Battery module balancing method, device and electronic device

Abstract

This application relates to the technical field of energy storage batteries, and specifically to a battery module balancing method, device, and electronic device. This method uses the remaining capacity of the battery module as the reference data for balancing, which can effectively avoid problems such as being unable to trigger balancing or over-balancing due to the long voltage plateau region, and has higher accuracy and reliability. After calculating the balancing capacity of the battery module, based on the battery module balancing circuit, by controlling the on / off states of each balancing switch, the energy transfer between the power supply device and the battery module, or between the battery module and the balancing load is realized, that is, charging balancing or discharging balancing of the battery module is performed until the voltage of the battery module reaches the balanced state, solving the problem of uneven power among battery modules, improving the consistency of the battery modules in the battery pack, as well as improving the overall performance and safety of the battery pack.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage batteries, and in particular to a battery module balancing method, device and electronic equipment. Background Art

[0002] With the development of new energy technology, lithium batteries are used more and more widely. When the battery module leaves the factory, the multiple series-connected cells in the module will have inconsistent voltages or power levels due to their own individual differences. At the same time, in the field of energy storage batteries, the series use of battery modules is becoming more and more common, such as assembling multiple battery modules into a battery pack and putting them into use. In this case, the above inconsistency will affect the service life and safety of the battery pack. In this regard, there are methods for balancing the series-connected cells in the battery module in the related art, such as disassembling the battery pack and then recharging the single battery module in turn, so that the voltages or power levels of the multiple cells in the battery module are balanced. However, this method is time-consuming, labor-intensive, and costly, and is not convenient enough. Moreover, for a battery pack containing multiple battery modules, the number and position of the battery modules contained in the battery pack are not fixed, and the number and position of the battery modules can be changed. Therefore, the balancing method in the related art usually requires multiple balancing to achieve a better balancing effect, and the balancing efficiency is low. In addition, the related art usually uses the dynamic voltage of a single battery module or the dynamic voltage of the battery cell in the battery module as a reference for equalization judgment, which has great limitations. Especially for iron-lithium batteries, the equalization method used in the related art is to equalize the battery cells to the same voltage. However, due to the consistency differences between the battery cells, and the battery cell voltage is a dynamic voltage during the equalization process, even if the dynamic voltage of each battery cell is adjusted to the same voltage, after the equalization is completed, when the dynamic voltage drops to the static voltage, due to the existence of the battery cell platform area, the capacity difference corresponding to each battery cell may also be large. Because the voltage difference in the platform area is very small, even if the battery cell voltage only differs by a few millivolts, the difference in the battery cell capacity may also be large. Therefore, the equalization method in the related art is not only inefficient but also has large errors. Summary of the invention

[0003] The embodiments of the present application mainly solve the technical problems that the existing battery balancing method is inefficient and has large errors.

[0004] To solve the above technical problems, a technical solution adopted in the embodiments of the present application is: to provide a battery module equalization method, which is applied to a battery module equalization circuit. The equalization includes at least two battery modules connected in series, and each of the battery modules includes a plurality of battery cells connected in series. Wherein, each of the battery modules is connected with an equalization charging switch and is connected to a power supply device through the corresponding equalization charging switch, and each of the battery modules is connected with an equalization charging switch and is connected to an equalization load through the corresponding equalization charging switch. The method includes: obtaining the voltage data of the battery cells after standing, and determining the lowest battery cell voltage corresponding to each battery module according to the voltage data after standing; calculating the equalization capacity to be processed corresponding to the battery module according to the lowest battery cell voltage; performing charge / discharge equalization on the battery module according to the equalization capacity to be processed, so as to equalize the battery modules in the battery pack.

[0005] In some embodiments, before the step of obtaining the voltage data of the battery cells after standing and determining the lowest battery cell voltage corresponding to each battery module according to the voltage data after standing, the method further includes: determining the working condition of the battery module according to the real-time operating state of the battery module, where the working condition includes charging, discharging or standing. When the working condition of the battery module is standing, the standing time of the battery module is obtained and updated in real time, and after the standing time is greater than a preset standing threshold, the step of obtaining the voltage data of the battery cells after standing is executed.

[0006] In some embodiments, calculating the equalization capacity to be processed corresponding to the battery module according to the lowest battery cell voltage includes: determining a charging reference value and a discharging reference value according to the lowest battery cell voltage; obtaining the charge state value corresponding to the lowest battery cell voltage as the charging SOC value of the battery module, and obtaining the discharge state value corresponding to the lowest battery cell voltage as the discharging SOC value of the battery module; calculating the difference between the charging SOC value of the battery module and the charging reference value as the charging SOC difference value of the battery module, and calculating the difference between the discharging SOC value of the battery module and the discharging reference value as the discharging SOC difference value of the battery module; determining the final value of the SOC difference of the battery module according to the charging SOC difference value and the discharging SOC difference value; calculating the equalization capacity to be processed corresponding to the battery module according to the final value of the SOC difference.

[0007] In some embodiments, determining a charging reference value and a discharging reference value according to the lowest battery cell voltage includes: determining a reference voltage according to the lowest battery cell voltage; obtaining the charge state value of the reference voltage as the charging reference value; obtaining the discharge state value of the reference voltage as the discharging reference value.

[0008] In some embodiments, determining a reference voltage according to the lowest cell voltage includes: when performing charge equalization, obtaining the maximum value among the lowest cell voltages as the reference voltage; when performing discharge equalization, obtaining the minimum value among the lowest cell voltages as the reference voltage.

[0009] In some embodiments, calculating the capacity to be equalized corresponding to the battery module according to the final SOC difference value includes: obtaining the total capacity of the battery module; calculating the product of the total capacity and the final SOC difference value as the capacity to be equalized of the battery module.

[0010] In some embodiments, performing charge / discharge equalization on the battery module with the capacity to be equalized includes: obtaining an equalization current, and calculating the equalized capacity in real time according to the equalization current; calculating the capacity difference between the capacity to be equalized and the equalized capacity in real time; when the capacity difference is zero, completing the charge / discharge equalization of the battery module.

[0011] In some embodiments, performing charge / discharge equalization on the battery module according to the capacity to be equalized includes: when performing charge equalization, controlling the equalization charge switch of the battery module to conduct, forming a charging circuit in combination with the power supply device, and performing charge equalization on the battery module; when performing discharge equalization, controlling the equalization discharge switch of the battery module to conduct, forming a discharge circuit in combination with the equalization load, and performing discharge equalization on the battery module.

[0012] In some embodiments, the method further includes: obtaining a preset time threshold; recording the equalization time in real time, and when the equalization time is greater than the preset time threshold, controlling both the equalization charge switch and the equalization charge switch to disconnect to temporarily stop the equalization process.

[0013] To solve the above technical problems, another technical solution adopted in the embodiments of the present application is: providing a battery module equalization device, including: a voltage acquisition module, configured to acquire the voltage data of the cells after standing, and determine the lowest cell voltage corresponding to each battery module according to the voltage data after standing; a capacity calculation module, configured to calculate the capacity to be equalized corresponding to the battery module according to the lowest cell voltage; an equalization control module, configured to perform charge / discharge equalization on the battery module according to the capacity to be equalized, so that the battery modules in the battery pack are equalized.

[0014] To solve the above technical problems, another technical solution adopted in the embodiments of the present application is: providing an electronic device, including: at least one processor and a memory; the memory is coupled to the processor, and the memory is used to store instructions or programs. When the instructions or programs are executed by the electronic device, the electronic device executes the battery module equalization method as described above.

[0015] To solve the above technical problems, another technical solution adopted in the embodiments of the present application is: to provide a computer storage medium, which stores instructions or programs. When the instructions or programs are executed by at least one processor, the at least one processor is caused to execute the battery module equalization method described above.

[0016] Different from the related art, the present application provides a battery module equalization method, device and electronic device. In this battery module equalization method, the static voltage data after standing is used as the basis for equalization, and the static voltage data after standing is converted into the remaining capacity of the battery module, and then equalization is performed based on the remaining capacity as the reference data, which can effectively avoid problems such as being unable to trigger equalization or over-equalization due to the long voltage plateau region, and has higher accuracy and reliability. After calculating the capacity to be equalized of the battery module, based on the battery module equalization circuit, by controlling the on / off states of each switch, the energy transfer between the power supply device and the battery module, or between the battery module and the equalization load is realized, that is, charging equalization or discharging equalization of the battery module is performed until the voltage of the battery module reaches the equalized state, solving the problem of unequal battery levels between battery modules, improving the consistency of the battery modules in the battery pack, and improving the overall performance and safety of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the drawings in the figures do not constitute a proportional limitation.

[0018] Figure 1 is a schematic structural diagram of a battery pack example provided by an embodiment of the present application;

[0019] Figure 2 is a schematic structural diagram of a battery module equalization circuit provided by an embodiment of the present application;

[0020] Figure 3 is a schematic flowchart of a battery module equalization method provided by an embodiment of the present application;

[0021] Figure 4 is a schematic flowchart of calculating the capacity to be equalized;

[0022] Figure 5 is an example diagram of an OCV-SOC curve of a battery cell provided by an embodiment of the present application;

[0023] Figure 6 is a schematic structural diagram of a battery module equalization device provided by an embodiment of the present application;

[0024] Figure 7 It is a schematic structural diagram of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0025] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0026] It should be noted that if there is no conflict, the various features in the embodiments of the present application can be combined with each other and are all within the protection scope of the present application. In addition, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different module division from that in the device schematic diagram or a different order from that in the flowchart. Unless otherwise defined, all the technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific implementation manners and are not used to limit the present application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0027] In battery-related technologies, especially in the fields of electric vehicles, energy storage systems, etc., multiple battery modules are usually assembled into a battery pack to provide the voltage and capacity required by the product. However, due to factors such as manufacturing differences, lack of pre-balancing before leaving the factory, and self-discharge after long-term storage, the performance of each battery module will vary, for example, performance parameters such as voltage or capacity are inconsistent. In this case, if not managed, it will affect the overall performance of the battery pack and reduce its service life and safety. The balancing method adopted in the related technologies is to perform voltage balancing on the cell voltages in a single battery module, and after disassembling the battery pack, charge each single battery module in turn to make the voltages or charges of multiple cells in the battery module balanced. However, this method is time-consuming, laborious and costly, not convenient enough, and has low balancing efficiency.

[0028] Please refer to Figure 1 , Figure 1This is a diagram showing an example of the structure of a battery pack. Generally speaking, a battery pack includes a battery management system BMS and multiple battery modules, and the battery module includes a battery control unit BCU and a battery module composed of multiple battery cells / battery cells. In the prior art, a fixed balancing circuit board is usually used for balancing between battery cells in a single battery module. However, for balancing between battery modules connected in series, since the number and position of the battery modules are not fixed, the balancing circuit board used for balancing between battery cells cannot be applied to balancing between battery modules. In the related art, there is a method of offline balancing of single battery modules for balancing between battery modules, that is, after disassembling the battery modules connected in series, the single battery modules are recharged in turn. However, this method is time-consuming, labor-intensive, and costly, and is not convenient enough. In addition, the dynamic voltage of the battery module / battery cell is usually used during the balancing process, so multiple balancing operations are required to achieve a better balancing effect, and the balancing efficiency is low.

[0029] In view of the above problems, the present application provides a battery module balancing method, which is applied to a battery module balancing circuit. Figure 2 , the balancing circuit includes at least two battery modules connected in series, and n battery modules are represented by BT1-BTn in the figure, and each battery module includes a plurality of battery cells connected in series / parallel / series-parallel. Among them, each battery module is connected to a balancing charging switch, and the balancing charging switch 1-balancing charging switch n in the figure represent the balancing charging switch corresponding to each battery module, and each battery module is connected to a power supply device through a corresponding balancing charging switch, and the power supply device is represented by capacitor C1 in the figure; each battery module is connected to a balancing discharge switch, and the balancing discharge switch 1-balancing discharge switch n in the figure represent the balancing discharge switch corresponding to each battery module, and each battery module is connected to a balancing load through a corresponding balancing discharge switch. When the balancing discharge switch of a battery module is closed, the battery module can supply power to the balancing load. In some embodiments, the balancing load can be a load device that comes with the battery module, for example, it can include a heater and a cooling fan. It can be understood that the quantitative relationship between the balancing load and the battery module is not limited in the embodiment of the present application. Although the structural example of each battery module corresponding to a balancing load is given in the embodiment of the present application, in actual use, a quantitative relationship different from that in this example can also be set. For example, in some application scenarios, only one balancing load may be set, and each battery module is correspondingly provided with a balancing discharge switch. When a balancing discharge switch is closed, the corresponding battery module can discharge to the balancing load.

[0030] It can be understood that the form of the power supply device is not limited in the embodiments of the present application. For example, in practical applications, it can be powered by a DC power supply or a generator. In a specific embodiment, the above power supply device can also be the commercial power, which is connected to the commercial power interface through a power cord and an AC / DC converter to convert the 220V commercial power into the power supply voltage value required by the scenario, such as 48V, and can further supply power to the battery module equalization circuit in combination with the capacitor C1.

[0031] Figure 2 The n battery modules in also connect to an external circuit, and the external circuit may include an external power supply, an external load, an external charging switch, and an external discharging switch. By opening and closing the external charging switch and the external discharging switch, the real-time operating state of the series-connected battery modules can be controlled and the working condition of the battery modules can be determined; when the external charging switch is closed, the external power supply can charge the series-connected n battery modules, and the battery modules are in the charging working condition; when the external discharging switch is closed, the series-connected n battery modules can supply power to the external load, and the battery modules are in the discharging working condition; when both the external discharging switch and the external charging switch are open, it means that the battery modules are in the static working condition.

[0032] Please refer to Figure 3 , the battery module equalization method provided by the embodiments of the present application includes:

[0033] Determine the working condition of the battery module according to the real-time operating state of the battery module. When the working condition of the battery module is static, obtain and update the static time of the battery module in real time.

[0034] According to the circuit as Figure 2 shown, the real-time operating state of the battery module refers to the real-time operating state of the series-connected n battery modules connecting to the external circuit. The static state of the battery module means that the multiple battery modules connecting to the external circuit are in a state of neither charging nor discharging; the static state of the battery module is the static state of the battery cells. When the battery module / battery cell has just finished charging (especially at the end of charging), its voltage may be relatively high, but after a period of static time, the voltage will gradually decrease and tend to be stable; similarly, when the battery module / battery cell has just finished discharging (especially at the end of discharging), its voltage may be relatively low, and after a period of static time, the voltage will gradually increase and tend to be stable.

[0035] The static time of the battery module / battery cell can be obtained through real-time sampling. In some embodiments, for the first equalization between battery modules, it is required that the voltage data of the battery cells collected is the voltage data when the static time of the battery module is not less than 30 minutes; in other embodiments, for non-first equalization, it is required that the voltage data of the battery cells collected is the voltage data when the static time of the battery module is not less than 20 hours. By having sufficient static time, more accurate voltage data of the battery module / battery cell can be obtained.

[0036] S11. Obtain the voltage data of the battery cell after standing, and determine the lowest battery cell voltage corresponding to each battery module according to the voltage data after standing.

[0037] In the embodiment of the present application, when the condition (sufficient standing time) is met and the balanced capacity calculation link is entered, the voltage of each battery cell can be sampled by sampling. For each battery module, the lowest battery cell voltage data in each battery module is associated with the battery module to obtain the lowest battery cell voltage corresponding to each battery module. In some embodiments, the battery modules can be numbered. After obtaining the lowest battery cell voltage of each battery module, the voltage value is associated with the corresponding module number for easy distinction. When the subsequent balancing process is carried out, the balancing method can be assisted and planned according to the module number. For example, assume that there are 3 battery modules in a certain battery module balancing circuit. The voltage of the battery cell with the lowest voltage value in battery module 1 is 3.2V, the voltage of the battery cell with the lowest voltage value in battery module 2 is 3.3V, and the voltage of the battery cell with the lowest voltage value in battery module 3 is 3.4V. Then, in the subsequent balancing process, the charging / discharging balance of the corresponding battery module can be assisted and planned according to the module number. For example, it can be planned that battery module 1 and battery module 2 perform charging balance, or it can be planned that battery module 2 and battery module 3 perform discharging balance. This solution can determine the lowest battery cell voltage corresponding to each battery module at any time by sampling the voltage of the battery cell, and analyze whether it is necessary to balance the battery module accordingly. Moreover, in most common battery packs, relevant data can be obtained at any time based on the BMS / BCU, which provides basic data for the subsequent calculation of the capacity to be balanced conveniently when balancing is required.

[0038] S12. Calculate the capacity to be balanced corresponding to the battery module according to the lowest battery cell voltage. After determining the lowest battery cell voltage corresponding to each battery module, calculate the capacity to be balanced corresponding to the battery module through the voltage value. If the calculation result is not zero, it means that the battery module needs to be balanced, and further balance the battery module according to the capacity to be balanced. Specifically, please refer to Figure 4 , this step specifically includes:

[0039] S121. Determine the charging reference value and the discharging reference value according to the lowest cell voltage corresponding to each battery module. In the embodiment of the present application, the charging reference value and the discharging reference value are used as reference values for balancing control, which can reflect what state the battery module needs to be balanced to, and then compare with the relevant data of the lowest cell voltage of each battery module accordingly, so as to determine whether each battery module needs to perform charging balance or discharging balance, and determine the specific capacity to be balanced. In the embodiment of the present application, the reference voltage can be determined according to the lowest cell voltage, and then the charging state of charge value of the reference voltage is obtained as the charging reference value, and the discharging state of charge value of the reference voltage is obtained as the discharging reference value. Among them, the state of charge value (State of Charge, SOC) represents the ratio of the remaining power of the cell to the total capacity, usually expressed in percentage form. Compared with directly using the voltage value to analyze whether balancing is needed, the SOC value can more accurately reflect the remaining energy and charging / discharging ability of the battery module. Therefore, the balancing judgment based on the SOC value can more accurately determine whether the battery module needs to be balanced and the specific capacity to be balanced, reducing the possibility of misbalancing.

[0040] S122. Obtain the charging state of charge value corresponding to the lowest cell voltage of each battery module as the charging SOC value of the battery module, and obtain the discharging state of charge value corresponding to the lowest cell voltage of each battery module as the discharging SOC value of the battery module. Usually, during the charging or discharging process of the cell, the OCV value (Open Circuit Voltage) of the cell has a corresponding SOC value. Please refer to Figure 5 , Figure 5This is an example of an OCV-SOC curve corresponding to a certain battery cell under a charging condition of 25°C and a discharging condition of 25°C. The test method of the OCV-SOC curve can be a hybrid power pulse characteristic (HPPC) test. The horizontal axis in the figure represents the SOC value, and the values ​​20, 40, 60, 80 and 100 shown therein represent the percentage values ​​of the SOC value. For example, 20 in the figure represents the SOC value of 20%; the vertical axis in the figure represents the OCV value. For example, 3.3 in the figure represents the OCV value of 3.3V. Based on this, this solution uses the lowest cell voltage as the OCV value corresponding to the battery module, calculates according to the OCV-SOC curve, uses the charging SOC value corresponding to the lowest cell voltage as the charging SOC value of the corresponding battery module, and uses the discharging SOC value corresponding to the lowest cell voltage as the discharging SOC value of the corresponding battery module. Thus, the charging SOC value and discharging SOC value corresponding to each battery module can be determined according to the lowest cell voltage. It is understandable that the above-mentioned use of the OCV-SOC curve to obtain the charging SOC value and the discharging SOC value corresponding to the minimum cell voltage is only an example of an implementation method provided in the embodiment of the present application. In some other embodiments, the charging SOC value and the discharging SOC value of the target cell can also be obtained according to the charging OCV-SOC table and the discharging OCV-SOC table corresponding to the voltage, or other reasonable methods. That is, this solution protects the technical concept of determining the charging SOC value and the discharging SOC value of the battery module according to the minimum cell voltage, but does not limit its specific acquisition method.

[0041] S123, calculating the difference between the charging SOC value of each battery module and the charging reference value as the charging SOC difference of the battery module, and calculating the difference between the discharging SOC value of each battery module and the discharging reference value as the discharging SOC difference of the battery module.

[0042] S124, determining the final SOC difference value of the battery module according to the charging SOC difference and the discharging SOC difference. This solution avoids the error that may be caused by the platform area in the static OCV-SOC curve as much as possible by obtaining the charging SOC value and the discharging SOC difference and taking the smaller one of the two, thereby improving the balancing effect of the battery module.

[0043] It can be understood that negative data may occur in the above process of calculating the charging SOC value and the discharging SOC difference. In the embodiments of the present application, after obtaining the charging SOC difference and the discharging SOC difference of the battery module, the absolute value can be taken, and the data with a relatively smaller value between the two can be selected as the final value of the SOC difference of the battery module. As a conservative assessment of the battery module, it helps to reserve some safety margins during balancing, and indirectly reduce the time required for balancing, improving the safety and balancing efficiency of the battery module balancing process. It should be noted that in this solution, when comparing the magnitudes of the charging SOC difference and the discharging SOC difference to determine the final value of the SOC difference of the battery module, only the magnitude is considered and the positive or negative sign is not considered. For example, assume that the charging SOC difference corresponding to battery module 1 is -5% (which can be regarded as -0.05), and the discharging SOC difference is -7% (which can be regarded as -0.07). When comparing the two, the absolute values are taken respectively, that is, 5% is selected as the final value of the SOC difference of the battery module from 5% and 7%.

[0044] S125. Calculate the capacity to be balanced corresponding to the battery module according to the final value of the SOC difference. Specifically, for each battery module, after obtaining the final value of the SOC difference corresponding to a battery module, the total capacity of the battery module can be obtained, and then the product of the total capacity and the final value of the SOC difference can be calculated as the capacity to be balanced of the battery module. Thus, the capacity to be balanced corresponding to each battery module can be determined according to the final value of the SOC difference of each battery module. This solution comprehensively considers the charging SOC difference and the discharging SOC difference corresponding to the lowest cell voltage of each battery module, and determines whether to perform charging balancing or discharging balancing on the battery module based on the charging reference value and the discharging reference value, as well as the corresponding capacity to be balanced, which can more accurately determine the capacity that needs to be balanced, thereby avoiding over-balancing or under-balancing and improving the balancing efficiency.

[0045] S13. Perform charging / discharging balancing on the battery module according to the capacity to be balanced, so as to balance the battery modules in the battery pack. In the embodiments of the present application, according to the calculated capacity to be balanced, each battery module is subjected to discharging balancing or charging balancing.

[0046] After determining the capacity to be balanced for each battery module, charge / discharge balancing is performed on the battery module according to the capacity to be balanced, including: obtaining a balancing current and calculating the balanced capacity in real time according to the balancing current; calculating in real time the capacity difference between the capacity to be balanced and the balanced capacity; and when the capacity difference is zero, completing the charge / discharge balancing of the battery module. For example, assume that the capacity to be balanced for battery module 1 is a, and discharge balancing is required, with a balancing current of I. Then, in the discharge balancing process of battery module 1, the balanced capacity b of this battery module 1 is calculated in real time according to the balancing current I, and the capacity difference c between the capacity to be balanced a and the balanced capacity b is calculated. It can be understood that at the moment when the balancing process starts, the balanced capacity is 0, and at this time the capacity difference is a - 0 = a. Then, as time increases, the balanced capacity will gradually approach a from 0, and the capacity difference c will also gradually approach 0 from a. When the capacity difference c is equal to 0, it means that the balancing of this battery module 1 is completed, and the balancing process of battery module 1 is stopped.

[0047] It should be noted that after obtaining the capacity to be balanced by acquiring static voltage data, charge / discharge balancing of the battery module can be performed under any working condition, that is, the real-time operating state of the battery module connected to the external circuit can be any one of charging, discharging, and standing still; and for charging or discharging, whether it is the front end, middle end, or end of charging / discharging, it can be performed. Under any working condition of the battery module, the balancing charging switch or the balancing discharging switch in the balancing circuit is turned on to perform balancing.

[0048] Specifically, based on the above series battery cell balancing circuit, after determining the capacity to be balanced for each battery module, for the battery module that needs to perform charging balancing, the balancing charging switch of this battery module can be controlled to conduct, combined with the power supply device to form a charging circuit, and charging balancing is performed on this battery module; for the battery module that needs to perform discharging balancing, the balancing charging switch of this battery module can be controlled to conduct, combined with the balancing load to form a discharging circuit, and discharging balancing is performed on this battery module.

[0049] In the battery module equalization method provided by this solution, the remaining capacity of the battery module is used as the reference data (this data is only related to the static voltage at startup) for equalization. The OCV at startup (the voltage after standing for a long time, i.e., OCV) is used to determine the corresponding SOC data, and the static voltage is only used once at startup, and the dynamic voltage is not used throughout the process. Compared with the traditional equalization method using dynamic voltage (real-time battery voltage) as the reference, it can effectively avoid problems such as being unable to trigger equalization or over-equalization due to the long voltage plateau, and has higher accuracy and reliability. After calculating the equalization capacity of the battery module, based on the battery module equalization circuit, by controlling the on / off states of each switch, the energy transfer between the power supply device and the battery module, or between the battery module and the equalization load is realized, that is, charging equalization or discharging equalization is performed on the battery module until the voltage of the battery module reaches the equalized state, solving the problem of uneven battery power between battery modules, improving the consistency of the battery modules in the battery pack, and improving the overall performance and safety of the battery pack.

[0050] Based on this, the charging / discharging equalization of the battery module according to the to-be-equalized capacity includes: during charging equalization, controlling the equalization charging switch of the battery module to conduct, forming a charging circuit in combination with the power supply device, and performing charging equalization on the battery module; during discharging equalization, controlling the equalization discharging switch of the battery module to conduct, forming a discharging circuit in combination with the load, and performing discharging equalization on the battery module. The above discharging equalization and charging equalization can be preset by the designer according to the actual usage scenario.

[0051] On this basis, determining the reference voltage according to the lowest cell voltage in the above step S121 may include: during charging equalization, obtaining the maximum value among the lowest cell voltages as the reference voltage; during discharging equalization, obtaining the minimum value among the lowest cell voltages as the reference voltage.

[0052] Specifically, the embodiments of the present application illustrate the above step S12 with relatively specific examples. Assume that there are 3 battery modules in a certain battery pack, and 5 cells are connected in series in each battery module. The battery module and cell numbers are as follows:

[0053] Battery module A: [A1, A2, A3, A4, A5]

[0054] Battery module B: [B1, B2, B3, B4, B5]

[0055] Battery module C: [C1, C2, C3, C4, C5]

[0056] The voltage of each cell in each battery module (unit: V):

[0057] U[A1,A2,A3,A4,A5] = [3.8, 3.6, 3.2, 3.5, 3.4]

[0058] U[B1,B2,B3,B4,B5] = [3.7, 3.5, 3.3, 3.5, 3.4]

[0059] U[C1,C2,C3,C4,C5] = [3.7, 3.5, 3.4, 3.5, 3.5]

[0060] According to the above data, the minimum cell voltage of each battery module can be determined. The minimum cell voltage of Module A is [3.2], the minimum cell voltage of Module B is [3.3], and the minimum cell voltage of Module C is [3.4]. At this time, combined with the equalization method, calculate the equalization capacity to be processed corresponding to the battery module:

[0061] P: Assume that the current is charging equalization. Obtain the maximum value among the minimum cell voltages as the reference voltage, that is, use the minimum cell voltage [3.4] of Module C as the reference voltage. Combining the OCV-SOC curve, for Module A, the charging SOC difference is |SOC_Achg - SOC_Cchg|, and the discharging SOC difference is |SOC_Adischg - SOC_Cdischg|. Then select the smaller of the two as the final SOC difference of Module A, and further calculate the equalization capacity to be processed corresponding to Module A; similarly, for Module B, the charging SOC difference is |SOC_Bchg - SOC_Cchg|, and the discharging SOC difference is |SOC_Bdischg - SOC_Cdischg|. Then select the smaller of the two as the final SOC difference of Module B, and further calculate the equalization capacity to be processed corresponding to Module B. It can be understood that because the minimum cell voltage of Module C is used as the reference voltage, the equalization capacity to be processed corresponding to Module C is 0, that is, Module C does not need to be equalized.

[0062] Q: Assume that the current is discharge equalization. Obtain the minimum value among the lowest cell voltages as the reference voltage, that is, use the lowest cell voltage [3.2] of Battery Module A as the reference voltage. Combining with the OCV-SOC curve, for Battery Module B, the charging SOC difference is |SOC_Bchg - SOC_Achg|, and the discharging SOC difference is |SOC_Bdischg - SOC_Adischg|. Then select the smaller of the two as the final SOC difference of Battery Module B, and further calculate the capacity to be equalized corresponding to Battery Module B; similarly, for Battery Module C, the charging SOC difference is |SOC_Cchg - SOC_Achg|, and the discharging SOC difference is |SOC_Cdischg - SOC_Adischg|. Then select the smaller of the two as the final SOC difference of Battery Module C, and further calculate the capacity to be equalized corresponding to Battery Module C. Similarly, since the lowest cell voltage of Battery Module A is used as the reference voltage, the capacity to be equalized corresponding to Battery Module A is 0, that is, Battery Module A does not need to be equalized.

[0063] In some embodiments, the battery module equalization method further includes: obtaining a preset time threshold and an interval time threshold; recording the equalization time in real time, and when the equalization time is greater than the preset time threshold, controlling both the equalization charging switch and the equalization charging switch to be turned off to temporarily stop the equalization process; restart the equalization after the stop equalization time exceeds the interval time threshold. This solution limits the continuous equalization time of the battery module by setting the preset time threshold and the interval time threshold. Specifically, this effect can be achieved by setting a timer to prevent circuit failures caused by excessive equalization time or overheating of the equalizer.

[0064] An embodiment of the present application provides a battery module equalization device. Please refer to Figure 6 , the battery module equalization device includes: a voltage acquisition module 201, a capacity calculation module 202, and an equalization control module 203. Specifically, the voltage acquisition module 201 can acquire the voltage data of the cells after standing, and determine the lowest cell voltage corresponding to each battery module according to the voltage data after standing; the capacity calculation module 202 can calculate the capacity to be equalized corresponding to the battery module according to the lowest cell voltage; the equalization control module 203 can perform charge / discharge equalization on the battery module according to the capacity to be equalized to equalize the battery modules in the battery pack.

[0065] It should be noted that the above battery module balancing device can execute the battery module balancing method provided by the embodiments of the present application, and has the corresponding functional modules and beneficial effects of the execution method. For technical details not described in detail in the embodiments of the battery module balancing device, reference may be made to the battery module balancing method provided by the embodiments of the present application.

[0066] Embodiments of the present application provide an electronic device, such as Figure 7 shown, the electronic device 300 includes: one or more processors 301 and a memory 302, Figure 7 Taking one processor 301 as an example.

[0067] The processor 301 and the memory 302 can be connected by a bus or other means, Figure 7 Taking connection by bus as an example.

[0068] The memory 302, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as the program instructions / modules corresponding to the series battery cell balancing method in the embodiments of the present invention. The processor 301 executes various functional applications and data processing of the solid-state drive by running the non-volatile software programs, instructions, and modules stored in the memory 302, that is, implements the battery module balancing method in the above method embodiments.

[0069] The memory 302 may include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function. In addition, the memory 302 may include a high-speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage devices. In some embodiments, the memory 302 may optionally include a memory remotely provided with respect to the processor 301.

[0070] The one or more modules are stored in the memory 302, and when executed by the one or more processors 301, execute the battery module balancing method in any of the above method embodiments. For example, execute the Figure 3 , Figure 4 method steps therein.

[0071] The above product can execute the battery module balancing method provided by the embodiments of the present invention, and has the corresponding functional modules of the execution method. For technical details not described in detail in this embodiment, reference may be made to the battery module balancing method provided by the embodiments of the present invention.

[0072] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0073] Through the description of the above embodiments, those of ordinary skill in the art can clearly understand that each embodiment can be implemented by means of software plus a general hardware platform, and of course, it can also be implemented by hardware. Those of ordinary skill in the art can understand that all or part of the processes in the above method embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above method embodiments. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. Under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. There are many other variations in different aspects of the present application as described above. For the sake of brevity, they are not provided in detail. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery module balancing method, applied to a battery module balancing circuit, characterized in that: The balancing circuit includes at least two battery modules connected in series, each of the battery modules includes a plurality of battery cells, wherein each of the battery modules is connected to a balancing charging switch and is connected to a power supply device through a corresponding balancing charging switch, and each of the battery modules is connected to a balancing discharging switch and is connected to a balancing load through a corresponding balancing discharging switch, and the method includes: Determine the working condition of the battery module according to the real-time operating state of the battery module, the working condition including charging, discharging or standing still, and when the working condition of the battery module is standing still, obtain and update the standing still time of the battery module in real time; After the resting time is greater than a preset resting threshold, the voltage data of the battery cell after resting is obtained, and the minimum battery cell voltage corresponding to each of the battery modules is determined according to the voltage data after resting, wherein the minimum battery cell voltage corresponding to the battery module is the battery cell voltage data with the lowest value among the multiple battery cells in the battery module; Calculating the capacity to be balanced corresponding to the battery module according to the lowest battery cell voltage; Performing charge / discharge balancing on the battery modules according to the capacity to be balanced, so as to balance the battery modules in the battery pack; The step of calculating the capacity to be balanced corresponding to the battery module according to the lowest cell voltage includes: Determine a charging reference value and a discharging reference value according to the minimum battery cell voltage; Obtaining a charging state of charge value corresponding to the minimum cell voltage as a charging SOC value of the battery module, and obtaining a discharging state of charge value corresponding to the minimum cell voltage as a discharging SOC value of the battery module; Calculating a difference between a charging SOC value of the battery module and the charging reference value as a charging SOC difference value of the battery module, and calculating a difference between a discharging SOC value of the battery module and the discharging reference value as a discharging SOC difference value of the battery module; Determining a final SOC difference value of the battery module according to the charging SOC difference and the discharging SOC difference; The capacity to be balanced corresponding to the battery module is calculated according to the final value of the SOC difference.

2. The method according to claim 1, characterized in that Determining a charging reference value and a discharging reference value according to the minimum cell voltage includes: Determine a reference voltage according to the minimum cell voltage; Acquiring a charging state of charge value of the reference voltage as a charging reference value; A discharge state value of the reference voltage is obtained as a discharge reference value.

3. The method according to claim 2, characterized in that Determining a reference voltage according to the minimum cell voltage includes: During charge balancing, obtaining the maximum value of the minimum cell voltages as the reference voltage; During discharge balancing, a minimum value among the minimum cell voltages is obtained as the reference voltage.

4. The method according to claim 1, characterized in that: Calculating the capacity to be balanced corresponding to the battery module according to the final value of the SOC difference includes: Obtaining the total capacity of the battery module; The product of the total capacity and the final value of the SOC difference is calculated as the capacity to be balanced of the battery module.

5. The method according to claim 1, characterized in that The method includes performing charge / discharge balancing on the battery module according to the capacity to be balanced, comprising: Acquire a balancing current, and calculate a balanced capacity in real time according to the balancing current; Calculating in real time the capacity difference between the to-be-balanced capacity and the balanced capacity; When the capacity difference is zero, the charge / discharge balancing of the battery module is completed.

6. The method according to claim 5, characterized in that The method further comprises: performing charge / discharge balancing on the battery module according to the capacity to be balanced; During charging balance, the balance charging switch of the battery module is controlled to be turned on, and a charging circuit is formed in combination with the power supply device to balance the charging of the battery module; During discharge balancing, the balancing discharge switch of the battery module is controlled to be turned on, and a discharge loop is formed in combination with the balancing load to perform discharge balancing on the battery module.

7. The method according to claim 1, characterized in that The method further comprises: Get the preset time threshold; The balancing time is recorded in real time, and when the balancing time is greater than the preset time threshold, the balancing charging switch and the balancing charging switch are controlled to be disconnected to temporarily stop the balancing process.

8. A battery module balancing device, characterized in that: include: A voltage acquisition module, used to determine the working condition of the battery module according to the real-time operating state of the battery module, the working condition includes charging, discharging or standing still, and when the working condition of the battery module is standing still, the standing time of the battery module is acquired and updated in real time; after the standing still time is greater than a preset standing still threshold, the voltage data of the battery cell after standing still is acquired, and the minimum battery cell voltage corresponding to each of the battery modules is determined according to the voltage data after standing still, wherein the minimum battery cell voltage corresponding to the battery module is the battery cell voltage data with the lowest value among the multiple battery cells in the battery module; A capacity calculation module, used for calculating the to-be-balanced capacity of the battery module according to the minimum cell voltage; A balancing control module, used for performing charge / discharge balancing on the battery modules according to the capacity to be balanced, so as to balance the battery modules in the battery pack; Wherein, the capacity calculation module is further used for: Determine a charging reference value and a discharging reference value according to the minimum battery cell voltage; Obtaining a charging state of charge value corresponding to the minimum cell voltage as a charging SOC value of the battery module, and obtaining a discharging state of charge value corresponding to the minimum cell voltage as a discharging SOC value of the battery module; Calculating a difference between a charging SOC value of the battery module and the charging reference value as a charging SOC difference value of the battery module, and calculating a difference between a discharging SOC value of the battery module and the discharging reference value as a discharging SOC difference value of the battery module; Determining a final SOC difference value of the battery module according to the charging SOC difference and the discharging SOC difference; The capacity to be balanced corresponding to the battery module is calculated according to the final value of the SOC difference.

9. An electronic device, characterized in that: include: at least one processor and memory; The memory is coupled to the processor, and the memory is used to store instructions or programs. When the instructions or programs are executed by the electronic device, the electronic device executes the battery module balancing method according to any one of claims 1 to 7.

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