Battery equalization control method, device, equipment and storage medium

Abstract

The application discloses a battery equalization control method, device, equipment and storage medium, and belongs to the technical field of vehicles. The method determines a first open circuit voltage, a second open circuit voltage, an ohmic internal resistance, a first polarization resistance, a second polarization resistance, a first polarization capacitance, a second polarization capacitance, a first polarization voltage and a second polarization voltage respectively under the condition that a first voltage difference between the highest voltage and the lowest voltage is greater than a first preset threshold value, then determines a first equalization current at different moments based on the parameters, and performs equalization control on the second cell based on the first equalization current at different moments. It can be known that the equalization current determined by the method changes with time, which can increase the voltage drop compensation, prolong the equalization time of the second cell, more greatly shorten the voltage difference between the first cell and the second cell, and thus improve the charging and discharging performance of the battery.

Description

Technical Field

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

[0002] For new energy vehicles, power batteries require multiple cells connected in series and parallel to meet load demands. However, after repeated use in series and parallel connections, differences in manufacturing processes and operating environments can lead to significant inconsistencies between cells. If the voltage of even one cell in the power battery reaches the charge / discharge threshold, the entire battery must be protected. Therefore, the battery management system needs to balance the charge and discharge of each cell in the power battery to improve its charging and discharging performance. Summary of the Invention

[0003] This application provides a battery balancing control method, apparatus, device, and storage medium, which can extend the balancing time of battery cells, thereby improving the charge and discharge performance of the battery. The technical solution is as follows:

[0004] On the one hand, a battery balancing control method is provided, the method comprising:

[0005] Obtain the voltage of each cell in the battery;

[0006] Based on the voltage of each cell, a first voltage difference between the highest and lowest voltages is determined;

[0007] If the first voltage difference is greater than the first preset threshold, then the first open circuit voltage and the second open circuit voltage are determined. The first open circuit voltage and the second open circuit voltage are the open circuit voltages of the first battery cell and the second battery cell, respectively. The first battery cell is the battery cell corresponding to the highest voltage, and the second battery cell is the battery cell corresponding to the lowest voltage.

[0008] Based on the second-order equivalent circuit model, the ohmic internal resistance, first polarization resistor, second polarization resistor, first polarization capacitor, second polarization capacitor, first polarization voltage, and second polarization voltage of the second cell are determined. The first polarization voltage and the second polarization voltage are the polarization voltages of the first polarization resistor and the second polarization resistor at the initial moment, respectively. The second-order equivalent circuit model is used to simulate the dynamic voltage response of the cell during the charging and discharging process.

[0009] Based on the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization capacitor, the second polarization capacitor, the first polarization voltage, and the second polarization voltage, determine the first equalization current at different times;

[0010] The second cell is balanced based on the first equalization current at different times.

[0011] In one possible implementation, determining the first equalization current at different times based on the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization capacitor, the second polarization capacitor, the first polarization voltage, and the second polarization voltage includes:

[0012] A first time constant is determined based on the first polarization resistor and the first polarization capacitor;

[0013] The second time constant is determined based on the second polarization resistor and the second polarization capacitor;

[0014] Substituting the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, and the second polarization voltage into the first relational data yields the second relational data. The first relational data represents the relationship between the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, the second polarization voltage, time, and the equalization current. The second relational data represents the relationship between the equalization current and time.

[0015] Multiple time points are obtained, and each time point is substituted into the second relational data to obtain the first equalization current at different time points.

[0016] In another possible implementation, determining the first open-circuit voltage and the second open-circuit voltage includes:

[0017] Obtain the first terminal voltage of the first battery cell at the initial time and the second terminal voltage of the second battery cell at the initial time;

[0018] The first terminal voltage is determined as the first open-circuit voltage, and the second terminal voltage is determined as the second open-circuit voltage.

[0019] In another possible implementation, the method further includes:

[0020] Determine the current difference between the first equilibrium currents corresponding to two adjacent time points;

[0021] If the current difference is less than the second preset threshold, then the third terminal voltage of the first cell at the current moment, the fourth terminal voltage of the second cell at the current moment, and the DC resistance of the second cell are obtained.

[0022] The second equalization current is determined based on the third terminal voltage, the fourth terminal voltage, and the DC resistance.

[0023] The second cell is balanced based on the second equalization current.

[0024] In another possible implementation, determining the second equalization current based on the third terminal voltage, the fourth terminal voltage, and the DC resistance includes:

[0025] Determine the second voltage difference between the third terminal voltage and the fourth terminal voltage;

[0026] The ratio of the second voltage difference to the DC resistance is determined to obtain the second equalization current.

[0027] In another possible implementation, the method further includes:

[0028] During the equalization control of the second battery cell, a third voltage difference between the first battery cell and the second battery cell is obtained;

[0029] If the third voltage difference is less than the third preset threshold, then the equalization control of the second battery cell is stopped.

[0030] On the other hand, a battery balancing control device is provided, the device comprising:

[0031] The first acquisition module is used to acquire the voltage of each cell in the battery;

[0032] The first determining module is used to determine a first voltage difference between the highest voltage and the lowest voltage based on the voltage of each battery cell;

[0033] The second determining module is used to determine the first open-circuit voltage and the second open-circuit voltage if the first voltage difference is greater than the first preset threshold. The first open-circuit voltage and the second open-circuit voltage are the open-circuit voltages of the first battery cell and the second battery cell, respectively. The first battery cell is the battery cell corresponding to the highest voltage, and the second battery cell is the battery cell corresponding to the lowest voltage.

[0034] The third determining module is used to determine the ohmic internal resistance, first polarization resistor, second polarization resistor, first polarization capacitor, second polarization capacitor, first polarization voltage and second polarization voltage of the second cell based on the second-order equivalent circuit model. The first polarization voltage and the second polarization voltage are the polarization voltages corresponding to the first polarization resistor and the second polarization resistor at the initial moment, respectively. The second-order equivalent circuit model is used to simulate the dynamic voltage response of the cell during the charging and discharging process.

[0035] The fourth determining module is used to determine the first equalization current at different times based on the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization capacitor, the second polarization capacitor, the first polarization voltage, and the second polarization voltage.

[0036] The equalization control module is used to perform equalization control on the second cell based on the first equalization current at different times.

[0037] In one possible implementation, the fourth determining module is used to determine a first time constant based on the first polarization resistor and the first polarization capacitor; determine a second time constant based on the second polarization resistor and the second polarization capacitor; substitute the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, and the second polarization voltage into first relational data to obtain second relational data. The first relational data is used to represent the relationship between the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, the second polarization voltage, time, and equalization current; the second relational data is used to represent the relationship between equalization current and time; obtain multiple times, substitute each time into the second relational data, and obtain the first equalization current at different times.

[0038] In another possible implementation, the second determining module is used to obtain the first terminal voltage of the first battery cell at the initial time and the second terminal voltage of the second battery cell at the initial time; determine the first terminal voltage as the first open-circuit voltage, and determine the second terminal voltage as the second open-circuit voltage.

[0039] In another possible implementation, the device further includes:

[0040] The fifth determining module is used to determine the current difference between the first equalization currents corresponding to two adjacent time points;

[0041] The second acquisition module is used to acquire the third terminal voltage of the first cell at the current moment, the fourth terminal voltage of the second cell at the current moment, and the DC resistance of the second cell if the current difference is less than the second preset threshold.

[0042] The sixth determining module is used to determine the second equalizing current based on the third terminal voltage, the fourth terminal voltage, and the DC resistance;

[0043] The equalization control module is also used to perform equalization control on the second battery cell based on the second equalization current.

[0044] In another possible implementation, the sixth determining module is used to determine a second voltage difference between the third terminal voltage and the fourth terminal voltage; determine the ratio of the second voltage difference to the DC resistance, and obtain the second equalizing current.

[0045] In another possible implementation, the device further includes:

[0046] The third acquisition module is used to acquire the third voltage difference between the first battery cell and the second battery cell during the process of equalization control of the second battery cell;

[0047] The equalization control module is further configured to stop equalization control of the second battery cell if the third voltage difference is less than a third preset threshold.

[0048] On the other hand, a battery management system is provided, the battery management system including a processor and a memory, the memory storing at least one piece of program code, the at least one piece of program code being loaded and executed by the processor to implement the battery equalization control method described above.

[0049] On the other hand, a computer-readable storage medium is provided, wherein at least one piece of program code is stored in the computer-readable storage medium, the at least one piece of program code being loaded and executed by a processor to implement the battery equalization control method described in any of the preceding claims.

[0050] On the other hand, a computer program product is provided, wherein at least one piece of program code is stored in the computer program product, the at least one piece of program code being loaded and executed by a processor to implement the battery equalization control method described in any of the above claims.

[0051] This application provides a battery balancing control method. When the voltage difference between the highest and lowest voltages exceeds a first preset threshold, the method determines a first open-circuit voltage, a second open-circuit voltage, an ohmic internal resistance, a first polarization resistor, a second polarization resistor, a first polarization capacitor, a second polarization capacitor, a first polarization voltage, and a second polarization voltage. Based on these parameters, a first balancing current is determined at different times. Based on this first balancing current, the second battery cell is balanced. Therefore, the balancing current determined by this method varies with time, which increases voltage drop compensation, extends the balancing time for the second battery cell, and further shortens the voltage difference between the first and second battery cells, thereby improving the battery's charge and discharge performance.

[0052] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this disclosure. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of an implementation environment provided in an embodiment of this application;

[0054] Figure 2 This is a flowchart of a battery balancing control method provided in an embodiment of this application;

[0055] Figure 3 This is a schematic diagram of a second-order equivalent circuit model provided in an embodiment of this application;

[0056] Figure 4 This is a schematic diagram of an balancing strategy provided in an embodiment of this application;

[0057] Figure 5 This is a schematic diagram of the structure of a battery balancing control device provided in an embodiment of this application;

[0058] Figure 6 This is a structural block diagram of a battery management system provided in an embodiment of this application. Detailed Implementation

[0059] To make the technical solution and advantages of this application clearer, the embodiments of this application will be described in further detail below.

[0060] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or means is not limited to the listed steps or means, but may optionally include steps or means not listed, or may optionally include other steps or means inherent to these processes, methods, products, or devices.

[0061] It should be noted that all information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data used for analysis, stored data, displayed data, etc.), and signals involved in this application have been 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. For example, the voltage, resistance, and capacitance involved in this application were all obtained with full authorization.

[0062] Figure 1 This is a schematic diagram of an implementation environment provided in an embodiment of this application. See also... Figure 1The implementation environment includes a battery management system 101 and a battery 102. The battery management system 101 is electrically connected to the battery 102. The battery management system 101 is used to acquire the voltage of each cell 103 in the battery 102 and determine a first voltage difference between the highest voltage and the lowest voltage. If the first voltage difference is greater than a first preset threshold, an equalization current is determined. Based on the equalization current, equalization control is performed on the cell 103 corresponding to the lowest voltage.

[0063] The electrical connection can be a circuit connection or a wireless connection, and there is no specific limitation on the latter. If the electrical connection is a circuit connection, the connection method can be a cable connection, such as a CAN (Controller Area Network) bus connection. If the electrical connection is a wireless connection, the connection method can be an infrared connection, a wireless LAN, or a WiFi (Wireless Fidelity) network connection. In the embodiments of this application, there is no specific limitation on the latter.

[0064] The battery 102 includes multiple battery cells 103. The number of battery cells 103 can be set and changed as needed, and there is no specific limitation on this. Furthermore, the multiple battery cells 103 can be connected in series and / or in parallel, and there is no specific limitation on this.

[0065] Figure 2 This is a flowchart of a battery balancing control method provided in an embodiment of this application, executed by the battery management system. See also... Figure 2 The method includes:

[0066] Step 201: The battery management system obtains the voltage of each cell in the battery.

[0067] The battery management system (BMS) can acquire the voltage of each cell in the battery using voltage sensors. Accordingly, the BMS sends a voltage acquisition command to the voltage sensor, which then acquires the voltage of each cell based on the command. Alternatively, the voltage sensor can monitor the voltage of each cell in real time or periodically and send the voltage data to the BMS.

[0068] The voltage sensor can be one or more. If there is only one voltage sensor, it can detect the voltage of each battery cell. If there are multiple voltage sensors, one voltage sensor can be assigned to one battery cell, and each voltage sensor can detect the voltage of its corresponding battery cell.

[0069] Step 202: The battery management system determines the first voltage difference between the highest and lowest voltages based on the voltage of each cell.

[0070] The battery management system determines the highest and lowest voltages from the voltages of multiple cells, and determines the first voltage difference between the highest and lowest voltages.

[0071] The battery management system determines whether the first voltage difference is greater than the first preset threshold. If it is greater than the first preset threshold, step 203 is executed. If it is not greater than the first preset threshold, the voltage of each cell is monitored.

[0072] Step 203: If the first voltage difference is greater than the first preset threshold, the battery management system determines the first open circuit voltage and the second open circuit voltage.

[0073] Wherein, the first open-circuit voltage and the second open-circuit voltage are the open-circuit voltages of the first battery cell and the second battery cell, respectively. The first battery cell is the battery cell corresponding to the highest voltage, and the second battery cell is the battery cell corresponding to the lowest voltage.

[0074] If the first voltage difference is greater than the first preset threshold, the battery management system performs equalization control on the second cell. Accordingly, the battery management system obtains the first terminal voltage of the first cell at the initial moment and the second terminal voltage of the second cell at the initial moment; the first terminal voltage is determined as the first open circuit voltage, and the second terminal voltage is determined as the second open circuit voltage.

[0075] Step 204: Based on the second-order equivalent circuit model, the battery management system determines the ohmic internal resistance, first polarization resistor, second polarization resistor, first polarization capacitor, second polarization capacitor, first polarization voltage, and second polarization voltage corresponding to the second cell.

[0076] Wherein, the first polarization voltage and the second polarization voltage are the polarization voltages corresponding to the first polarization resistor and the second polarization resistor at the initial moment, respectively. The second-order equivalent circuit model is used to simulate the dynamic voltage response of the battery cell during the charging and discharging process.

[0077] See Figure 3 , Figure 3 This is a schematic diagram of a second-order equivalent circuit model. Wherein, This indicates the open-circuit voltage of the battery cell. This indicates the ohmic internal resistance of the battery cell. and These represent different polarization resistances. and These represent different second-polarization capacitors. This indicates the terminal voltage of the battery cell. This represents the charging and discharging current of the battery cell. It can be expressed by the following formula (1):

[0078] (1)

[0079] in, and They represent and The polarization voltage at the initial moment Indicates time, and Both represent time constants.

[0080] The battery management system pre-establishes a second-order equivalent circuit model. Based on the second-order equivalent circuit model, it determines and stores the ohmic internal resistance, two polarization resistors, two polarization capacitors, and two polarization voltages corresponding to each cell. When executing this step, it obtains the stored ohmic internal resistance, first polarization resistor, second polarization resistor, first polarization capacitor, second polarization capacitor, first polarization voltage, and second polarization voltage corresponding to the second cell.

[0081] Step 205: The battery management system determines the first equalization current at different times based on the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization capacitor, the second polarization capacitor, the first polarization voltage, and the second polarization voltage.

[0082] This step can be achieved through the following steps (1) to (4), including:

[0083] (1) The battery management system determines the first time constant based on the first polarization resistor and the first polarization capacitor.

[0084] The battery management system determines the product of the first polarization resistor and the first polarization capacitor to obtain the first time constant.

[0085] For example, with Represents the first time constant. and Let represent the first polarization resistor and the first polarization capacitor, respectively. .

[0086] (2) The battery management system determines the second time constant based on the second polarization resistor and the second polarization capacitor.

[0087] The battery management system determines the product of the second polarization resistor and the second polarization capacitor to obtain the second time constant.

[0088] For example, with Indicates the second time constant. and Let the second polarization resistor and the second polarization capacitor represent the two polarization capacitors, respectively. .

[0089] (3) The battery management system substitutes the first time constant, the second time constant, the first open circuit voltage, the second open circuit voltage, the ohmic internal resistance, the first polarization resistance, the second polarization resistance, the first polarization voltage and the second polarization voltage into the first relational data to obtain the second relational data.

[0090] The first relational data is used to represent the relationship between the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistance, the second polarization resistance, the first polarization voltage, the second polarization voltage, the time, and the equalization current. The second relational data is used to represent the relationship between the equalization current and the time.

[0091] In this embodiment of the application, the first relational data can be represented by the following formula (2):

[0092] (2)

[0093] in, and These represent the first open-circuit voltage and the second open-circuit voltage, respectively. Indicates the first equalization current. and These represent the first polarization voltage and the second polarization voltage corresponding to the second battery cell, respectively. This indicates the ohmic internal resistance of the second battery cell. and These represent the first polarization resistor and the second polarization resistor corresponding to the second battery cell, respectively. and These represent the first time constant and the second time constant corresponding to the second battery cell, respectively. Indicates the time.

[0094] The battery management system substitutes the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistance, the second polarization resistance, the first polarization voltage, and the second polarization voltage into the first relational data to obtain the second relational data. The second relational data can be expressed by the following formula (3):

[0095] (3)

[0096] Since the battery management system has already acquired the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistance, the second polarization resistance, the first polarization voltage, and the second polarization voltage, all of these are known quantities. Therefore, only the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistance, the second polarization resistance, the first polarization voltage, and the second polarization voltage are known quantities in formula (3). and Since it is an unknown quantity, formula (3) represents the relationship between the equilibrium current and time.

[0097] (4) The battery management system acquires multiple time points and substitutes each time point into the second relational data to obtain the first equalization current at different time points.

[0098] The battery management system determines multiple time points, which can be arranged at equal intervals or at unequal intervals, without any specific limitation.

[0099] The battery management system substitutes each moment into the second relational data to obtain the first equalization current corresponding to each moment.

[0100] Step 206: The battery management system performs equalization control on the second cell based on the first equalization current at different times.

[0101] The battery management system charges the second cell through the first cell based on the first equalization current at different times, so as to perform equalization control on the second cell.

[0102] It should be noted that in the initial and middle stages of equalization, the battery management system can determine the first equalization current at different times using the method described above. Then, based on the first equalization current at different times, equalization control is applied to the second cell to extend the equalization time and bring the voltage of the second cell closer to the target value. However, in the final stage of equalization, the impact of the equalization current on the cell has reached a steady state. In this case, a fixed equalization current can be used to equalize the second cell. Accordingly, the process can be:

[0103] The battery management system determines the current difference between the first equalization currents corresponding to two adjacent time points; if the current difference is less than the second preset threshold, it obtains the third terminal voltage of the first cell at the current time, the fourth terminal voltage of the second cell at the current time, and the DC resistance of the second cell; based on the third terminal voltage, the fourth terminal voltage, and the DC resistance, it determines the second equalization current; based on the second equalization current, it performs equalization control on the second cell.

[0104] In this implementation, the battery management system can determine the current difference in real time or periodically during the process of equalizing the second cell based on the first equalizing current. If the current difference is less than the second preset threshold, it indicates that the equalization period has been reached. In this case, the battery management system can obtain the third terminal voltage of the first cell and the fourth terminal voltage of the second cell at the current moment through the voltage sensor, and obtain the DC resistance of the second cell stored in the memory.

[0105] The DC resistance is the sum of the ohmic internal resistance, the first polarization resistance, and the second polarization resistance. This value is known when the second cell is shipped as a group. The battery management system can store the DC resistance of each cell in the memory. When performing this step, the DC resistance of the second cell is directly obtained from the memory.

[0106] The battery management system determines the second voltage difference between the third and fourth terminal voltages, determines the ratio of the second voltage difference to the DC resistance, and obtains the second equalization current.

[0107] The process by which the battery management system determines the second equalization current can be represented by the following formula (4):

[0108] (4)

[0109] in, This represents the second equilibrium current. Indicates the voltage at the third terminal. This indicates the voltage at the fourth terminal. This indicates DC resistance.

[0110] According to formula (4), the second equilibrium current is a fixed value and is independent of time.

[0111] The battery management system performs equalization control on the second cell based on the second equalization current.

[0112] In this embodiment of the application, during the process of the battery management system performing equalization control on the second cell based on the first equalization current and the second equalization current, the third voltage difference between the first cell and the second cell is acquired in real time or periodically. If the third voltage difference is less than the third preset threshold, the equalization control on the second cell is stopped.

[0113] If the third voltage difference is less than the third preset threshold, it means that the voltage difference between the first cell and the second cell is already very small. In this case, the equalization control of the second cell can be stopped.

[0114] The third preset threshold can be set and changed as needed, without specific limitations. For example, the third preset threshold can be 0, 1mV, 2mV, 3mV, etc. For example, if the third preset threshold is 0, then when the third voltage difference is 0, the battery management system stops the equalization control of the second cell. Accordingly, this process can be represented by the following formula (5):

[0115] (5)

[0116] The above explanation uses voltage difference as an example to illustrate the criterion for stopping the balancing process. See also... Figure 4 , Figure 4 This is a schematic diagram illustrating an balancing strategy provided in an embodiment of this application. Figure 4 As can be seen from the diagram: The battery management system collects the voltage of each cell in the battery and records the highest and lowest voltages. If the first voltage difference between the highest and lowest voltages is greater than the first preset threshold, then the second cell corresponding to the lowest voltage is subjected to equalization control, and the first equalization current at different times is calculated using formula (3). Equalization control is performed based on the first equalization current. As equalization control progresses, when the equalization period ends, the second equalization current is calculated using formula (4), and then equalization control is performed based on the second equalization current. When the third voltage difference between the first and second cells is less than the third preset threshold, equalization stops. If the first voltage difference is not greater than the first preset threshold, then the voltage of each cell continues to be collected until the first voltage difference is greater than the first preset threshold, and then the second cell is subjected to equalization control.

[0117] In this embodiment, SOC (State of Charge) can also be used as a judgment condition. Accordingly, the process can be as follows: the battery management system acquires the first SOC of the first cell and the second SOC of the second cell in real time or periodically, determines the SOC difference between the first SOC and the second SOC, and if the SOC difference is less than a fourth preset threshold, then the equalization control of the second cell is stopped.

[0118] In summary, the equalization control method provided in this application extends the equalization time of the battery cell by adding equalization current voltage drop compensation, making its voltage closer to the target value. It can improve the performance of the power battery with almost no increase in workload, and it is easy to implement and has good application prospects.

[0119] This application provides a battery balancing control method. When the voltage difference between the highest and lowest voltages exceeds a first preset threshold, the method determines a first open-circuit voltage, a second open-circuit voltage, an ohmic internal resistance, a first polarization resistor, a second polarization resistor, a first polarization capacitor, a second polarization capacitor, a first polarization voltage, and a second polarization voltage. Based on these parameters, a first balancing current is determined at different times. Based on this first balancing current, the second battery cell is balanced. Therefore, the balancing current determined by this method varies with time, which increases voltage drop compensation, extends the balancing time for the second battery cell, and further shortens the voltage difference between the first and second battery cells, thereby improving the battery's charge and discharge performance.

[0120] Figure 5 This is a schematic diagram of the structure of a battery balancing control device provided in an embodiment of this application. See also... Figure 5 The device includes:

[0121] The first acquisition module 501 is used to acquire the voltage of each cell in the battery;

[0122] The first determining module 502 is used to determine a first voltage difference between the highest voltage and the lowest voltage based on the voltage of each cell;

[0123] The second determining module 503 is used to determine the first open-circuit voltage and the second open-circuit voltage if the first voltage difference is greater than the first preset threshold. The first open-circuit voltage and the second open-circuit voltage are the open-circuit voltages of the first battery cell and the second battery cell, respectively. The first battery cell is the battery cell corresponding to the highest voltage and the second battery cell is the battery cell corresponding to the lowest voltage.

[0124] The third determining module 504 is used to determine the ohmic internal resistance, first polarization resistor, second polarization resistor, first polarization capacitor, second polarization capacitor, first polarization voltage and second polarization voltage of the second cell based on the second-order equivalent circuit model. The first polarization voltage and the second polarization voltage are the polarization voltages corresponding to the first polarization resistor and the second polarization resistor at the initial moment, respectively. The second-order equivalent circuit model is used to simulate the dynamic voltage response of the cell during the charging and discharging process.

[0125] The fourth determining module 505 is used to determine the first equalization current at different times based on the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization capacitor, the second polarization capacitor, the first polarization voltage, and the second polarization voltage.

[0126] The equalization control module 506 is used to perform equalization control on the second cell based on the first equalization current at different times.

[0127] In one possible implementation, the fourth determining module 505 is used to determine a first time constant based on a first polarization resistor and a first polarization capacitor; determine a second time constant based on a second polarization resistor and a second polarization capacitor; substitute the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, and the second polarization voltage into first relational data to obtain second relational data. The first relational data is used to represent the relationship between the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, the second polarization voltage, time, and equalization current; the second relational data is used to represent the relationship between equalization current and time; obtain multiple times, substitute each time into the second relational data, and obtain the first equalization current at different times.

[0128] In another possible implementation, the second determining module 503 is used to obtain the first terminal voltage of the first battery cell at the initial moment and the second terminal voltage of the second battery cell at the initial moment; determine the first terminal voltage as the first open circuit voltage and the second terminal voltage as the second open circuit voltage.

[0129] In another possible implementation, the device further includes:

[0130] The fifth determining module is used to determine the current difference between the first equalization currents corresponding to two adjacent time points;

[0131] The second acquisition module is used to acquire the third terminal voltage of the first cell at the current moment, the fourth terminal voltage of the second cell at the current moment, and the DC resistance of the second cell if the current difference is less than the second preset threshold.

[0132] The sixth determining module is used to determine the second equalizing current based on the third terminal voltage, the fourth terminal voltage, and the DC resistance;

[0133] The equalization control module 506 is also used to perform equalization control on the second cell based on the second equalization current.

[0134] In another possible implementation, the sixth determining module is used to determine the second voltage difference between the third terminal voltage and the fourth terminal voltage; determine the ratio of the second voltage difference to the DC resistance to obtain the second equalizing current.

[0135] In another possible implementation, the device further includes:

[0136] The third acquisition module is used to acquire the third voltage difference between the first and second cells during the equalization control of the second cell.

[0137] The equalization control module 506 is also used to stop the equalization control of the second cell if the third voltage difference is less than the third preset threshold.

[0138] This application provides a battery balancing control device. When the voltage difference between the highest and lowest voltages exceeds a first preset threshold, the device determines a first open-circuit voltage, a second open-circuit voltage, an ohmic internal resistance, a first polarization resistor, a second polarization resistor, a first polarization capacitor, a second polarization capacitor, a first polarization voltage, and a second polarization voltage. Based on these parameters, it determines a first balancing current at different times and performs balancing control on the second battery cell based on this first balancing current. Therefore, the balancing current determined by this device varies with time, which increases voltage drop compensation, extends the balancing time for the second battery cell, and significantly shortens the voltage difference between the first and second battery cells, thereby improving the battery's charge and discharge performance.

[0139] The block diagram of the battery management system can be found in [reference needed]. Figure 6The battery management system 600 can vary considerably depending on its configuration or performance. It may include a central processing unit (CPU) 601 and a memory 602. The memory 602 stores at least one line of program code, which is loaded and executed by the processor 601 to implement the operations performed by the battery management system 600 in the aforementioned battery balancing control method. Of course, the battery management system 600 may also have wired or wireless network interfaces, a keyboard, and input / output interfaces for input / output. It may also include other components for implementing device functions, which will not be elaborated upon here.

[0140] In an exemplary embodiment, a computer-readable storage medium is also provided, which stores at least one piece of program code that is loaded and executed by a processor to implement the battery equalization control method in the above embodiments.

[0141] In an exemplary embodiment, a computer program product is also provided, which stores at least one piece of program code that is loaded and executed by a processor to implement the battery equalization control method in the above embodiments.

[0142] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware or by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0143] The above description is only for the purpose of enabling those skilled in the art to understand the technical solution of this application and is 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 battery equalization control method characterized by, The method includes: Obtain the voltage of each cell in the battery; Based on the voltage of each cell, a first voltage difference between the highest and lowest voltages is determined; If the first voltage difference is greater than the first preset threshold, then the first open circuit voltage and the second open circuit voltage are determined. The first open circuit voltage and the second open circuit voltage are the open circuit voltages of the first battery cell and the second battery cell, respectively. The first battery cell is the battery cell corresponding to the highest voltage, and the second battery cell is the battery cell corresponding to the lowest voltage. Based on the second-order equivalent circuit model, the ohmic internal resistance, first polarization resistor, second polarization resistor, first polarization capacitor, second polarization capacitor, first polarization voltage, and second polarization voltage of the second cell are determined. The first polarization voltage and the second polarization voltage are the polarization voltages of the first polarization resistor and the second polarization resistor at the initial moment, respectively. The second-order equivalent circuit model is used to simulate the dynamic voltage response of the cell during the charging and discharging process. A first time constant is determined based on the first polarization resistor and the first polarization capacitor; The second time constant is determined based on the second polarization resistor and the second polarization capacitor; Substituting the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, and the second polarization voltage into the first relational data yields the second relational data. The first relational data represents the relationship between the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, the second polarization voltage, time, and the equalization current. The second relational data represents the relationship between the equalization current and time. Multiple time points are obtained, and each time point is substituted into the second relational data to obtain the first equalization current at different time points; The second cell is balanced based on the first equalization current at different times.

2. The method of claim 1, wherein, Determining the first open-circuit voltage and the second open-circuit voltage includes: Obtain the first terminal voltage of the first battery cell at the initial time and the second terminal voltage of the second battery cell at the initial time; The first terminal voltage is determined as the first open-circuit voltage, and the second terminal voltage is determined as the second open-circuit voltage.

3. The method of claim 1, wherein, The method further includes: Determine the current difference between the first equilibrium currents corresponding to two adjacent time points; If the current difference is less than the second preset threshold, then the third terminal voltage of the first cell at the current moment, the fourth terminal voltage of the second cell at the current moment, and the DC resistance of the second cell are obtained. The second equalization current is determined based on the third terminal voltage, the fourth terminal voltage, and the DC resistance. The second cell is balanced based on the second equalization current.

4. The method of claim 3, wherein, Determining the second equalization current based on the third terminal voltage, the fourth terminal voltage, and the DC resistance includes: Determine the second voltage difference between the third terminal voltage and the fourth terminal voltage; The ratio of the second voltage difference to the DC resistance is determined to obtain the second equalization current.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: During the equalization control of the second battery cell, a third voltage difference between the first battery cell and the second battery cell is obtained; If the third voltage difference is less than the third preset threshold, then the equalization control of the second battery cell is stopped.

6. A battery equalization control device characterized by comprising: The device includes: The first acquisition module is used to acquire the voltage of each cell in the battery; The first determining module is used to determine a first voltage difference between the highest voltage and the lowest voltage based on the voltage of each battery cell; The second determining module is used to determine the first open-circuit voltage and the second open-circuit voltage if the first voltage difference is greater than the first preset threshold. The first open-circuit voltage and the second open-circuit voltage are the open-circuit voltages of the first battery cell and the second battery cell, respectively. The first battery cell is the battery cell corresponding to the highest voltage, and the second battery cell is the battery cell corresponding to the lowest voltage. The third determining module is used to determine the ohmic internal resistance, first polarization resistor, second polarization resistor, first polarization capacitor, second polarization capacitor, first polarization voltage and second polarization voltage of the second cell based on the second-order equivalent circuit model. The first polarization voltage and the second polarization voltage are the polarization voltages corresponding to the first polarization resistor and the second polarization resistor at the initial moment, respectively. The second-order equivalent circuit model is used to simulate the dynamic voltage response of the cell during the charging and discharging process. The fourth determining module is used to determine a first time constant based on the first polarization resistor and the first polarization capacitor; to determine a second time constant based on the second polarization resistor and the second polarization capacitor; to substitute the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, and the second polarization voltage into first relational data to obtain second relational data. The first relational data is used to represent the relationship between the first time constant, the second time constant, the first open-circuit voltage, the second open-circuit voltage, the ohmic internal resistance, the first polarization resistor, the second polarization resistor, the first polarization voltage, the second polarization voltage, time, and equalization current. The second relational data is used to represent the relationship between equalization current and time. Multiple times are obtained, and each time is substituted into the second relational data to obtain the first equalization current at different times. The equalization control module is used to perform equalization control on the second cell based on the first equalization current at different times.

7. A battery management system, characterized by, The battery management system includes a processor and a memory, wherein the memory stores at least one piece of program code, which is loaded and executed by the processor to implement the battery equalization control method as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one piece of program code, which is loaded and executed by a processor to implement the battery equalization control method as described in any one of claims 1 to 5.

9. A computer program product, characterised in that, The computer program product stores at least one program code, and the at least one program code is loaded and executed by the processor to implement the battery equalization control method according to any one of claims 1 to 5.

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