Balancing control method and device of power battery, vehicle and storage medium

Abstract

The embodiment of the application discloses a kind of equalization control method, device, vehicle and storage medium of power battery, belong to new energy technical field.The method includes: the terminal voltage of the multiple battery cells included in power battery is collected at current time;From multiple battery cells, select first battery cell and second battery cell, first battery cell is the highest battery cell corresponding to the terminal voltage at current time, and the second battery cell is the lowest battery cell corresponding to the terminal voltage at current time;The open-circuit voltage of first battery cell and second battery cell at current time is collected, and first equalization current is determined;First battery cell is controlled to charge second battery cell with first equalization current.In the application, battery management system can be fine, smoothly equalization control, without the case that battery management system needs to repeatedly start equalization control for the same two battery cells.

Description

Technical Field

[0001] This application relates to the field of new energy technology, and in particular to a method, device, vehicle, and storage medium for equalization control of a power battery. Background Technology

[0002] Electric vehicle batteries typically consist of multiple battery cells. Due to limitations in battery materials and manufacturing processes, the State of Charge (SOC) of these cells may vary significantly after prolonged use. During the charging and discharging process, if the SOC of even one cell reaches its charging / discharging threshold, the entire battery will stop charging and discharging. This can result in some cells not being fully charged or discharged, leading to reduced charging and discharging efficiency. Therefore, balanced control of the charging and discharging process is necessary. Summary of the Invention

[0003] This application provides a method, device, vehicle, and storage medium for equalization control of a power battery, which can solve the problem of repeatedly starting equalization control in related technologies. The technical solution is as follows:

[0004] On the one hand, a method for equalization control of a power battery is provided, the method comprising:

[0005] The terminal voltage of the multiple battery cells included in the power battery is collected at the current moment, and the terminal voltage indicates the remaining power of the corresponding battery cell;

[0006] A first battery cell and a second battery cell are selected from the plurality of battery cells, wherein the first battery cell is the battery cell with the highest terminal voltage at the current time, and the second battery cell is the battery cell with the lowest terminal voltage at the current time.

[0007] The open-circuit voltages of the first battery cell and the second battery cell at the current time are collected. Based on the open-circuit voltages of the first battery cell and the second battery cell at the current time, the first equivalent polarization resistance, the first equivalent polarization capacitance, the second equivalent polarization resistance, the second equivalent polarization capacitance, the ohmic internal resistance of the second battery cell, the first polarization voltage, the second polarization voltage, and the duration of battery equalization performed by the first battery cell and the second battery cell, the first equalization current is determined.

[0008] Wherein, the first equivalent polarization resistance and the second equivalent polarization resistance refer to the resistance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction; the first equivalent polarization capacitance and the second equivalent polarization capacitance refer to the capacitance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction; the first polarization voltage and the second polarization voltage refer to the potential difference generated by electrode polarization when current begins to flow through the second battery cell; the first polarization voltage corresponds to the first equivalent polarization resistance and the first equivalent polarization capacitance; and the second polarization voltage corresponds to the second equivalent polarization resistance and the second equivalent polarization capacitance.

[0009] The first battery cell is controlled to charge the second battery cell with the first equalizing current.

[0010] Optionally, before determining the first equalization current, the method further includes:

[0011] If the first battery cell and the second battery cell are not currently undergoing battery equalization, and the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is greater than a threshold voltage, then the step of collecting the open-circuit voltages of the first battery cell and the second battery cell at the current moment is executed.

[0012] Optionally, before determining the first equalization current, the method further includes:

[0013] If the first battery cell and the second battery cell are currently undergoing battery balancing, then the second balancing current is obtained, which is the current of the first battery cell and the second battery cell currently undergoing battery balancing.

[0014] If the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is greater than the product of the second equalization current and the equivalent DC resistance, then the step of collecting the open-circuit voltages of the first battery cell and the second battery cell at the current moment is performed. The equivalent DC resistance refers to the resistance presented by the second battery cell after a DC voltage is applied.

[0015] Optionally, after obtaining the second equalization current, the method further includes:

[0016] If the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is equal to the product of the second equalizing current and the equivalent DC resistance, then the first battery cell is controlled to continue charging the second battery cell with the second equalizing current.

[0017] Optionally, after obtaining the second equalization current, the method further includes:

[0018] If the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is less than the product of the second equalizing current and the equivalent DC resistance, then the first battery cell is controlled to stop charging the second battery cell.

[0019] Optionally, the first equalization current is determined by the following formula:

[0020]

[0021] Where I1 represents the first equalizing current, U OCVA U represents the open-circuit voltage of the first battery cell at the current moment. OCVB R1 represents the open-circuit voltage of the second battery cell at the current moment, C1 represents the first equivalent polarization resistance, C1 represents the first equivalent polarization capacitance, R2 represents the second equivalent polarization resistance, C2 represents the second equivalent polarization capacitance, R0 represents the ohmic internal resistance of the second battery cell, and U represents the open-circuit voltage of the second battery cell at the current moment. p1 (0) represents the first polarization voltage, U p2 (0) represents the second polarization voltage, and t represents the duration for which the first and second battery cells have undergone battery equalization.

[0022] On the other hand, a power battery equalization control device is provided, the device comprising:

[0023] The first acquisition module is used to acquire the terminal voltage of the multiple battery cells included in the power battery at the current moment, and the terminal voltage indicates the remaining power of the corresponding battery cell;

[0024] The selection module is used to select a first battery cell and a second battery cell from the plurality of battery cells, wherein the first battery cell is the battery cell with the highest terminal voltage at the current time, and the second battery cell is the battery cell with the lowest terminal voltage at the current time.

[0025] The second acquisition module is used to acquire the open-circuit voltage of the first battery cell and the second battery cell at the current time, and determine the first equalization current based on the open-circuit voltage of the first battery cell at the current time, the open-circuit voltage of the second battery cell at the current time, the first equivalent polarization resistance, the first equivalent polarization capacitance, the second equivalent polarization resistance, the second equivalent polarization capacitance, the ohmic internal resistance of the second battery cell, the first polarization voltage, the second polarization voltage, and the duration of battery equalization of the first battery cell and the second battery cell.

[0026] Wherein, the first equivalent polarization resistance and the second equivalent polarization resistance refer to the resistance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction; the first equivalent polarization capacitance and the second equivalent polarization capacitance refer to the capacitance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction; the first polarization voltage and the second polarization voltage refer to the potential difference generated by electrode polarization when current begins to flow through the second battery cell; the first polarization voltage corresponds to the first equivalent polarization resistance and the first equivalent polarization capacitance; and the second polarization voltage corresponds to the second equivalent polarization resistance and the second equivalent polarization capacitance.

[0027] The first control module is used to control the first battery cell to charge the second battery cell with the first equalizing current.

[0028] Optionally, the device further includes:

[0029] The first trigger module is configured to trigger the second acquisition module to perform the step of acquiring the open-circuit voltage of the first battery unit and the second battery unit at the current time if the first battery unit and the second battery unit are not currently undergoing battery equalization and the difference between the terminal voltages of the first battery unit and the second battery unit at the current time is greater than a threshold voltage.

[0030] Optionally, the device further includes:

[0031] The acquisition module is used to acquire a second equalization current if the first battery cell and the second battery cell are currently undergoing battery equalization. The second equalization current is the current at which the first battery cell and the second battery cell are currently undergoing battery equalization.

[0032] The second trigger module is used to trigger the second acquisition module to perform the step of acquiring the open-circuit voltage of the first battery cell and the second battery cell at the current time if the difference between the terminal voltages of the first battery cell and the second battery cell at the current time is greater than the product of the second equalization current and the equivalent DC resistance. The equivalent DC resistance refers to the resistance presented by the second battery cell after a DC voltage is applied.

[0033] Optionally, the device further includes:

[0034] The second control module is configured to control the first battery unit to continue charging the second battery unit with the second equalizing current if the difference between the terminal voltages of the first battery unit and the second battery unit at the current moment is equal to the product of the second equalizing current and the equivalent DC resistance.

[0035] Optionally, the device further includes:

[0036] The third control module is configured to control the first battery unit to stop charging the second battery unit if the difference between the terminal voltages of the first battery unit and the second battery unit at the current time is less than the product of the second equalizing current and the equivalent DC resistance.

[0037] Optionally, the first equalization current is determined by the following formula:

[0038]

[0039] Where I1 represents the first equalizing current, U OCVA U represents the open-circuit voltage of the first battery cell at the current moment. OCVB R1 represents the open-circuit voltage of the second battery cell at the current moment, C1 represents the first equivalent polarization resistance, C1 represents the first equivalent polarization capacitance, R2 represents the second equivalent polarization resistance, C2 represents the second equivalent polarization capacitance, R0 represents the ohmic internal resistance of the second battery cell, and U represents the open-circuit voltage of the second battery cell at the current moment. p1 (0) represents the first polarization voltage, U p2 (0) represents the second polarization voltage, and t represents the duration for which the first and second battery cells have undergone battery equalization.

[0040] On the other hand, a vehicle is provided, the vehicle including a memory, a battery management system and a power battery, the memory for storing computer programs, and the battery management system for executing the computer programs stored in the memory to implement the steps of the above-described power battery equalization control method.

[0041] On the other hand, a computer-readable storage medium is provided, wherein a computer program is stored therein, and when the computer program is executed by a processor, the steps of the above-described power battery equalization control method are implemented.

[0042] On the other hand, a computer program product is provided, which stores computer instructions that, when executed by a processor, implement the steps of the above-described power battery equalization control method.

[0043] The technical solution provided in this application can bring at least the following beneficial effects:

[0044] When determining the required balancing current at different time points during a single balancing process, the polarization phenomenon of the battery cells and the gradual change in the open-circuit voltage difference between the first and second battery cells as the balancing process progresses are considered. This allows the required balancing current to be determined based on the current balancing status. As the balancing process continues, the determined balancing current gradually decreases. Ultimately, under the control of the battery management system, the first battery cell charges the second battery cell with a relatively small balancing current. The battery management system can perform precise and stable balancing control, ensuring that the balancing requirements of both battery cells are met after one balancing control cycle, avoiding the need for the battery management system to repeatedly initiate balancing control for the same two battery cells. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of an implementation environment provided in an embodiment of this application;

[0047] Figure 2 This is a schematic diagram of another implementation environment provided in the embodiments of this application;

[0048] Figure 3 This is a flowchart of a power battery equalization control method provided in an embodiment of this application;

[0049] Figure 4 This is a schematic diagram of a second-order equivalent circuit of a first battery cell provided in an embodiment of this application;

[0050] Figure 5 This is a schematic diagram of a second-order equivalent circuit of a second battery cell provided in an embodiment of this application;

[0051] Figure 6 This is a flowchart of another power battery equalization control method provided in the embodiments of this application;

[0052] Figure 7 This is a schematic diagram of the structure of a power battery balancing control device provided in an embodiment of this application;

[0053] Figure 8 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0055] Before providing a detailed explanation of the power battery equalization control method provided in the embodiments of this application, the application scenarios and implementation environments involved in the embodiments of this application will be introduced first.

[0056] Currently, with the continuous development of the new energy vehicle sector, new energy and hybrid vehicles are gradually becoming the first choice for public transportation. Electric vehicle power batteries typically consist of multiple battery cells. Due to limitations in battery materials and manufacturing processes, the State of Charge (SOC) of these multiple battery cells may vary significantly after prolonged use. During the charging and discharging process, if the SOC of even one battery cell reaches its charging / discharging threshold, the entire power battery will stop charging and discharging. This may result in some battery cells not being fully charged or discharged, leading to a decrease in the charging and discharging efficiency of the power battery. Therefore, it is necessary to implement balanced control during the charging and discharging process of the power battery.

[0057] Currently, some battery management systems (BMS) use passive balancing for equalization control. For example, they control the discharge of battery cells with higher State of Charge (SOC) through resistors or capacitors to ensure all battery cells have roughly the same SOC. However, this method wastes energy. Other BMS systems use active balancing for equalization control. Current active balancing methods typically have a preset equalization value. During charging and discharging, the battery cell with higher SOC provides additional charging to the battery cell with lower SOC through an equalization current. The equalization control stops when the voltage difference between the two equalized battery cells is less than the preset value. If, after one equalization cycle, the voltage difference between the two equalized battery cells is found to be greater than the preset value, and the equalization requirement is not met, then equalization control needs to be performed again.

[0058] However, the current active balancing control method uses a relatively large, fixed balancing current. Assume that the SOC of battery cell A is greater than that of battery cell B, and battery cells A and B are in the process of balancing and are nearing the end of the balancing phase. At this point, the difference in SOC between battery cells A and B is small. Since it takes time for battery cell A to charge battery cell B through the balancing current, and the balancing current remains a large, fixed value, when the voltage difference between battery cells A and B reaches a preset value and the current balancing control stops (i.e., when battery cell A stops charging battery cell B), after the balancing current that has reached battery cell B has actually been absorbed by battery cell B, and the voltage of battery cell B drops (after absorbing the balancing current, the voltage of battery cell B will suddenly rise to a high value and then drop), the voltage difference between battery cells A and B may still not meet the balancing requirements. For example, the voltage of battery cell B may actually be higher than that of battery cell A, and the voltage difference between the two may exceed the preset balancing value. In this case, balancing control needs to be performed again. Therefore, this method makes it difficult to perform precise equalization control of the power battery, and the battery management system may need to repeatedly initiate equalization control. This increases the total time required for equalization control of the entire power battery and may lead to problems such as excessively high battery temperature, accelerated battery degradation, and reduced overall efficiency of the battery management system.

[0059] Based on this, this application provides a power battery equalization control method. According to the second-order equivalent circuit of the battery cell, the equalization current corresponding to different time periods in one equalization process is determined. As the equalization process proceeds, the equalization current gradually decreases. Finally, under the control of the battery management system, the battery cell with higher terminal voltage will charge the battery cell with lower terminal voltage with a relatively small equalization current. The battery management system can perform equalization control in a precise and stable manner, so that the two battery cells can meet the equalization requirements after one equalization control is completed, without the battery management system needing to repeatedly start equalization control for the same two battery cells.

[0060] Please refer to Figure 1 , Figure 1 This is a schematic diagram of an implementation environment provided in an embodiment of this application. The implementation environment includes a battery management system 101 and a battery system 102. The battery system 102 includes a power battery 1021, and the power battery 1021 includes at least two battery cells, such as... Figure 1 Battery cell A and battery cell B are shown. There may or may not be a circuit connection between the battery management system 101 and the battery system 102. When there is no circuit connection between the battery management system 101 and the battery system 102, such as... Figure 2As shown, the battery system 102 also includes a data acquisition module 1022 and an equalization module 1023. In this case, the communication connection between the battery management system 101 and the battery system 102 can be a wired or wireless connection, and this application embodiment does not limit this.

[0061] When there is a circuit connection between the battery management system 101 and the battery system 102, the battery management system 101 is used to directly collect the terminal voltage of the battery cells, directly collect the open-circuit voltage of the two battery cells with the highest and lowest terminal voltages, determine the equalization current corresponding to different time periods during a single equalization control process, and directly control the power battery 1021 to perform battery equalization, etc.

[0062] When there is no circuit connection between the battery management system 101 and the battery system 102, the battery management system 101 is used to send a first acquisition command to the battery system 102 and receive the terminal voltage of the battery cell sent by the acquisition module 1022 of the battery system 102, thereby indirectly acquiring the terminal voltage of the battery cell. It is also used to send a second acquisition command to the battery system 102 and receive the open-circuit voltage of the two battery cells with the highest and lowest terminal voltages sent by the acquisition module 1022 of the battery system 102, thereby indirectly acquiring the open-circuit voltage of the two battery cells with the highest and lowest terminal voltages. It is also used to determine the equalization current corresponding to different time periods during a single equalization control process. Furthermore, it is used to send an equalization control command to the battery system 102 so that the equalization module 1023 of the battery system 102 controls the power battery 1021 to perform battery equalization, thereby indirectly controlling the power battery 1021 to perform battery equalization.

[0063] It should be noted that the application scenarios and implementation environments described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the emergence of new application scenarios and the evolution of implementation environments, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0064] The equalization control method for power batteries provided in the embodiments of this application will be explained in detail below.

[0065] Figure 3 This is a flowchart of a power battery balancing control method provided in an embodiment of this application. This method is applied to the aforementioned battery management system. The following description uses the case where there is a circuit connection between the battery management system 101 and the battery system 102 as an example. Please refer to... Figure 3 The method includes the following steps.

[0066] Step 301: Collect the terminal voltage of the multiple battery cells included in the power battery at the current moment. The terminal voltage indicates the remaining power of the corresponding battery cell.

[0067] A battery cell may include one or more batteries. If a battery cell includes multiple batteries, these batteries may be connected in series or in parallel. Typically, each battery cell in a battery cell is almost identical at the time of manufacture.

[0068] The terminal voltage of a battery cell is the voltage remaining after deducting the internal consumption of the cell's electromotive force. Therefore, the terminal voltage of a battery cell indicates the remaining charge of the cell, or in other words, the state of charge (SOC) of the cell.

[0069] After the power battery begins charging and discharging, the battery management system can directly collect the terminal voltages of the multiple battery cells included in the power battery at multiple different times. The battery management system can start collecting data simultaneously when the power battery begins charging and discharging, or it can start collecting data some time after the power battery begins charging and discharging; this application embodiment does not limit this.

[0070] Typically, the moment when the power battery begins charging / discharging is defined as moment 0. The battery management system can periodically collect data at different times. For example, starting at moment 0 when the power battery begins charging / discharging, it can collect the terminal voltage of multiple battery cells in 2-second cycles, i.e., data is collected at different times such as 0s, 2s, 4s, etc. The battery management system can also collect the terminal voltage of multiple battery cells non-periodically. For example, starting 1 second after the power battery begins charging / discharging, data can be collected at different times such as 1s, 2s, 5s, 8s, 18s, etc. This application embodiment does not limit this approach.

[0071] Step 302: Select a first battery cell and a second battery cell from multiple battery cells. The first battery cell is the battery cell with the highest terminal voltage at the current time, and the second battery cell is the battery cell with the lowest terminal voltage at the current time.

[0072] Step 303: Collect the open-circuit voltage of the first battery cell and the second battery cell at the current moment. Based on the open-circuit voltage of the first battery cell at the current moment, the open-circuit voltage of the second battery cell at the current moment, the first equivalent polarization resistance, the first equivalent polarization capacitance, the second equivalent polarization resistance, the second equivalent polarization capacitance, the ohmic internal resistance of the second battery cell, the first polarization voltage, the second polarization voltage, and the duration of battery equalization for the first battery cell and the second battery cell, determine the first equalization current.

[0073] It should be noted that the open-circuit voltages of the first and second battery cells at the current moment are equal to their respective electromotive forces (EMFs). In other words, the open-circuit voltage of the first battery cell at the current moment refers to the difference in electrode potential between its positive and negative terminals when the circuit is open; the open-circuit voltage of the second battery cell at the current moment refers to the difference in electrode potential between its positive and negative terminals when the circuit is open. The magnitudes of the open-circuit voltages of the first and second battery cells at the current moment will change with the remaining charge in the first and second battery cells.

[0074] In some embodiments, the first equalization current can be determined by the following formula (4):

[0075]

[0076] Where I1 represents the first equalization current, U OCVA U represents the open-circuit voltage of the first battery cell at the current moment. OCVB R1 represents the open-circuit voltage of the second battery cell at the current moment, C1 represents the first equivalent polarization resistance, C1 represents the first equivalent polarization capacitance, R2 represents the second equivalent polarization resistance, C2 represents the second equivalent polarization capacitance, R0 represents the ohmic internal resistance of the second battery cell, and U represents the open-circuit voltage of the second battery cell at the current moment. p1 (0) represents the first polarization voltage, U p2 (0) represents the second polarization voltage, and t represents the duration during which the first and second battery cells have undergone battery equalization.

[0077] Wherein, the first equivalent polarization resistance and the second equivalent polarization resistance are the resistances caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction; the first equivalent polarization capacitance and the second equivalent polarization capacitance are the capacitances caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction; the ohmic internal resistance of the second battery cell is the internal resistance of the system composed of the electrode material, electrolyte, separator resistance, and contact resistance between various components. Furthermore, the first polarization voltage and the second polarization voltage refer to the potential difference generated by electrode polarization when current begins to flow through the second battery cell, and the first polarization voltage corresponds to the first equivalent polarization resistance and the first equivalent polarization capacitance, and the second polarization voltage corresponds to the second equivalent polarization resistance and the second equivalent polarization capacitance.

[0078] In some embodiments, the first equivalent polarization resistor, the second equivalent polarization resistor, the first equivalent polarization capacitor, the second equivalent polarization capacitor, the ohmic internal resistance of the second battery cell, the first polarization voltage, and the second polarization voltage are all fixed values.

[0079] In some embodiments, the first equivalent polarization resistance, the second equivalent polarization resistance, the first equivalent polarization capacitor, the second equivalent polarization capacitor, the ohmic internal resistance of the second battery cell, the first polarization voltage, and the second polarization voltage are all stored in the memory of the battery management system. The battery management system can determine the magnitude of the first equivalent polarization resistance, the second equivalent polarization resistance, the first equivalent polarization capacitor, the second equivalent polarization capacitor, the ohmic internal resistance of the second battery cell, the first polarization voltage, and the second polarization voltage by reading the corresponding data in the memory.

[0080] As mentioned above, t represents the duration of battery equalization between the first and second battery cells. More precisely, t represents the duration of battery equalization between the first and second battery cells during this equalization process. Based on this, the following two examples will more clearly illustrate how to determine the first equalization current using the above formula (1):

[0081] Example 1: Suppose that after the power battery starts charging / discharging, the battery management system collects the terminal voltage of the multiple battery cells included in the power battery every 2 seconds, and assume that the current time is the time of the second terminal voltage collection. If the first battery cell and the second battery cell are controlled to perform battery balancing at this time, then t=0s should be substituted into formula (1) to determine the first balancing current corresponding to the current time.

[0082] Example 2: Assume that the battery management system (BMS) collects the terminal voltage of the multiple battery cells in the power battery every 5 seconds after the power battery starts charging / discharging for 3 seconds, and assume that the current time is the sixth time the terminal voltage is collected. Also assume that after the second time the terminal voltage is collected, the BMS starts controlling the first and second battery cells to perform battery balancing; after the third time the terminal voltage is collected, the BMS stops the battery balancing; and after the fifth time the terminal voltage is collected, the BMS starts controlling the first and second battery cells to perform battery balancing again, and battery balancing is still in progress at the current time. Let the time when the BMS collects the terminal voltage of the multiple battery cells in the power battery for the fifth time be recorded as the first time, and the time when the BMS collects the terminal voltage of the multiple battery cells in the power battery for the sixth time be recorded as the second time. The duration of battery balancing between the first and second battery cells during this balancing process is the duration between the first and second times. Therefore, t = 5 seconds should be substituted into formula (1) to determine the first balancing current corresponding to the current time.

[0083] The origin of formula (1) above will be explained below:

[0084] When no current flows through a battery cell, it can be considered to be at a static, relatively idealized electrode potential, which is called the equilibrium potential. When a battery cell is charging or discharging, current flows through it, and the electrode potential deviates from the equilibrium potential; this phenomenon is called electrode polarization. Once electrode polarization occurs in a battery cell, its corresponding second-order equivalent circuit can be established.

[0085] Since the power battery is currently charging / discharging, current is flowing through both the first and second battery cells at the current moment. Therefore, second-order equivalent circuits for the first and second battery cells can be established respectively, such as... Figure 4 and Figure 5 As shown. In the second-order equivalent circuit corresponding to the first battery cell, U OCVA R is the open-circuit voltage of the first battery cell at the current moment. n R m C is the equivalent polarization resistance of the first battery cell; n C m This represents the equivalent polarization capacitance of the first battery cell; r0 is the ohmic internal resistance of the first battery cell; U A This is the terminal voltage of the first battery cell.

[0086] In the second-order equivalent circuit corresponding to the second battery cell, U OCVB R1 and R2 are the open-circuit voltage of the second battery cell at the current moment; C1 and C2 are the first and second equivalent polarization resistors; C1 and C2 are the first and second equivalent polarization capacitors; R0 is the ohmic internal resistance of the second battery cell; U B This is the terminal voltage of the second battery cell.

[0087] Assuming that current I flows through both the first and second battery cells, the second-order equivalent circuits corresponding to the first and second battery cells satisfy the following formulas (2) and (3), respectively:

[0088]

[0089]

[0090] In formula (2), U1(0) is the R value at time 0 when current begins to flow through the first battery cell. n C n The voltage on the battery, U2(0), is the voltage at time 0 when the first battery cell begins to have current flowing through it. m C m The voltages on the surface are all polarization voltages. In formula (3), U p1 (0) represents the first polarization voltage mentioned above, Up2 (0) represents the second polarization voltage mentioned above. That is, U p1 (0) represents the voltage across R1 and C1 at time 0 when current begins to flow through the second battery cell, and U. p2 (0) is the voltage across R2 and C2 at time 0 when the second battery cell begins to have current flowing through it.

[0091] Where t′ refers to the time during which current flows through the first and second battery cells.

[0092] During the charging / discharging process of a power battery, the amount of electricity gained / consumed by the first and second battery cells due to external charging / discharging is consistent. Therefore, it can be assumed that they are not charging / discharging, but only undergoing battery balancing, which is a perfectly feasible assumption. The following only considers the changes in the balancing current to the first and second battery cells.

[0093] Assume that the first battery cell is charging the second battery cell with a first equalization current I1. When the first battery cell charges the second battery cell with this equalization current, the resulting loss of electromotive force in the first battery cell is not exactly equal to the increase in electromotive force in the second battery cell. This is because the equivalent polarization resistance, equivalent polarization capacitance, and ohmic internal resistance of the first battery cell, as well as the equivalent polarization resistance (the first and second equivalent polarization resistances mentioned above), equivalent polarization capacitance (the first and second equivalent polarization capacitances mentioned above), and ohmic internal resistance of the second battery cell, all contribute to the loss of the equalization current. However, during the equalization process, only the polarization capacitance, polarization resistance, and ohmic internal resistance of the battery cell being charged are generally considered. Therefore, without considering the polarization resistance, polarization capacitance, and ohmic internal resistance in the first battery cell, based on the above formulas (2) and (3), the following formula (4) is satisfied:

[0094]

[0095] The meanings of the symbols in formula (4) are the same as those described above. By transforming formula (4), we can obtain the above formula (1).

[0096] In other words, this method determines the balancing current required at different time periods during a single balancing process based on the second-order equivalent circuit of the battery cell. As described above, this method considers the polarization phenomenon of the battery cell, and the U in the formula... OCVA -U OCVB It can be seen that this method also takes into account the problem that the difference between the open-circuit voltages of the first battery cell and the second battery cell will gradually change as the equalization process proceeds. Therefore, the required equalization current can be determined based on the current equalization situation using the above formula (1).

[0097] Step 304: Control the first battery cell to charge the second battery cell with the first equalization current.

[0098] In some embodiments, before performing step 303 above, the method further includes: if the first battery cell and the second battery cell are not currently undergoing battery equalization, and the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is greater than a threshold voltage, then step 303 above is performed.

[0099] The threshold voltage can be set by technicians or users according to application requirements, and this application embodiment does not limit this.

[0100] If the first and second battery cells are not currently undergoing battery equalization, and the voltage difference between their terminals at the current moment is greater than a threshold voltage, then the first and second battery cells meet the battery equalization activation condition at the current moment. In other words, the activation condition for the battery management system to perform battery equalization control at the current moment is: the voltage difference between the first and second battery cells at the current moment is greater than a threshold voltage. For ease of description, this condition is referred to as the first condition.

[0101] In some embodiments, before performing step 303 above, the method further includes: if the first battery cell and the second battery cell are currently undergoing battery balancing, then obtaining a second balancing current, which is the current during the current battery balancing of the first battery cell and the second battery cell; if the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is greater than the product of the second balancing current and the equivalent DC resistance, then performing step 303 above.

[0102] It should be noted that the equivalent DC resistance is a fixed value and is typically very small. This equivalent DC resistance is the resistance exhibited by the second battery cell after a DC voltage is applied. In some embodiments, the equivalent DC resistance is stored in the memory of the battery management system, which can determine the magnitude of the equivalent DC resistance by reading the corresponding data from the memory.

[0103] During battery balancing, the impact of the balancing current on the second battery cell gradually reaches a steady state (hereinafter referred to as "entering steady state"). At the moment of entering steady state, the second battery cell is no longer suitable for... Figure 5 The second-order equivalent circuit shown is therefore no longer applicable to the above formula (1). At this time, the difference between the terminal voltage of the first battery cell and the terminal voltage of the second battery cell satisfies the following formula (5):

[0104] U A -U B =I bal Rd (5)

[0105] Among them, I bal The equalization current I used by the first battery cell to charge the second battery cell when it reaches a steady state. bal It is determined by the above formula (1) at a certain moment before entering steady state, R d The above represents the equivalent DC resistance; the meanings of other symbols are the same as described above.

[0106] It should be noted that, as shown in formula (1) above, the longer the first and second battery cells have been balancing, the smaller the determined first balancing current will be when determining the first balancing current at the current moment. In other words, before entering steady state, as the balancing time of the first and second battery cells increases, the balancing current used by the first battery cell to provide additional charging to the second battery cell will gradually decrease. Since the moment of entering steady state is usually a certain moment at the end of the balancing process, the balancing time of the first and second battery cells has been relatively long. Therefore, at this moment of entering steady state, the balancing current I used by the first battery cell to provide additional charging to the second battery cell will be smaller. bal It is very small.

[0107] Based on this, if the first battery cell and the second battery cell are currently undergoing battery balancing, and the difference between their terminal voltages at the current moment is greater than the product of the second balancing current and the equivalent DC resistance, it indicates that the current moment has not yet reached a steady state, and the above formula (1) still applies. Therefore, the balancing current, i.e., the first balancing current, can be re-determined using the above formula (1), and then the first battery cell can be controlled to continue charging the second battery cell with the first balancing current.

[0108] In some embodiments, after obtaining the second equalization current, the method further includes: if the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is equal to the product of the second equalization current and the equivalent DC resistance, then controlling the first battery cell to continue charging the second battery cell with the second equalization current.

[0109] As described above, if the voltage difference between the first and second battery cells at the current moment is equal to the product of the second equalizing current and the equivalent DC resistance, then the current moment indicates that the battery has entered a steady state, and therefore the second equalizing current is very small. Since the equivalent DC resistance is usually very small, and the second equalizing current is also very small, the voltage difference between the first and second battery cells at the current moment is also very small. In this case, it is necessary to control the first battery cell to charge the second battery cell with a very small equalizing current.

[0110] As described above, formula (1) is no longer applicable at the current moment, and therefore the equalization current cannot be re-determined using formula (1). Since the second equalization current is very small, in some embodiments, it is not necessary to consider re-determining the equalization current through other methods. Instead, the first battery cell can be directly controlled to continue charging the second battery cell with the second equalization current, thereby further reducing the voltage difference between the terminals of the first and second battery cells.

[0111] In some embodiments, after obtaining the second equalization current, the method further includes: if the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is less than the product of the second equalization current and the equivalent DC resistance, then controlling the first battery cell to stop charging the second battery cell.

[0112] Assuming the third moment is the moment of entering steady state, if this third moment is the moment when the terminal voltages of multiple battery cells in the power battery are collected, then as mentioned above, the first battery cell will continue to charge the second battery cell with the equalization current at this third moment, and the difference between the terminal voltages of the first and second battery cells will further decrease. If this third moment is not the moment when the terminal voltages of multiple battery cells in the power battery are collected, then after this third moment and before the next moment when the terminal voltages of multiple battery cells in the power battery are collected, the first battery cell will also continue to charge the second battery cell with the equalization current at this third moment. Therefore, after the third moment, the above formula (5) no longer holds, and the difference between the terminal voltages of the first and second battery cells will be less than the product of the second equalization current and the equivalent DC resistance.

[0113] Based on this, if the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is less than the product of the second equalization current and the equivalent DC resistance, it indicates that the current moment is the closest time to the moment of entering steady state after entering steady state. At this time, the difference between the terminal voltages of the first battery cell and the second battery cell has further decreased compared to the moment of entering steady state. Therefore, it can be considered that the terminal voltages of the first battery cell and the second battery cell are approximately equal at the current moment. Thus, the first battery cell can be controlled to stop charging the second battery cell, that is, the equalization process can be stopped.

[0114] In addition, since the second equalization current used by the first battery cell to continue charging the second battery cell after entering steady state is very small, and the time interval between the two voltage samplings in practical applications is not too long, the situation will not occur where the voltage of the second battery cell is much higher than that of the first battery cell after the equalization process stops.

[0115] Using the above method, the battery management system will eventually control the first battery cell to charge the second battery cell with a relatively small equalization current, thereby performing precise and stable equalization control. After one equalization process, the terminal voltages of the first and second battery cells will be almost equal, and the battery management system will not need to repeatedly start equalization control for these two battery cells.

[0116] In summary, the battery management system can periodically or non-periodically collect the terminal voltages of multiple battery cells in the power battery at the moment when the power battery starts charging / discharging or at a certain time after the power battery starts charging / discharging, and designate the battery cell with the highest terminal voltage as the first battery cell and the battery cell with the lowest terminal voltage as the second battery cell.

[0117] Taking the voltage at a certain acquisition terminal at a certain moment as an example, such as Figure 6 As shown, after data acquisition is complete, it is first necessary to determine whether the first and second battery cells are currently undergoing battery balancing. If the first and second battery cells have not yet started battery balancing, it is necessary to first determine whether the above-mentioned first condition is met. If it is met, balancing control is initiated, the open-circuit voltages of the first and second battery cells at the current moment are acquired, the first balancing current is determined, and then the first battery cell is controlled to charge the second battery cell with the first balancing current. If the above-mentioned first condition is not met, balancing control is not initiated at the current moment, and the system waits for the next time to acquire the terminal voltage. If the first and second battery cells are undergoing battery balancing, the second balancing current needs to be acquired, and it needs to be determined whether the difference between the terminal voltages of the first and second battery cells at the current moment is greater than, equal to, or less than the product of the second balancing current and the above-mentioned equivalent DC resistance. If it is greater than, the open-circuit voltages of the first and second battery cells at the current moment are acquired, the first balancing current is determined, and then the first battery cell is controlled to charge the second battery cell with the first balancing current. If it is equal to, the balancing current is not re-determined, and the first battery cell is directly controlled to continue charging the second battery cell with the second balancing current. If the value is less than the specified value, then the battery balancing between the first and second battery cells will be stopped immediately.

[0118] The above describes the balancing control process of the battery management system during the charging / discharging of the power battery. Even when the power battery is not charging / discharging, after executing step 302, it is still possible to determine whether the first and second battery cells are undergoing battery balancing based on the first condition. If so, steps 303 and 304 can still be executed. If not, the first battery cell can be controlled to charge the second battery cell with a third balancing current, the magnitude of which is a pre-set fixed value. In this way, current flows through both the first and second battery cells, allowing them to establish a balancing mechanism. Figure 4 and Figure 5 The second-order equivalent circuit is shown. Steps 301-304 above can be executed the next time the terminal voltages of the multiple battery cells comprising the power battery are collected at the current moment.

[0119] In this embodiment, the equalization current corresponding to different time periods during an equalization process is determined based on the second-order equivalent circuit of the battery cell. As the equalization process progresses, the determined equalization current gradually decreases. After the impact of the equalization current on the second battery cell reaches a steady state, under the control of the battery management system, the first battery cell charges the second battery cell with the equalization current at the steady-state moment. Finally, at a certain voltage sampling point, if the voltage difference between the first and second battery cells is less than the product of the second equalization current and the equivalent DC resistance, the equalization process stops. Through the method provided in this embodiment, the battery management system ultimately controls the first battery cell to charge the second battery cell with a relatively small equalization current, thereby performing precise and stable equalization control. This ensures that after an equalization process, the voltages of the first and second battery cells are almost equal, avoiding the need for the battery management system to repeatedly initiate equalization control for these two battery cells. Therefore, the equalization control method for power batteries provided in this embodiment can reduce the total time required for equalization control of the entire power battery and avoids problems such as excessively high battery temperature, accelerated battery wear, and reduced overall efficiency of the battery management system.

[0120] Figure 7 This is a schematic diagram of the structure of a power battery balancing control device provided in an embodiment of this application. Please refer to it. Figure 7 The device includes: a first acquisition module 701, a selection module 702, a second acquisition module 703, and a first control module 704.

[0121] The first acquisition module 701 is used to acquire the terminal voltage of the multiple battery cells included in the power battery at the current moment, and the terminal voltage indicates the remaining power of the corresponding battery cell.

[0122] Selection module 702 is used to select a first battery cell and a second battery cell from the plurality of battery cells, wherein the first battery cell is the battery cell with the highest terminal voltage at the current time and the second battery cell is the battery cell with the lowest terminal voltage at the current time.

[0123] The second acquisition module 703 is used to acquire the open-circuit voltage of the first battery cell and the second battery cell at the current moment, and determine the first equalization current based on the open-circuit voltage of the first battery cell at the current moment, the open-circuit voltage of the second battery cell at the current moment, the first equivalent polarization resistance, the first equivalent polarization capacitance, the second equivalent polarization resistance, the second equivalent polarization capacitance, the ohmic internal resistance of the second battery cell, the first polarization voltage, the second polarization voltage, and the duration of battery equalization of the first battery cell and the second battery cell.

[0124] Wherein, the first equivalent polarization resistance and the second equivalent polarization resistance refer to the resistance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction; the first equivalent polarization capacitance and the second equivalent polarization capacitance refer to the capacitance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction; the first polarization voltage and the second polarization voltage refer to the potential difference generated by electrode polarization when current begins to flow through the second battery cell; the first polarization voltage corresponds to the first equivalent polarization resistance and the first equivalent polarization capacitance, and the second polarization voltage corresponds to the second equivalent polarization resistance and the second equivalent polarization capacitance.

[0125] The first control module 704 is used to control the first battery cell to charge the second battery cell with a first equalization current.

[0126] Optionally, the device further includes:

[0127] The first trigger module is used to trigger the second acquisition module to perform the step of acquiring the open-circuit voltage of the first battery unit and the second battery unit at the current time if the first battery unit and the second battery unit are not currently undergoing battery equalization and the difference between the terminal voltages of the first battery unit and the second battery unit at the current time is greater than a threshold voltage.

[0128] Optionally, the device further includes:

[0129] The acquisition module is used to acquire the second equalization current if the first battery cell and the second battery cell are currently undergoing battery equalization. The second equalization current is the current of the first battery cell and the second battery cell currently undergoing battery equalization.

[0130] The second trigger module is used to trigger the second acquisition module to perform the step of acquiring the open-circuit voltage of the first battery cell and the second battery cell at the current moment if the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is greater than the product of the second equalization current and the equivalent DC resistance. The equivalent DC resistance refers to the resistance presented by the second battery cell after a DC voltage is applied.

[0131] Optionally, the device further includes:

[0132] The second control module is used to control the first battery cell to continue charging the second battery cell with the second equalization current if the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is equal to the product of the second equalization current and the equivalent DC resistance.

[0133] Optionally, the device further includes:

[0134] The third control module is used to control the first battery unit to stop charging the second battery unit if the difference between the terminal voltages of the first battery unit and the second battery unit at the current moment is less than the product of the second equalization current and the equivalent DC resistance.

[0135] Optionally, the first equalization current is determined by the following formula:

[0136]

[0137] Where I1 represents the first equalization current, U OCVA U represents the open-circuit voltage of the first battery cell at the current moment. OCVB R1 represents the open-circuit voltage of the second battery cell at the current moment, C1 represents the first equivalent polarization resistance, C1 represents the first equivalent polarization capacitance, R2 represents the second equivalent polarization resistance, C2 represents the second equivalent polarization capacitance, R0 represents the ohmic internal resistance of the second battery cell, and U represents the open-circuit voltage of the second battery cell at the current moment. p1 (0) represents the first polarization voltage, U p2 (0) represents the second polarization voltage, and t represents the duration during which the first and second battery cells have undergone battery equalization.

[0138] In this embodiment, when determining the balancing current required at different time points during a single balancing process, the polarization phenomenon of the battery cells is considered, as well as the gradual change in the open-circuit voltage difference between the first and second battery cells as the balancing process progresses. Therefore, the required balancing current can be determined based on the current balancing status. As the balancing process continues, the balancing current determined by this embodiment gradually decreases, and eventually, the first battery cell charges the second battery cell with a relatively small balancing current. This demonstrates that this embodiment can perform precise and stable balancing control, ensuring that the two battery cells meet the balancing requirements after one balancing control operation, avoiding the need for the battery management system to repeatedly initiate balancing control for the same two battery cells. Therefore, the balancing control device for the power battery provided by this embodiment can reduce the total time required for balancing control of the entire power battery, and will not lead to problems such as excessively high battery temperature, accelerated battery wear, or reduced overall efficiency of the battery management system.

[0139] It should be noted that the power battery balancing control device provided in the above embodiments is only illustrated by the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the power battery balancing control provided in the above embodiments and the power battery balancing control method embodiments belong to the same concept, and the specific implementation process can be found in the method embodiments, which will not be repeated here.

[0140] Figure 8 This is a structural block diagram of a vehicle 800 provided in an embodiment of this application. Typically, the vehicle 800 includes: a memory 801, a battery management system 802, and a power battery 803.

[0141] The memory 801 may include one or more computer-readable storage media, which may be non-transitory. The memory 801 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In some embodiments, the non-transitory computer-readable storage media in the memory 801 are used to store at least one instruction, which is executed by the battery management system 802 to implement the power battery equalization control method provided in the method embodiments of this application.

[0142] The battery management system 802 is a crucial link connecting the vehicle's power battery and the electric vehicle. It is used to collect, process, and store important information during the battery pack's operation in real time, ensuring the safe and reliable operation of the power battery. In this embodiment, the battery management system 802 executes the computer program stored in the memory 801 to implement the steps of the aforementioned power battery balancing control method.

[0143] The power battery 803 may include multiple battery cells, and each battery cell may include one or more batteries. If a battery cell includes multiple batteries, these batteries may be connected in series or in parallel. The battery cells in the power battery 803 are controlled by the battery management system 802 to perform battery balancing.

[0144] Those skilled in the art will understand that Figure 8 The structure shown does not constitute a limitation on vehicle 800 and may include more or fewer components than shown, or combine certain components, or use different component arrangements.

[0145] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the battery balancing control steps described in the above embodiments. For example, the computer-readable storage medium may be a ROM, RAM, CD-ROM, magnetic tape, floppy disk, or optical data storage device.

[0146] It is worth noting that the computer-readable storage medium mentioned in the embodiments of this application can be a non-volatile storage medium, in other words, it can be a non-transient storage medium.

[0147] It should be understood that all or part of the steps of the above embodiments can be implemented by software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented wholly or partially in the form of a computer program product. The computer program product includes one or more computer instructions. The computer instructions can be stored in the above-described computer-readable storage medium.

[0148] That is, in some embodiments, a computer program product is also provided, which stores computer instructions that, when executed by a processor, implement the steps of the above-described power battery equalization control method.

[0149] It should be understood that "at least one" as mentioned herein refers to one or more, and "multiple" refers to two or more. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B; "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. In addition, in order to clearly describe the technical solutions of the embodiments of this application, the terms "first," "second," etc., are used in the embodiments of this application to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or execution order, and the terms "first," "second," etc., are not necessarily different.

[0150] It should be noted that the information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data used for analysis, data stored, data displayed, etc.) and signals involved in the embodiments of this application are all authorized by the user or fully authorized by all parties, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0151] The above descriptions are embodiments provided in this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for equalization control of a power battery, characterized in that, The method includes: The terminal voltage of the multiple battery cells included in the power battery is collected at the current moment, and the terminal voltage indicates the remaining power of the corresponding battery cell; A first battery cell and a second battery cell are selected from the plurality of battery cells, wherein the first battery cell is the battery cell with the highest terminal voltage at the current time, and the second battery cell is the battery cell with the lowest terminal voltage at the current time. The open-circuit voltages of the first battery cell and the second battery cell at the current time are collected. Based on the open-circuit voltages of the first battery cell and the second battery cell at the current time, the first equivalent polarization resistance, the first equivalent polarization capacitance, the second equivalent polarization resistance, the second equivalent polarization capacitance, the ohmic internal resistance of the second battery cell, the first polarization voltage, the second polarization voltage, and the duration of battery equalization for the first battery cell and the second battery cell, the first equalization current is determined according to the following formula. Where I1 represents the first equalizing current, U OCVA U represents the open-circuit voltage of the first battery cell at the current moment. OCVB R1 represents the open-circuit voltage of the second battery cell at the current moment, C1 represents the first equivalent polarization resistance, C1 represents the first equivalent polarization capacitance, R2 represents the second equivalent polarization resistance, C2 represents the second equivalent polarization capacitance, R0 represents the ohmic internal resistance of the second battery cell, and U represents the open-circuit voltage of the second battery cell at the current moment. p1 (0) represents the first polarization voltage, U p2 (0) represents the second polarization voltage, t represents the duration of battery equalization of the first battery cell and the second battery cell; the first equivalent polarization resistance and the second equivalent polarization resistance refer to the resistance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction, the first equivalent polarization capacitance and the second equivalent polarization capacitance refer to the capacitance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction, the first polarization voltage and the second polarization voltage refer to the potential difference generated by electrode polarization when current begins to flow in the second battery cell, the first polarization voltage corresponds to the first equivalent polarization resistance and the first equivalent polarization capacitance, and the second polarization voltage corresponds to the second equivalent polarization resistance and the second equivalent polarization capacitance; The first battery cell is controlled to charge the second battery cell with the first equalizing current.

2. The method as described in claim 1, characterized in that, Before determining the first equalization current, the method further includes: If the first battery cell and the second battery cell are not currently undergoing battery equalization, and the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is greater than a threshold voltage, then the step of collecting the open-circuit voltages of the first battery cell and the second battery cell at the current moment is executed.

3. The method as described in claim 1 or 2, characterized in that, Before determining the first equalization current, the method further includes: If the first battery cell and the second battery cell are currently undergoing battery balancing, then the second balancing current is obtained, which is the current of the first battery cell and the second battery cell currently undergoing battery balancing. If the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is greater than the product of the second equalization current and the equivalent DC resistance, then the step of collecting the open-circuit voltages of the first battery cell and the second battery cell at the current moment is performed. The equivalent DC resistance refers to the resistance presented by the second battery cell after a DC voltage is applied.

4. The method as described in claim 3, characterized in that, After obtaining the second equalization current, the method further includes: If the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is equal to the product of the second equalizing current and the equivalent DC resistance, then the first battery cell is controlled to continue charging the second battery cell with the second equalizing current.

5. The method as described in claim 3, characterized in that, After obtaining the second equalization current, the method further includes: If the difference between the terminal voltages of the first battery cell and the second battery cell at the current moment is less than the product of the second equalizing current and the equivalent DC resistance, then the first battery cell is controlled to stop charging the second battery cell.

6. A power battery equalization control device, characterized in that, The device includes: The first acquisition module is used to acquire the terminal voltage of the multiple battery cells included in the power battery at the current moment, and the terminal voltage indicates the remaining power of the corresponding battery cell; The selection module is used to select a first battery cell and a second battery cell from the plurality of battery cells, wherein the first battery cell is the battery cell with the highest terminal voltage at the current time, and the second battery cell is the battery cell with the lowest terminal voltage at the current time. The second acquisition module is used to acquire the open-circuit voltage of the first battery cell and the second battery cell at the current time. Based on the open-circuit voltage of the first battery cell at the current time, the open-circuit voltage of the second battery cell at the current time, the first equivalent polarization resistance, the first equivalent polarization capacitance, the second equivalent polarization resistance, the second equivalent polarization capacitance, the ohmic internal resistance of the second battery cell, the first polarization voltage, the second polarization voltage, and the duration of battery equalization of the first battery cell and the second battery cell, the first equalization current is determined according to the following formula. Where I1 represents the first equalizing current, U OCVA U represents the open-circuit voltage of the first battery cell at the current moment. OCVB R1 represents the open-circuit voltage of the second battery cell at the current moment, C1 represents the first equivalent polarization resistance, C1 represents the first equivalent polarization capacitance, R2 represents the second equivalent polarization resistance, C2 represents the second equivalent polarization capacitance, R0 represents the ohmic internal resistance of the second battery cell, and U represents the open-circuit voltage of the second battery cell at the current moment. p1 (0) represents the first polarization voltage, U p2 (0) represents the second polarization voltage, t represents the duration of battery equalization of the first battery cell and the second battery cell; the first equivalent polarization resistance and the second equivalent polarization resistance refer to the resistance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction, the first equivalent polarization capacitance and the second equivalent polarization capacitance refer to the capacitance caused by the polarization of the electrodes of the second battery cell during the electrochemical reaction, the first polarization voltage and the second polarization voltage refer to the potential difference generated by electrode polarization when current begins to flow in the second battery cell, the first polarization voltage corresponds to the first equivalent polarization resistance and the first equivalent polarization capacitance, and the second polarization voltage corresponds to the second equivalent polarization resistance and the second equivalent polarization capacitance; The first control module is used to control the first battery cell to charge the second battery cell with the first equalizing current.

7. A vehicle, characterized in that, The vehicle includes a memory, a battery management system, and a power battery. The memory is used to store computer programs, and the battery management system is used to execute the computer programs stored in the memory to implement the steps of the method according to any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the steps of the method according to any one of claims 1-5.

9. A computer program product, characterized in that, The computer program product stores computer instructions, which, when executed by a processor, implement the steps of the method according to any one of claims 1-5.

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