Balancing structure and method of battery pack, battery pack and household energy storage device

Abstract

The invention provides a battery pack equalization structure and method, a battery pack and a household energy storage device, the equalization structure comprises a plurality of battery modules, and each battery module comprises a plurality of single cells; the method comprises the following steps: acquiring the SOC (state of charge) of each battery module and the SOC of each single battery cell in each battery module; respectively calculating the SOC average value of each battery module and the SOC average value of each single battery cell in each battery module; according to the SOC average value of each battery module and the SOC average value of each single cell, whether inter-cell equalization is carried out on each battery module or not is judged, and / or whether intra-cell equalization needs to be carried out on each single cell or not is judged, so that the problems that the cell difference of each cell in the battery pack is increased along with the increase of the service time and the change of the environment temperature, and the service life of the battery pack is influenced are solved. Therefore, the problems of low battery utilization rate and short service life caused by the switching between the inter-group equalization and the intra-group equalization under different working conditions are solved, and the utilization rate of the battery is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery pack balancing management, and in particular to a battery pack balancing structure and method, a battery pack, and a household energy storage device. Background Art

[0002] Battery packs are widely used in household energy storage. There are differences in voltage, capacity, internal resistance, etc. among the cells in the battery pack. With the increase of usage time and changes in ambient temperature, the differences in cells gradually increase, resulting in low battery utilization and short battery life.

[0003] To solve the above problems, most power battery systems used in household energy storage use balancing technology, which is divided into passive balancing technology and active balancing technology. Passive balancing technology usually uses resistors to dissipate excess energy in over-voltage cells through heat generation. This method directly leads to a large amount of energy waste and reduces the energy utilization rate of the entire battery pack. Therefore, passive balancing technology is gradually replaced by active balancing. At present, active balancing technology mainly uses capacitors, inductors, transformers, redundant batteries, etc. as energy conversion devices to achieve energy transfer from batteries with high capacity to batteries with low available capacity, thereby achieving the balance of each single battery.

[0004] However, electric vehicles, especially buses and trucks, require relatively large amounts of battery energy. Considering the volume, weight and battery management, their power battery systems are generally composed of multiple independent battery packs connected in series and parallel. Each battery pack is composed of several single cells connected in series and parallel. The battery management unit is integrated inside the battery to manage and balance the batteries within the pack. Most current battery balancing methods balance the batteries within the battery pack. As the battery packs are physically relatively independent, the voltage difference between the battery packs is large, and the series and parallel structures between the battery packs are complex and diverse, it is difficult to achieve inter-pack balancing. Therefore, there is currently no mature inter-pack balancing solution.

[0005] Therefore, the prior art needs to be further developed. Summary of the invention

[0006] The purpose of the present invention is to overcome the above technical deficiencies and provide a battery pack balancing structure and method, a battery pack, and a household energy storage device to solve the problem that there are differences in voltage, capacity, internal resistance, etc. among the cells in the battery pack. With the increase of usage time and changes in ambient temperature, the differences in cells gradually increase, resulting in low battery utilization and short battery life. In addition, since most current battery balancing methods balance the batteries in the battery pack, there is currently no mature technical solution for balancing between groups.

[0007] To achieve the above technical objectives, according to a first aspect of the present invention, the present invention provides a balancing structure of a battery pack, comprising: A plurality of battery modules, each battery module comprising a plurality of single cells; A first switch array, used to control the charging or discharging of single cells that need to be balanced; The second switch array is used to control the charging or discharging of the battery modules that need to be balanced.

[0008] Specifically, the balancing structure of the battery pack also includes a plurality of intra-group DC / DC bidirectional buck-boost converters, each battery module corresponds to an intra-group DC / DC bidirectional buck-boost converter, the battery module includes an input end and an output end, the input end of the battery module is electrically connected to the output end of the corresponding intra-group DC / DC bidirectional buck-boost converter, and the output end of the battery module is electrically connected to the input end of the corresponding intra-group DC / DC bidirectional buck-boost converter.

[0009] Specifically, the balancing structure of the battery pack also includes a plurality of inter-group DC / DC bidirectional buck-boost converters, each battery module corresponds to an inter-group DC / DC bidirectional buck-boost converter, the battery module includes an input end and an output end, the input end of the battery module is electrically connected to the output end of the corresponding inter-group DC / DC bidirectional buck-boost converter, and the output end of the battery module is electrically connected to the input end of the corresponding inter-group DC / DC bidirectional buck-boost converter.

[0010] According to a second aspect of the present invention, there is provided a battery pack, comprising: The above-mentioned balancing structure of the battery pack.

[0011] According to a third aspect of the present invention, there is provided a household energy storage device, comprising: The battery pack described above.

[0012] According to a fourth aspect of the present invention, there is provided a battery pack balancing method, comprising: S100, obtaining the SOC of each battery module and the SOC of each single cell in each battery module; S200, respectively calculating the average SOC value of each battery module and the average SOC value of each single cell in each battery module; S300: Determine whether to perform inter-group balancing on each battery module and / or determine whether to perform intra-group balancing on each single cell according to the average SOC value of each battery module and the average SOC value of each single cell in each battery module.

[0013] Specifically, the S300 includes: It is determined whether the difference between the SOC of each battery module and the average SOC of each battery module is greater than a first preset threshold value, and whether to perform inter-group balancing on each battery module is determined according to the determination result.

[0014] Specifically, the S300 further includes: It is determined whether the difference between the SOC of each single cell in each battery module and the average SOC of each single cell is greater than a second preset threshold value, and whether to perform intra-group balancing on each single cell in each battery module according to the determination result.

[0015] Specifically, judging whether to perform inter-group balancing on each battery module according to the judgment result includes: If the difference between the SOC of each battery module and the average SOC of each battery module is greater than a first preset threshold, performing inter-group balancing on the battery module; If the difference between the SOC of the battery module and the average SOC of each battery module is less than or equal to the first preset threshold, the battery module is not subjected to inter-group balancing.

[0016] Specifically, the inter-group balancing of the battery module includes: Determine whether the SOC of the battery module is greater than the average SOC of each battery module, and determine whether to charge the battery module through the inter-group DC / DC bidirectional buck-boost converter according to the determination result. If the SOC of the battery module is less than the average SOC of each battery module, the battery module is charged through the inter-group DC / DC bidirectional buck-boost converter; If the SOC of the battery module is greater than the average SOC of each battery module, the battery module is discharged through the inter-group DC / DC bidirectional buck-boost converter.

[0017] Specifically, judging whether to perform intra-group balancing on each single cell in each battery module according to the judgment result includes: If the difference between the SOC of the single cell and the average SOC of each single cell is greater than a second preset threshold, the single cell corresponding to the maximum difference is selected for intra-group balancing; If the differences between the SOC of each single battery cell and the average SOC of each single battery cell are all less than or equal to the second preset threshold, the single battery cells are not subjected to intra-group balancing.

[0018] Specifically, the selecting of the single cell corresponding to the maximum difference value for intra-group balancing includes: Determine whether the SOC of the single cell corresponding to the maximum difference is greater than the average SOC of each single cell, and determine whether to charge the single cell according to the determination result; If the SOC of the single cell is less than the average SOC of all the single cells, the single cell is charged through the DC / DC bidirectional buck-boost converter in the group; If the SOC of the single cell is greater than the average SOC of all the single cells, the single cell is discharged through the DC / DC bidirectional buck-boost converter in the group.

[0019] Specifically, the method further includes: Automatically identifying the working condition of the battery module according to the current value of the battery module, if the current value of the battery module is greater than or equal to the third preset threshold, it is determined that the current battery module is in a fast charge and discharge state, and the judgment of intra-group balancing is first initiated; If the current value of the battery module is less than the third preset threshold, it is determined that the battery module is in a slow charge and discharge or static state, and the judgment of inter-group balancing is first initiated.

[0020] Beneficial effects: The present invention provides a battery pack balancing structure, including multiple battery modules, each battery module including multiple single cells; a first switch array, used to control the charging or discharging of the single cells that need to be balanced; and a second switch array, used to control the charging or discharging of the battery modules that need to be balanced. By obtaining the SOC of each battery module and the SOC of each single cell in each battery module, and judging whether to perform inter-group balancing on each battery module and / or judging whether to perform intra-group balancing on each single cell according to the average SOC value of each battery module and the average SOC value of each single cell in each battery module, the problem of differences in voltage, capacity, internal resistance, etc. among the cells in the battery pack is solved. With the increase of use time and the change of ambient temperature, the difference of the cells gradually increases, resulting in low battery utilization and short battery service life is solved. The present invention further realizes the inter-group balancing and intra-group balancing of the series battery modules, and realizes the efficient switching of inter-group balancing and intra-group balancing under different working conditions, ensuring that the voltage of each cell in the battery module is basically consistent, greatly improving the utilization rate of the battery, increasing the service life of the battery, and greatly improving the intelligence, availability and reliability of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the composition of the balancing structure of the battery pack provided in a specific embodiment of the present invention; Figure 2 is a flow chart of a battery pack balancing method provided in a specific embodiment of the present invention; Figure 3 is a schematic diagram of an intra-group and inter-group equilibrium structure provided in a specific embodiment of the present invention; Figure 4 is a schematic diagram of a balancing structure between each battery module group provided in a specific embodiment of the present invention; Figure 5 is a schematic diagram of the structure of an intra-group balancing module provided in a specific embodiment of the present invention; Figure 6 It is a structural schematic diagram of the inter-group balanced charging and discharging process provided in a specific embodiment of the present invention; Figure 7 It is a logic block diagram of the inter-group balancing control algorithm provided in a specific embodiment of the present invention; Figure 8 It is a logic block diagram of the intra-group balancing control algorithm provided in a specific embodiment of the present invention; Fig. 9 It is a logic block diagram of a battery system balancing priority control algorithm provided in a specific implementation manner of the present invention. DETAILED DESCRIPTION In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the embodiments in this application, other similar embodiments obtained by ordinary technicians in this field without making creative work should all fall within the scope of protection of this application. In addition, the directional words mentioned in the following embodiments, such as "up", "down", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional words used are used to illustrate rather than limit the invention.

[0022] The present invention will be further described below in conjunction with the accompanying drawings and preferred embodiments.

[0023] Embodiment 1 See also Figure 1 , this embodiment provides a balancing structure of a battery pack, including: A plurality of battery modules 100, each battery module comprising a plurality of single cells; A first switch array 200, used to control the charging or discharging of single cells that need to be balanced; The second switch array 300 is used to control the charging or discharging of the battery modules that need to be balanced.

[0024] See also Figure 3 The intra-group and inter-group balancing structure includes: a battery module, a first switch array (switch array 1), a DC / DC bidirectional buck-boost converter, and a second switch array (switch array 2). The switch array 1 controls the charging or discharging of each single cell in the battery module, and the switch array 2 controls the charging and discharging of each battery module.

[0025] Specifically, the balancing structure of the battery pack also includes a plurality of intra-group DC / DC bidirectional buck-boost converters, each battery module corresponds to an intra-group DC / DC bidirectional buck-boost converter, the battery module includes an input end and an output end, the input end of the battery module is electrically connected to the output end of the corresponding intra-group DC / DC bidirectional buck-boost converter, and the output end of the battery module is electrically connected to the input end of the corresponding intra-group DC / DC bidirectional buck-boost converter.

[0026] See also Figure 5 Each battery module may contain M single cells, corresponding to M+1 switches, and the balancing structure of each single cell is formed by the DC / DC bidirectional buck-boost converter in the group; when the single cell corresponding to the largest difference is selected for group balancing, the two switches corresponding to the selected single cell are turned on to establish a connection path between it and the DC / DC bidirectional buck-boost converter in the group. When the single cell needs to be discharged, the single cell will be discharged to the battery pack as a whole through the DC / DC bidirectional buck-boost converter in the group, releasing excess electric energy to narrow the SOC gap between it and other single cells in the battery module; when the single cell needs to be discharged, the DC / DC bidirectional buck-boost converter in the group is used to charge the single cell until its SOC reaches the average level.

[0027] Specifically, the balancing structure of the battery pack also includes a plurality of inter-group DC / DC bidirectional buck-boost converters, each battery module corresponds to an inter-group DC / DC bidirectional buck-boost converter, the battery module includes an input end and an output end, the input end of the battery module is electrically connected to the output end of the corresponding inter-group DC / DC bidirectional buck-boost converter, and the output end of the battery module is electrically connected to the input end of the corresponding inter-group DC / DC bidirectional buck-boost converter.

[0028] See also Figure 4 , Figure 4 It is an inter-group balancing structure of the battery module. The inter-group DC / DC bidirectional buck-boost converter in the inter-group balancing structure adapts the battery module voltage and controls the battery module to perform charging and discharging operations. The MOS tube controls the charging and discharging direction. Qn_1 and Qn_4 are discharge MOS, Qn_2 and Qn_3 are charge MOS, and the total battery module average voltage is Vmodule_avg, that is, the balanced bus voltage. When the battery module needs to be discharged, Qn_1 and Qn_4 are turned on. At this time, the battery module with a high SOC is stepped down to Vmodule_avg by the inter-group DC / DC bidirectional buck-boost converter for discharge. When the battery module needs to be charged, Qn_2 and Qn_3 are turned on. At this time, the battery module with a low SOC is stepped up to Vmodule_avg by the inter-group DC / DC bidirectional buck-boost converter for charging.

[0029] It should be noted here that the present invention provides a balancing structure of a battery pack based on intra-group balancing and inter-group balancing, which solves the problems of differences in voltage, capacity, internal resistance, etc. among the battery cells in the battery pack. With the increase of usage time and changes in ambient temperature, the differences in the battery cells gradually increase, resulting in low battery utilization and short battery life. The present invention further realizes inter-group balancing and intra-group balancing of series-connected battery modules, which greatly improves the intelligence, usability and reliability of the present invention.

[0030] Embodiment 2 This embodiment provides a battery pack, including: the balancing structure of the battery pack in the first embodiment.

[0031] Specifically, the balancing structure of the battery pack includes: A plurality of battery modules, each battery module comprising a plurality of single cells; A first switch array, used to control the charging or discharging of single cells that need to be balanced; The second switch array is used to control the charging or discharging of the battery modules that need to be balanced.

[0032] Specifically, the balancing structure of the battery pack also includes multiple intra-group DC / DC bidirectional buck-boost converters, each battery module corresponds to an intra-group DC / DC bidirectional buck-boost converter, the battery module includes an input end and an output end, the input end of the battery module is electrically connected to the output end of the corresponding intra-group DC / DC bidirectional buck-boost converter, and the output end of the battery module is electrically connected to the input end of the corresponding intra-group DC / DC bidirectional buck-boost converter.

[0033] Specifically, the balancing structure of the battery pack also includes multiple inter-group DC / DC bidirectional buck-boost converters, each battery module corresponds to an inter-group DC / DC bidirectional buck-boost converter, the battery module includes an input end and an output end, the input end of the battery module is electrically connected to the output end of the corresponding inter-group DC / DC bidirectional buck-boost converter, and the output end of the battery module is electrically connected to the input end of the corresponding inter-group DC / DC bidirectional buck-boost converter.

[0034] It should be noted here that the present embodiment provides a battery pack based on intra-group balancing and inter-group balancing structures, which solves the problem that there are differences in voltage, capacity, internal resistance, etc. among the battery cells in the battery pack. With the increase of usage time and changes in ambient temperature, the differences in battery cells gradually increase, resulting in low battery utilization and short battery life. The present invention further realizes inter-group balancing and intra-group balancing of series-connected battery modules, which greatly improves the intelligence, usability and reliability of the present invention.

[0035] Embodiment 3 This embodiment provides a household energy storage device, including: the battery pack in the second embodiment.

[0036] Specifically, the above-mentioned battery pack can be applied to household energy storage devices, each battery pack includes multiple battery modules, each battery module includes multiple single cells; the battery pack also includes a first switch array for controlling the charging or discharging of single cells that need to be balanced; and a second switch array for controlling the charging or discharging of battery modules that need to be balanced.

[0037] It should be noted here that the present embodiment provides a household energy storage device of a battery pack based on intra-group balancing and inter-group balancing structures, which solves the problem that there are differences in voltage, capacity, internal resistance, etc. among the battery cells in the battery pack. With the increase of usage time and changes in ambient temperature, the differences in the battery cells gradually increase, resulting in low battery utilization and short battery life. The present invention further realizes inter-group balancing and intra-group balancing of series-connected battery modules, which greatly improves the intelligence, usability and reliability of the present invention.

[0038] Embodiment 4 See also Figure 2 , this embodiment provides a battery pack balancing method, including: S100, obtaining the SOC of each battery module and the SOC of each single cell in each battery module; It can be understood that the battery management system BMS is responsible for monitoring and managing the status of the battery pack, which includes collecting the voltage of each battery cell in the battery pack and estimating the SOC (state of charge) of the battery module. SOC is an important parameter for measuring the remaining power of the battery. After the battery management system BMS collects the voltage of each battery cell in the battery pack, it can obtain the SOC of the battery module and the SOC of each single cell in the battery module by table lookup or estimation.

[0039] S200 , respectively calculating the average SOC value of each battery module and the average SOC value of each single cell in each battery module.

[0040] S300: Determine whether to perform inter-group balancing on each battery module and / or determine whether to perform intra-group balancing on each single cell according to the average SOC value of each battery module and the average SOC value of each single cell in each battery module.

[0041] Specifically, the S300 includes: It is determined whether the difference between the SOC of each battery module and the average SOC of each battery module is greater than a first preset threshold value, and whether to perform inter-group balancing on each battery module is determined according to the determination result.

[0042] Specifically, judging whether to perform inter-group balancing on each battery module according to the judgment result includes: If the difference between the SOC of each battery module and the average SOC of each battery module is greater than a first preset threshold, performing inter-group balancing on the battery module; If the difference between the SOC of the battery module and the average SOC of each battery module is less than or equal to the first preset threshold, the battery module is not subjected to inter-group balancing.

[0043] Specifically, the inter-group balancing of the battery module includes: Determine whether the SOC of the battery module is greater than the average SOC of each battery module, and determine whether to charge the battery module through the inter-group DC / DC bidirectional buck-boost converter according to the determination result. If the SOC of the battery module is less than the average SOC of each battery module, the battery module is charged through the inter-group DC / DC bidirectional buck-boost converter; If the SOC of the battery module is greater than the average SOC of each battery module, the battery module is discharged through the inter-group DC / DC bidirectional buck-boost converter.

[0044] Specifically, the S300 further includes: It is determined whether the difference between the SOC of each single cell in each battery module and the average SOC of each single cell is greater than a second preset threshold value, and whether to perform intra-group balancing on each single cell in each battery module according to the determination result.

[0045] Specifically, judging whether to perform intra-group balancing on each single cell in each battery module according to the judgment result includes: If the difference between the SOC of the single cell and the average SOC of each single cell is greater than a second preset threshold, the single cell corresponding to the maximum difference is selected for intra-group balancing; If the differences between the SOC of each single battery cell and the average SOC of each single battery cell are all less than or equal to the second preset threshold, the single battery cells are not subjected to intra-group balancing.

[0046] Specifically, the selecting of the single cell corresponding to the maximum difference value for intra-group balancing includes: Determine whether the SOC of the single cell corresponding to the maximum difference is greater than the average SOC of each single cell, and determine whether to charge the single cell according to the determination result; If the SOC of the single cell is less than the average SOC of all the single cells, the single cell is charged through the DC / DC bidirectional buck-boost converter in the group; If the SOC of the single cell is greater than the average SOC of all the single cells, the single cell is discharged through the DC / DC bidirectional buck-boost converter in the group.

[0047] Specifically, the method further includes: Automatically identifying the working condition of the battery module according to the current value of the battery module, if the current value of the battery module is greater than or equal to the third preset threshold, it is determined that the current battery module is in a fast charge and discharge state, and the judgment of intra-group balancing is first initiated; If the current value of the battery module is less than the third preset threshold, it is determined that the battery module is in a slow charge and discharge or static state, and the judgment of inter-group balancing is first initiated.

[0048] See also Fig. 9 Before balancing, it is necessary to determine which working condition the battery system is in. When the battery system is in a fast charging and discharging condition, the system prioritizes intra-group balancing; when the battery system is in a slow charging and discharging or static condition, the system prioritizes inter-group balancing. The third preset threshold can be specifically set according to the maximum charging and discharging capacity of the battery module. The third preset threshold is preferably 10A in the present invention, that is, if the current value of the current battery module is greater than or equal to 10A, intra-group balancing is prioritized to ensure that each single cell in each battery module achieves the maximum charging and discharging energy. If the current value of the battery module is less than 10A, inter-group balancing is prioritized to ensure that each battery module in series achieves the maximum charging and discharging energy. Dynamically adjust the balancing strategy to maximize the overall performance of the battery pack and extend the battery life. According to the current charging and discharging current of the battery module, intelligently select intra-group balancing or inter-group balancing to optimize the energy utilization efficiency and balancing effect of the battery system, and can adapt to different charging and discharging conditions to ensure that the battery system can achieve the best working state in various usage scenarios.

[0049] The working principle of this embodiment is explained below through a specific example: The present invention introduces an active balancing method, which is to realize the transfer of energy from high-voltage monomers to low-voltage monomers through a certain circuit topology. However, in the series-connected battery module, it can be divided into intra-group balancing and inter-group balancing, as well as control algorithms for inter-group balancing and intra-group balancing under different working conditions of the battery module, to achieve efficient balancing of the series-connected battery modules.

[0050] 1. Balance between groups See also Figure 7 , Figure 7 The implementation steps for inter-group balance are: S11, real-time acquisition of the SOC of each battery module in the battery module, i.e., SOC1, SOC2, SOC3, etc., and calculation of the average SOC of the battery module, recorded as SOC 平均 ; S12. Calculate the SOC and SOC of each battery module 平均 The difference between them is recorded as ∆SOC; S13. When ∆SOC > the first preset threshold, inter-group balancing is performed. The first preset threshold here can be set to 5%. The first preset threshold can be set according to the balancing requirements, and is generally set within the range of 3-8%. S14: When the SOC of the battery module that needs to be balanced between groups is greater than SOC 平均 When the SOC of the battery module that needs to be balanced between groups is less than SOC 平均 When charging, the battery module is charged, the charging MOS of the battery module is turned on, and the discharging MOS is turned off; The SOC of each battery module is adjusted to the SOC through the inter-group DC / DC bidirectional buck-boost converter 平均 ,like Figure 6 As shown, module 1, module 3, and module 4 are discharged, and module 2 and module 5 are charged. The voltages of modules 1, 3, and 4 are respectively reduced to SOC by the inter-group DC / DC bidirectional buck-boost converter. 平均 Module 2 and module 5 increase the SOC to SOC through the inter-group DC / DC bidirectional buck-boost converter 平均 ; S15. When ∆SOC of all battery modules is less than or equal to the first preset threshold, the charging and discharging MOS of the switch array 2 is disconnected, and the inter-group balancing is disconnected.

[0051] 2. Balance within the group See also Figure 8 , Figure 8 The implementation steps for within-group balancing are: S21, obtain the SOC of each single cell in each battery module, that is, SOC 第一单体 , SOC 第二单体 , SOC 第三单体 ..., calculate the average SOC of the single cells in the battery module, recorded as SOC 单体平均 ; S22. Calculate the difference between the SOC of each battery module cell and the average SOC of the cell, denoted as ∆SOC 单体 ; S23, when ∆SOC 单体 > the second preset threshold, perform intra-group balancing. The second preset threshold can be set according to the balancing requirements, generally within the range of 3-8%. Here, the second preset threshold can be set to 3%. The single cell corresponding to the maximum difference value is selected for intra-group balancing, and the switch of the channel corresponding to the single cell is turned on. , The single cell is charged / discharged evenly with the battery module through the DC / DC bidirectional buck-boost converter in the group; S24, when the SOC corresponding to the single cell is greater than SOC 单体平均 When the SOC of the single cell is less than SOC 单体平均 When the battery module charges the single cell; S25, when all the single cells correspond to ∆SOC 单体 When the second preset threshold is reached, all switches of the switch array 1 are turned off, and the intra-group balance is turned off.

[0052] 3. Switch between intra-group balancing and inter-group balancing according to the current working conditions of the battery module Fig. 9 The specific steps for switching between intra-group balance and inter-group balance are as follows: In the normal battery module charging and discharging process, generally first fast charging / fast discharging (high current) is performed, then slow charging / slow discharging (low current), and finally the charging / discharging is completed and the module is in a static state; fast or slow charging and discharging mainly refers to the size of the charging and discharging current, which mainly depends on the charging and discharging capacity of the battery module. The specific process is as follows: S31. If the maximum charge and discharge capacity of a battery module is 50A, it can be set to be greater than or equal to 10A for fast charge and discharge, and determine whether the battery system is in the process of fast charge / discharge. If the battery system is in the process of fast charge / discharge, intra-group balancing is prioritized to ensure that each cell in each battery pack achieves the maximum charge and discharge energy.

[0053] S32. If the battery system is not in a fast charging / discharging process, set less than 10A as slow charging and discharging, and determine whether the battery system is in a slow charging / slow discharging / stationary state. If the battery system is determined to be in a slow charging / slow discharging / stationary state, prioritize inter-group balancing to ensure that the series-connected battery modules achieve maximum charging and discharging energy.

[0054] It is understandable that although the existing active balancing can achieve effective energy transfer, it lacks efficient and intelligent intra-group and inter-group balancing switching strategies in the series battery modules, especially the poor adaptability under different charging and discharging conditions. The present invention intelligently selects intra-group balancing or inter-group balancing according to the current charging and discharging current of the battery module, thereby further improving the energy utilization efficiency and balancing effect of the battery system.

[0055] It should be noted here that this embodiment obtains the SOC of each battery module and the SOC of each single cell in each battery module, and judges whether to perform inter-group balancing on each battery module and / or judges whether to perform intra-group balancing on each single cell according to the average SOC value of each battery module and the average SOC value of each single cell in each battery module, thereby solving the problem that there are differences in voltage, capacity, internal resistance, etc. among the cells in the battery pack. With the increase of usage time and changes in ambient temperature, the difference in cells gradually increases, resulting in low battery utilization and short battery service life. The present invention further realizes inter-group balancing and intra-group balancing of series-connected battery modules, and at the same time realizes efficient switching between inter-group balancing and intra-group balancing under different working conditions, thereby ensuring that the voltage of each cell in the battery module is basically consistent, greatly improving the battery utilization, increasing the battery service life, and greatly improving the intelligence, usability and reliability of the present invention.

[0056] In a preferred embodiment, the present application further provides an electronic device, the electronic device comprising: A memory; and a processor, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the battery pack balancing method is implemented. The computer device can be broadly a server, a terminal, or any other electronic device with necessary computing and / or processing capabilities. In one embodiment, the computer device may include a processor, a memory, a network interface, a communication interface, etc. connected via a system bus. The processor of the computer device can be used to provide necessary computing, processing and / or control capabilities. The memory of the computer device may include a non-volatile storage medium and an internal memory. An operating system, a computer program, etc. may be stored in or on the non-volatile storage medium. The internal memory can provide an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface and the communication interface of the computer device can be used to connect and communicate with external devices via a network. When the computer program is executed by the processor, the steps of the method of the present invention are performed.

[0057] The present invention may be implemented as a computer-readable storage medium having a computer program stored thereon, which causes the steps of the method of an embodiment of the present invention to be executed when executed by a processor. In one embodiment, the computer program is distributed on a plurality of computer devices or processors coupled to a network so that the computer program is stored, accessed and executed in a distributed manner by one or more computer devices or processors. A single method step / operation, or two or more method steps / operations, may be performed by a single computer device or processor or by two or more computer devices or processors. One or more method steps / operations may be performed by one or more computer devices or processors, and one or more other method steps / operations may be performed by one or more other computer devices or processors. One or more computer devices or processors may perform a single method step / operation, or perform two or more method steps / operations.

[0058] It should be noted here that the present invention obtains the SOC of each battery module and the SOC of each single cell in each battery module, and judges whether to perform inter-group balancing on each battery module and / or judges whether to perform intra-group balancing on each single cell according to the average SOC value of each battery module and the average SOC value of each single cell in each battery module, thereby solving the problem that there are differences in voltage, capacity, internal resistance, etc. among the cells in the battery pack. With the increase of usage time and changes in ambient temperature, the difference in cells gradually increases, resulting in low battery utilization and short battery life. The present invention further realizes inter-group balancing and intra-group balancing of series-connected battery modules, and at the same time realizes efficient switching between inter-group balancing and intra-group balancing under different working conditions, thereby ensuring that the voltage of each cell in the battery module is basically consistent, greatly improving the battery utilization, increasing the battery life, and greatly improving the intelligence, usability and reliability of the present invention.

[0059] The various technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by this specification as long as there is no contradiction in such combination.

[0060] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A battery pack balancing structure, characterized in that: include: A plurality of battery modules (100), each battery module comprising a plurality of single battery cells; A first switch array (200), used to control the charging or discharging of single cells that need to be balanced; The second switch array (300) is used to control the charging or discharging of the battery modules that need to be balanced.

2. The balancing structure of the battery pack according to claim 1, characterized in that: The balancing structure of the battery pack also includes multiple intra-group DC / DC bidirectional buck-boost converters, each battery module corresponds to an intra-group DC / DC bidirectional buck-boost converter, the battery module includes an input end and an output end, the input end of the battery module is electrically connected to the output end of the corresponding intra-group DC / DC bidirectional buck-boost converter, and the output end of the battery module is electrically connected to the input end of the corresponding intra-group DC / DC bidirectional buck-boost converter.

3. The balancing structure of the battery pack according to claim 1, characterized in that: The balancing structure of the battery pack also includes a plurality of inter-group DC / DC bidirectional buck-boost converters, each battery module corresponds to an inter-group DC / DC bidirectional buck-boost converter, the battery module includes an input end and an output end, the input end of the battery module is electrically connected to the output end of the corresponding inter-group DC / DC bidirectional buck-boost converter, and the output end of the battery module is electrically connected to the input end of the corresponding inter-group DC / DC bidirectional buck-boost converter.

4. A battery pack, characterized in that: include: The balancing structure of the battery pack according to any one of claims 1 to 3.

5. A household energy storage device, characterized in that: include: The battery pack according to claim 4.

6. A battery pack balancing method, characterized in that: include: S100, obtaining the SOC of each battery module and the SOC of each single cell in each battery module; S200, respectively calculating the average SOC value of each battery module and the average SOC value of each single cell in each battery module; S300: Determine whether to perform inter-group balancing on each battery module and / or determine whether to perform intra-group balancing on each single cell according to the average SOC value of each battery module and the average SOC value of each single cell in each battery module.

7. The battery pack balancing method according to claim 6, characterized in that: The S300 includes: It is determined whether the difference between the SOC of each battery module and the average SOC of each battery module is greater than a first preset threshold value, and whether to perform inter-group balancing on each battery module is determined according to the determination result.

8. The battery pack balancing method according to claim 6, characterized in that: The S300 further includes: It is determined whether the difference between the SOC of each single cell in each battery module and the average SOC of each single cell is greater than a second preset threshold value, and whether to perform intra-group balancing on each single cell in each battery module according to the determination result.

9. The battery pack balancing method according to claim 7, characterized in that: The step of judging whether to perform inter-group balancing on each battery module according to the judgment result includes: If the difference between the SOC of each battery module and the average SOC of each battery module is greater than a first preset threshold, performing inter-group balancing on the battery module; If the difference between the SOC of the battery module and the average SOC of each battery module is less than or equal to the first preset threshold, the battery module is not subjected to inter-group balancing.

10. The battery pack balancing method according to claim 9, characterized in that: The inter-group balancing of the battery module comprises: Determine whether the SOC of the battery module is greater than the average SOC of each battery module, and determine whether to charge the battery module through the inter-group DC / DC bidirectional buck-boost converter according to the determination result. If the SOC of the battery module is less than the average SOC of all battery modules, the battery module is charged through the inter-group DC / DC bidirectional buck-boost converter; If the SOC of the battery module is greater than the average SOC of each battery module, the battery module is discharged through the inter-group DC / DC bidirectional buck-boost converter.

11. The battery pack balancing method according to claim 8, characterized in that: The step of judging whether to perform intra-group balancing on each single cell in each battery module according to the judgment result includes: If the difference between the SOC of the single cell and the average SOC of each single cell is greater than a second preset threshold, the single cell corresponding to the maximum difference is selected for intra-group balancing; If the differences between the SOC of each single battery cell and the average SOC of each single battery cell are all less than or equal to the second preset threshold, the single battery cells are not subjected to intra-group balancing.

12. The battery pack balancing method according to claim 11, characterized in that: The selecting the single cell corresponding to the maximum difference value for intra-group balancing includes: Determine whether the SOC of the single cell corresponding to the maximum difference is greater than the average SOC of each single cell, and determine whether to charge the single cell according to the determination result; If the SOC of the single cell is less than the average SOC of all the single cells, the single cell is charged through the DC / DC bidirectional buck-boost converter in the group; If the SOC of the single cell is greater than the average SOC of all the single cells, the single cell is discharged through the DC / DC bidirectional buck-boost converter in the group.

13. The battery pack balancing method according to claim 6, characterized in that: The method further comprises: Automatically identifying the working condition of the battery module according to the current value of the battery module, if the current value of the battery module is greater than or equal to the third preset threshold, it is determined that the current battery module is in a fast charge and discharge state, and the judgment of intra-group balancing is first initiated; If the current value of the battery module is less than the third preset threshold, it is determined that the battery module is in a slow charge and discharge or static state, and the judgment of inter-group balancing is first initiated.

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