Battery pack equalization method and device and computer storage medium

Abstract

The invention relates to a battery pack equalization method and device and a computer storage medium, and belongs to the technical field of battery management.The battery pack equalization method comprises the steps that state information of all single batteries in a battery pack is obtained, and the residual energy density of all the single batteries is calculated based on the state information; the unbalance degree of the battery pack is calculated based on the residual energy density; when it is judged that the single battery is in an overcharge state based on the state information and / or the residual energy density, discharging the single battery; and when the unbalance degree is greater than or equal to a preset unbalance degree threshold value, determining a high-energy-density single battery and a low-energy-density single battery in the battery pack, and transmitting electric energy of the high-energy-density single battery to the low-energy-density single battery. When the battery pack is equalized, the response is timely, the error is small, and the efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of battery management technology, and in particular to a battery pack balancing method, apparatus, and computer storage medium. Background Technology

[0002] In modern marine power battery management systems, the performance balancing and health maintenance of marine power battery cells are key issues.

[0003] Power batteries are typically composed of multiple battery cells. These cells may exhibit minor variations during manufacturing, and these variations can amplify over long-term use, leading to inconsistencies in state parameters such as voltage, current, temperature, and remaining capacity. This inconsistency can affect the overall performance of the power battery, causing a decrease in system efficiency and potentially even safety issues. Currently, most power battery balancing algorithms are based on static balancing strategies, meaning that balancing adjustments are only performed when significant differences in state parameters between battery cells are detected. This strategy has the following main shortcomings: First, it lacks timely response. The static balancing algorithm can only adjust after the battery state is significantly unbalanced, failing to achieve real-time monitoring and dynamic balancing of battery cell states. This may lead to prolonged state differences between battery cells, affecting battery health and lifespan. Second, it has large balancing errors. Existing balancing strategies mostly use SOC (State of Charge) or voltage differences as control targets, but due to the relatively flat voltage plateau region of lithium batteries, SOC estimation errors are large and cannot reflect the actual usable energy differences of the battery. Third, it has low balancing efficiency for high-voltage battery packs. Existing balancing strategies typically fail to finely adjust to the specific characteristics and changes of battery cells, resulting in poor balancing effects and an inability to fully improve system stability and energy efficiency.

[0004] It is evident that existing power battery balancing technologies suffer from problems such as slow response, large errors, and low efficiency. Summary of the Invention

[0005] In view of this, it is necessary to provide a battery pack balancing method, device and computer storage medium to solve the problems of untimely response, large error and low efficiency of the existing power battery balancing technology.

[0006] To address the aforementioned problems, in a first aspect, the present invention provides a battery pack balancing method, comprising:

[0007] Obtain the state information of each individual cell in the battery pack, calculate the remaining energy density of each individual cell based on the state information, and calculate the imbalance of the battery pack based on the remaining energy density. When a single cell is determined to be overcharged based on state information and / or remaining energy density, the single cell is discharged. When the imbalance is greater than or equal to the preset imbalance threshold, the high-energy-density cells and low-energy-density cells in the battery pack are identified, and the electrical energy of the high-energy-density cells is transferred to the low-energy-density cells.

[0008] In one possible implementation, the state information of each individual battery cell includes instantaneous terminal voltage, instantaneous current, temperature, charged / discharged capacity, and battery mass.

[0009] In one possible implementation, the formula for calculating the remaining energy density of each individual battery cell is:

[0010] in, For the first i Individual cells in t The remaining energy density at time t. For the first i The remaining energy density of a single cell at time t-1 No. i Individual cells in t The instantaneous terminal voltage at time t. This refers to the lower limit of safe discharge voltage for a single battery cell. For the first i Individual cells in t Instantaneous current at a given moment The sampling period is This refers to the mass of a single battery cell.

[0011] In one possible implementation, the imbalance of the battery pack is the difference between the highest and lowest remaining energy densities of individual cells in the battery pack.

[0012] In one possible implementation, when a single-cell battery is determined to be in an overcharged state based on state information and / or remaining energy density, the single-cell battery is discharged, including: When the instantaneous voltage of a single cell is greater than the average voltage of the battery pack and the duration is greater than or equal to a duration threshold, the single cell is determined to be in an overcharged state; and / or When the remaining energy density of a single cell is greater than the average remaining energy density of the battery pack and the duration is greater than or equal to the second duration threshold, the single cell is determined to be in an overcharged state. Connect the individual cell to the discharge resistor to continue discharging the individual cell.

[0013] In one possible implementation, identifying high-energy-density and low-energy-density individual cells in the battery pack includes: Individual cells with a remaining energy density greater than the average remaining energy density of the battery pack are classified as high-energy-density individual cells, while individual cells with a remaining energy density less than the average remaining energy density of the battery pack are classified as low-energy-density individual cells.

[0014] In one possible implementation, identifying high-energy-density and low-energy-density individual cells in the battery pack includes: The first number of individual cells with the highest remaining energy density in the battery pack are designated as high-energy individual cells, and the second number of individual cells with the lowest remaining energy density in the battery pack are designated as low-energy individual cells.

[0015] In one possible implementation, transferring electrical energy from a high-energy-density single-cell battery to a low-energy-density single-cell battery includes: The power transfer current is determined based on the difference in residual energy density between high-energy-density and low-energy-density single cells. The electrical energy is transferred from high-energy-density cells to low-energy-density cells using an electrical energy transfer current.

[0016] In a second aspect, the present invention also provides a battery pack balancing device, comprising: The information acquisition module is used to acquire the state information of each individual cell in the battery pack, calculate the remaining energy density of each individual cell based on the state information, and calculate the imbalance of the battery pack based on the remaining energy density. The passive balancing module is used to discharge the individual battery when it is determined that the individual battery is in an overcharged state based on the state information and / or the remaining energy density. The active balancing module is used to identify high-energy-density cells and low-energy-density cells in the battery pack when the imbalance degree is greater than or equal to a preset imbalance degree threshold, and to transfer the electrical energy of the high-energy-density cells to the low-energy-density cells.

[0017] Thirdly, the present invention also provides a computer-readable storage medium for storing a computer-readable program or instructions, which, when executed by a processor, can implement the steps in the battery pack balancing method of any of the above implementations.

[0018] The beneficial effects of the present invention are as follows: The battery pack balancing method provided by the present invention obtains the state information of each individual cell in the battery pack, calculates the remaining energy density of each individual cell based on the state information, and calculates the imbalance of the battery pack based on the remaining energy density; by using the state information of each individual cell and the remaining energy density calculated based on the state information as the basis for battery balancing, the technical problem of large balancing error caused by the single basis for battery balancing in the prior art is solved. When a single cell is determined to be overcharged based on state information and / or remaining energy density, it is discharged. When the battery is determined to be overcharged, passive balancing is achieved by discharging the single cell. When the imbalance is greater than or equal to a preset imbalance threshold, high-energy-density and low-energy-density single cells in the battery pack are identified, and the energy of the high-energy-density single cell is transferred to the low-energy-density single cell. When the battery pack is determined to be unbalanced, active balancing is achieved by transferring the energy of the high-energy-density cell to the low-energy-density cell. This combination of active and passive balancing reduces energy loss while increasing the balancing rate. When the energy difference is small, passive balancing reduces the circuit load, while active balancing quickly transfers energy when the difference is large. The combination of the two can improve efficiency and reduce losses. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of a battery pack balancing method provided in an embodiment of the present invention; Figure 2 A topology diagram of a battery pack balancing circuit provided in an embodiment of the present invention; Figure 3 A flowchart illustrating a passive balancing method provided in an embodiment of the present invention; Figure 4 A flowchart illustrating an active balancing method provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a battery pack balancing device provided in an embodiment of the present invention. Detailed Implementation

[0021] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0022] In the description of the embodiments of the present invention, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0023] The terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] A specific embodiment of the present invention, such as Figure 1 As shown, a battery pack balancing method is disclosed, including: S101, obtain the state information of each individual cell in the battery pack, calculate the remaining energy density of each individual cell based on the state information, and calculate the imbalance of the battery pack based on the remaining energy density.

[0026] In this embodiment of the invention, the provided battery pack balancing method can balance a battery pack composed of multiple individual cells. These individual cells can be connected in series or parallel to form the battery pack, such as in power batteries used in ships and automobiles. For each individual cell in the battery pack, its state information can be acquired. Specifically, the state information of each individual cell can be acquired through a battery state acquisition circuit. For ease of explanation, a possible circuit topology is provided, such as... Figure 2 As shown, the battery pack balancing method provided in this embodiment of the invention can be implemented based on this circuit topology. This topology consists of four parts: a battery state acquisition and passive balancing circuit, a battery gating circuit, a DC-DC converter, and a controllable current source. The acquisition and passive balancing circuit forms a complete energy dissipation loop, while the battery gating circuit, DC-DC converter, and controllable current source form a complete energy transfer loop. The controllable current source also falls under the category of DC-DC converters, but compared to a typical DC-DC converter, the controlled object changes from output voltage to output current. The battery state acquisition circuit is responsible for acquiring the state information of individual batteries and transmitting it to the internal storage unit of the microcontroller, providing a data source for battery consistency evaluation.

[0027] In this embodiment of the invention, after obtaining the state information of each individual cell in the battery pack, the remaining energy density of each individual cell in the battery pack can be calculated based on the state information, and the imbalance of the battery pack can be calculated based on the remaining energy density. The calculation methods for the remaining energy density and the imbalance of the battery pack will be described in detail later in this invention.

[0028] S102, when it is determined that a single cell is in an overcharged state based on state information and / or remaining energy density, the single cell is discharged.

[0029] In this embodiment of the invention, when a single battery cell is determined to be in an overcharged state based on state information and / or remaining energy density, it indicates that the single battery cell has excess energy and needs to be passively balanced. Specifically, the single battery cell can be discharged. The specific discharge strategy can be set according to the actual situation.

[0030] S103, when the imbalance degree is greater than or equal to the preset imbalance degree threshold, identify the high energy density single cell and the low energy density single cell in the battery pack, and transfer the electrical energy of the high energy density single cell to the low energy density single cell.

[0031] In this embodiment of the invention, when the calculated imbalance of the battery pack is greater than or equal to a preset imbalance threshold, active balancing is required. This involves first identifying the high-energy-density and low-energy-density individual cells in the battery pack, and then transferring the energy from the high-energy-density cells to the low-energy-density cells. The method for determining the high-energy-density and low-energy-density cells will be described in detail later in this invention. Furthermore, the specific implementation method for transferring the energy from the high-energy-density cells to the low-energy-density cells will also be described in detail later.

[0032] The battery pack balancing method provided by this invention obtains the state information of each individual cell in the battery pack, calculates the remaining energy density of each individual cell based on the state information, and calculates the imbalance of the battery pack based on the remaining energy density. By using the state information of each individual cell and the remaining energy density calculated based on the state information as the basis for battery balancing, this method solves the technical problem of large balancing errors caused by the single basis for battery balancing in the prior art. When a single cell is determined to be overcharged based on state information and / or remaining energy density, it is discharged. When the battery is determined to be overcharged, passive balancing is achieved by discharging the single cell. When the imbalance is greater than or equal to a preset imbalance threshold, high-energy-density and low-energy-density single cells in the battery pack are identified, and the energy of the high-energy-density single cell is transferred to the low-energy-density single cell. When the battery pack is determined to be unbalanced, active balancing is achieved by transferring the energy of the high-energy-density cell to the low-energy-density cell. This combination of active and passive balancing reduces energy loss while increasing the balancing rate. When the energy difference is small, passive balancing reduces the circuit load, while active balancing quickly transfers energy when the difference is large. The combination of the two can improve efficiency and reduce losses.

[0033] In some possible embodiments of the present invention, the state information of each individual battery cell includes instantaneous terminal voltage, instantaneous current, temperature, charged and discharged capacity, and battery mass.

[0034] In embodiments of the present invention, such as Figure 2 As shown, the microcontroller first collects relevant state information for each battery in the battery pack, such as the battery's instantaneous terminal voltage, instantaneous current, temperature, charged / discharged capacity, and battery mass. Through complex algorithmic calculations on these parameters, the remaining usable energy density of each battery is determined, quantifying the energy redundancy of a single battery cell.

[0035] The formula for calculating the remaining energy density of each individual battery cell is as follows:

[0036] in, For the first i Individual cells in t The remaining energy density at time t. For the first i The remaining energy density of a single cell at time t-1 No. i Individual cells in t The instantaneous terminal voltage at time t. This refers to the lower limit of safe discharge voltage for a single battery cell. For the first i Individual cells in t Instantaneous current at a given moment The sampling period is This refers to the mass of a single battery cell.

[0037] Furthermore, the average remaining usable energy density of the battery pack is defined as:

[0038] in, is the average remaining usable energy density of the battery pack, and N is the number of individual cells in the battery pack.

[0039] Furthermore, the imbalance of the battery pack is the difference between the highest and lowest remaining energy densities of individual cells in the battery pack, calculated using the following formula:

[0040] in, For the imbalance of the battery pack, It has the highest remaining energy density in the battery pack. This represents the lowest remaining energy density in the battery pack.

[0041] In some possible embodiments of the present invention, such as Figure 3 As shown, when a single cell is determined to be in an overcharged state based on state information and / or remaining energy density, the single cell is discharged, including: S301, when the instantaneous voltage of a single cell is greater than the average voltage of the battery pack and the duration is greater than or equal to a duration threshold, the single cell is determined to be in an overcharged state; and / or S302, when the remaining energy density of a single cell is greater than the average remaining energy density of the battery pack and the duration is greater than or equal to the second duration threshold, the single cell is determined to be in an overcharged state. S303 connects the individual battery cell to the discharge resistor to continue discharging the individual battery cell.

[0042] In this embodiment of the invention, the passive equalization process mentioned in the foregoing embodiments is mainly for battery overcharging. Whether a battery is overcharged can be determined based on the battery's state information or remaining energy density. Specifically, the following two situations can determine that a single battery cell is overcharged: (1) The instantaneous voltage of a single cell is greater than the average voltage of the battery pack and the duration is greater than or equal to the duration threshold; (2) The remaining energy density of a single cell is greater than the average remaining energy density of the battery pack and the duration is greater than or equal to the second duration threshold.

[0043] When an overcharged battery cell is detected, it can be connected to a heating resistor to release electrical energy through heating. Specifically, for example... Figure 2As shown, when the terminal voltage of a single cell is continuously higher than the average voltage of the battery pack or the remaining usable energy density is continuously higher than the average remaining usable energy density of the battery pack, it is determined that the cell is in an overcharged state and passive balancing needs to be initiated. At this time, the microcontroller outputs a control signal through the GPIO interface to drive the MOSFET switch of the corresponding single cell bypass branch to turn on, and connects the preset bypass resistor in parallel to the single cell circuit. After the switch is turned on, the charging and discharging current will flow in two paths: the main circuit current continues to participate in the overall charging and discharging of the battery pack, while the bypass current flows through the MOSFET and bypass resistor, dissipating energy in the form of Joule heat, thereby reducing the charging current of the overcharged cell and suppressing its voltage from rising further. When the single cell voltage drops to within the safe range of the average voltage or the single cell remaining usable energy density drops to within the safe range of the average remaining usable energy density, it is determined that the overcharge risk has been eliminated, the microcontroller outputs a turn-off signal to turn off the MOSFET, the bypass resistor stops working, and the passive balancing is completed.

[0044] The embodiments of the present invention can respond quickly when the battery is overcharged through a passive balancing strategy, and quickly achieve single-cell voltage peak reduction through heat dissipation, thereby avoiding the risk of increased battery polarization, capacity decay or even thermal runaway caused by overcharging.

[0045] In some possible embodiments of the present invention, identifying high-energy-density individual cells and low-energy-density individual cells in a battery pack includes: Individual cells with a remaining energy density greater than the average remaining energy density of the battery pack are classified as high-energy-density individual cells, while individual cells with a remaining energy density less than the average remaining energy density of the battery pack are classified as low-energy-density individual cells.

[0046] In this embodiment of the invention, when the imbalance of the battery pack is determined to be greater than a preset imbalance threshold, it indicates that the imbalance of the battery pack is too high and needs to be adjusted. Before that, it is necessary to determine the high-energy-density cells and low-energy-density cells in the battery pack. The high-energy-density cells and low-energy-density cells are relative. There are two methods for determining them: one is to regard the cells with a remaining energy density greater than the average remaining energy density of the battery pack as high-energy-density cells and the cells with a remaining energy density less than the average remaining energy density of the battery pack as low-energy-density cells; the other is to regard the first number of cells with the largest remaining energy density in the battery pack as high-energy-density cells and the second number of cells with the smallest remaining energy density in the battery pack as low-energy-density cells.

[0047] Furthermore, such as Figure 2As shown, the microcontroller first collects relevant status information for each battery in the battery pack, such as voltage, current, temperature, and charge / discharge capacity. Through complex algorithmic calculations on these parameters, it determines the remaining usable energy density of each battery and arranges them in descending or ascending order. After obtaining the RAED ranking results, the microcontroller compares the current imbalance with a typical set value. When this imbalance reaches the preset typical value, it indicates a significant difference in energy distribution within the battery pack, requiring active balancing. Based on the RAED ranking results, the microcontroller selects batteries with excess energy as power suppliers (batteries with relatively high remaining usable energy) and batteries with insufficient energy as power receivers (batteries with relatively low remaining usable energy). For example, if battery B1 has the highest remaining usable energy and battery B4 has the lowest, and the imbalance reaches the set value, then battery B1 will be selected as the power supplier, and battery B4 will be selected as the power receiver. Once the high-capacity battery (power supply) is identified, the microcontroller sends a control signal to turn on the corresponding So+ and So- MOSFET switches. For example, if battery B1 is a high-capacity battery, its corresponding So1+ and So1- MOSFET switches will be turned on. After turning on, the high-capacity battery is connected to the input of the controllable current source through a DC-DC converter. The DC-DC converter here acts as a voltage converter and isolation mechanism, transforming the voltage of the high-capacity battery into a voltage range suitable for the input of the controllable current source and providing a certain degree of electrical isolation to ensure the safety and stability of the system. In this way, the high-capacity battery provides energy input to the controllable current source. Simultaneously, the microcontroller controls the Si+ and Si- MOSFET switches corresponding to the low-capacity battery (power receiver) to turn on. Assuming battery B4 is a low-capacity battery, its corresponding Si4+ and Si4- MOSFET switches will be turned on. After turning on, the low-capacity battery is connected to the output of the controllable current source through a DC-DC converter. At this time, the low-charge battery receives energy output from the controllable current source, thereby realizing the transfer of energy from the high-charge battery to the low-charge battery.

[0048] This invention employs an active balancing strategy to transfer the electrical energy of high-energy-density cells to low-energy-density cells when the imbalance of the battery pack exceeds a preset imbalance threshold, thereby achieving rapid energy transfer.

[0049] In some possible embodiments of the present invention, such as Figure 4 The method shown involves transferring electrical energy from a high-energy-density single-cell battery to a low-energy-density single-cell battery, including: S401, determine the power transfer current based on the difference in residual energy density between high-energy-density single cells and low-energy-density single cells; S402 uses an electrical energy transfer current to transfer electrical energy from a high-energy-density cell to a low-energy-density cell.

[0050] In this embodiment of the invention, the controller adjusts the current of the controllable current source according to the degree of imbalance between the batteries. When the imbalance between the batteries is large, the microcontroller controls the controllable current source to make the output current approach its maximum value in order to accelerate the balancing process. For example, in the initial stage of balancing, if the difference in remaining usable energy between the high-capacity and low-capacity batteries is large, the controllable current source will output a larger current to transfer more energy in a shorter time. As the balancing process progresses, the imbalance between the batteries gradually decreases. At this time, the microcontroller will gradually reduce the output current of the controllable current source. This gradual reduction can achieve smooth convergence and avoid damage to the batteries due to sudden current changes. For example, when the imbalance decreases to a certain extent, the current will gradually decrease at a certain slope until the energy between the batteries reaches a balanced state, satisfying the balancing stop condition, such as the imbalance falling below a very small threshold, at which point the active balancing process ends.

[0051] In this embodiment of the invention, the balancing process mainly includes two steps: selecting the balancing object and implementing energy transfer. The core of the balancing controller lies in introducing RAED (Remaining Available Energy Density) as a consistency evaluation index. In terms of balancing strategy, an energy routing scheme using graph theory maximum matching + water level filling is used. 1) Selection of active and passive collaborative strategies: when Time: Use only passive equilibrium to quickly consume slight energy differences; when At this time: Active balancing is activated to quickly move energy and improve balancing efficiency. Imbalance threshold.

[0052] Furthermore, when some battery cells show signs of overcharging / over-discharging: The passive balancing circuit is activated to immediately discharge and reduce the peak voltage of the high-voltage cells to prevent overvoltage risks. At the same time, the active balancing circuit is activated to transfer excess energy to the low-capacity cells to prevent energy waste and achieve peak shaving and valley filling. The active and passive circuits work together to balance response speed and energy utilization efficiency.

[0053] 2) The balanced scheduling principle includes the maximum matching principle and the water level filling principle. Among them, the maximum matching principle sorts all individuals in descending order of RAED to obtain the sequence. Sort the sequence from smallest to largest to obtain the sequence Pairing is established sequentially to form energy transfer pairs. For each pair The balanced current distribution is as follows:

[0054] in, For battery pair Electrical energy transfer current between them This represents the maximum electrical energy transfer current between battery pairs. High energy density single cell battery The remaining energy density, Low energy density single cell battery The remaining energy density. Furthermore, the principle of water level filling is based on Water level line, if If so, then this single unit participates in the balanced output as a power supply unit; if Then, this single unit participates in the equilibrium input as an energy-receiving unit. Energy flow satisfies:

[0055] in, This refers to the energy transferred between the i-th group of battery cells.

[0056] 3) Dynamic adjustment of equalization current, defining normalized imbalance degree:

[0057] in, This refers to the degree of imbalance.

[0058] Therefore, the current dispatch function can be obtained as follows:

[0059] in, To adjust the parameters, the current is made to approach the maximum value when the imbalance is large and gradually decrease when the imbalance is small, so as to achieve smooth convergence.

[0060] This invention optimizes the energy balancing path by constructing an active-passive collaborative balancing topology model, reducing energy loss while improving the balancing rate. Each balancing module is independent and can be expanded to multiple batteries without increasing circuit complexity. Using RAED instead of SOC as the balancing basis overcomes voltage plateau errors and more accurately reflects the differences in available battery energy. An active-passive collaborative strategy is proposed: passive balancing reduces circuit load when energy differences are small, while active balancing quickly transfers energy when differences are large. The combination of these two approaches improves efficiency and reduces losses. The maximum matching + water level filling energy routing algorithm ensures optimal energy allocation and convergence.

[0061] To better implement the battery pack balancing method in this embodiment of the invention, based on the battery pack balancing method, correspondingly, as follows: Figure 5 As shown, this embodiment of the invention also provides a battery pack balancing device, the battery pack balancing device 500 including: The information acquisition module 501 is used to acquire the state information of each individual cell in the battery pack, calculate the remaining energy density of each individual cell based on the state information, and calculate the imbalance of the battery pack based on the remaining energy density. The passive balancing module 502 is used to discharge the individual battery when it is determined that the individual battery is in an overcharged state based on the state information and / or the remaining energy density. The active balancing module 503 is used to identify high-energy-density cells and low-energy-density cells in the battery pack when the imbalance degree is greater than or equal to a preset imbalance degree threshold, and to transfer the electrical energy of the high-energy-density cells to the low-energy-density cells.

[0062] The battery pack balancing device 500 provided in the above embodiments can realize the technical solutions described in the above battery pack balancing method embodiments. The specific implementation principles of each module or unit can be found in the corresponding content in the above battery pack balancing method embodiments, and will not be repeated here.

[0063] Accordingly, this application also provides a computer-readable storage medium for storing a computer-readable program or instruction. When the program or instruction is executed by a processor, it can implement the steps or functions of the battery pack balancing method provided in the above-described method embodiments.

[0064] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0065] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A battery pack balancing method, characterized in that, include: Obtain the state information of each individual cell in the battery pack, calculate the remaining energy density of each individual cell based on the state information, and calculate the imbalance of the battery pack based on the remaining energy density. When it is determined that a single battery cell is in an overcharged state based on the state information and / or the remaining energy density, the single battery cell is discharged. When the imbalance is greater than or equal to a preset imbalance threshold, the high-energy-density cells and low-energy-density cells in the battery pack are identified, and the electrical energy of the high-energy-density cells is transferred to the low-energy-density cells.

2. The battery pack balancing method according to claim 1, characterized in that, The status information of each individual battery cell includes instantaneous terminal voltage, instantaneous current, temperature, charged / discharged capacity, and battery mass.

3. The battery pack balancing method according to claim 1, characterized in that, The formula for calculating the remaining energy density of each individual battery cell is as follows: in, For the first i Individual cells in t The remaining energy density at time 10:00 For the first i The remaining energy density of a single cell at time t-1 No. i Individual cells in t The instantaneous terminal voltage at time t. This refers to the lower limit of safe discharge voltage for a single battery cell. For the first i Individual cells in t Instantaneous current at a given moment The sampling period is This refers to the mass of a single battery cell.

4. The battery pack balancing method according to claim 3, characterized in that, The imbalance of the battery pack is the difference between the highest and lowest remaining energy density of a single cell in the battery pack.

5. The battery pack balancing method according to claim 2, characterized in that, The step of discharging the single battery when it is determined to be in an overcharged state based on the state information and / or the remaining energy density includes: When the instantaneous voltage of a single battery cell is greater than the average voltage of the battery pack and the duration is greater than or equal to a duration threshold, the single battery cell is determined to be in an overcharged state; and / or When the remaining energy density of a single battery cell is greater than the average remaining energy density of the battery pack and the duration is greater than or equal to the second duration threshold, the single battery cell is determined to be in an overcharged state. Connect the individual battery cell to the discharge resistor to continue discharging the individual battery cell.

6. The battery pack balancing method according to claim 4, characterized in that, The process of determining the high-energy-density and low-energy-density individual cells in the battery pack includes: Individual cells with a remaining energy density greater than the average remaining energy density of the battery pack are classified as high-energy-density individual cells, while individual cells with a remaining energy density less than the average remaining energy density of the battery pack are classified as low-energy-density individual cells.

7. The battery pack balancing method according to claim 4, characterized in that, The process of determining the high-energy-density and low-energy-density individual cells in the battery pack includes: The first number of individual cells with the highest remaining energy density in the battery pack are designated as high-energy individual cells, and the second number of individual cells with the lowest remaining energy density in the battery pack are designated as low-energy individual cells.

8. The battery pack balancing method according to claim 1, characterized in that, The step of transferring electrical energy from the high-energy-density single cell to the low-energy-density single cell includes: The power transfer current is determined based on the difference in remaining energy density between the high-energy-density single cell and the low-energy-density single cell. The electrical energy of the high-energy-density single cell is transferred to the low-energy-density single cell using the electrical energy transfer current.

9. A battery pack balancing device, characterized in that, include: The information acquisition module is used to acquire the state information of each individual cell in the battery pack, calculate the remaining energy density of each individual cell based on the state information, and calculate the imbalance of the battery pack based on the remaining energy density. A passive balancing module is used to discharge a single battery cell when it is determined that the single battery cell is in an overcharged state based on the state information and / or the remaining energy density. An active balancing module is used to identify high-energy-density cells and low-energy-density cells in the battery pack when the imbalance degree is greater than or equal to a preset imbalance degree threshold, and to transfer the electrical energy of the high-energy-density cells to the low-energy-density cells.

10. A computer-readable storage medium, characterized in that, Used to store computer-readable programs or instructions, which, when executed by a processor, can implement the steps in the battery pack balancing method according to any one of claims 1 to 8.

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