current of the battery cell. During the discharge process, the balancing current of the battery cell may change, and the balancing current of the battery cell may be obtained in real time.

[0121] The balanced time may be the current balanced time of the battery cell, and the balanced time of the battery cell may be obtained in real time.

[0122] Specifically, by acquiring the balancing current and balancing time of a battery cell in real time, the remaining amount of electricity to be balanced of the battery cell can be calculated in real time.

[0123] The remaining amount of electricity to be balanced of the battery cell being the third preset value may indicate that the battery cell has completed balancing.

[0124] The third preset value can be set according to actual needs. For example, the third preset value can be 0.

[0125] For example, the calculation formula for the balanced power can be:

[0126]

[0127] in, The power has been balanced. is the balancing current, The balanced duration.

[0128] The remaining amount of electricity to be balanced may be the difference between the first amount of electricity to be balanced and the amount of electricity that has been balanced.

[0129] For example, the calculation formula for the remaining power to be balanced may be:

[0130]

[0131] in, is the remaining power to be balanced, is the first amount of electricity to be balanced, The power is balanced.

[0132] In this way, by calculating the remaining power to be balanced in real time, the power balancing of the battery cells is stopped when the remaining power to be balanced is less than or equal to the third preset value. This can stop the power balancing of the battery cells in time and achieve accurate balancing control of individual battery cells.

[0133] In some embodiments, in order to accurately determine the balancing current of the battery cells, the obtained balancing current of the battery cells may include:

[0134] obtaining a second voltage of the battery cell;

[0135] The balancing current of the battery cell is determined according to the second voltage and the resistance value of the balancing resistor.

[0136] Here, the second voltage may be the current discharge voltage of the battery cell. During the discharge process, the second voltage may change, so the second voltage of the battery cell can be obtained in real time and the balancing current can be calculated in real time.

[0137] The balancing current may be a ratio of the second voltage to the resistance of the balancing resistor.

[0138] In this way, the balancing current of the battery cells can be accurately calculated through the above process.

[0139] In some embodiments, in order to accurately balance and control the battery pack, the method may further include:

[0140] Before charging the battery pack, stop balancing the battery cells.

[0141] Here, before the battery pack is charged, the charge balancing of the plurality of battery cells included in the battery pack may be stopped.

[0142] For example, when the battery pack is connected to the charging device, the charge balancing of the multiple battery cells included in the battery pack may be stopped before charging is started.

[0143] In addition, the direction of the current can also be used to determine whether the battery pack is ready for charging.

[0144] In this way, through the above process, the power balancing of each battery cell can be stopped before charging the battery pack, thereby achieving precise balancing control of the battery pack.

[0145] After stopping the battery balancing for each battery cell and starting to charge the battery pack, the process may return to S110 to perform the next round of battery balancing.

[0146] In order to better describe the entire solution, based on the above embodiments, a specific example is given. Figure 3As shown, the battery pack power balancing method may include S301-S307, which will be explained in detail below.

[0147] S301 : When charging of the battery pack is completed, obtain a first corresponding relationship of the battery pack, and obtain a first temperature and a first voltage of each battery cell when charging is completed.

[0148] S302 : Determine a first remaining charge capacity of each battery cell according to the first temperature, the first voltage, and the first corresponding relationship.

[0149] S303: Determine the largest of the plurality of first remaining charging capacities as the target remaining charging capacities.

[0150] S304 : For each battery cell, calculate the difference between the target remaining charge capacity and the first remaining charge capacity corresponding to the battery cell to obtain a first to-be-balanced capacity of the battery cell.

[0151] S305 , for each battery cell, when a first to-be-balanced power level of the battery cell is greater than a preset threshold, balance the power level of the battery cell based on the first to-be-balanced power level during the next discharge of the battery cell.

[0152] S306 , for each battery cell, when the battery pack is in a non-charging state and the remaining amount of power to be balanced of the battery cell is less than or equal to a third preset value, stop power balancing for the battery cell.

[0153] S307: When the battery pack is ready to be charged, stop balancing the battery cells and return to S301.

[0154] The specific process of S301-S307 can be found in the above embodiment and will not be described again here.

[0155] The battery pack power balancing method provided in the embodiment of the present application performs balancing control based on the consistency of the remaining charging power. The remaining charging power estimation method is based on the voltage similarity theory of the charging stage, which avoids the occurrence of misbalancing caused by SOC estimation errors. As long as the balancing conditions are met, balancing can be turned on during the entire discharge process, greatly improving the balancing efficiency. Not only does it have the widest constraints and is less prone to over-balancing and repeated balancing, it also improves the actual capacity of the battery pack, can meet the needs of engineering implementation, and can increase the cruising range of electric vehicles.

[0156] Based on the same inventive concept, the present application also provides a battery pack power balancing device. Figure 4 The power balancing device of the battery pack provided in the embodiment of the present application is described in detail.

[0157] Figure 4A schematic structural diagram of a battery pack power balancing device provided in one embodiment of the present application is shown.

[0158] like Figure 4 As shown, the battery pack power balancing device may include:

[0159] A first acquisition module 401 is configured to acquire, when charging of the battery pack is completed, a first correspondence of the battery pack and a first temperature and a first voltage of each battery cell at the end of charging, wherein the first correspondence is a correspondence between the temperature, voltage, and remaining charge of the battery cell during charging, and the battery pack includes a plurality of battery cells;

[0160] A first determining module 402 is configured to determine a first remaining charge capacity of each battery cell according to the first temperature, the first voltage, and the first corresponding relationship;

[0161] A second determining module 403 is configured to determine a maximum of the plurality of first remaining charging capacities as a target remaining charging capacities;

[0162] The first processing module 404 is configured to perform the following steps for each of the plurality of battery cells:

[0163] Calculating the difference between the target remaining charge capacity and the first remaining charge capacity corresponding to the battery cell to obtain a first to-be-balanced capacity of the battery cell;

[0164] When the first amount of electricity to be balanced is greater than a preset threshold, during the next discharge process of the battery cells, the electricity of the battery cells is balanced based on the first amount of electricity to be balanced.

[0165] Thus, when charging of the battery pack is completed, a first correspondence of the battery pack can be obtained, as well as the first temperature and first voltage of each battery cell at the end of charging. The first correspondence is the correspondence between the temperature, voltage, and remaining charge of the battery cell during the charging process. The first remaining charge of each battery cell is determined based on the first temperature, first voltage, and first correspondence, and the largest of multiple first remaining charge capacities is determined as the target remaining charge. For each of the multiple battery cells, the difference between the target remaining charge and the first remaining charge corresponding to the battery cell is calculated to obtain the first charge to be balanced of the battery cell. Then, if the first charge to be balanced is greater than a preset threshold, the charge of the battery cell is balanced based on the first charge to be balanced during the next discharge of the battery cell. In this way, the charge to be balanced of the battery cell can be determined based on the remaining charge of the battery cell, thereby accurately balancing the charge of the battery cells.

[0166] In some implementations, in order to obtain an accurate first correspondence, the apparatus may further include:

[0167] The third determining module is configured to, before obtaining the first corresponding relationship of the battery pack, determine the corresponding relationship between the voltage and the remaining charge capacity at each temperature by performing the following steps for each of a plurality of different temperatures to obtain the first corresponding relationship:

[0168] When the battery pack is at temperature, charge the battery pack;

[0169] When the battery pack reaches a fully charged state, calibrating the initial remaining charge capacity of the first battery cell with the largest voltage to a first preset value;

[0170] discharging the battery pack, and determining a second remaining charge capacity of the first battery cell when the battery pack is discharged to a preset state;

[0171] charging the battery pack, and recording a plurality of voltages of the first battery cell and the remaining charge capacity corresponding to each voltage during a process in which the remaining charge capacity of the first battery cell decreases from a second remaining charge capacity to a second preset value;

[0172] A corresponding relationship between the voltage and the remaining charge capacity at a temperature is determined based on the plurality of voltages and the remaining charge capacity corresponding to each voltage.

[0173] In some embodiments, to improve the accuracy of the first remaining charge level, the first determining module 402 may include:

[0174] A first determining submodule, configured to determine a minimum target voltage among the plurality of first voltages and a target corresponding relationship corresponding to the first temperature in the first corresponding relationship;

[0175] The search submodule is used to search for the remaining charge capacity corresponding to the first voltage from the target correspondence for each battery cell when the target voltage is not in the platform area in the target correspondence, and obtain the first remaining charge capacity of the battery cell, and the change in the remaining charge capacity corresponding to the unit voltage change in the platform area is greater than the first threshold.

[0176] In some embodiments, to improve the accuracy of the first remaining charge capacity, the apparatus may further include:

[0177] The fourth determining module is configured to correct the first remaining charge capacities of the plurality of battery cells to the remaining charge capacities corresponding to the end points of the plateau region when the target voltage is in the plateau region.

[0178] In some embodiments, to avoid over-balancing due to errors in the amount of electricity to be balanced, the first processing module 404 may include:

[0179] a calculation submodule, configured to calculate a difference between a target remaining charge capacity and a first remaining charge capacity corresponding to a battery cell, to obtain a second remaining charge capacity to be balanced of the battery cell;

[0180] The second determining submodule is configured to determine that the product of the second to-be-balanced electric quantity and the first preset coefficient is the first to-be-balanced electric quantity, where the first preset coefficient is a positive number less than 1.

[0181] In some embodiments, to avoid repeated balancing, the preset threshold is the product of the rated capacity of the battery cell and the second preset coefficient.

[0182] In some embodiments, in order to accurately perform balancing control, the device may further include:

[0183] A second acquisition module is configured to acquire a balancing current and a balancing time of the battery cells during a process of balancing the electric quantity of the battery cells based on the first electric quantity to be balanced;

[0184] a fifth determining module, configured to determine a balanced amount of power of the battery cell based on the balancing current and the balancing time;

[0185] a sixth determining module, configured to determine the remaining power to be balanced of the battery cell according to the first power to be balanced and the balanced power;

[0186] The second processing module stops balancing the battery cells when the remaining power to be balanced of the battery cells is less than or equal to a third preset value.

[0187] In some embodiments, in order to accurately determine the balancing current of the battery cells, the second acquisition module may include:

[0188] An acquisition submodule, configured to acquire a second voltage of the battery cell;

[0189] The third determining submodule is configured to determine the balancing current of the battery cell according to the second voltage and the resistance value of the balancing resistor.

[0190] In some embodiments, in order to accurately balance and control the battery pack, the device may further include:

[0191] The third processing module is configured to stop power balancing for each battery cell before charging the battery pack.

[0192] Figure 5 A schematic structural diagram of an electronic device provided by an embodiment of the present application is shown.

[0193] like Figure 5As shown, the electronic device 5 is a structural diagram of an exemplary hardware architecture of an electronic device that can implement the battery pack power balancing method and battery pack power balancing device according to the embodiments of the present application. The electronic device can refer to the electronic device in the embodiments of the present application.

[0194] The electronic device 5 may include a processor 501 and a memory 502 storing computer program instructions.

[0195] Specifically, the processor 501 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0196] Memory 502 may include a large-capacity memory for data or instructions. By way of example, and not limitation, memory 502 may include a hard disk drive (HDD), a floppy disk drive, flash memory, an optical disk, a magneto-optical disk, magnetic tape, or a Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 502 may include removable or non-removable (or fixed) media. Where appropriate, memory 502 may be internal or external to the integrated gateway disaster recovery device. In certain embodiments, memory 502 is non-volatile solid-state memory. In certain embodiments, memory 502 may include read-only memory (ROM), random access memory (RAM), a magnetic disk storage media device, an optical storage media device, a flash memory device, or an electrical, optical, or other physical / tangible memory storage device. Therefore, generally, memory 502 includes one or more tangible (non-transitory) computer-readable storage media (e.g., a memory device) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to one aspect of the present application.

[0197] The processor 501 reads and executes computer program instructions stored in the memory 502 to implement any one of the battery pack power balancing methods in the above embodiments.

[0198] In one example, the electronic device may further include a communication interface 503 and a bus 504. Figure 5 As shown, the processor 501 , the memory 502 , and the communication interface 503 are connected via a bus 504 and communicate with each other.

[0199] The communication interface 503 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiments of the present application.

[0200] The bus 504 includes hardware, software, or both, and couples the components of the electronic device to each other. By way of example, and not limitation, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industrial Standard Architecture (EISA) bus, a Front Side Bus (FSB), a HyperTransport (HT) interconnect, an Industrial Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or a combination of two or more of these. Where appropriate, the bus 504 may include one or more buses. Although the embodiments of the present application describe and illustrate specific buses, the present application contemplates any suitable bus or interconnect.

[0201] The electronic device can execute the battery pack power balancing method in the embodiment of the present application, thereby realizing the combination Figures 1 to 4 A method and apparatus for balancing the charge of a battery pack are described.

[0202] In addition, in conjunction with the battery pack charge balancing method in the above embodiments, embodiments of the present application may provide a computer storage medium for implementation. The computer storage medium stores computer program instructions, which, when executed by a processor, implement any of the battery pack charge balancing methods in the above embodiments.

[0203] It should be understood that the present application is not limited to the specific configurations and processes described above and illustrated in the figures. For the sake of brevity, a detailed description of known methods is omitted here. In the above embodiments, several specific steps are described and illustrated as examples. However, the method process of the present application is not limited to the specific steps described and illustrated. Those skilled in the art can make various changes, modifications, and additions, or change the order of the steps after understanding the spirit of the present application.

[0204] The functional blocks shown in the block diagrams described above can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they may be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, and the like. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments may be stored in a machine-readable medium or transmitted via a data signal carried in a carrier wave over a transmission medium or communication link. "Machine-readable medium" may include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memory, erasable ROMs (EROMs), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, and the like. Code segments may be downloaded via a computer network such as the Internet or an intranet.

[0205] It should also be noted that the exemplary embodiments mentioned in this application describe some methods or systems based on a series of steps or devices. However, this application is not limited to the order of the above steps. In other words, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0206] Aspects of the present application have been described above with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present application. It should be understood that each block in the flowcharts and / or block diagrams, as well as combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine such that execution of these instructions by the processor of the computer or other programmable data processing device enables the implementation of the functions / actions specified in one or more blocks in the flowcharts and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field programmable logic circuit. It should also be understood that each block in the block diagrams and / or flowcharts, as well as combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by dedicated hardware that performs the specified functions or actions, or by a combination of dedicated hardware and computer instructions.

[0207] The above description is only a specific embodiment of the present application. Those skilled in the art will clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the scope of protection of the present application.

Claims

1. A battery pack charge balancing method, characterized in that: The method comprises: When charging of the battery pack is completed, obtaining a first correspondence relationship of the battery pack, and obtaining a first temperature and a first voltage of each battery cell at the end of charging, wherein the first correspondence relationship is a correspondence relationship between the temperature, voltage, and remaining charge of the battery cell during the charging process, and the battery pack includes a plurality of the battery cells; determining a first remaining charge capacity of each battery cell according to the first temperature, the first voltage, and the first corresponding relationship; determining a maximum of the plurality of first remaining charging capacities as a target remaining charging capacities; For each of the plurality of battery cells, the following steps are performed respectively: Calculating a difference between the target remaining charge capacity and a first remaining charge capacity corresponding to the battery cell to obtain a first to-be-balanced capacity of the battery cell; When the first amount of electricity to be balanced is greater than a preset threshold, during the next discharge process of the battery cell, the electricity of the battery cell is balanced based on the first amount of electricity to be balanced; The determining the first remaining charge capacity of each battery cell according to the first temperature, the first voltage, and the first corresponding relationship includes: determining a minimum target voltage among a plurality of first voltages and a target correspondence relationship corresponding to the first temperature in the first correspondence relationships; When the target voltage is not in the plateau region of the target corresponding relationship, searching, for each battery cell, the remaining charge capacity corresponding to the first voltage from the target corresponding relationship to obtain a first remaining charge capacity of the battery cell, and a change in the remaining charge capacity corresponding to a unit voltage change in the plateau region is greater than a first threshold; When the target voltage is in the platform region, the first remaining charge capacities of the plurality of battery cells are corrected to remaining charge capacities corresponding to the end points of the platform region.

2. The battery pack power balancing method according to claim 1, characterized in that: Before acquiring the first correspondence relationship of the battery pack, the method further includes: The first corresponding relationship is obtained by performing the following steps for each of a plurality of different temperatures, respectively, to determine a corresponding relationship between the voltage and the remaining charge capacity at the temperature: When the battery pack is at the temperature, charging the battery pack; When the battery pack reaches a fully charged state, calibrating the initial remaining charge capacity of the first battery cell with the largest voltage to a first preset value; discharging the battery pack, and determining a second remaining charge capacity of the first battery cell when the battery pack is discharged to a preset state; charging the battery pack, and recording a plurality of voltages of the first battery cell and the remaining charge capacity corresponding to each of the voltages during a process in which the remaining charge capacity of the first battery cell decreases from the second remaining charge capacity to a second preset value; A corresponding relationship between the voltage and the remaining charge capacity at the temperature is determined based on the multiple voltages and the remaining charge capacity corresponding to each of the voltages.

3. The battery pack charge balancing method according to claim 1, wherein: The calculating the difference between the target remaining charge capacity and the first remaining charge capacity corresponding to the battery cell to obtain the first to-be-balanced capacity of the battery cell includes: Calculating a difference between the target remaining charge capacity and a first remaining charge capacity corresponding to the battery cell to obtain a second to-be-balanced capacity of the battery cell; The product of the second power to be balanced and a first preset coefficient is determined to be the first power to be balanced, where the first preset coefficient is a positive number less than 1.

4. The battery pack charge balancing method according to claim 1, wherein: The preset threshold is the product of the rated capacity of the battery cell and a second preset coefficient.

5. The battery pack power balancing method according to claim 1 or 4, characterized in that: The method further comprises: In a process of balancing the electric quantity of the battery cells based on the first electric quantity to be balanced, obtaining a balancing current and a balancing time of the battery cells; determining a balanced amount of electricity of the battery cell based on the balancing current and the balancing time; Determine the remaining amount of power to be balanced of the battery cell according to the first amount of power to be balanced and the balanced amount of power; When the remaining power to be balanced of the battery cells is less than or equal to a third preset value, power balancing of the battery cells is stopped.

6. The battery pack charge balancing method according to claim 5, characterized in that: The obtaining of the balancing current of the battery cell includes: obtaining a second voltage of the battery cell; The balancing current of the battery cell is determined according to the second voltage and the resistance value of the balancing resistor.

7. The battery pack power balancing method according to claim 1 or 4, characterized in that: The method further comprises: Before charging the battery pack, power balancing of each battery cell is stopped.

8. A battery pack power balancing device, characterized in that: The device comprises: a first acquiring module, configured to acquire, when charging of the battery pack is completed, a first corresponding relationship of the battery pack, and a first temperature and a first voltage of each battery cell at the end of charging, wherein the first corresponding relationship is a corresponding relationship between the temperature, voltage, and remaining charge of the battery cell during the charging process, and the battery pack includes a plurality of the battery cells; a first determining module, configured to determine a first remaining charge capacity of each battery cell according to the first temperature, the first voltage, and the first corresponding relationship; a second determining module, configured to determine a maximum of the plurality of first remaining charging capacities as a target remaining charging capacities; The first processing module is configured to perform the following steps for each of the plurality of battery cells: Calculating a difference between the target remaining charge capacity and a first remaining charge capacity corresponding to the battery cell to obtain a first to-be-balanced capacity of the battery cell; When the first amount of electricity to be balanced is greater than a preset threshold, during the next discharge process of the battery cell, the electricity of the battery cell is balanced based on the first amount of electricity to be balanced; The first determination module is further used to determine the minimum target voltage among multiple first voltages and the target correspondence corresponding to the first temperature in the first correspondence; when the target voltage is not in the platform area of ​​the target correspondence, for each battery cell, the remaining charging capacity corresponding to the first voltage is found from the target correspondence to obtain the first remaining charging capacity of the battery cell, and the change in the remaining charging capacity corresponding to the unit voltage change in the platform area is greater than the first threshold; when the target voltage is in the platform area, the first remaining charging capacity of multiple battery cells are corrected to the remaining charging capacity corresponding to the end point of the platform area.

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