Pre-charging method, battery management system, battery system, energy storage system and device

Abstract

The invention relates to the technical field of pre-charging, in particular to a pre-charging method, a battery management system, a battery system, an energy storage system and a device, and the scheme comprises the steps: sorting all energy storage modules in the energy storage system before high-voltage power-on of the energy storage system, and obtaining a sorting result; based on the sorting result, target energy storage modules to be subjected to pre-charging operation are selected from the energy storage system, and the target energy storage modules are part of energy storage modules in all the energy storage modules; and sending a pre-charging instruction to the target energy storage module to control the target energy storage module to execute a pre-charging process before high-voltage power-on through a pre-charging circuit configured by the target energy storage module. Therefore, a centralized pre-charging device does not need to be additionally arranged, the system reliability is improved, the system structure is simplified, the hardware cost is reduced, the target energy storage module can be screened based on the charging and discharging working conditions, and the pre-charging operation is matched with the actual working state of the system.

Description

Pre-charging methods, battery management systems, battery systems, energy storage systems and devices Technical Field

[0001] This application relates to the field of pre-charging technology, and in particular to a pre-charging method, a battery management system, a battery system, an energy storage system, and a device. Background Technology

[0002] Some electrical devices employ a high-voltage architecture where multiple energy storage modules are connected in parallel and then uniformly connected to a high-voltage box. This high-voltage box contains a single pre-charging circuit that pre-charges the capacitors in the electrical device that require charging. If this pre-charging circuit fails, the device's battery management system will be unable to connect to the high voltage, resulting in very low availability. Summary of the Invention

[0003] This application provides a pre-charging method, a battery management system, a battery system, an energy storage system, and an apparatus, which can improve the operational reliability and availability of electrical devices.

[0004] To achieve the above objectives, this application adopts the following technical solution: Firstly, a pre-charging method is provided, comprising: before the energy storage system is powered on at high voltage, sorting each energy storage module in the energy storage system to obtain a sorting result; at least one of the energy storage modules is configured with a pre-charging circuit for pre-charging the high-voltage bus capacitor; based on the sorting result, selecting a target energy storage module from the energy storage system to perform a pre-charging operation, wherein the target energy storage module is a subset of the energy storage modules; and sending a pre-charging command to the target energy storage module to control the target energy storage module to perform a pre-charging process before high-voltage power-on through the pre-charging circuit configured in the target energy storage module.

[0005] In the above solution, since at least one energy storage module of the energy storage system is equipped with a pre-charging circuit, it does not rely on the pre-charging circuit inside the high-voltage box, eliminating the need for an additional centralized pre-charging device. This improves system reliability, simplifies the system structure, and reduces hardware costs. Furthermore, the energy storage system is compatible with different types of electrical devices, offering higher reusability. It can select target energy storage modules based on charging and discharging conditions, ensuring that pre-charging operations match the actual operating state of the system. This avoids energy waste caused by indiscriminate pre-charging and improves pre-charging efficiency.

[0006] Optionally, sorting the energy storage modules in the energy storage system to obtain a sorting result includes: obtaining the battery status parameter values ​​of each energy storage module, wherein the battery status parameter values ​​are voltage values ​​or remaining power values; and sorting the energy storage modules according to the order of the battery status parameter values ​​to obtain a sorting result.

[0007] In the above scheme, the energy storage modules are sorted based on battery state parameters such as voltage or remaining capacity, which makes the pre-charging resource allocation more scientific, helps to balance the system state and improve the reliability of pre-charging.

[0008] Optionally, selecting the target energy storage module to perform the pre-charging operation from the energy storage system based on the ranking result includes: when the energy storage system is in charging mode, selecting the energy storage module with the lowest battery state parameter value as the target energy storage module based on the ranking result, wherein the charging mode refers to the working state in which the energy storage system is injecting electrical energy into the energy storage module by an external power source; and when the energy storage system is in discharging mode, selecting the energy storage module with the highest battery state parameter value as the target energy storage module based on the ranking result, wherein the discharging mode refers to the working state in which the energy storage system is outputting electrical energy to the electrical load.

[0009] In the above scheme, the module with the lowest or highest charge level is selected as the pre-charge source according to the charging / discharging conditions, thereby optimizing energy utilization and protecting battery safety.

[0010] Optionally, the energy storage system includes multiple parallel energy storage module groups, with energy storage modules in each energy storage module group connected in series, and each energy storage module group includes one or more energy storage modules; the step of sorting the energy storage modules in the energy storage system to obtain a sorting result includes: obtaining the battery status parameter values ​​of each energy storage module, where the battery status parameter values ​​are voltage values ​​or remaining capacity values; determining the sum of the battery status parameter values ​​corresponding to each energy storage module group based on the battery status parameter values ​​of each energy storage module; and sorting the energy storage modules in each energy storage module group according to the order of the sum of the battery status parameter values ​​corresponding to the energy storage module group to obtain a sorting result.

[0011] In the above scheme, for the multi-module group architecture, the module group with the lowest sum of parameter values ​​is selected first during charging, and the module group with the highest sum of parameter values ​​is selected first during discharging, so as to achieve energy balance and power coordination among module groups and avoid overloading of some module groups.

[0012] Optionally, selecting the target energy storage module to be pre-charged from the energy storage system based on the ranking result includes: when the energy storage system is in charging mode, selecting the energy storage module in the energy storage module group with the lowest sum of battery state parameter values ​​as the target energy storage module based on the ranking result, wherein the charging mode refers to the working state in which the energy storage system is injecting electrical energy into the energy storage module from an external power source; and when the energy storage system is in discharging mode, selecting the energy storage module in the energy storage module group with the highest sum of battery state parameter values ​​as the target energy storage module based on the ranking result, wherein the discharging mode refers to the working state in which the energy storage system is outputting electrical energy to the electrical load.

[0013] Optionally, after sending a pre-charge command to the target energy storage module to control the target energy storage module to perform a pre-charge process through the pre-charge circuit configured in the target energy storage module, the method further includes: in response to not receiving a pre-charge success signal from the target energy storage module within a preset time, controlling the target energy storage module to exit the pre-charge process; determining a new target energy storage module from other energy storage modules besides the target energy storage module; and sending the pre-charge command to the new target energy storage module.

[0014] The above solution avoids prolonged occupation of pre-charging resources and CAN bus communication resources, prevents process blockage, improves the execution efficiency of the pre-charging process, and promptly exits unresponsive modules to prevent them from interfering with other energy storage modules due to abnormal working conditions.

[0015] Optionally, determining the target energy storage module from other energy storage modules besides the target energy storage module includes: when the energy storage system is in a charging state, selecting energy storage modules whose battery state parameters are only higher than those of the target energy storage module based on the ranking result; and when the energy storage system is in a discharging state, selecting energy storage modules whose battery state parameters are only lower than those of the target energy storage module based on the ranking result.

[0016] Optionally, after selecting a target energy storage module to perform a pre-charging operation from the energy storage system based on the sorting result, the method further includes: determining the number of times the pre-charging circuit of each energy storage module executes the pre-charging process; determining the average value of each number of times; if the number of times corresponding to the target energy storage module is more than the average value by a preset threshold, determining a new target energy storage module from other energy storage modules besides the target energy storage module; and sending the pre-charging command to the new target energy storage module.

[0017] The above solution avoids the accelerated aging and reduced lifespan of the pre-charging circuit of a single energy storage module due to frequent operation, achieves balanced loss of the pre-charging circuit of each module group, and improves the overall service life of the energy storage system.

[0018] Optionally, the method further includes: in the event of an anomaly in the target energy storage module, determining a new target energy storage module from other energy storage modules besides the target energy storage module; and sending the pre-charge command to the new target energy storage module.

[0019] In the above scheme, the target energy storage module with abnormality is switched immediately to improve the safety of the pre-charging process and the energy storage system.

[0020] Optionally, after sending a pre-charge command to the target energy storage module to control the target energy storage module to perform a pre-charge process before high-voltage power-on through the pre-charge circuit configured in the target energy storage module, the method further includes: in response to receiving a pre-charge failure signal from the target energy storage module, controlling the target energy storage module to exit the pre-charge process.

[0021] In the above scheme, upon receiving a pre-charging failure signal, the target energy storage module is immediately controlled to exit, terminating the pre-charging operation of the faulty module, preventing the fault from escalating, improving the system's fault isolation capability, and promptly releasing the pre-charging-related resources of the faulty module.

[0022] Optionally, the energy storage system is configured in the vehicle, and sending a pre-charging command to the target energy storage module includes: determining whether the target energy storage module meets preset preconditions; if the target energy storage module meets the preconditions, sending a pre-charging command to the target energy storage module; wherein, the preconditions include: the number of energy storage modules with high-voltage pre-charging conditions in driving scenarios is not less than 1; the number of energy storage modules with high-voltage conditions in driving scenarios is not less than a preset minimum threshold; receiving a high-voltage start command sent by the vehicle controller; the vehicle charging interface is in an unconnected state; and none of the energy storage modules are in a high-voltage power-on state.

[0023] The above solution adds multiple precondition judgments for the driving scenario of the vehicle energy storage system to avoid erroneous precharging when the power-on conditions are not met. This improves the safety and accuracy of the precharging process in the vehicle scenario, verifies key information such as vehicle controller commands, charging interface status, and energy storage module power-on status, and ensures that the precharging operation is deeply adapted to the vehicle's workflow, avoiding conflicts with other vehicle functions.

[0024] Optionally, after sending a pre-charge command to the target energy storage module to control the target energy storage module to perform a pre-charge process before high-voltage power-on through the pre-charge circuit configured in the target energy storage module, the method further includes: determining whether the voltage difference between the high-voltage bus capacitor being charged and each energy storage module is within a preset safe range; and stopping the pre-charge process if each voltage difference is within the preset safe range.

[0025] In the above scheme, the voltage difference between the high-voltage bus capacitor and the energy storage module is monitored in real time. When the voltage difference is within a safe range, precharging is stopped in time to avoid excessive voltage and energy waste caused by overcharging, thereby improving the accuracy of precharging.

[0026] Secondly, a battery management system is provided, including a main battery management unit and multiple slave battery management units; the main battery management unit is used to: sort the various energy storage modules in the energy storage system before the energy storage system is powered on at high voltage, and obtain a sorting result; at least one of the energy storage modules is configured with a pre-charging circuit for pre-charging the high-voltage bus capacitor; based on the sorting result, determine a target slave battery management unit, the target slave battery management unit is used to control the target energy storage module to be pre-charged, the target energy storage module being a subset of the various energy storage modules; and send a pre-charging command to the target energy storage module through the target slave battery management unit to control the target energy storage module to perform the pre-charging process before high voltage power-on through the pre-charging circuit configured in the target energy storage module.

[0027] Thirdly, an energy storage system is provided, including multiple energy storage modules, each energy storage module containing a pre-charging circuit. Before the energy storage system is powered on at high voltage, at least a portion of the multiple energy storage modules, upon receiving a pre-charging command, perform a pre-charging operation based on the pre-charging circuit contained in the energy storage module.

[0028] Fourthly, embodiments of this application provide a battery system, including the battery management system described in the second aspect and the energy storage system described in the third aspect, wherein the battery management system is used to perform pre-charge control on the energy storage system.

[0029] Fifthly, embodiments of this application provide an electrical device, including the battery management system described in the second aspect, the energy storage system described in the third aspect, or the battery system described in the fourth aspect.

[0030] It is understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0031] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 shows a schematic diagram of a conventional centralized pre-charging architecture; Figure 2 is a flowchart illustrating the pre-charging method provided in the first embodiment of this application; Figure 3 is a flowchart illustrating the pre-charging method provided in the second embodiment of this application; Figure 4 is a structural block diagram of the battery management system of the energy storage system provided in an embodiment of this application. Detailed Implementation

[0033] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of this application, and are therefore merely examples and should not be used to limit the scope of protection of this application. When the following description relates to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. Various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will become apparent after understanding this application. For example, the order of operations described herein is merely illustrative and is not limited to those orders set forth herein, but can be changed as will become apparent after understanding this application, except for operations that must be performed in a specific order. Furthermore, for clarity and conciseness, descriptions of features known in the art may be omitted.

[0034] The embodiments described in the following examples of this application do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0035] The following is an illustrative description of the scenarios that may be involved in the embodiments of this application.

[0036] In electric vehicles or plug-in hybrid vehicles, energy storage systems typically consist of multiple energy storage modules. These modules are grouped into several energy storage module groups according to their electrical topology. The energy storage modules within each module group are connected in series to increase the output voltage level, while multiple module groups are connected in parallel to increase system capacity and redundancy. When the vehicle starts or wakes up from hibernation, a high-voltage power-on operation is required, which involves closing the main positive and main negative relays to establish an electrical path between the energy storage system and the high-voltage load. However, a large-capacity filter capacitor is usually connected in parallel on the high-voltage bus, and its initial voltage is zero. If the main relay is closed directly, the instantaneous charging of the capacitor will generate a huge surge current, which may burn out the relay contacts, damage the power semiconductor devices, or even cause insulation failure or thermal runaway.

[0037] To avoid the aforementioned risks, a pre-charging strategy is required.

[0038] The traditional pre-charging strategy is to connect multiple battery packs in parallel and then connect them to a high-voltage box. The high-voltage box is equipped with a single pre-charging circuit, which performs pre-charging operations on the high-voltage bus capacitor of the entire vehicle.

[0039] Figure 1 shows a schematic diagram of a centralized pre-charging architecture for a traditional pre-charging strategy.

[0040] As shown in Figure 1, the left side shows the series-parallel structure of the battery packs. The left side of Figure 1 is divided into two parallel branches, each containing four battery packs connected in series (PACK1, PACK2, PACK3, PACK4). Each battery pack is equipped with a fuse and a cell monitoring unit (CMC). The fuse is used for overcurrent protection, and the cell monitoring unit is responsible for collecting information such as cell voltage and temperature. The right side of Figure 1 shows the high voltage box (HVBOX), which includes a pre-charge circuit, a manual service disconnect (MSD), and a battery management unit (BMU). The pre-charge circuit, consisting of a pre-charge relay and a pre-charge resistor (R), is the only pre-charge unit in the entire system, used to pre-charge the high-voltage bus capacitors of the entire vehicle. Since the pre-charge circuit exists only within the high voltage box, if this circuit fails, the system will be unable to power on the high voltage, and the high-voltage outputs of all packs are collected in the high voltage box, resulting in a complex system architecture and large size. The pre-charging circuit is bound to the high-voltage box, making it difficult for the same PACK to be directly adapted to the high-voltage box design of different vehicle models.

[0041] Therefore, this application proposes a pre-charging method, a battery management system, a battery system, an energy storage system, and an electrical device, eliminating the centralized high-voltage box and integrating the pre-charging circuit in the original high-voltage box into the energy storage module.

[0042] In this application, the energy storage system is preferably a vehicle power energy storage system, which is adapted to the needs of vehicle driving power supply, energy recovery and other scenarios. It can switch between charging and discharging modes according to actual working needs, and before high voltage power-on, it needs to complete the stable voltage build-up of the high voltage circuit through a pre-charging process to avoid surge current damage to system components.

[0043] The energy storage module in this application is preferably a vehicle battery pack, which can be composed of single or multiple cells connected in series or parallel. It has independent energy storage and energy output / input capabilities, and can supply power to the electrical load of the vehicle's power energy storage system, as well as receive power injection from external power sources to complete charging.

[0044] The Centre Battery Management Unit (CBMU) in this application is the highest control unit of the energy storage system. It manages the high-voltage control, operating condition determination, data aggregation, and command issuance of the entire energy storage system, and performs unified monitoring of the operating status of each branch and each energy storage pack in the system.

[0045] The Master Battery Management Unit (MBMU) in this application is the branch control unit of the energy storage system. It is controlled by the CBMU and is responsible for the overall management of the corresponding energy storage branch.

[0046] The Slave Battery Management Unit (SBMU) in this application is the energy storage module control unit of the energy storage system. It is directly controlled by the corresponding branch MBMU and is adapted to a single energy storage module (PACK) within the energy storage branch.

[0047] In this embodiment, the entity executing the pre-charging method can be a battery management system, a battery system, or an electrical device; this application does not limit this.

[0048] Referring to Figure 2, it is a flowchart illustrating the pre-charging method provided in the first embodiment of this application. As shown in Figure 2, the method may include the following steps: Step 101, before the energy storage system is powered on at high voltage, the various energy storage modules in the energy storage system are sorted to obtain a sorting result.

[0049] In this energy storage system, at least one energy storage module is equipped with a pre-charging circuit. Specifically, a pre-charging circuit can be configured in each energy storage module of the energy storage system, or it can be configured in some of the energy storage modules of the energy storage system. The number of energy storage modules equipped with pre-charging circuits is greater than or equal to one.

[0050] The pre-charging circuit refers to the power electronic circuit configured in the energy storage system to realize the pre-charging function of high voltage power-on, and it is configured in at least one energy storage module of the energy storage system.

[0051] Optionally, the pre-charge circuit consists of a pre-charge relay and a pre-charge resistor, integrated within the energy storage module. When the energy storage system is powered on at high voltage, the system's high-voltage bus voltage is gradually established through current limiting and voltage division, preventing instantaneous surge currents generated by direct connection of the high-voltage power supply to the energy storage module or high-voltage circuit. This protects components within the battery management system, such as contactors, fuses, high-voltage relays, and energy storage module cells, from damage caused by current surges. No specific limitations are imposed here.

[0052] At least one of the energy storage modules is equipped with a pre-charging circuit for pre-charging the high-voltage bus capacitor.

[0053] Among them, the high-voltage bus capacitor is an electronic component that is connected in series or parallel between phase lines in the high-voltage circuit, and is the charging object of the target energy storage module during the high-voltage power-on pre-charging process.

[0054] One possible approach is to obtain the battery status parameter values ​​of each energy storage module, which are either voltage values ​​or remaining capacity values. Then, the energy storage modules are sorted according to the magnitude of their battery status parameter values ​​to obtain the sorting result.

[0055] The sorting result can be either sorting the energy storage modules from largest to smallest according to the battery state parameter values, or sorting the energy storage modules from smallest to largest according to the battery state parameter values; there is no limitation on this.

[0056] In some embodiments, before the energy storage system is powered on at high voltage, the battery status parameters of each energy storage module, such as voltage and remaining charge (SOC) values, can be acquired. Taking the battery status parameter value as voltage as an example, during the power-on phase after the energy storage system receives the high-voltage power-on command but has not yet performed the high-voltage power-on operation, the voltage information of each energy storage module can be acquired through the system's voltage acquisition unit to obtain the real-time voltage value of each energy storage module.

[0057] For example, when the battery status parameter is a voltage value, the four energy storage modules are M1, M2, M3, and M4, with corresponding voltage values ​​of 750V, 760V, 775V, and 780V respectively. The order of the voltage values ​​of M1, M2, M3, and M4 from largest to smallest is M4, M3, M2, and M1, while the order of the voltage values ​​of M1, M2, M3, and M4 from smallest to largest is M1, M2, M3, and M4.

[0058] As another possible approach, the battery state parameter values ​​of each energy storage module can be obtained. Then, based on the battery state parameter values ​​of each energy storage module, the sum of the battery state parameter values ​​corresponding to each energy storage module group can be determined. After that, the energy storage modules in each energy storage module group can be sorted according to the order of the sum of the battery state parameter values ​​corresponding to the energy storage module group to obtain the sorting result.

[0059] Optionally, the energy storage system may include multiple parallel energy storage module groups, with each energy storage module in each group connected in series. Each energy storage module group includes one or more energy storage modules, and the energy storage modules within the group are connected in series. In this application, the energy storage system is preferably an on-board energy storage system architecture. For example, the on-board energy storage system includes N energy storage module groups (N≥2), each energy storage module group includes M energy storage modules (M≥1), the M energy storage modules within a group are connected in series, and the groups are connected in parallel to the high-voltage circuit of the energy storage system.

[0060] For example, there are currently four energy storage module groups: N1, N2, N3, and N4. N1 contains energy storage modules m1 and m2, with a combined voltage of 800V. N2 contains energy storage modules m3 and m4, with a combined voltage of 850V. N3 contains energy storage modules m5 and m6, with a combined voltage of 780V. N4 contains energy storage modules m7 and m8, with a combined voltage of 860V. Therefore, the sum of the voltage values ​​(sum of battery state parameters) for N1, N2, N3, and N4, ordered from largest to smallest, is N4, N2, N1, N3. Conversely, the sum of the voltage values ​​(sum of battery state parameters) for N1, N2, N3, and N4, ordered from smallest to largest, is N3, N1, N2, N4.

[0061] Step 102: Based on the sorting results, select the target energy storage modules to be precharged from the energy storage system. The target energy storage modules are some of the energy storage modules in each energy storage system.

[0062] The target energy storage module refers to the energy storage module currently selected from the energy storage system for performing the pre-charging operation. The number of target energy storage modules can be one or more, and this is not limited here.

[0063] Optionally, when the energy storage system is in charging mode, the energy storage module with the lowest battery state parameter value is selected as the target energy storage module based on the ranking results.

[0064] Among them, the charging condition refers to the working state in which the energy storage system is in which an external power source injects electrical energy into the energy storage module.

[0065] Specifically, for the charging condition, the system can determine whether it is currently in a charging condition by detecting information such as the access signal of the external charging power supply, the conduction status of the charging interface, and the system charging enable command.

[0066] For example, when the battery status parameter is the voltage value and the energy storage system is in charging mode, the four energy storage modules are M1, M2, M3, and M4. The voltage values ​​of M1, M2, M3, and M4, sorted from largest to smallest, are M4, M3, M2, and M1. The voltage values ​​of M1, M2, M3, and M4, sorted from smallest to largest, are M1, M2, M3, and M4. Therefore, M1 can be used as the target energy storage module.

[0067] Optionally, when the energy storage system is in a discharge state, the energy storage module with the highest battery state parameter value is selected as the target energy storage module based on the ranking results.

[0068] Among them, the discharge condition refers to the working state in which the energy storage system is in the state of outputting electrical energy from the energy storage module to the electrical load.

[0069] For the discharge condition, it can be determined whether the current condition is a discharge condition by detecting information such as the access signal of the electrical load, the conduction status of the discharge interface, the system discharge enable command, and the power demand of the electrical load. No specific restrictions are imposed here.

[0070] For example, when the battery state parameter is the voltage value and the energy storage system is in discharge mode, the four energy storage modules are M1, M2, M3, and M4. The voltage values ​​of M1, M2, M3, and M4, sorted from largest to smallest, are M4, M3, M2, and M1. The voltage values ​​of M1, M2, M3, and M4, sorted from smallest to largest, are M1, M2, M3, and M4. Therefore, M4 can be used as the target energy storage module.

[0071] Optionally, when the energy storage system is in charging mode, based on the ranking results, the energy storage module in the energy storage module group with the lowest sum of battery state parameter values ​​is selected as the target energy storage module.

[0072] Specifically, when the main battery management unit confirms that the current state is charging, it can sort and compare the sum of the battery status parameter values ​​of all parallel energy storage module groups, select the energy storage module group with the lowest sum of battery status parameter values, and determine the energy storage module in the energy storage module group with the lowest sum of battery status parameter values ​​as the target energy storage module to be pre-charged.

[0073] The following explanation uses the battery status parameter value as an example, which is the voltage value.

[0074] In some embodiments, the real-time individual cell voltage data of each energy storage module is first collected by the built-in slave battery management unit of each energy storage module, and the individual cell voltage data is uploaded to the main battery management unit of the energy storage system. The main battery management unit sums the individual cell voltage data of all series-connected energy storage modules in the same energy storage module group to obtain the sum of the voltage values ​​of the energy storage module group (the sum of the battery state parameter values).

[0075] It should be noted that during the charging process, the energy storage system injects electrical energy into the energy storage modules from an external power source. It prioritizes the energy storage module group with the lowest sum of battery state parameter values ​​for pre-charging, which can avoid problems such as excessive voltage difference and sudden changes in charging current caused by direct pre-charging of high-voltage module groups.

[0076] The following explanation uses the battery status parameter value as the remaining power value as an example.

[0077] In some embodiments, the real-time remaining power data of each energy storage module is first collected by the slave battery management unit built into each energy storage module, and the remaining power data is uploaded to the main battery management unit of the energy storage system. The main battery management unit sums the remaining power data of all series-connected energy storage modules in the same energy storage module group to obtain the sum of the remaining power values ​​of the energy storage module group (the sum of battery state parameter values).

[0078] Specifically, when the main battery management unit confirms that the current charging and discharging condition is a charging condition, it can sort and compare the sum of the battery state parameter values ​​of all parallel energy storage module groups, select the energy storage module group with the lowest sum of battery state parameter values, and determine the energy storage module in the energy storage module group with the lowest sum of battery state parameter values ​​as the target energy storage module to be pre-charged.

[0079] It should be noted that during the charging process, the energy storage system injects electrical energy into the energy storage modules from an external power source. It prioritizes the energy storage module group with the lowest sum of battery state parameter values ​​for pre-charging. This avoids problems such as uneven charging, overcharging risk, and current surges caused by directly pre-charging module groups with higher remaining power.

[0080] Optionally, when the energy storage system is in a discharge state, based on the ranking results, the energy storage module in the energy storage module group with the highest sum of battery state parameter values ​​is selected as the target energy storage module.

[0081] Specifically, when the main battery management unit confirms that the current charging and discharging condition is a discharging condition, it can sort and compare the sum of the battery state parameter values ​​of all parallel energy storage module groups, select the energy storage module group with the highest sum of battery state parameter values, and determine the energy storage module in the energy storage module group with the highest sum of battery state parameter values ​​as the target energy storage module to be precharged.

[0082] It should be noted that under discharge conditions, the energy storage system outputs electrical energy from the energy storage modules to the electrical load. It prioritizes the energy storage module group with the highest sum of voltage values ​​(sum of battery state parameter values) to perform pre-charging, which can avoid the problem of insufficient output power after the low voltage module group is pre-charged.

[0083] It should be noted that during discharge, the energy storage system outputs electrical energy from the energy storage modules to the electrical load. Priority is given to selecting the energy storage module group with the highest sum of remaining power values ​​(sum of battery state parameter values) to perform pre-charging. This can avoid problems such as insufficient power, excessive voltage drop, and limited system power output when the module group with lower remaining power participates in the discharge.

[0084] Step 103: Send a pre-charge command to the target energy storage module to control the target energy storage module to perform the pre-charge process before high-voltage power-on through the pre-charge circuit configured in the target energy storage module.

[0085] The pre-charge command is a control command issued by the main battery management unit or central battery management unit of the energy storage system to the selected target energy storage module to trigger the pre-charge process.

[0086] Understandably, after receiving the pre-charge command, the target energy storage module triggers its own pre-charge circuit to enter the working state, inputting the electrical energy of the target energy storage module into the high-voltage circuit of the energy storage system, charging the high-voltage bus capacitor, gradually raising the overall voltage of the high-voltage circuit, so that the voltage of the high-voltage bus capacitor gradually approaches the voltage of each energy storage module.

[0087] As one possible implementation, it is first determined whether the target energy storage module meets the preset preconditions. If the target energy storage module meets the preconditions, a pre-charging command is sent to the target energy storage module.

[0088] The preconditions are the conditions for verifying the status of the energy storage system and the vehicle before issuing a pre-charging command to the target energy storage module. The preconditions include the following: the number of energy storage modules with the conditions for pre-charging and high voltage in the driving scenario is not less than 1; the number of energy storage modules with the conditions for high voltage in the driving scenario is not less than a preset minimum threshold; the high voltage start command sent by the vehicle controller is received; the vehicle charging interface is in an unconnected state; and none of the energy storage modules are in a high voltage power-on state.

[0089] The requirement that the number of energy storage modules with high voltage conditions for pre-charging in driving scenarios is not less than 1 means that at least one energy storage module in the energy storage system can perform pre-charging operations, thus avoiding pre-charging failure due to the lack of available modules.

[0090] The requirement that the number of energy storage modules capable of meeting the high-voltage requirements of a vehicle driving scenario is not less than a preset minimum threshold indicates that after pre-charging, there are a sufficient number of energy storage modules to meet the high-voltage power supply needs of the vehicle. The preset minimum threshold refers to the minimum number of energy storage modules required to meet the high-voltage power supply needs of the vehicle.

[0091] The vehicle charging interface is in an unconnected state to avoid conflicts between the pre-charging process and the external charging process, and to prevent damage to components caused by multiple voltage inputs in the high-voltage circuit.

[0092] The reason why none of the energy storage modules are in a high-voltage powered state is to ensure that the high-voltage circuit is in a completely de-energized initial state before the pre-charging process starts, so as to avoid the surge current impact caused by pre-charging under pressure.

[0093] Optionally, in response to receiving a pre-charge failure signal from the target energy storage module, the target energy storage module is controlled to exit the pre-charge process.

[0094] Among them, the pre-charge failure signal is a fault status signal fed back by the target energy storage module when it detects an abnormality during the execution of the pre-charge process.

[0095] It should be noted that if the pre-charging circuit of the target energy storage module detects an abnormality during the pre-charging operation, it can send a pre-charging failure signal to the main battery management unit. In response to this pre-charging failure signal, the main battery management unit sends an exit command to the target energy storage module, controlling the target energy storage module to terminate the pre-charging operation and exit the pre-charging process.

[0096] Alternatively, if no pre-charge success signal is received from the target energy storage module within a preset time, the target energy storage module is controlled to exit the pre-charge process, a new target energy storage module is selected from other energy storage modules besides the target energy storage module, and then a pre-charge command is sent to the new target energy storage module.

[0097] Among them, the pre-charge success signal is a status confirmation signal fed back by the target energy storage module after the pre-charge process is completed.

[0098] The preset time is set by the energy storage system based on hardware performance and pre-charge control strategy. It is the maximum timeout from the sending of the pre-charge command to the feedback of the pre-charge success signal. It can be calibrated according to actual needs, such as 100ms or 500ms, and is not limited here.

[0099] The newly selected target energy storage module is used to continue the system's pre-charging process.

[0100] As one possible approach, when the energy storage system is in charging mode, based on the ranking results, the energy storage module whose battery state parameters are only higher than those of the target energy storage module is selected as the target energy storage module.

[0101] It is understandable that when the energy storage system is in charging mode, if the target energy storage module does not receive a pre-charging success signal within a preset time after issuing a pre-charging command, it means that the target energy storage module cannot pre-charge normally. Therefore, based on the sorting results, the energy storage module whose battery state parameters are only higher than those of the target energy storage module can be selected as the target energy storage module.

[0102] For example, when the battery status parameter is a voltage value and the energy storage system is in charging mode, the order of energy storage module voltage values ​​from smallest to largest is P1, P2, P3, and P4. If the current target energy storage module is P1, and no pre-charge success signal is received from P1 within a preset time, P2 is selected as the new target energy storage module because its voltage value is only higher than P1. A pre-charge command is then sent to P2. If no pre-charge success signal is received from P2 within the preset time, P3 is selected as the new target energy storage module.

[0103] For example, when the battery status parameter value is the remaining capacity value and the energy storage system is in charging mode, the energy storage modules are ordered from smallest to largest by their remaining capacity values: W1, W2, W3, and W4. If the current target energy storage module is W1, and no pre-charge success signal is received from W1 within a preset time, W2 is selected as the new target energy storage module because its remaining capacity value is only higher than W1's. A pre-charge command is then sent to W2. If no pre-charge success signal is received from W2 within the preset time, W3 is selected as the new target energy storage module.

[0104] As another possible approach, when the energy storage system is in a discharge state, based on the ranking results, the energy storage module whose battery state parameters are only lower than those of the target energy storage module is selected as the target energy storage module.

[0105] It should be noted that under discharge conditions, if a pre-charge success signal is not received from the target energy storage module within a preset time, it means that the current target energy storage module cannot be pre-charged normally. Therefore, based on the sorting results, the energy storage module whose battery state parameters are only lower than those of the target energy storage module can be selected as the target energy storage module.

[0106] For example, when the battery status parameter is a voltage value and the energy storage system is in discharge mode, the order of energy storage module voltage values ​​from largest to smallest is Q1, Q2, Q3, and Q4. If the current target energy storage module is Q2, and no pre-charge success signal is received from Q2 within a preset time, Q3 is selected as the new target energy storage module because its voltage value is only lower than Q2. A pre-charge command is then sent to Q3. If no pre-charge success signal is received from Q3 within the preset time, Q4 is selected as the new target energy storage module.

[0107] For example, when the battery status parameter value is the remaining capacity value and the energy storage system is in discharge mode, the remaining capacity values ​​of the energy storage modules, sorted from largest to smallest, are Z1, Z2, Z3, and Z4. If the current target energy storage module is Z1, and no pre-charge success signal is received from Z1 within a preset time, Z2 is selected as the new target energy storage module because its remaining capacity value is only lower than Z1's. A pre-charge command is then sent to Z2. If no pre-charge success signal is received from Z2 within the preset time, Z3 is selected as the new target energy storage module.

[0108] The above solution enables rapid and accurate reselection of the target energy storage module, which can maximize the continuity of system operation, while avoiding system shocks caused by excessive voltage differences, thus improving the fault tolerance and operational stability of the energy storage system.

[0109] It should be noted that after the main battery management unit issues the pre-charge command, it starts timing. If it does not receive a pre-charge success signal from the target energy storage module within the preset time, the main battery management unit can determine that there is an abnormality in the pre-charge process and then control the target energy storage module to terminate the pre-charge operation, causing the target energy storage module to exit the pre-charge process.

[0110] Optionally, it can be determined whether the voltage difference between the high-voltage bus capacitor being charged and each energy storage module is within a preset safe range. If the voltage difference is within the preset safe range, the pre-charging process is stopped.

[0111] The preset safety range is a pre-calibrated voltage difference threshold range used to determine whether the pre-charging process can be terminated. It should be noted that when the voltage difference between the high-voltage bus capacitor and the energy storage module is within the preset safety range, other branches do not need to perform the pre-charging process and can directly complete the high-voltage process by closing the main circuit relay.

[0112] Specifically, the system first collects real-time battery status parameters of the high-voltage bus capacitor and each energy storage module. Then, it calculates the voltage difference between the high-voltage bus capacitor and each energy storage module, obtaining multiple voltage differences. If all voltage differences are within a preset safety range, it indicates that the voltage matching requirements for high-voltage power-on have been met. Furthermore, the main battery management unit can control the pre-charging circuit of the target energy storage module to stop working, terminating the pre-charging process.

[0113] In the above solution, since at least one energy storage module of the energy storage system is equipped with a pre-charging circuit, it does not rely on the pre-charging circuit inside the high-voltage box, eliminating the need for an additional centralized pre-charging device. This improves system reliability, simplifies the system structure, and reduces hardware costs. Furthermore, the energy storage system is compatible with different types of electrical devices, offering higher reusability. It can select target energy storage modules based on charging and discharging conditions, ensuring that pre-charging operations match the actual operating state of the system. This avoids energy waste caused by indiscriminate pre-charging and improves pre-charging efficiency.

[0114] Referring to Figure 3, it is a flowchart illustrating the pre-charging method provided in the second embodiment of this application. As shown in Figure 3, the method may include the following steps: Step 201, before the energy storage system is powered on at high voltage, the various energy storage modules in the energy storage system are sorted to obtain a sorting result.

[0115] Step 202: Based on the sorting results, select the target energy storage module to be precharged from the energy storage system.

[0116] It should be noted that the specific implementation methods of steps 201 and 202 can refer to the above embodiments, and will not be repeated here.

[0117] Step 203: Determine the number of times the pre-charging circuit of each energy storage module performs the pre-charging process.

[0118] It should be noted that after each precharge process is started, the SBMU increments the number of times the precharge circuit has executed the precharge process by 1 and stores it synchronously in the non-volatile memory.

[0119] Optionally, the CBMU or MBMU of the energy storage system can send a data read command to the SBMU of each energy storage module. This data read command is used to trigger the SBMU to report the number of times its corresponding energy storage module's pre-charging circuit has performed the pre-charging process.

[0120] Each SBMU internally stores the execution record of each pre-charging process of its corresponding energy storage module's pre-charging circuit, including information such as pre-charging start time, execution result, and cumulative number of times.

[0121] Specifically, after each SBMU receives a data read command, it can feed back in real time the number of times its own pre-charging circuit has executed the pre-charging process to the CBMU or MBMU. The CBMU or MBMU receives and stores the number of times the pre-charging circuit of all energy storage modules has executed the pre-charging process.

[0122] Step 204: Determine the average value of each number of times.

[0123] Specifically, the number of times each energy storage module's pre-charging circuit executes the pre-charging process is obtained is summed to obtain a total value. Then, the total number of energy storage modules participating in the pre-charging process in the energy storage system is counted. Finally, the total value is divided by the total number of energy storage modules to obtain the average value of each number of times.

[0124] Among them, the energy storage module participating in the pre-charging process can refer to an energy storage module that has pre-charging capability and can be used as a target energy storage module, excluding energy storage modules that are abnormal or unable to perform pre-charging.

[0125] For example, suppose the energy storage system has 4 energy storage modules with pre-charging capabilities, and their pre-charging execution counts are 120, 115, 105, and 100 respectively. Then the total number of pre-charging execution counts for all energy storage modules is 120 + 115 + 105 + 100 = 440 times. The total number of energy storage modules is 4, and the calculated average is 440 ÷ 4 = 110 times. This is not a limitation.

[0126] Step 205: If the number of times corresponding to the target energy storage module is more than the average value by a preset threshold, determine the target energy storage module to be reselected from other energy storage modules besides the target energy storage module.

[0127] The preset threshold is a critical value used to determine whether the number of pre-charging operations of the target energy storage module is too high. This threshold can be customized according to the actual application scenario and is not limited here.

[0128] It should be noted that if the pre-charging circuit of the target energy storage module executes the pre-charging process more times than the average and exceeds a preset threshold, it indicates that the number of times the target energy storage module performs the pre-charging process is too high. Continuing to perform the pre-charging process based on this target energy storage module may reduce the lifespan of the pre-charging relay and pre-charging resistor. Therefore, to balance the number of pre-charging operations across different pre-charging circuits and improve the lifespan of the BMS system, a different target energy storage module can be selected from those other than the target module to perform the pre-charging process.

[0129] It should be noted that the specific implementation method for determining the target energy storage module from other energy storage modules besides the target energy storage module can refer to the description in the above embodiments.

[0130] Optionally, if the target energy storage module is abnormal, a new target energy storage module can be selected from other energy storage modules besides the target energy storage module.

[0131] It should be noted that in some scenarios, the currently selected target energy storage module may fail to execute the pre-charging process normally due to an anomaly. To ensure the pre-charging process can continue, a new target energy storage module can be selected from among other energy storage modules. The specific process for reselecting a target energy storage module can be referred to the description in the above embodiments, and will not be repeated here. This solution can improve the fault tolerance and reliability of the energy storage system's pre-charging process, ensuring that the pre-charging process can continue and preventing the entire energy storage system from failing to complete high-voltage power-on due to an anomaly in a single module.

[0132] When monitoring for anomalies in the target energy storage module, the operating status of the target energy storage module (such as temperature, voltage, pre-charge circuit status, communication status, etc.) can be monitored in real time through the CBMU or MBMU to determine if there are any anomalies. If anomalies are detected in the target energy storage module (such as relay failure, module overheating, or communication interruption), it indicates that the target energy storage module cannot perform the pre-charge process normally, and a new target energy storage module needs to be selected.

[0133] Step 206: Send a pre-charge command to the reselected target energy storage module to control the reselected target energy storage module to perform the pre-charge process before high-voltage power-on through the configured pre-charge circuit.

[0134] It should be noted that the specific implementation of step 206 can be referred to the above embodiments, and will not be repeated here.

[0135] In this embodiment, the pre-charging circuit of a single energy storage module can be prevented from aging faster and having a shorter lifespan due to frequent operations, thereby achieving a balance in the losses of the pre-charging circuits of each module group and improving the overall lifespan of the energy storage system.

[0136] Figure 4 is a schematic diagram of the structure of a battery management system proposed in an embodiment of this application.

[0137] As shown in Figure 4, the battery management system includes a main battery management unit and multiple slave battery management units. Each energy storage module is equipped with a pre-charging circuit. The main battery management unit is used to: sort the energy storage modules in the energy storage system before high-voltage power-on, obtaining a sorting result; at least one of the energy storage modules is equipped with a pre-charging circuit for pre-charging the high-voltage bus capacitor; based on the sorting result, determine the target slave battery management unit, which is used to control the target energy storage module to be pre-charged, and the target energy storage module is a subset of the energy storage modules; and send a pre-charging command to the target energy storage module through the pre-charging circuit configured in the target energy storage module to control the target energy storage module to perform the pre-charging process before high-voltage power-on.

[0138] Optionally, the energy storage system is a vehicle-grade power energy storage system, and the energy storage module is a battery pack.

[0139] It should be noted that the specific implementation of the above steps can be referred to the description in the above embodiments, and will not be repeated here.

[0140] The Battery Management System (BMS) of this application is used to perform at least one of the following functions for individual battery cells: state monitoring, state analysis, charge / discharge control, safety protection, thermal management, high-voltage power distribution, and information management. In addition, the Battery Management System of this application can also implement the functions of a controller in an electrical device, such as a vehicle control unit (VCU) or a motor control unit (MCU), etc., and this application does not impose any limitations on this.

[0141] It should be noted that the battery management system in this application can be integrated as a controller into the battery device, such as into the battery pack or energy storage box. The battery management system in this application can also be integrated as a controller into electrical devices, such as into a vehicle or vehicle chassis. The battery management system in this application can also be integrated as a controller into charging devices, such as into charging devices or battery swapping devices. The battery management system in this application can also be deployed as control software on a server. The server can be a standalone physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, CDN (Content Delivery Network), and big data and artificial intelligence platforms, such as vehicle networking cloud, APP backend, etc.

[0142] This application also provides an energy storage system including multiple energy storage modules. Each energy storage module includes a pre-charging circuit. Before the energy storage system is powered on at high voltage, at least some of the multiple energy storage modules perform a pre-charging operation based on the pre-charging circuit included in the energy storage module upon receiving a pre-charging command.

[0143] This application also proposes a battery system, including an energy storage system and the aforementioned battery management system, wherein the battery management system is used to perform pre-charge control on the energy storage system.

[0144] The connection method between multiple energy storage modules in the energy storage system can be conventional in the field, such as series connection, parallel connection, or a hybrid connection that includes these connection methods. Hybrid connection refers to the series and parallel connection between multiple energy storage modules, and there are no special restrictions on this.

[0145] This application also proposes an electrical device, including the battery management system or the battery system described above.

[0146] In this application, the electrical device includes a battery device and an electrical load. The electrical device can be, but is not limited to, power equipment (such as electric vehicles, electric cars, electric boats, spacecraft), electronic equipment (such as mobile phones, tablets, laptops, bionic machines, digital cameras, electric toys, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), energy storage power stations, etc.

[0147] In this application, "high voltage" and "low voltage" are relative concepts; that is, high voltage involves a voltage higher than low voltage. Generally speaking, the difference between high-voltage and low-voltage related circuits or components is that high-voltage related circuits or components refer to circuits or components that can be directly or indirectly connected to the battery system. This is because the battery system consists of several battery cells, providing a relatively high voltage.

[0148] As will be understood by those skilled in the art, high voltage generally refers to voltages greater than tens of volts, hundreds of volts, or higher. Circuits and components operating at voltages greater than tens of volts, hundreds of volts, or higher can be used or processed. For example, circuits and components operating at voltages greater than 30V AC RMS and less than or equal to 1000V AC RMS, or greater than 60V DC and less than or equal to 1500V DC. Here, V represents volts, AC RMS represents the effective power in the alternating current waveform, and DC represents direct current.

[0149] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0150] If the integrated unit is implemented as a software functional unit and used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a device / electronic device, a recording medium, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks.

[0151] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0152] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0153] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0154] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0155] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A pre-charging method, characterized in that, include: Before the energy storage system is powered on at high voltage, the energy storage modules in the system are sorted to obtain a sorting result. At least one of the energy storage modules is configured with a pre-charging circuit for pre-charging the high-voltage bus capacitor. Based on the sorting result, a target energy storage module to be pre-charged is selected from the energy storage system. The target energy storage module is a subset of the energy storage modules. A pre-charging command is sent to the target energy storage module to control it to perform the pre-charging process before high voltage power-on through the pre-charging circuit configured in the target energy storage module.

2. The method according to claim 1, characterized in that, The step of sorting the energy storage modules in the energy storage system to obtain a sorting result includes: obtaining the battery status parameter values ​​of each energy storage module, wherein the battery status parameter values ​​are voltage values ​​or remaining power values; and sorting the energy storage modules according to the order of the battery status parameter values ​​to obtain a sorting result.

3. The method according to claim 2, characterized in that, The step of selecting a target energy storage module to perform a pre-charging operation from the energy storage system based on the ranking results includes: when the energy storage system is in a charging state, selecting the energy storage module with the lowest battery state parameter value as the target energy storage module based on the ranking results, wherein the charging state refers to the working state in which the energy storage system is injecting electrical energy into the energy storage module by an external power source; and when the energy storage system is in a discharging state, selecting the energy storage module with the highest battery state parameter value as the target energy storage module based on the ranking results, wherein the discharging state refers to the working state in which the energy storage system is outputting electrical energy to the electrical load.

4. The method according to claim 1, characterized in that, The energy storage system includes multiple parallel energy storage module groups, with energy storage modules in each energy storage module group connected in series. Each energy storage module group includes one or more energy storage modules. The step of sorting the energy storage modules in the energy storage system to obtain a sorting result includes: obtaining the battery status parameter values ​​of each energy storage module, where the battery status parameter values ​​are voltage values ​​or remaining capacity values; determining the sum of the battery status parameter values ​​corresponding to each energy storage module group based on the battery status parameter values ​​of each energy storage module; and sorting the energy storage modules in each energy storage module group according to the order of the sum of the battery status parameter values ​​corresponding to the energy storage module group to obtain a sorting result.

5. The method according to claim 4, characterized in that, The step of selecting a target energy storage module to perform a pre-charging operation from the energy storage system based on the ranking result includes: when the energy storage system is in a charging state, based on the ranking result, selecting the energy storage module in the energy storage module group with the lowest sum of battery state parameter values ​​as the target energy storage module, where the charging state refers to the working state in which the energy storage system is injecting electrical energy into the energy storage module from an external power source; and when the energy storage system is in a discharging state, based on the ranking result, selecting the energy storage module in the energy storage module group with the highest sum of battery state parameter values ​​as the target energy storage module, where the discharging state refers to the working state in which the energy storage system is outputting electrical energy to the electrical load.

6. The method according to any one of claims 1-5, characterized in that, After sending a pre-charge command to the target energy storage module to control the target energy storage module to perform a pre-charge process through the pre-charge circuit configured in the target energy storage module, the method further includes: in response to not receiving a pre-charge success signal from the target energy storage module within a preset time, controlling the target energy storage module to exit the pre-charge process; determining a new target energy storage module from other energy storage modules besides the target energy storage module; and sending the pre-charge command to the new target energy storage module.

7. The method according to claim 6, characterized in that, The step of determining a new target energy storage module from other energy storage modules besides the target energy storage module includes: when the energy storage system is in a charging state, based on the ranking result, selecting energy storage modules whose battery state parameters are only higher than those of the target energy storage module as target energy storage modules; and when the energy storage system is in a discharging state, based on the ranking result, selecting energy storage modules whose battery state parameters are only lower than those of the target energy storage module as target energy storage modules.

8. The method according to any one of claims 1-5, characterized in that, After selecting a target energy storage module to perform a pre-charging operation from the energy storage system based on the sorting result, the method further includes: determining the number of times the pre-charging circuit of each energy storage module executes the pre-charging process; determining the average value of each number of executions; if the number of executions corresponding to the target energy storage module is more than the average value by a preset threshold, determining a new target energy storage module from other energy storage modules besides the target energy storage module; and sending the pre-charging command to the new target energy storage module.

9. The method according to claim 7, characterized in that, The method further includes: in the event of an anomaly in the target energy storage module, determining a new target energy storage module from other energy storage modules besides the target energy storage module; and sending the pre-charge command to the new target energy storage module.

10. The method according to claim 7, characterized in that, After sending a pre-charge command to the target energy storage module to control the target energy storage module to perform a pre-charge process before high-voltage power-on through the pre-charge circuit configured in the target energy storage module, the method further includes: in response to receiving a pre-charge failure signal from the target energy storage module, controlling the target energy storage module to exit the pre-charge process.

11. The method according to claim 10, characterized in that, The energy storage system is configured in the vehicle. Sending a pre-charging command to the target energy storage module includes: determining whether the target energy storage module meets preset preconditions; and sending a pre-charging command to the target energy storage module if the target energy storage module meets the preconditions. The preconditions include: the number of energy storage modules with high-voltage pre-charging conditions for driving scenarios is not less than 1; the number of energy storage modules with high-voltage conditions for driving scenarios is not less than a preset minimum threshold; receiving a high-voltage start command from the vehicle controller; the vehicle charging interface being in an unconnected state; and all energy storage modules not being in a high-voltage energized state.

12. The method according to claim 11, characterized in that, After sending a pre-charge command to the target energy storage module to control the target energy storage module to perform a pre-charge process before high-voltage power-on through the pre-charge circuit configured in the target energy storage module, the method further includes: determining whether the voltage difference between the high-voltage bus capacitor being charged and each energy storage module is within a preset safe range; and stopping the pre-charge process if each voltage difference is within the preset safe range.

13. A battery management system, characterized in that, The system includes a main battery management unit and multiple slave battery management units. The main battery management unit is used to: sort the energy storage modules in the energy storage system before high-voltage power-on, and obtain a sorting result; at least one of the energy storage modules is configured with a pre-charging circuit for pre-charging the high-voltage bus capacitor; based on the sorting result, determine a target slave battery management unit, which is used to control the target energy storage module to be pre-charged, the target energy storage module being a subset of the energy storage modules; and send a pre-charging command to the target energy storage module through the target slave battery management unit to control the target energy storage module to perform the pre-charging process before high-voltage power-on through the pre-charging circuit configured in the target energy storage module.

14. An energy storage system, characterized in that, The system includes multiple energy storage modules, each containing a pre-charging circuit. Before the energy storage system is powered on at high voltage, at least a portion of the multiple energy storage modules perform a pre-charging operation based on the pre-charging circuit contained in the energy storage module upon receiving a pre-charging command.

15. A battery system, characterized in that, Includes the battery management system as described in claim 13 and the energy storage system as described in claim 14, wherein the battery management system is used for pre-charging control of the energy storage system.

16. An electrical appliance, characterized in that, This includes the battery management system as described in claim 13, the energy storage system as described in claim 14, or the battery system as described in claim 15.

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