State of charge equalization method, apparatus, control device, system, medium, and product

Abstract

The application relates to a state-of-charge equalization method, device, control equipment, system, medium and product of an energy storage device. The method comprises the following steps: determining a target battery device in the energy storage device according to the voltage of each battery device in the energy storage device and the power demand state of the energy storage device; performing energy conversion on the powered target battery device according to a preset request current of the energy storage device until the battery devices other than the target battery device meet the power-on condition; powering on the battery devices other than the target battery device, and performing energy conversion on all the battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches a preset voltage, so that the state-of-charge of all the battery devices is equalized. The method can improve the state-of-charge equalization efficiency of each battery device in the energy storage device.

Description

Technical Field

[0001] This application relates to the field of new energy technology, and in particular to a method, apparatus, control equipment, system, medium and product for balancing the state of charge of an energy storage device. Background Technology

[0002] With the rapid development of the new energy industry, energy storage devices are being used more and more widely. Energy storage devices are usually constructed by combining multiple battery devices, and large-scale energy storage and release are achieved through the coordinated work of the battery devices. Among them, it is very important to balance the state of charge (SOC) of each battery device in the energy storage device.

[0003] In related technologies, the state of charge (SOC) of each battery in an energy storage device is often balanced by performing SOC balancing on the already powered battery devices.

[0004] However, the related technologies suffer from the problem of low efficiency in balancing the state of charge of each battery device in the energy storage device. Summary of the Invention

[0005] Based on this, this application provides a method, apparatus, control device, system, medium, and product for balancing the state of charge of an energy storage device, which can improve the efficiency of balancing the state of charge of each battery device in the energy storage device.

[0006] In a first aspect, this application provides a method for balancing the state of charge (SCC) of an energy storage device. The method includes: determining a target battery device in the energy storage device based on the voltage of each battery device in the energy storage device and the energy demand state of the energy storage device; the target battery device or a battery device other than the target battery device supporting power-on; performing energy conversion on the target battery device based on a preset request current of the energy storage device until the battery devices other than the target battery device meet the power-on conditions; powering on the battery devices other than the target battery device, and performing energy conversion on all battery devices in the energy storage device when all battery devices in the energy storage device are powered on, until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches a preset voltage, so as to balance the SCC of all battery devices.

[0007] In the technical solution provided in this application embodiment, when the target battery device or a battery device other than the target battery device in the energy storage device supports power-on, the target battery device is powered on, and energy conversion is performed on the powered target battery device, so that the voltage of the target battery device and the voltage of the battery devices other than the target battery device can be gradually equalized, so that the battery devices other than the target battery device also meet the power-on conditions. In this way, all battery devices in the energy storage device can be powered on. Therefore, even if the voltage difference between some battery devices and other battery devices in the energy storage device is large, causing some battery devices to be unable to be powered on, the charging or discharging function of the energy storage device itself can also enable the battery devices that cannot be powered on to be powered on, thereby achieving state of charge equalization of all battery devices in the energy storage device, avoiding the problem of low state of charge equalization efficiency caused by using external power supply. Therefore, it can improve the efficiency of state of charge equalization of each battery device in the energy storage device. Furthermore, when the state of charge of the battery device is close to the highest or lowest state of charge, the voltage change amplitude is large with the change of state of charge, that is, the voltage change corresponding to a unit change of state of charge is large. When the state of charge (SOC) of a battery device is close to the intermediate SOC, the voltage change is relatively small with the change in SOC; that is, the voltage change corresponding to a unit change in SOC is small. Therefore, by performing energy conversion on all battery devices until the voltage of any cell in at least one battery device reaches a preset voltage, the voltage change corresponding to a unit change in SOC increases. Since the SOC of a battery device is determined by its voltage, this reduces the possibility of a small voltage measurement error leading to a large error in the SOC, thus improving the reliability of the determined SOC and the reliability of SOC balance among the battery devices in the energy storage device. Furthermore, by ensuring that the voltage of any cell in at least one battery device reaches the preset voltage, energy conversion ceases for each battery device once the voltage of any cell reaches the preset voltage, reducing the probability of overcharging or over-discharging cells and improving the operational reliability of the energy storage device.

[0008] In some embodiments, determining a target battery device in an energy storage device based on the voltage of each battery device in the energy storage device and the power demand state of the energy storage device includes: determining a battery device with balanced voltage in the energy storage device as a first battery device, and determining battery devices other than the first battery device as second battery devices, based on the voltage of the first battery device, the voltage of the second battery device, and the power demand state of the energy storage device.

[0009] In the technical solution provided in this application, battery devices with similar voltage levels are classified as first battery devices, and the rest are classified as second battery devices. Based on this, the actual voltages of the first and second battery devices and the current power demand status of the energy storage system are combined to dynamically and reasonably select the target battery device. This avoids the problem of unreasonable selection of the target battery device, which would prevent other battery devices from meeting the power-on conditions even if the target battery device is charged or discharged. Therefore, the effectiveness of the determined target battery device is improved.

[0010] In some embodiments, determining a target battery device based on the voltage of a first battery device, the voltage of a second battery device, and the energy demand state of the energy storage device includes at least one of the following: when the energy demand state of the energy storage device is a charging demand state and the voltage of the first battery device is less than the voltage of the second battery device, determining the first battery device as the target battery device; when the energy demand state of the energy storage device is a charging demand state and the voltage of the first battery device is greater than the voltage of the second battery device, determining the second battery device as the target battery device; when the energy demand state of the energy storage device is a discharging demand state and the voltage of the first battery device is less than the voltage of the second battery device, determining the first battery device as the target battery device; when the energy demand state of the energy storage device is a discharging demand state and the voltage of the first battery device is greater than the voltage of the second battery device, determining the first battery device as the target battery device.

[0011] In the technical solution provided in this application embodiment, when the energy demand state of the energy storage device is a charging demand state, a battery device with a lower voltage is identified as the target battery device, so that the energy storage device charges the battery device with a lower voltage, thereby enabling other battery devices to meet the power-on conditions. When the energy demand state of the energy storage device is a discharging demand state, a battery device with a higher voltage is identified as the target battery device, so that the energy storage device discharges the battery device with a higher voltage, thereby enabling other battery devices to meet the power-on conditions. This avoids the problem of unreasonable selection of target battery devices, which would prevent other battery devices from meeting the power-on conditions even if the target battery device is charged or discharged. Therefore, the effectiveness of the identified target battery device is improved.

[0012] In some embodiments, the preset request current includes a first request current and a second request current, wherein the second request current is less than the first request current; energy conversion is performed on the powered target battery device according to the preset request current of the energy storage device, including: performing energy conversion on the powered target battery device according to the first request current until the voltage difference between the voltage of the target battery device and the voltage of a battery device other than the target battery device is less than or equal to a first preset voltage threshold; and performing energy conversion on the powered target battery device according to the second request current.

[0013] In the technical solution provided in this application embodiment, since the second requested current is less than the first requested current, the scheme of converting energy for the powered target battery device according to the second requested current, compared with the scheme of converting energy for the powered target battery device according to the first requested current, can reduce the polarization voltage of the battery device due to charging or discharging. When the requested current of the energy storage device is set to 0 and a battery device other than the target battery device is powered on, even if the target battery device is undergoing a depolarization process, the measured voltage of the target battery device is closer to the actual voltage of the target battery device because the polarization voltage of the target battery device is lower. This not only avoids the situation where the polarization voltage of the target battery device is too high, and the voltage difference between the target battery device and other battery devices after depolarization is no longer less than or equal to the second preset voltage threshold, thus preventing the other battery devices from being powered on, but also improves the efficiency of the state of charge balancing of the energy storage device. It also avoids the problem that a large voltage difference between the target battery device and other battery devices leads to an uneven distribution of current to these two types of battery devices, causing some battery devices to overheat and thus affecting the operational reliability of the energy storage device. Therefore, it can improve the operational reliability of the energy storage device.

[0014] In some embodiments, the power-on condition for a battery device other than the target battery device includes at least one of the following: the voltage difference between the voltage of the target battery device and the voltage of the battery device other than the target battery device is less than or equal to a second preset voltage threshold for a duration greater than or equal to a first preset duration; the duration of energy conversion of the target battery device powered on according to the second requested current is greater than or equal to the second preset duration; and the second preset voltage threshold is less than the first preset voltage threshold.

[0015] In the technical solution provided in this application embodiment, by ensuring that the voltage difference between the target battery device and the voltage of a battery device other than the target battery device is less than or equal to a second preset voltage threshold for a duration greater than or equal to a first preset duration, the problem of uneven current distribution from the energy storage device to the two battery devices is avoided. This is because the target battery device has a polarization voltage, which causes inconsistency between the actual voltage and the measured voltage of the target battery device when the voltage difference initially falls below or equals the second preset voltage threshold. Furthermore, by ensuring that the energy conversion time of the powered target battery device according to the second requested current is greater than or equal to the second preset duration, sufficient time is provided to reduce the large polarization voltage. This large polarization voltage is the polarization voltage generated by the target battery device when the first requested current is used for energy conversion. This reduces the polarization voltage of the target battery device, decreases the difference between the measured voltage and the actual voltage of the target battery device, and improves the accuracy of the determined voltage of the target battery device.

[0016] In some embodiments, determining that a battery device other than the target battery device meets the power-on conditions includes: determining the polarization voltage of the target battery device based on a preset request current of the energy storage device and the voltage of the target battery device; determining the voltage difference between the voltage of the target battery device and the polarization voltage of the target battery device as the actual voltage of the target battery device; and determining that the battery device other than the target battery device meets the power-on conditions if the voltage difference between the actual voltage of the target battery device and the voltage of the battery device other than the target battery device is less than or equal to a second preset voltage threshold.

[0017] In the technical solution provided in this application embodiment, the voltage difference between the voltage of the target battery device and the polarization voltage of the target battery device is determined as the actual voltage of the target battery device. Since the battery devices other than the target battery device have not yet been charged or discharged, their voltages are also the actual voltages. Therefore, based on the actual voltages of the target battery device and the battery devices other than the target battery device, it is determined whether the battery devices other than the target battery device meet the power-on conditions. This improves the accuracy of determining whether the battery devices other than the target battery device meet the power-on conditions and reduces the actual voltage difference between the target battery device and the battery devices other than the target battery device.

[0018] In some embodiments, the method further includes: determining a target requested current for each battery device in the target battery device based on a voltage difference between the voltage of the target battery device and the voltage of battery devices other than the target battery device; and determining a preset requested current based on the number of battery devices in the target battery device and the target requested current for each battery device in the target battery device.

[0019] In the technical solution provided in this application embodiment, the target requested current of each battery device in the target battery device can be flexibly determined according to the voltage difference value. When the voltage difference value is large, the target requested current of each battery device in the target battery device is increased, thereby improving the energy conversion rate of the target battery device. When the voltage difference value is small, the target requested current of each battery device in the target battery device is reduced, thereby reducing the polarization voltage of each battery device in the target battery device. This not only improves the accuracy of whether the battery devices other than the target battery device meet the power-on conditions, but also reduces the actual voltage difference between the target battery device and the battery devices other than the target battery device.

[0020] In some embodiments, the preset voltage includes a first preset voltage or a second preset voltage; performing energy conversion on all battery devices in the energy storage device until the voltage of any cell in each battery device reaches the preset voltage includes: charging all battery devices in the energy storage device when the energy demand state of the energy storage device is a charging demand state until the voltage of any cell in each energy storage device reaches the first preset voltage; discharging all battery devices in the energy storage device when the energy demand state of the energy storage device is a discharging demand state until the voltage of any cell in any battery device reaches the second preset voltage.

[0021] In the technical solution provided in this application embodiment, by having the voltage of any cell in each energy storage device of the entire battery device reach a first set voltage, and the voltage of any cell in any battery device in the energy storage device reach a second set voltage, the state of charge (SOC) of the cell can be accurately determined through the cell voltage. Furthermore, the SOC of the battery device can be determined through the cell SOC, thus improving the reliability of determining the SOC of each battery device in the energy storage device and improving the effectiveness of SOC balancing for each battery device. Moreover, by having the voltage of any cell in any battery device in the energy storage device reach a first set voltage, the SOC of the battery device can be accurately determined through the cell voltage. By setting a voltage, charging is stopped once the voltage of any cell in any battery device reaches a first set voltage, reducing the probability of overcharging the cells in the battery device. By ensuring that the voltage of any cell in any battery device in the energy storage device reaches a second set voltage, the voltage of all battery devices in the energy storage device is prevented from reaching the second set voltage, which would result in all battery devices in the energy storage device being at a very low voltage and causing over-discharge of the battery device due to self-discharge. Therefore, the embodiments of this application can reduce the probability of over-discharge of the battery device and improve the reliability of the energy storage device operation.

[0022] In some embodiments, charging all battery devices in an energy storage device until the voltage of any cell in each energy storage device reaches a first set voltage includes: acquiring a charging request current of the energy storage device and charging the battery devices in the powered-on state according to the charging request current of the energy storage device; when the voltage of any cell in any battery device in the powered-on state reaches the first set voltage, controlling the charging current of the energy storage device to 0, powering off any battery device, and proceeding to the step of acquiring the charging request current of the energy storage device until all battery devices are powered off.

[0023] In the technical solution provided in this application embodiment, by powering down any battery device when the voltage of any cell in any battery device in the powered-on state reaches a first set voltage, overcharging of the battery device is avoided, thereby improving the operational reliability of the energy storage device. Furthermore, by first controlling the charging current of the energy storage device to 0 before powering down any battery device, not only is the current surge generated by the switch connected to the battery device due to the large current disconnection, which could easily damage the switch, avoided, but the current surge generated by the switch disconnection could also prevent overcharging of the battery device, thereby further improving the operational reliability of the energy storage device.

[0024] In some embodiments, the method further includes: when all battery devices are powered down, powering up all battery devices at intervals of a preset waiting time, starting from the end time when all battery devices are powered down.

[0025] In the technical solution provided in this application embodiment, when each battery device is powered off, each battery device begins depolarization. Since the power-off times of different battery devices are different, the depolarization duration of different battery devices is different, resulting in differences in the measured voltage of different battery devices. By starting from the end time when all battery devices are powered off and then waiting for a preset time interval, the depolarization duration of each battery device is at least the preset waiting time, so as to avoid the polarization voltage of the battery device from affecting the measured voltage of the cell as much as possible. That is, the measured voltage of different battery devices is different, thereby reducing the circulating current generated in the battery devices after all battery devices are powered on, and reducing the energy loss of the battery devices in the energy storage device.

[0026] In some embodiments, obtaining the charging request current of the energy storage device includes: obtaining the number of battery devices in a powered-on state and the characteristic voltage of the battery devices in a powered-on state; determining a target charging current for each battery device in a powered-on state based on the characteristic voltage of the battery devices in a powered-on state; and determining the charging request current of the energy storage device based on the number of battery devices in a powered-on state and the target charging current of each battery device in a powered-on state.

[0027] In the technical solution provided in this application embodiment, the target charging current of each battery device in the powered-on state is determined based on the characteristic voltage of the battery device in the powered-on state. This avoids the situation where the target charging current is a fixed charging current, which does not take into account the influence of the characteristic voltage of the battery device, thus leading to the battery cells in the battery device being easily damaged by overcharging or the battery device having low charging current resulting in low charging efficiency. Furthermore, the charging request current of the energy storage device is determined based on the number of battery devices in the powered-on state and the target charging current of each battery device in the powered-on state. This avoids the situation where the charging request current of the energy storage device is fixed, which leads to the battery devices being easily damaged by overcharging or the battery device having low charging current resulting in low charging efficiency when the number of battery devices in the powered-on state decreases. Therefore, the effectiveness of the determined target charging current of each battery device in the powered-on state can be improved.

[0028] In some embodiments, discharging all battery devices in the energy storage device until the voltage of any cell in any battery device in the energy storage device reaches a second preset voltage includes: acquiring a first discharge request current of the energy storage device, and discharging the battery devices in the powered-on state according to the first discharge request current of the energy storage device; acquiring a second discharge request current of the energy storage device when the voltage of any cell in any battery device in the powered-on state is less than or equal to a third preset voltage; the third preset voltage is greater than the second preset voltage, and the second discharge request current is less than the first discharge request current; discharging the battery devices in the powered-on state according to the second discharge request current of the energy storage device until the voltage of any cell in any battery device is less than or equal to the second preset voltage, and controlling the discharge current of the energy storage device to be 0, thus completing the discharge of all battery devices.

[0029] In the technical solution provided by this application embodiment, the battery device in the powered-on state is first discharged according to the first discharge request current of the energy storage device, and then discharged according to the second discharge request current which is less than the first discharge request current. This avoids the problem that using a large first discharge request current to discharge the battery device in the powered-on state can easily lead to an excessively high polarization voltage of the battery device, a large difference between the obtained voltage of the battery device and the actual voltage of the battery device, and consequently, a large difference between the voltage of the battery device and the second set voltage. This results in an inaccurate state of charge of the battery device determined based on the voltage of the battery device. Therefore, this application embodiment can improve the accuracy of the determined state of charge of the battery device, thereby improving the effectiveness of balancing the state of charge of each battery device.

[0030] In some embodiments, obtaining a first discharge request current of an energy storage device includes: obtaining the number of battery devices in a powered-on state and the characteristic voltage of the battery devices in a powered-on state; determining a target discharge current for each battery device in a powered-on state based on the characteristic voltage of the battery devices in a powered-on state; and determining a first discharge request current of the energy storage device based on the number of battery devices in a powered-on state and the target discharge current of each battery device in a powered-on state.

[0031] In the technical solution provided in this application embodiment, the target discharge current of each battery device in the powered-on state is determined based on the characteristic voltage of the battery device in the powered-on state. This avoids the situation where the target discharge current is a fixed discharge current, which does not take into account the influence of the characteristic voltage of the battery device. This would lead to the battery cells in the battery device being easily damaged by over-discharge or the battery device having low discharge current, resulting in low discharge efficiency. Therefore, the effectiveness of the determined target discharge current of each battery device in the powered-on state can be improved.

[0032] Secondly, this application provides a state-of-charge balancing device for an energy storage device, the state-of-charge balancing device comprising:

[0033] The determination module is used to determine the target battery device in the energy storage device based on the voltage of each battery device in the energy storage device and the power demand status of the energy storage device; the target battery device or the battery device other than the target battery device supports power-on.

[0034] The energy conversion module is used to convert energy for the target battery device that is powered on, based on the preset request current of the energy storage device, until the battery device other than the target battery device meets the power-on conditions.

[0035] The balancing module is used to power up battery devices other than the target battery device, and when all battery devices in the energy storage device are powered up, to perform energy conversion on all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches a preset voltage, so as to balance the state of charge of all battery devices.

[0036] Thirdly, this application provides a control device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method of any one of the first aspects.

[0037] Fourthly, this application provides an energy storage device, which includes the control device described in the third aspect and a plurality of battery devices, each connected to the control device.

[0038] Fifthly, this application provides an energy storage system, which includes a power conversion device and an energy storage device as described in the fourth aspect, wherein the power conversion device is connected between the energy storage device and the power generation device.

[0039] In a sixth aspect, this application provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method of any one of the first aspects.

[0040] In a seventh aspect, this application provides a computer program product, including a computer program, wherein when the computer program is executed by a processor, it implements the steps of the method of any one of the first aspects. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a structural schematic diagram of an energy storage container for some embodiment systems;

[0043] Figure 2 A circuit diagram of an energy storage device provided for some embodiments;

[0044] Figure 3 Schematic diagrams of the energy storage system provided for some embodiments;

[0045] Figure 4 A schematic flowchart of the state-of-charge balancing method for the energy storage device provided in the first embodiment;

[0046] Figure 5 A schematic flowchart of the state-of-charge balancing method for the energy storage device provided in the second embodiment;

[0047] Figure 6 A schematic flowchart of the state-of-charge balancing method for the energy storage device provided in the third embodiment;

[0048] Figure 7 A schematic diagram of the state-of-charge equalization device provided in some embodiments;

[0049] Figure 8 Schematic diagrams of the control device provided for some embodiments;

[0050] Figure 9 Schematic diagrams of the energy storage device provided for some embodiments;

[0051] Figure 10 A schematic diagram of the energy storage system provided for other embodiments. Detailed Implementation

[0052] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These 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.

[0053] 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.

[0054] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, "multiple groups" means two or more, and "each" means each of the multiple, unless otherwise explicitly defined.

[0055] 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.

[0056] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0057] Unless otherwise specified, the order of execution steps in the embodiments of this application is not limited. It should also be noted that any step in the embodiments of this application can be executed independently, that is, the execution of any step in the above embodiments can be performed without depending on the execution of other steps.

[0058] From a market perspective, energy storage devices are becoming increasingly widely used, bringing significant convenience to daily production and life. Energy storage devices typically include multiple battery units, which can be connected in series, parallel, or a combination of series and parallel connections. For example, in this embodiment, multiple battery units are connected in parallel. Each battery unit in the energy storage device can be charged and discharged. By controlling the charging and discharging of each battery unit, large-scale energy storage and release can be achieved. The battery unit is a whole formed by connecting multiple battery packs together. Exemplarily, a single battery unit can be obtained by connecting multiple battery packs in series, parallel, or a combination of series and parallel connections.

[0059] In the embodiments of this application, the battery device may include a battery cabinet or a battery cluster. For example, a battery device includes multiple battery packs connected in series, each battery pack including multiple cells connected in series, parallel, or mixed series.

[0060] Energy storage devices may include energy storage containers, energy storage cabinets, home energy storage, energy storage power supplies, or other devices capable of energy storage. For example, Figure 1 Here are some schematic diagrams of the energy storage container structure of the embodiment system, such as Figure 1 As shown, an energy storage container can be, for example, a regular cuboid structure, where the six faces of the cuboid serve as the six outer walls of the energy storage device. Setting the energy storage device in a cuboid structure facilitates its fixed placement and transportation. Of course, the energy storage device can also have other shapes; for example, at least one wall of the energy storage device may be angled.

[0061] Figure 2 A circuit structure diagram of an energy storage device provided for some embodiments, such as Figure 2 As shown, the energy storage device includes a combiner module and S groups of energy storage modules. Each group of energy storage modules includes a battery unit and a high-voltage box. The high-voltage box includes a pre-charge unit, a positive switch, a negative switch, and a controller. The positive terminal of each battery unit is connected to the combiner module through a pre-charge unit, and the negative terminal of each battery unit is connected to the combiner module through a negative switch, forming a pre-charge circuit (i.e., a circuit where the positive terminal of the battery unit passes through the pre-charge unit, the combiner module, and the negative switch in sequence back to the negative terminal of the battery unit). The positive terminal of each battery unit is also connected to the combiner module through a positive switch, and the negative terminal of each battery unit is connected to the combiner module through a negative switch, forming a high-voltage circuit (i.e., a circuit where the positive terminal of the battery unit passes through the positive switch, the combiner module, and the negative switch in sequence back to the negative terminal of the battery unit). The control terminals of the pre-charge unit, the positive switch, and the negative switch in each group of energy storage modules are all connected to the controller in that group of energy storage modules, so that the controller can control the conduction, disconnection, conduction, and disconnection of the pre-charge circuit, the high-voltage circuit, and the high-voltage circuit in that group of energy storage modules.

[0062] In this embodiment of the application, powering on a battery device (or applying high voltage) may include: closing the positive and negative switches connected to the battery device to connect the battery device to the DC bus in the combiner module. Powering off a battery device (or applying high voltage) may include: disconnecting the positive and negative switches connected to the battery device to disconnect the battery device from the DC bus in the combiner module.

[0063] Figure 3 The diagram below illustrates the structure of an energy storage system provided in some embodiments. The energy storage system 300 includes R sub-battery systems: a first sub-battery system 1 to an Rth sub-battery system R. One of the R sub-battery systems includes one or more battery clusters. Each of the R sub-battery systems independently inputs or outputs energy, where R ≥ 2 and R is an integer.

[0064] The energy storage system 300 may include R bidirectional converter modules: a first bidirectional converter module 121 to an Rth bidirectional converter module 12R, which are respectively connected to a first sub-battery system 1 to an Rth sub-battery system R.

[0065] In some embodiments of this application, the energy storage system 300 may include R combiner devices: a first combiner device 131 to an Rth combiner device 13R, one end of which is connected to a first sub-battery system 1 to an Rth sub-battery system R respectively, and the other end of which is connected to a first bidirectional converter module 121 to an Rth bidirectional converter module 12R respectively.

[0066] In some embodiments of this application, one of the R sub-battery systems includes one or more main control boxes. For example, the first sub-battery system 1 may include a first A main control box 171 to an nA main control box 17n, one end of which is connected to a first A battery cluster to an nA battery cluster, and the other end of which is connected to a first combiner device 131. For example, the Rth sub-battery system R may include a first B main control box R71 to an mB main control box R7m, one end of which is connected to a first B battery cluster to an mB battery cluster, and the other end of which is connected to the Rth combiner device 13R.

[0067] The energy storage system 300 may further include cluster-level management units. Exemplarily, the number of cluster-level management units may be the same as the number of battery clusters in the energy storage system 300. Each battery cluster may be associated with one cluster-level management unit. The first sub-battery system 1 may include 1A to nA cluster-level management units 15n. Figure 3 In the example shown, one end of the first A cluster-level management unit 151 to the nA cluster-level management unit 15n is connected to the first A battery cluster to the nA battery cluster, respectively, and the other end of the first A cluster-level management unit 151 to the nA cluster-level management unit 15n is connected to the first combiner device 131. The Rth sub-battery system R may include the first B cluster-level management unit R51 to the mB cluster-level management unit R5m, one end of the first B cluster-level management unit R51 to the mB cluster-level management unit R5m is connected to the first B battery cluster to the mB battery cluster, respectively, and the other end of the first B cluster-level management unit R51 to the mB cluster-level management unit R5m is connected to the Rth combiner device 13R.

[0068] Optionally, the energy storage system 300 may further include an insulation detection module, which can be connected to the battery cluster and also to the central control unit 141 (i.e., the control device described above). The central control unit 141 may also be connected to the energy management unit 400.

[0069] In some embodiments of this application, the R sub-battery systems include a first sub-battery system 1 and a second sub-battery system, wherein the first sub-battery system 1 includes at least one battery cluster, the second battery system includes at least one battery cluster, and each battery cluster includes at least one battery module. This scheme can increase the power capacity of the energy storage system 300.

[0070] like Figure 3 As shown, in some embodiments of this application, the energy storage system 300 may further include a thermal management module 161, which is used to adjust the temperature of the R sub-battery systems.

[0071] The thermal management module 161 can lower the temperature of the sub-battery system when it is too high, and raise the temperature of the sub-battery system when it is too low. For example, the thermal management module 161 may include a heating module, a cooling module, and a fluid circulation loop. The heating or cooling module heats or cools the fluid in the fluid circulation loop, which is located around the battery clusters. The fluid then exchanges heat with the battery clusters of the sub-battery system to adjust the temperature of the sub-battery system.

[0072] The thermal management module 161 adjusts the temperature of the R sub-battery systems, which can reduce the space occupied by the thermal management module 161 and the structural components of the energy storage system 300, thereby improving the energy density of the energy storage system 300 and reducing costs.

[0073] The energy storage system 300 includes two sub-battery systems, which are placed side by side along the length of the energy storage system 300 (i.e., the length x of the housing). Each sub-battery system includes two rows of batteries, and each row of batteries includes two battery clusters. Each battery cluster is connected in parallel, and multiple battery modules within the battery cluster are connected in series. This arrangement is conducive to group installation.

[0074] Each battery device in the energy storage device may include battery clusters of one or more sub-battery systems from the first sub-battery system to the Rth sub-battery system. The control device may include a central control unit 141.

[0075] Balancing the state of charge (SOC) of each battery in an energy storage device can prevent large differences in SOC between the devices. This avoids issues such as excessive charging or discharging current in some batteries during charging or discharging, which could lead to overcharging or over-discharging of the cells. It can also prevent excessive charging or discharging current in some batteries, which could cause severe overheating. Furthermore, it can prevent large voltage differences between batteries, which could prevent some batteries from being powered on and thus fail to charge or discharge, resulting in low energy utilization. Finally, it can prevent inaccurate determination of the SOC of the energy storage device due to an unbalanced SOC among the batteries.

[0076] In related technologies, the state of charge (SOC) of the powered-on battery devices in an energy storage device is often balanced to achieve this balance. For example, in related technologies, after the battery devices in the energy storage device are powered on, they are charged to achieve SOC balance.

[0077] However, if there is a significant voltage difference between some battery cells and others in an energy storage device, some battery cells may fail to power on, making it impossible to perform state-of-charge (POC) balancing on these non-powerable cells. In related technologies, external power is often used to perform POC balancing on these non-powerable cells during energy storage device maintenance. However, using external power for POC balancing suffers from low efficiency in balancing the POC of the individual battery cells within the energy storage device.

[0078] To alleviate the above problems, research has shown that, based on the preset request current of the energy storage device, energy conversion is performed on some battery devices in the energy storage device until the battery devices other than the target battery device meet the power-on conditions. In this way, all battery devices in the energy storage device can be powered on, thereby avoiding the need to use an external power source to balance the state of charge of the battery devices that cannot be powered on, and improving the efficiency of the state of charge balancing of the battery devices in the energy storage device.

[0079] Based on the above considerations, this application provides a method for balancing the state of charge (SCC) of an energy storage device. The method involves determining a target battery device within the energy storage device based on the voltage of each battery device and the energy demand state of the energy storage device; the target battery device or a battery device other than the target battery device is supported for power-on; energy conversion is performed on the target battery device based on a preset current request from the energy storage device until the battery device other than the target battery device meets the power-on conditions; power is applied to the battery device other than the target battery device, and SCC is performed on each battery device. In this way, when the target battery device or other battery devices in the energy storage device cannot be powered on, the target battery device is powered on, and energy conversion is performed on the powered target battery device. This allows the voltage of the target battery device to gradually equalize with the voltage of other battery devices, so that the other battery devices also meet the power-on conditions. In this way, all battery devices in the energy storage device can be powered on. Even if there is a large voltage difference between some battery devices and other battery devices in the energy storage device, causing some battery devices to be unable to be powered on, the energy storage device's own charging or discharging function can also enable the battery devices that cannot be powered on. This achieves state-of-charge (POC) balancing for all battery devices in the energy storage device, avoiding the problem of low POC balancing efficiency caused by using external power sources. Therefore, it can improve the efficiency of POC balancing for each battery device in the energy storage device. Furthermore, when the POC of a battery device is close to its highest or lowest POC, the voltage change is large with the change in POC, that is, the voltage change corresponding to a unit change in POC is large. When the state of charge (SOC) of the device is close to the intermediate SOC, the voltage change is relatively small with the change in SOC; that is, the voltage change corresponding to a unit change in SOC is small. Therefore, by performing energy conversion on all battery devices until the voltage of any cell in at least one battery device reaches a preset voltage, the voltage change corresponding to a unit change in SOC of the battery device becomes larger. Since the SOC of the battery device is determined by the battery device's voltage, this reduces the possibility of a small error in voltage measurement leading to a large error in SOC, thus improving the reliability of the determined SOC of the battery device and the reliability of the SOC balance among the battery devices in the energy storage device. Furthermore, by ensuring that the voltage of any cell in at least one battery device in the energy storage device reaches the preset voltage, energy conversion ceases for each battery device once the voltage of any cell in the at least one battery device reaches the preset voltage, thereby reducing the probability of overcharging or over-discharging of the cells in the battery device and improving the operational reliability of the energy storage device.

[0080] For example, each step in the state-of-charge balancing method in the embodiments of this application can be applied to a control device in an energy storage device. The control device may include a main controller or a primary controller in the energy storage device.

[0081] Figure 4 A schematic flowchart of the state-of-charge balancing method for the energy storage device provided in the first embodiment is shown below. Figure 3 As shown, the method includes the following steps:

[0082] S401. Based on the voltage of each battery device in the energy storage device and the power demand status of the energy storage device, determine the target battery device in the energy storage device; the target battery device or a battery device other than the target battery device supports power-on.

[0083] For example, the energy storage device in the embodiments of this application may be one of the energy storage devices listed above or a variation thereof, and the embodiments of this application do not limit this.

[0084] Unless otherwise specified, the battery devices in the embodiments of this application can refer to each battery device among all battery devices in the energy storage device. In the embodiments of this application, "all battery devices in the energy storage device" can refer to all battery devices or all available battery devices.

[0085] The energy demand state in an energy storage device can include a charging demand state or a discharging demand state. When the energy storage device is in a charging demand state, it can receive external electrical energy to charge the powered battery, causing the state of charge and voltage of the powered battery to gradually increase. When the energy storage device is in a discharging demand state, it can release electrical energy to discharge the powered battery, causing the state of charge and voltage of the powered battery to gradually decrease.

[0086] For example, the state of energy demand in the energy storage device can be pre-configured to the energy storage device. As another example, the energy storage device is connected to external equipment (e.g., a power grid system), and the state of energy demand in the energy storage device is determined based on the power demand of the external equipment. As yet another example, the average voltage of all battery cells in the energy storage device can be obtained; if the average voltage is greater than the voltage corresponding to the target state of charge, the energy demand state of the energy storage device is determined to be a discharge demand state; if the average voltage is less than or equal to the voltage corresponding to the target state of charge, the energy demand state of the energy storage device is determined to be a charging demand state. The target state of charge can be a state of charge between 40% and 60% (e.g., 50%).

[0087] The target battery device may include one or more battery devices. The battery devices other than the target battery device are one or more battery devices in the energy storage device that are not part of the target battery device. For example, the battery devices other than the target battery device may be all battery devices in the energy storage device other than the target battery device, or it may be a portion of all battery devices. For example, the target battery device includes N battery devices (N is an integer greater than or equal to 1), and the battery devices other than the target battery device include M battery devices (M is an integer greater than or equal to 1). The voltage difference between each of the N battery devices and each of the M battery devices is greater than a first preset voltage threshold. Since if another battery device is also powered on after one battery device is powered on, it may cause a large current surge to the other battery device, affecting not only the operational reliability of the other battery device but also the operational reliability of the positive and negative switches connected to the other battery device. Therefore, the target battery device or the battery devices other than the target battery device cannot be powered on. The voltage difference value in the embodiments of this application includes the absolute value of the voltage difference. In some embodiments, the first preset voltage threshold may be greater than the allowable voltage difference for power-on.

[0088] For example, if the target battery device supports power-on, other battery devices do not support power-on. For example, if other battery devices are powered on, the target battery device does not support power-on.

[0089] For example, the energy storage device includes battery device X1, battery device X2, and battery device X3. Battery device X1 has a voltage of 900V, battery device X2 has a voltage of 905V, and battery device X3 has a voltage of 800V. The target battery device may include battery device X1 and battery device X2, and a battery device other than the target battery device may include battery device X3; alternatively, the target battery device may include battery device X3, and a battery device other than the target battery device may include battery device X1 and battery device X2.

[0090] In some embodiments, battery devices with voltage differences less than or equal to a first preset voltage threshold can be grouped into multiple groups. The group with the highest or lowest voltage among the multiple groups is identified as the target battery device, and the group with the voltage closest to the target battery device is identified as the battery device other than the target battery device.

[0091] For example, the energy storage device includes battery device X4, battery device X5, and battery device X6. Battery device X4 has a voltage of 900V, battery device X5 has a voltage of 800V, and battery device X6 has a voltage of 700V. If one of battery devices X4 to X6 supports power-on, the other battery devices do not. The target battery device is either the battery device with the highest voltage or the battery device with the lowest voltage among battery devices X4 to X6. The battery device other than the target battery device is battery device X5.

[0092] S402. Based on the preset request current of the energy storage device, perform energy conversion on the target battery device until the battery device other than the target battery device meets the power-on conditions.

[0093] The preset request current may include a charging current or a discharging current. In some embodiments, the preset request current may include a direct current, such as the current on the DC bus of the energy storage device or the current on the DC side of the power conversion system (PCS). In other embodiments, the preset request current may include an alternating current, such as the current on the AC side of the power conversion system. The following example illustrates the preset request current as including the current on the DC bus of the energy storage device. In some embodiments, the preset request current may be a request current with a constant current value; in other embodiments, the preset request current may be a request current with a changing current value.

[0094] Energy conversion of the target battery device may include charging the target battery device or discharging the target battery device.

[0095] When the voltage of the target battery device is lower than the voltage of other battery devices, the target battery device is charged to gradually reduce the voltage difference between the target battery device and the other battery devices. When the voltage of the target battery device is higher than the voltage of other battery devices, the target battery device is discharged to gradually reduce the voltage difference between the target battery device and the other battery devices.

[0096] In some embodiments, the power-on condition for a battery device other than the target battery device includes: the power-on condition includes a voltage difference between the voltage of the target battery device and the voltage of the battery device other than the target battery device being less than or equal to a second preset voltage threshold, wherein the second preset voltage threshold is less than a first preset voltage threshold.

[0097] The second preset voltage threshold can be a preset value. For example, in an energy storage device, if the voltage difference between one battery device and another is less than or equal to the second preset voltage threshold, both battery devices are allowed to be powered on. In some embodiments, the second preset voltage threshold can be less than or equal to the allowable voltage difference during power-on. In some embodiments, when the energy storage device is in a charging demand state, the second preset voltage threshold can be less than or equal to the difference between the allowable voltage difference during power-on and the battery device charging voltage difference; wherein, the battery device charging voltage difference refers to the difference between the DC bus voltage and the battery device voltage. For example, when multiple battery devices are charging simultaneously, the battery device charging voltage difference can include the voltage difference between the DC bus voltage and the highest voltage among the multiple battery devices. In some embodiments, when the energy storage device is in a discharging demand state, the second preset voltage threshold can be less than or equal to the difference between the allowable voltage difference during power-on and the battery device discharge voltage difference; wherein, the battery device discharge voltage difference refers to the difference between the battery device discharge voltage and the DC bus voltage. For example, when multiple battery devices are discharging simultaneously, the battery device discharge voltage difference can include the voltage difference between the lowest voltage among the multiple battery devices and the DC bus voltage.

[0098] In this embodiment, when the voltage of the target battery device increases or decreases, the DC bus voltage of the energy storage device also increases or decreases. For example, when the energy storage device is in a charging demand state, the maximum voltage in the DC bus of the energy storage device is greater than or equal to the charging voltage difference of the battery device. For example, when the energy storage device is in a discharging demand state, the minimum voltage in the target battery device is greater than or equal to the discharging voltage difference of the battery device.

[0099] S403. Power on the battery device other than the target battery device.

[0100] In some embodiments, powering on a battery device other than the target battery device may include setting the requested current of the energy storage device to 0 and powering on the battery device other than the target battery device.

[0101] For example, when the battery devices other than the target battery device include multiple battery devices (e.g., M battery devices greater than or equal to 2), energy conversion is performed on the target battery device according to the preset request current of the energy storage device until at least one of the M battery devices meets the power-on condition. At this time, there are K unpowered battery devices. The at least one battery device is incorporated into the last target battery device to obtain a new target battery device. Energy conversion is performed on the target battery device according to the preset request current of the energy storage device until at least one of the K battery devices meets the power-on condition. At this time, the at least one battery device is powered on. This process is repeated until all battery devices other than the target battery device meet the power-on condition and all M battery devices are powered on.

[0102] In this way, when the battery devices other than the target battery device are powered on, all battery devices in the energy storage device are powered on.

[0103] S404. When all battery devices in the energy storage device are powered on, energy conversion is performed on all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches a preset voltage, so as to balance the state of charge of all battery devices.

[0104] Continuing with battery devices X4 to X6, and taking battery device X4 as the target battery device as an example, battery device X4 is powered on and energy conversion is performed on it until battery device X5 meets the power-on conditions. Then, battery device X5 is powered on. However, battery device X6 still cannot be powered on. Battery devices X4 and X5 are then used as new target battery devices, and energy conversion is performed on the new target battery devices until battery device X6 meets the power-on conditions. Thus, all battery devices in the energy storage device are powered on, and the state of charge of each battery device can be balanced.

[0105] For example, the preset voltage may include a first set voltage. In some embodiments, performing energy conversion on all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches the preset voltage may include: charging each battery device in all battery devices until the voltage of any cell in each battery device is the first set voltage, or the state of charge of each battery device is the first preset state of charge, so that the state of charge of each battery device is balanced, or until the voltage of any cell in any battery device is the first set voltage, so that the state of charge of all battery devices is balanced.

[0106] For example, the preset voltage may include a second set voltage. In some embodiments, performing energy conversion on all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches the preset voltage may include: discharging each battery device in all battery devices until the voltage of any cell in each battery device is the second set voltage, or the state of charge of each battery device is the second preset state of charge, or until the voltage of any cell in any battery device is the second set voltage, so as to balance the state of charge of all battery devices.

[0107] Whether to charge or discharge each battery device depends on whether the energy storage device is in a charging or discharging demand state. When the energy storage device is in a charging demand state, each battery device is charged; when the energy storage device is in a discharging demand state, each battery device is discharged.

[0108] For example, the first set voltage may include the voltage value corresponding to a first preset state of charge. The first preset state of charge may include a state of charge greater than or equal to 95%. For example, the first preset state of charge may include 95%, 98%, or 100% state of charge. For example, the second set voltage may include the voltage value corresponding to a second preset state of charge. The second preset state of charge may include a state of charge less than or equal to 15%. For example, the second preset state of charge may include 15%, 10%, 5%, or 0% state of charge.

[0109] For example, when the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches a preset voltage, the rate of change of voltage of each battery device under a unit state of charge is greater than or equal to a set rate of change. Before energy conversion is performed on all battery devices in the energy storage device, the rate of change of voltage of each battery device under a unit state of charge is less than a set rate of change.

[0110] For example, when the cell voltage does not reach the preset voltage, the rate of change of the cell voltage per unit state of charge is less than the preset rate of change. When the cell voltage reaches the preset voltage, the rate of change of the cell voltage per unit state of charge is greater than or equal to the preset rate of change.

[0111] For example, both the first set voltage and the second set voltage can be voltages where the rate of change of the cell's voltage under a unit state of charge is greater than or equal to a preset rate of change. For example, when the cell's voltage is between the first set voltage and the second set voltage, the rate of change of the cell's voltage is less than the preset rate of change.

[0112] For example, setting the voltage of any cell in a battery device to a first set voltage can include setting the maximum voltage of the cell in the battery device to the first set voltage, thereby preventing overcharging of the cell. Similarly, setting the voltage of any cell in a battery device to a second set voltage can include setting the minimum voltage of the cell in the battery device to the second set voltage, thereby preventing over-discharging of the cell.

[0113] In this embodiment, the state of charge (SOC) of the energy storage device can be calibrated by equalizing the SOC of each battery device. For example, if the SOC of each battery device (i.e., the SOC of any single cell in each battery device) reaches 100%, the SOC of the energy storage device is calibrated to 100%. Alternatively, if the SOC of any single battery device (i.e., the SOC of any single cell in each battery device) reaches 0%, the SOC of the energy storage device is calibrated to 0%.

[0114] In the technical solution provided in this application embodiment, when the target battery device or other battery devices in the energy storage device cannot be powered on, the target battery device is powered on, and energy conversion is performed on the powered target battery device. This allows the voltage of the target battery device to gradually equalize with the voltage of other battery devices, so that the other battery devices also meet the power-on conditions. In this way, all battery devices in the energy storage device can be powered on. Even if the voltage difference between some battery devices and other battery devices in the energy storage device is large, causing some battery devices to be unable to be powered on, the charging or discharging function of the energy storage device itself can also enable the battery devices that cannot be powered on to be powered on. This achieves state-of-charge balancing for all battery devices in the energy storage device, avoiding the problem of low state-of-charge balancing efficiency caused by using an external power source. Therefore, it can improve the efficiency of state-of-charge balancing for each battery device in the energy storage device. Furthermore, when the state of charge of a battery device is close to the highest or lowest state of charge, the voltage change is large with the change in state of charge, that is, the voltage change corresponding to a unit change in state of charge is large. When the state of charge (SOC) of a battery device is close to the intermediate SOC, the voltage change is relatively small with the change in SOC; that is, the voltage change corresponding to a unit change in SOC is small. Therefore, by performing energy conversion on all battery devices until the voltage of any cell in at least one battery device reaches a preset voltage, the voltage change corresponding to a unit change in SOC increases. Since the SOC of a battery device is determined by its voltage, this reduces the possibility of a small voltage measurement error leading to a large error in the SOC, thus improving the reliability of the determined SOC and the reliability of SOC balance among the battery devices in the energy storage device. Furthermore, by ensuring that the voltage of any cell in at least one battery device reaches the preset voltage, energy conversion ceases for each battery device once the voltage of any cell reaches the preset voltage, reducing the probability of overcharging or over-discharging cells and improving the operational reliability of the energy storage device.

[0115] In some embodiments, determining a target battery device in an energy storage device based on the voltage of each battery device in the energy storage device and the power demand state of the energy storage device includes: determining a battery device with balanced voltage in the energy storage device as a first battery device, and determining battery devices other than the first battery device as second battery devices, based on the voltage of the first battery device, the voltage of the second battery device, and the power demand state of the energy storage device.

[0116] In a voltage-equalized battery device, the voltage difference between battery devices is less than or equal to a second preset voltage threshold.

[0117] For example, the first battery device may include a voltage-supported battery device, and the second battery device may include a voltage-unsupported battery device. In some embodiments, the first battery device may be powered on.

[0118] In some embodiments, the first battery device may include at least one battery device with the highest voltage value in the energy storage device, and the voltage difference between the at least one battery device is less than or equal to a second preset voltage threshold, while the voltage difference between the at least one battery device and other battery devices is greater than a first preset voltage threshold. In other embodiments, the first battery device may include at least one battery device with the lowest voltage value in the energy storage device, and the voltage difference between the at least one battery device is less than or equal to a second preset voltage threshold, while the voltage difference between the at least one battery device and other battery devices is greater than a first preset voltage threshold.

[0119] For example, if an energy storage device includes four battery devices with voltages of 900V, 895V, 890V, and 700V respectively, the first three battery devices can be designated as the first battery device, or the last battery device can be designated as the first battery device.

[0120] In the technical solution provided in this application, battery devices with similar voltage levels are classified as first battery devices, and the rest are classified as second battery devices. Based on this, the actual voltages of the first and second battery devices and the current power demand status of the energy storage system are combined to dynamically and reasonably select the target battery device. This avoids the problem of unreasonable selection of the target battery device, which would prevent other battery devices from meeting the power-on conditions even if the target battery device is charged or discharged. Therefore, the effectiveness of the determined target battery device is improved.

[0121] In some embodiments, the target battery device is determined based on the voltage of the first battery device, the voltage of the second battery device, and the energy demand state of the energy storage device, including at least one of the following:

[0122] When the energy demand state of the energy storage device is the charging demand state, and the voltage of the first battery device is less than the voltage of the second battery device, the first battery device is identified as the target battery device.

[0123] When the energy demand state of the energy storage device is the charging demand state, and the voltage of the first battery device is greater than the voltage of the second battery device, the second battery device is identified as the target battery device.

[0124] When the energy demand state of the energy storage device is the discharge demand state, and the voltage of the first battery device is less than the voltage of the second battery device, the second battery device is identified as the target battery device.

[0125] When the energy demand state of the energy storage device is the discharge demand state, and the voltage of the first battery device is greater than the voltage of the second battery device, the first battery device is identified as the target battery device.

[0126] For example, if the first battery device is powered on, the first battery device is identified as the target battery device. For example, if the first battery device is powered on, the first battery device is powered off, and the second battery device is powered on, and the second battery device is identified as the target battery device.

[0127] In the technical solution provided in this application embodiment, when the energy demand state of the energy storage device is a charging demand state, a battery device with a lower voltage is identified as the target battery device, so that the energy storage device charges the battery device with a lower voltage, thereby enabling other battery devices to meet the power-on conditions. When the energy demand state of the energy storage device is a discharging demand state, a battery device with a higher voltage is identified as the target battery device, so that the energy storage device discharges the battery device with a higher voltage, thereby enabling other battery devices to meet the power-on conditions. This avoids the problem of unreasonable selection of target battery devices, which would prevent other battery devices from meeting the power-on conditions even if the target battery device is charged or discharged. Therefore, the effectiveness of the identified target battery device is improved.

[0128] Figure 5 A schematic flowchart of the state-of-charge balancing method for the energy storage device provided in the second embodiment is shown below. Figure 5 As shown, Figure 5 The illustrated embodiments and Figure 4 The difference in the illustrated embodiment is that: the preset requested current includes a first requested current and a second requested current, and the second requested current is less than the first requested current; S402 includes:

[0129] S4021. Based on the first requested current, perform energy conversion on the powered target battery device until the voltage difference between the voltage of the target battery device and the voltage of the battery device other than the target battery device is less than or equal to the first preset voltage threshold.

[0130] For example, the first requested current may include a first charging current or a first requested current. If the first requested current is the first charging current, the target battery device is charged; if the first requested current is the first discharging current, the target battery device is discharged.

[0131] For example, the first requested current may include the maximum requested current of the energy storage device. For example, the first requested current may be determined by: acquiring the battery device with the smallest voltage difference from the DC bus voltage among the target battery devices; acquiring an ammeter that includes the maximum current under multiple consecutive temperature ranges and / or multiple consecutive state of charge ranges; acquiring the temperature and / or state of charge of the battery device; determining the maximum current of the battery device based on the temperature and / or state of charge of the battery device and the ammeter; and determining the first requested current as the product of the maximum current of the battery device and the number of battery devices in the target battery device.

[0132] In some embodiments, if the voltage difference between the voltage of the target battery device and the voltage of a battery device other than the target battery device is less than or equal to a first preset voltage threshold, the requested current of the energy storage device can be set to 0, and S4022 can be executed after a set time interval, thereby minimizing the impact of polarization voltage.

[0133] S4022. Based on the second requested current, perform energy conversion on the target battery device until the battery device other than the target battery device meets the power-on conditions.

[0134] For example, the second requested current may include a second charging current or a second discharging current. If the second requested current is a second charging current, the target battery device is charged; if the second requested current is a second discharging current, the target battery device is discharged.

[0135] The first request current and the second request current are either both charging currents or both discharging currents.

[0136] In some embodiments, the first requested current and the second requested current may both include DC current, such as the current of the DC bus in the energy storage device or the current on the DC side of the energy storage converter.

[0137] In some embodiments, both the first requested current and the second requested current can be fixed currents. In other embodiments, both the first requested current and the second requested current can be variable currents, or one requested current can be a fixed current and the other requested current can be a variable current.

[0138] For example, the second requested current can be the difference between the first requested current and a preset current. Also for example, the second requested current can be the ratio between the first requested current and a preset coefficient, where the preset coefficient is greater than 1.

[0139] In the technical solution provided in this application embodiment, since the second requested current is less than the first requested current, the scheme of converting energy for the powered target battery device according to the second requested current, compared with the scheme of converting energy for the powered target battery device according to the first requested current, can reduce the polarization voltage of the battery device due to charging or discharging. When the requested current of the energy storage device is set to 0 and a battery device other than the target battery device is powered on, even if the target battery device is undergoing a depolarization process, the measured voltage of the target battery device is closer to the actual voltage of the target battery device because the polarization voltage of the target battery device is lower. This not only avoids the situation where the polarization voltage of the target battery device is too high, and the voltage difference between the target battery device and other battery devices after depolarization is no longer less than or equal to the second preset voltage threshold, thus preventing the other battery devices from being powered on, but also improves the efficiency of the state of charge balancing of the energy storage device. It also avoids the problem that a large voltage difference between the target battery device and other battery devices leads to an uneven distribution of current to these two types of battery devices, causing some battery devices to overheat and thus affecting the operational reliability of the energy storage device. Therefore, it can improve the operational reliability of the energy storage device.

[0140] In some embodiments, the power-on condition for a battery device other than the target battery device includes at least one of the following: the voltage difference between the voltage of the target battery device and the voltage of the battery device other than the target battery device is less than or equal to a second preset voltage threshold for a duration greater than or equal to a first preset duration; the duration of energy conversion of the target battery device powered on according to the second requested current is greater than or equal to the second preset duration; and the second preset voltage threshold is less than the first preset voltage threshold.

[0141] Unless otherwise specified, in the embodiments of this application, when the target battery device is a single battery device, the voltage of the target battery device is the measured voltage of the target battery device. When the target battery device consists of multiple battery devices, the voltage of the target battery device may include the maximum, minimum, or average value of the measured voltages of the multiple battery devices. Unless otherwise specified, in the embodiments of this application, when there is a single battery device other than the target battery device, the voltage of the battery device other than the target battery device is the measured voltage of the battery device other than the target battery device. When there are multiple battery devices other than the target battery device, the voltage of the battery device other than the target battery device may include the maximum, minimum, or average value of the measured voltages of the multiple battery devices other than the target battery device.

[0142] In some instances, the first preset duration can be a predefined fixed duration, and the second preset duration can be a predefined fixed duration. The first preset duration is shorter than the second preset duration.

[0143] In the technical solution provided in this application embodiment, by ensuring that the voltage difference between the target battery device and the voltage of a battery device other than the target battery device is less than or equal to a second preset voltage threshold for a duration greater than or equal to a first preset duration, the problem of uneven current distribution from the energy storage device to the two battery devices is avoided. This is because the target battery device has a polarization voltage, which causes inconsistency between the actual voltage and the measured voltage of the target battery device when the voltage difference initially falls below or equals the second preset voltage threshold. Furthermore, by ensuring that the energy conversion time of the powered target battery device according to the second requested current is greater than or equal to the second preset duration, sufficient time is provided to reduce the large polarization voltage. This large polarization voltage is the polarization voltage generated by the target battery device when the first requested current is used for energy conversion. This reduces the polarization voltage of the target battery device, decreases the difference between the measured voltage and the actual voltage of the target battery device, and improves the accuracy of the determined voltage of the target battery device.

[0144] In some embodiments, determining that a battery device other than the target battery device meets the power-on conditions includes: determining the polarization voltage of the target battery device based on a preset request current of the energy storage device and the voltage of the target battery device; determining the voltage difference between the voltage of the target battery device and the polarization voltage of the target battery device as the actual voltage of the target battery device; and determining that the battery device other than the target battery device meets the power-on conditions if the voltage difference between the actual voltage of the target battery device and the voltage of the battery device other than the target battery device is less than or equal to a second preset voltage threshold.

[0145] In some embodiments, the operating current of each battery device in the target battery device can be determined based on the preset requested current of the energy storage device, and the polarization voltage of each battery device in the target battery device can be determined based on the operating current of each battery device in the target battery device and the voltage of each battery device in the target battery device.

[0146] For example, for any one of the target battery devices, when the battery device is charging, the higher the voltage of the battery device, the higher the polarization voltage of the battery device; and the higher the operating current of the battery device, the higher the polarization voltage of the battery device. When the battery device is discharging, the lower the voltage of the battery device, the higher the polarization voltage of the battery device; and the higher the operating current of the battery device, the higher the polarization voltage of the battery device.

[0147] In some embodiments, a polarization voltmeter can be obtained, which includes polarization voltages corresponding to different requested currents in each of a plurality of consecutive voltage ranges. The polarization voltage of the target battery device is determined based on the polarization voltmeter, the preset requested current of the energy storage device, and the voltage of the target battery device.

[0148] In the technical solution provided in this application embodiment, the voltage difference between the voltage of the target battery device and the polarization voltage of the target battery device is determined as the actual voltage of the target battery device. Since the battery devices other than the target battery device have not yet been charged or discharged, their voltages are also the actual voltages. Therefore, based on the actual voltages of the target battery device and the battery devices other than the target battery device, it is determined whether the battery devices other than the target battery device meet the power-on conditions. This improves the accuracy of determining whether the battery devices other than the target battery device meet the power-on conditions and reduces the actual voltage difference between the target battery device and the battery devices other than the target battery device.

[0149] In some embodiments, the method further includes: determining a target requested current for each battery device in the target battery device based on a voltage difference between the voltage of the target battery device and the voltage of battery devices other than the target battery device; and determining a preset requested current based on the number of battery devices in the target battery device and the target requested current for each battery device in the target battery device.

[0150] For example, the larger the voltage difference value, the higher the target requested current of each battery device in the target battery device; the smaller the voltage difference value, the lower the target requested current of each battery device in the target battery device.

[0151] In some embodiments, the maximum requested current of each battery device in the target battery device can be obtained, the ratio of the voltage difference value to the maximum requested current of each battery device can be determined as the requested current decrease rate, and the target requested current of each battery device in the target battery device can be determined based on the requested current decrease rate and the current voltage difference value.

[0152] In other embodiments, the maximum requested current of each battery device in the target battery device can be obtained. The larger the voltage difference value, the higher the rate of change of the target requested current of each battery device. The smaller the voltage difference value, the lower the rate of change of the target requested current of each battery device, thereby minimizing the polarization voltage generated by each battery device in the target battery device.

[0153] In some embodiments, the preset requested current can be determined by multiplying the number of battery devices in the target battery device by the target requested current of each battery device in the target battery device.

[0154] In the technical solution provided in this application embodiment, the target requested current of each battery device in the target battery device can be flexibly determined according to the voltage difference value. When the voltage difference value is large, the target requested current of each battery device in the target battery device is increased, thereby improving the energy conversion rate of the target battery device. When the voltage difference value is small, the target requested current of each battery device in the target battery device is reduced, thereby reducing the polarization voltage of each battery device in the target battery device. This not only improves the accuracy of whether the battery devices other than the target battery device meet the power-on conditions, but also reduces the actual voltage difference between the target battery device and the battery devices other than the target battery device.

[0155] In some embodiments, the preset voltage includes a first set voltage; energy conversion is performed on all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches the preset voltage, including: when the energy demand state of the energy storage device is a charging demand state, charging all battery devices in the energy storage device until the voltage of any cell in each energy storage device of all battery devices reaches the first set voltage.

[0156] In some embodiments, the preset voltage includes a second preset voltage; energy conversion is performed on all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches the preset voltage, including: discharging all battery devices in the energy storage device when the energy demand state of the energy storage device is a discharge demand state until the voltage of any cell in any battery device in the energy storage device reaches the second preset voltage.

[0157] Figure 6 A schematic flowchart of the state-of-charge balancing method for the energy storage device provided in the third embodiment is shown below. Figure 6 As shown, Figure 6 The illustrated embodiments and Figure 4 The difference in the illustrated embodiment is that S404 includes the following steps:

[0158] S4041. When the energy demand state of the energy storage device is the charging demand state, all battery devices in the energy storage device are charged until the voltage of any cell in each energy storage device reaches the first set voltage, so as to balance the state of charge of all battery devices.

[0159] For example, charging all the battery devices in an energy storage device may include: simultaneously charging the powered battery devices in the energy storage device.

[0160] The explanation of the first set voltage can be found in the description of the above embodiments, and will not be repeated here.

[0161] S4042. When the energy demand state of the energy storage device is the discharge demand state, all battery devices in the energy storage device are discharged until the voltage of any cell in any battery device in the energy storage device reaches the second set voltage, so as to balance the state of charge of all battery devices.

[0162] For example, discharging all battery devices in an energy storage device may include simultaneously discharging the powered battery devices in the energy storage device.

[0163] The explanation of the second set voltage can be found in the description of the above embodiments, and will not be repeated here.

[0164] For example, the first set voltage can be a voltage value corresponding to a 95% state of charge, and the first set voltage can be a voltage value whose rate of change of voltage relative to the state of charge is greater than or equal to a preset rate of change.

[0165] For example, the second set voltage can be a voltage value corresponding to a state of charge of less than or equal to 15%, and the second set voltage can be a voltage value whose rate of change of voltage relative to the state of charge is greater than or equal to a preset rate of change.

[0166] If a cell's voltage falls within a range where the rate of change of voltage relative to its state of charge (SOC) is less than a preset rate (e.g., the voltage corresponding to 15% to 95% SOC), the voltage change is minimal as the SOC changes. Therefore, due to voltage measurement errors, the determined SOC of the cell is inaccurate, leading to significant differences in SOC between cells and hindering the achievement of SOC balance across battery packs. Conversely, if a cell's voltage falls within a range where the rate of change of voltage relative to its SOC is greater than a preset rate (e.g., the voltage corresponding to 15% SOC, or greater than or equal to 95% SOC), the voltage change is significant as the SOC changes. Therefore, the accurate SOC determined based on the measured cell voltage is beneficial for achieving effective SOC balance across battery packs.

[0167] In the technical solution provided in this application embodiment, by having the voltage of any cell in each energy storage device of the entire battery device reach a first set voltage, and the voltage of any cell in any battery device in the energy storage device reach a second set voltage, the state of charge (SOC) of the cell can be accurately determined through the cell voltage. Furthermore, the SOC of the battery device can be determined through the cell SOC, thus improving the reliability of determining the SOC of each battery device in the energy storage device and improving the effectiveness of SOC balancing for each battery device. Moreover, by having the voltage of any cell in any battery device in the energy storage device reach a first set voltage, the SOC of the battery device can be accurately determined through the cell voltage. By setting a voltage, charging is stopped once the voltage of any cell in any battery device reaches a first set voltage, reducing the probability of overcharging the cells in the battery device. By ensuring that the voltage of any cell in any battery device in the energy storage device reaches a second set voltage, the voltage of all battery devices in the energy storage device is prevented from reaching the second set voltage, which would result in all battery devices in the energy storage device being at a very low voltage and causing over-discharge of the battery device due to self-discharge. Therefore, the embodiments of this application can reduce the probability of over-discharge of the battery device and improve the reliability of the energy storage device operation.

[0168] In some embodiments, charging all battery devices in an energy storage device until the voltage of any cell in each energy storage device reaches a first set voltage includes: acquiring a charging request current of the energy storage device and charging the battery devices in the powered-on state according to the charging request current of the energy storage device; when the voltage of any cell in any battery device in the powered-on state reaches the first set voltage, controlling the charging current of the energy storage device to 0, powering off any battery device, and proceeding to the step of acquiring the charging request current of the energy storage device until all battery devices are powered off.

[0169] In some embodiments, when the voltage of any cell in any battery device in the powered-on state reaches a fourth set voltage, and the fourth set voltage is less than the first set voltage and has a small interval between the two, the battery device in the powered-on state can be charged with a charging current smaller than the charging request current, thereby reducing the impact of polarization voltage.

[0170] In the technical solution provided in this application embodiment, by powering down any battery device when the voltage of any cell in any battery device in the powered-on state reaches a first set voltage, overcharging of the battery device is avoided, thereby improving the operational reliability of the energy storage device. Furthermore, by first controlling the charging current of the energy storage device to 0 before powering down any battery device, not only is the current surge generated by the switch connected to the battery device due to the large current disconnection, which could easily damage the switch, avoided, but the current surge generated by the switch disconnection could also prevent overcharging of the battery device, thereby further improving the operational reliability of the energy storage device.

[0171] In some embodiments, the method may further include: when all battery devices are powered down, powering on all battery devices at intervals of a preset waiting time, starting from the end time when all battery devices are powered down.

[0172] For example, the preset waiting time can be a fixed duration. Alternatively, the preset waiting time can be determined based on the charging request current of the energy storage device, where charging the battery device in its powered-on state is determined by the polarization voltage of the battery device. For instance, the larger the charging request current, the larger the polarization voltage of the battery device, and the longer the preset waiting time. In some embodiments, a mapping relationship can be obtained, which includes a waiting time corresponding to each of a plurality of consecutive battery device polarization voltage ranges. The preset waiting time is determined based on this mapping relationship and the polarization voltage of the battery device.

[0173] In this embodiment, it is noted that in related technologies, when performing state-of-charge balancing on battery devices, the battery device is powered off whenever it is fully charged (e.g., when the voltage of any cell in the battery device reaches the voltage corresponding to 100% state of charge). When the last battery device is fully charged, the powered-off battery device is powered on. However, related technologies do not consider that the different power-off times of the battery devices in the energy storage device lead to inconsistent depolarization times, resulting in inconsistent battery device voltages. This can lead to excessively large voltage differences among the battery devices in the energy storage device, preventing some battery devices from being powered on. In this embodiment, by starting from the end of the power-off of all battery devices and waiting for a preset time interval, all battery devices are powered on. This ensures that the depolarization time of each battery device is at least greater than or equal to the preset waiting time, thereby minimizing the impact of the planned voltage on the battery device's voltage and preventing excessively large voltage differences among the battery devices in the energy storage device.

[0174] In the technical solution provided in this application embodiment, when each battery device is powered off, each battery device begins depolarization. Since the power-off times of different battery devices are different, the depolarization duration of different battery devices is different, resulting in differences in the measured voltage of different battery devices. By starting from the end time when all battery devices are powered off and then waiting for a preset time interval, the depolarization duration of each battery device is at least the preset waiting time, so as to avoid the polarization voltage of the battery device from affecting the measured voltage of the cell as much as possible. That is, the measured voltage of different battery devices is different, thereby reducing the circulating current generated in the battery devices after all battery devices are powered on, and reducing the energy loss of the battery devices in the energy storage device.

[0175] In some embodiments, obtaining the charging request current of the energy storage device includes: obtaining the number of battery devices in a powered-on state and the characteristic voltage of the battery devices in a powered-on state; determining a target charging current for each battery device in a powered-on state based on the characteristic voltage of the battery devices in a powered-on state; and determining the charging request current of the energy storage device based on the number of battery devices in a powered-on state and the target charging current of each battery device in a powered-on state.

[0176] When a battery device in a powered state comprises a single battery device, the voltage of that single battery device is determined as the characteristic voltage. When a battery device in a powered state comprises multiple battery devices, the maximum, minimum, or average value of the voltages of the multiple battery devices is determined as the characteristic voltage.

[0177] For example, the energy storage device contains P battery devices (P being an integer greater than or equal to 2). When all P battery devices are powered on, the charging request current corresponding to each of the P battery devices is determined based on P and the characteristic voltages of the P battery devices. Based on the charging request currents corresponding to the P battery devices, the P battery devices are charged synchronously. When the voltage of a cell in at least one of the P battery devices reaches the full charge voltage (i.e., the charging voltage corresponding to 100% state of charge), that battery device is powered off. At this point, the number of battery devices in the powered-on state is P- 1. Determine the charging request current corresponding to P-1 battery devices based on the characteristic voltages of P-1 and P-1 battery devices. Based on the charging request current corresponding to P-1 battery devices, synchronously charge P-1 battery devices. When the voltage of the cell in at least one of the P-1 battery devices reaches the full charge voltage (i.e., the charging voltage corresponding to 100% state of charge), power off that battery device. At this time, the number of battery devices in the powered-on state is P-2. And so on, until all battery devices in the energy storage device (i.e., P battery devices) are powered off.

[0178] In some implementations, determining the target charging current for each powered-on battery device based on the characteristic voltage of the powered-on battery device may include: acquiring a first charging current meter, the first charging current meter including the maximum charging current in each of a plurality of consecutive voltage ranges, and determining the target charging current for each powered-on battery device based on the first charging current meter and the characteristic voltage of the powered-on battery device.

[0179] In other embodiments, determining the target charging current for each battery device in a powered-on state based on the characteristic voltage of the battery device in a powered-on state may include: acquiring a second charging current meter, the second charging current meter including the maximum charging current in each of a plurality of consecutive state of charge intervals, and determining the target charging current for each battery device in a powered-on state based on the second charging current meter and the state of charge corresponding to the characteristic voltage of the battery device in a powered-on state.

[0180] In some other embodiments, determining the target charging current for each battery device in a powered-on state based on the characteristic voltage of the battery device in a powered-on state may include: acquiring a third charging ammeter and the maximum temperature of the battery device in a powered-on state, the third charging ammeter including the maximum charging current under a series of consecutive temperature ranges and / or a series of consecutive state of charge ranges, and determining the target charging current for each battery device in a powered-on state based on the third charging ammeter, the characteristic voltage of the battery device in a powered-on state, and the maximum temperature of the battery device in a powered-on state.

[0181] In some implementations, the charging request current of the energy storage device can be determined by multiplying the number of battery devices in the powered-on state and the target charging current of each battery device in the powered-on state.

[0182] In the technical solution provided in this application embodiment, the target charging current of each battery device in the powered-on state is determined based on the characteristic voltage of the battery device in the powered-on state. This avoids the situation where the target charging current is a fixed charging current, which does not take into account the influence of the characteristic voltage of the battery device, thus leading to the battery cells in the battery device being easily damaged by overcharging or the battery device having low charging current resulting in low charging efficiency. Furthermore, the charging request current of the energy storage device is determined based on the number of battery devices in the powered-on state and the target charging current of each battery device in the powered-on state. This avoids the situation where the charging request current of the energy storage device is fixed, which leads to the battery devices being easily damaged by overcharging or the battery device having low charging current resulting in low charging efficiency when the number of battery devices in the powered-on state decreases. Therefore, the effectiveness of the determined target charging current of each battery device in the powered-on state can be improved.

[0183] In some embodiments, discharging all battery devices in the energy storage device until the voltage of any cell in any battery device in the energy storage device reaches a second preset voltage includes: acquiring a first discharge request current of the energy storage device, and discharging the battery devices in the powered-on state according to the first discharge request current of the energy storage device; acquiring a second discharge request current of the energy storage device when the voltage of any cell in any battery device in the powered-on state is less than or equal to a third preset voltage; the third preset voltage is greater than the second preset voltage, and the second discharge request current is less than the first discharge request current; discharging the battery devices in the powered-on state according to the second discharge request current of the energy storage device until the voltage of any cell in any battery device is less than or equal to the second preset voltage, and controlling the discharge current of the energy storage device to be 0, thus completing the discharge of all battery devices.

[0184] For example, the voltage difference between the third set voltage and the second set voltage is less than or equal to the preset voltage difference, thereby reducing the polarization of the battery device while improving the discharge efficiency of the battery device.

[0185] In some embodiments, the second discharge request current may be a preset value. In other embodiments, the second discharge request current may be determined based on the first discharge request current. For example, exemplarily, the second discharge request current may be the difference between the first discharge request current and a preset current. Also exemplarily, the second discharge request current may be the ratio between the first discharge request current and a preset coefficient, where the preset coefficient is greater than 1.

[0186] In the technical solution provided by this application embodiment, the battery device in the powered-on state is first discharged according to the first discharge request current of the energy storage device, and then discharged according to the second discharge request current which is less than the first discharge request current. This avoids the problem that using a large first discharge request current to discharge the battery device in the powered-on state can easily lead to an excessively high polarization voltage of the battery device, a large difference between the obtained voltage of the battery device and the actual voltage of the battery device, and consequently, a large difference between the voltage of the battery device and the second set voltage. This results in an inaccurate state of charge of the battery device determined based on the voltage of the battery device. Therefore, this application embodiment can improve the accuracy of the determined state of charge of the battery device, thereby improving the effectiveness of balancing the state of charge of each battery device.

[0187] In some embodiments, obtaining a first discharge request current of an energy storage device includes: obtaining the number of battery devices in a powered-on state and the characteristic voltage of the battery devices in a powered-on state; determining a target discharge current for each battery device in a powered-on state based on the characteristic voltage of the battery devices in a powered-on state; and determining a first discharge request current of the energy storage device based on the number of battery devices in a powered-on state and the target discharge current of each battery device in a powered-on state.

[0188] For example, the energy storage device contains P battery devices (P is an integer greater than or equal to 2). When all P battery devices are powered on, the discharge request current corresponding to each of the P battery devices is determined based on P and the characteristic voltages of the P battery devices. Based on the discharge request currents corresponding to the P battery devices, the P battery devices are synchronously discharged. When the voltage of a cell in at least one of the P battery devices reaches a second set voltage (e.g., a discharge cutoff voltage), the discharge current of the energy storage device is controlled to be 0. This embodiment does not require all battery devices in the energy storage device to discharge to the second set voltage. Instead, only when the voltage of any cell in any battery device reaches the second set voltage is the discharge of all battery devices stopped. Thus, when the discharge current of the energy storage device is controlled to be 0, the circulating current between the battery devices will cause the voltage of that cell to be slightly higher than the second set voltage, thereby avoiding the problem of over-discharge of the cell due to self-discharge and improving the operational reliability of the energy storage device.

[0189] In some implementations, determining the target discharge current for each powered-on battery device based on the characteristic voltage of the powered-on battery device may include: acquiring a first discharge current meter, the first discharge current meter including the maximum discharge current in each of a plurality of consecutive voltage ranges, and determining the target discharge current for each powered-on battery device based on the first discharge current meter and the characteristic voltage of the powered-on battery device.

[0190] In other embodiments, determining the target discharge current for each powered-on battery device based on the characteristic voltage of the powered-on battery device may include: acquiring a second discharge current meter, which includes the maximum discharge current in each of a plurality of consecutive state of charge intervals, and determining the target discharge current for each powered-on battery device based on the second discharge current meter and the state of charge corresponding to the characteristic voltage of the powered-on battery device.

[0191] In some other embodiments, determining the target discharge current for each powered-on battery device based on the characteristic voltage of the powered-on battery device may include: acquiring a third discharge ammeter and the maximum temperature of the powered-on battery device, the third discharge ammeter including the maximum discharge current under a series of consecutive temperature ranges and / or a series of consecutive state of charge ranges, and determining the target discharge current for each powered-on battery device based on the third discharge ammeter, the characteristic voltage of the powered-on battery device, and the maximum temperature of the powered-on battery device.

[0192] In some implementations, the first discharge request current of the energy storage device can be determined by multiplying the number of battery devices in the powered-on state and the target discharge current of each battery device in the powered-on state.

[0193] In the technical solution provided in this application embodiment, the target discharge current of each battery device in the powered-on state is determined based on the characteristic voltage of the battery device in the powered-on state. This avoids the situation where the target discharge current is a fixed discharge current, which does not take into account the influence of the characteristic voltage of the battery device. This would lead to the battery cells in the battery device being easily damaged by over-discharge or the battery device having low discharge current, resulting in low discharge efficiency. Therefore, the effectiveness of the determined target discharge current of each battery device in the powered-on state can be improved.

[0194] In some embodiments, the Energy Management System (EMS) sends a state-of-charge (POC) balancing command to the control device. The control device can determine whether the operating current of the energy storage device (e.g., the current of the DC bus or the current of the battery device) is less than or equal to a specified current. If it is less than or equal to the specified current, it indicates that the energy storage device is not in a normal charging or discharging state, and POC balancing can be performed, limiting the requested current of the energy storage device to 0. If it is greater than the specified current, it indicates that the energy storage device is in a normal charging or discharging state, and POC balancing cannot be performed, otherwise it will affect the normal charging or discharging of the energy storage device. The control device can then report the reason why POC balancing cannot be performed to the EMS. When the operating current of the energy storage device is less than or equal to the specified current, the control equipment can also determine whether all battery devices are in a powered-on state. If so, it can perform state-of-charge (POC) balancing, determining whether to perform POC balancing under charging or discharging conditions. If not, it can determine whether the unpowered battery devices are faulty. If a fault exists, it can report the reason why POC balancing cannot be performed to the EMS. If the unpowered battery devices are not faulty, it can perform POC balancing, powering on all battery devices that can be powered on, and determining whether to perform POC balancing under charging or discharging conditions.

[0195] The following sections explain the state-of-charge (POC) balancing process during charging and discharging, respectively:

[0196] State of charge equilibrium during charging:

[0197] If there are unpowered battery devices, it indicates that the voltage difference between the battery devices in the energy storage device is large, and this voltage difference does not support the power-on of all battery devices. In this case, the process starts from step A1. If there are no unpowered battery devices, it indicates that all battery devices in the energy storage device have been powered on. In this case, the process starts from step A3.

[0198] Step A1: If the voltage of the unpowered battery device is greater than the voltage of the powered battery device, perform the following steps (1), (2) and (3). If the voltage of the unpowered battery device is less than the voltage of the powered battery device, perform the following steps (4), (1), (2) and (3).

[0199] Step (1): The control device charges the powered battery device according to the first charging current of the energy storage device (including the first requested current) until the absolute value of the voltage difference between the average voltage of the powered battery device and the voltage of any unpowered battery device is less than or equal to the first preset voltage threshold.

[0200] Step (2): The control device charges the powered battery device according to the second charging current of the energy storage device (including the second request current, where the second charging current is less than the first charging current) until any one or more unpowered battery devices meet the power-on conditions, such as the DC bus voltage being less than or equal to the second preset voltage threshold and greater than or equal to the polarization voltage for a duration greater than or equal to the first preset duration, and the charging time of the powered battery device according to the second charging current of the energy storage device being greater than or equal to the second preset duration.

[0201] Step (3): Power on one or more unpowered battery devices. After step (3), proceed to step A2.

[0202] In step (3), powering on any one or more unpowered battery devices may include: first setting the charging current in the energy storage device to 0, and then powering on any one or more unpowered battery devices.

[0203] Step (4): The control device controls the already powered-on battery device to power off, so that the previously unpowered battery device can be powered on. At this time, the control device controls at least one previously unpowered battery device to power on. The previously unpowered battery device is the one with the lowest voltage among the previously unpowered battery devices, and the voltage difference is less than or equal to the second preset voltage threshold.

[0204] Step A2: Determine if there are any unpowered battery devices.

[0205] If there is a battery device that is not powered on, proceed to step A1; if there is no battery device that is not powered on, proceed to step A3.

[0206] Step A3: The control device charges all battery devices in the energy storage device according to the charging request current of the energy storage device. When the voltage of any cell in any battery device reaches the first set voltage (e.g., full charge voltage), the charging current in the energy storage device is set to 0, the battery device is powered off, and the charging current is restored. Then, the powered battery devices are charged according to the charging request current of the energy storage device, and so on, until all battery devices are powered off.

[0207] Step A4: At the moment when the last battery device is powered down, after a preset waiting time, control all battery devices in the energy storage device to be powered up, and the state of charge of the battery devices is balanced.

[0208] In any embodiment of this application, when the state of charge equalization of the battery devices is completed, the voltage in each battery device can be obtained, and the state of charge of each battery device can be determined based on the voltage of each battery device. Alternatively, the state of charge of each battery device can be determined based on the lowest voltage among the cell voltages in each battery device. For example, the state of charge corresponding to the lowest voltage among the cell voltages in each battery device can be determined as the state of charge of that battery device.

[0209] State of charge equilibrium during discharge:

[0210] If there are unpowered battery devices, it indicates that the voltage difference between the battery devices in the energy storage device is large, and this voltage difference does not support the power-on of all battery devices. In this case, the process starts from step B1. If there are no unpowered battery devices, it indicates that all battery devices in the energy storage device have been powered on. In this case, the process starts from step B3.

[0211] Step B1: If the voltage of the unpowered battery device is greater than the voltage of the powered battery device, perform the following steps (4), (1), (2) and (3). If the voltage of the unpowered battery device is less than the voltage of the powered battery device, perform the following steps (1), (2) and (3).

[0212] Step (1): The control device discharges the powered battery device according to the first discharge current of the energy storage device (including the first requested current) until the absolute value of the voltage difference between the average voltage of the powered battery device and the voltage of any unpowered battery device is less than or equal to the first preset voltage threshold.

[0213] Step (2): The control device discharges the powered battery device according to the second discharge current of the energy storage device (including the second request current, where the second discharge current is less than the first discharge current) until any one or more unpowered battery devices meet the power-on conditions, such as the DC bus voltage being less than or equal to the second preset voltage threshold and the duration being greater than or equal to the polarization voltage being greater than or equal to the first preset duration, and the duration of discharging the powered battery device according to the second discharge current of the energy storage device being greater than or equal to the second preset duration.

[0214] Step (3): Power on one or more unpowered battery devices. After step (3), proceed to step B2.

[0215] In step (3), powering on any one or more unpowered battery devices may include: first setting the discharge current in the energy storage device to 0, and then powering on any one or more unpowered battery devices.

[0216] Step (4): The control device controls the already powered-on battery device to power off, so that the previously unpowered battery device can be powered on. At this time, the control device controls at least one previously unpowered battery device to power on. The previously unpowered battery device is the one with the lowest voltage among the previously unpowered battery devices, and the voltage difference is less than or equal to the second preset voltage threshold.

[0217] Step B2: Determine if there are any unpowered battery devices.

[0218] If there is a battery device that is not powered on, proceed to step B1; if there is no battery device that is not powered on, proceed to step B3.

[0219] Step B3: The control device discharges all battery cells in the energy storage device according to the first discharge request current. When the voltage of any cell in any battery cell reaches the third preset voltage, the control device discharges all battery cells in the energy storage device according to the second discharge request current until the voltage of any cell in any battery cell reaches the second preset voltage. At this point, the discharge current of the energy storage device is controlled to be 0, and the state of charge balancing of the battery cells is completed. The second discharge request current is less than the first discharge request current.

[0220] Based on the same inventive concept, this application also provides a state-of-charge (SOC) equalization device for implementing the aforementioned SOC equalization method. The solution provided by this device is similar to the implementation described in the above method; therefore, the specific limitations of one or more SOC equalization device embodiments provided below can be found in the limitations of the SOC equalization method described above, and will not be repeated here.

[0221] In one exemplary embodiment, Figure 7 Here are some schematic diagrams of the state-of-charge balancing device provided in some embodiments, such as Figure 7 As shown, the state-of-charge equalization device 700 includes:

[0222] The determination module 701 is used to determine the target battery device in the energy storage device based on the voltage of each battery device in the energy storage device and the power demand status of the energy storage device; the target battery device or the battery device other than the target battery device supports power-on.

[0223] The energy conversion module 702 is used to convert energy for the target battery device that is powered on, according to the preset request current of the energy storage device, until the battery device other than the target battery device meets the power-on conditions.

[0224] The balancing module 703 is used to power on battery devices other than the target battery device, and when all battery devices in the energy storage device are powered on, to perform energy conversion on all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches a preset voltage, so as to balance the state of charge of all battery devices.

[0225] In some embodiments, the determining module includes a first determining unit and a second determining unit. The first determining unit is used to determine the battery device with balanced voltage in the energy storage device as the first battery device and the battery devices other than the first battery device as the second battery device based on the voltage of each battery device in the energy storage device. The second determining unit is used to determine the target battery device based on the voltage of the first battery device, the voltage of the second battery device and the power demand state of the energy storage device.

[0226] In some embodiments, the second determining unit is further configured to: determine the first battery device as the target battery device when the energy demand state of the energy storage device is a charging demand state and the voltage of the first battery device is less than the voltage of the second battery device; determine the second battery device as the target battery device when the energy demand state of the energy storage device is a charging demand state and the voltage of the first battery device is greater than the voltage of the second battery device; determine the second battery device as the target battery device when the energy demand state of the energy storage device is a discharging demand state and the voltage of the first battery device is less than the voltage of the second battery device; and determine the first battery device as the target battery device when the energy demand state of the energy storage device is a discharging demand state and the voltage of the first battery device is greater than the voltage of the second battery device.

[0227] In some embodiments, the preset request current includes a first request current and a second request current, wherein the second request current is less than the first request current; the energy conversion module includes a first conversion unit and a second conversion unit, wherein the first conversion unit is used to perform energy conversion on the powered target battery device according to the first request current until the voltage difference between the voltage of the target battery device and the voltage of a battery device other than the target battery device is less than or equal to a first preset voltage threshold; and the second conversion unit is used to perform energy conversion on the powered target battery device according to the second request current.

[0228] In some embodiments, the power-on condition for a battery device other than the target battery device includes at least one of the following: the voltage difference between the voltage of the target battery device and the voltage of the battery device other than the target battery device is less than or equal to a second preset voltage threshold for a duration greater than or equal to a first preset duration; the duration of energy conversion of the target battery device powered on according to the second requested current is greater than or equal to the second preset duration; and the second preset voltage threshold is less than the first preset voltage threshold.

[0229] In some embodiments, the energy conversion module is further configured to determine the polarization voltage of the target battery device based on the preset request current of the energy storage device and the voltage of the target battery device; determine the voltage difference between the voltage of the target battery device and the polarization voltage of the target battery device as the actual voltage of the target battery device; and determine that the battery device other than the target battery device meets the power-on conditions if the voltage difference between the actual voltage of the target battery device and the voltage of the battery device other than the target battery device is less than or equal to a second preset voltage threshold.

[0230] In some embodiments, the determining module is further configured to: determine a target requested current for each battery device in the target battery device based on the voltage difference between the voltage of the target battery device and the voltage of battery devices other than the target battery device; and determine a preset requested current based on the number of battery devices in the target battery device and the target requested current for each battery device in the target battery device.

[0231] In some embodiments, the preset voltage includes a first preset voltage or a second preset voltage; the balancing module is further configured to charge all battery devices in the energy storage device when the energy demand state of the energy storage device is a charging demand state, until the voltage of any cell in each energy storage device of the energy storage device reaches the first preset voltage; and to discharge all battery devices in the energy storage device when the energy demand state of the energy storage device is a discharging demand state, until the voltage of any cell in any battery device of the energy storage device reaches the second preset voltage.

[0232] In some embodiments, the balancing module includes an acquisition unit and a balancing unit. The acquisition unit is used to acquire the charging request current of the energy storage device. The balancing unit is used to charge the battery devices in the powered-on state according to the charging request current of the energy storage device. When the voltage of any cell in any battery device in the powered-on state reaches a first set voltage, the charging current of the energy storage device is controlled to be 0, the battery device is powered off, and the process returns to the step of acquiring the charging request current of the energy storage device until all battery devices are powered off.

[0233] In some embodiments, the equalization unit is further configured to: when all battery devices are powered down, power on all battery devices at intervals of a preset waiting time, starting from the end time when all battery devices are powered down.

[0234] In some embodiments, the acquisition unit is further configured to: acquire the number of battery devices in a powered-on state and the characteristic voltage of the battery devices in a powered-on state; determine the target charging current of each battery device in a powered-on state based on the characteristic voltage of the battery devices in a powered-on state; and determine the charging request current of the energy storage device based on the number of battery devices in a powered-on state and the target charging current of each battery device in a powered-on state.

[0235] In some embodiments, the balancing module includes an acquisition unit and a balancing unit. The acquisition unit is used to acquire a first discharge request current of the energy storage device. The balancing unit is used to: discharge the battery devices in the powered-on state according to the first discharge request current of the energy storage device; when the voltage of any cell in any battery device in the powered-on state is less than or equal to a third set voltage, acquire a second discharge request current of the energy storage device; the third set voltage is greater than a second set voltage, and the second discharge request current is less than the first discharge request current; discharge the battery devices in the powered-on state according to the second discharge request current of the energy storage device until the voltage of any cell in any battery device is less than or equal to the second set voltage, and control the discharge current of the energy storage device to be 0, and all battery devices are discharged.

[0236] In some embodiments, the acquisition unit is further configured to: acquire the number of battery devices in a powered-on state and the characteristic voltage of the battery devices in a powered-on state; determine a target discharge current for each battery device in a powered-on state based on the characteristic voltage of the battery devices in a powered-on state; and determine a first discharge request current for the energy storage device based on the number of battery devices in a powered-on state and the target discharge current of each battery device in a powered-on state.

[0237] The descriptions of the above device embodiments are similar to those of the above method embodiments, and have similar beneficial effects. For technical details not disclosed in the device embodiments of this application, please refer to the descriptions of the method embodiments of this application for understanding.

[0238] Each module in the aforementioned state-of-charge balancing device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of the control device in hardware form or independent of it, or stored in the memory of the control device in software form, so that the processor can call and execute the corresponding operations of each module.

[0239] In one exemplary embodiment, Figure 8This is a schematic diagram of a control device provided in some embodiments. The control device includes a processor, a memory, an input / output interface, a communication interface, a display unit, and an input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor of the control device provides computing and control capabilities. The memory of the control device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface of the control device is used for exchanging information between the processor and external devices. The communication interface of the control device is used for wired or wireless communication with external terminals. Wireless communication can be achieved through Wireless Fidelity (WIFI), mobile cellular networks, Near Field Communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a state-of-charge balancing method for an energy storage device. The display unit of the control device is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the control device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the housing of the control device, or external keyboards, touchpads, or mice, etc.

[0240] Those skilled in the art will understand that Figure 8 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the control device to which the present application is applied. The specific control device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0241] For example, the control device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the steps of the method of any of the above embodiments.

[0242] Figure 9 Schematic diagrams of the energy storage device provided for some embodiments, such as Figure 8 As shown, the energy storage device includes a control device in any of the above embodiments and a plurality of battery devices, all of which are connected to the control device.

[0243] Figure 10 The diagram below illustrates the structure of an energy storage system provided in other embodiments. The energy storage system includes a power conversion device and an energy storage device as described in the above embodiments. The power conversion device is connected between the energy storage device and the power generation device.

[0244] In some embodiments, the energy storage system further includes an energy management system, which communicates and controls the power conversion device and the energy storage device.

[0245] In one embodiment, a computer-readable storage medium is provided, wherein a computer program, when executed by a processor, implements the steps of the method provided in any of the above embodiments.

[0246] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps of the method provided in any of the above embodiments.

[0247] Those skilled in the art will understand that 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 non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the methods described above.

[0248] The processor, functional modules, or functional units in any embodiment of this application may include an integration of one or more of the following: a general-purpose processor, an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a central processing unit (CPU), a graphics processing unit (GPU), an embedded neural network processing unit (NPU), a controller, a microcontroller, a microprocessor, a programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, a quantum computing-based data processing logic unit, an artificial intelligence (AI) processor, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0249] The memory or computer-readable storage medium in any embodiment of this application may include at least one of non-volatile memory and volatile memory. Non-volatile memory includes integration of one or more of the following: Read Only Memory (ROM), Programmable Read-Only Memory (PROM), Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Ferromagnetic Random Access Memory (FRAM), Flash Memory, Magnetic Surface Memory, Optical Disc, Compact Disc Read-Only Memory (CD-ROM), Magnetic Tape, Floppy Disk, Flash Memory, Optical Memory, High-Density Embedded Non-Volatile Memory, Resistive Random Access Memory (ReRAM), Magnetoresistive Random Access Memory (MRAM), Ferroelectric Random Access Memory (FRAM), Phase Change Memory (PCM), Graphene Memory, Volatile Memory, etc. Volatile memory includes one or more of the following: Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0250] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0251] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for state-of-charge balancing in an energy storage device, characterized in that, The method includes: Based on the voltage of each battery device in the energy storage device, the battery device with balanced voltage in the energy storage device is identified as the first battery device, and the battery devices other than the first battery device are identified as the second battery device. The target battery device is determined based on the voltage of the first battery device, the voltage of the second battery device, and the power demand status of the energy storage device; the target battery device or a battery device other than the target battery device supports power-on. According to the preset request current of the energy storage device, the energy is converted to power the target battery device until the battery device other than the target battery device meets the power-on conditions. Power on battery devices other than the target battery device, and with all battery devices in the energy storage device powered on, perform energy conversion on all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches a preset voltage, so as to balance the state of charge of all battery devices. The step of determining the target battery device based on the voltage of the first battery device, the voltage of the second battery device, and the energy demand state of the energy storage device includes at least one of the following: When the energy demand state of the energy storage device is a charging demand state, and the voltage of the first battery device is less than the voltage of the second battery device, the first battery device is identified as the target battery device. When the energy demand state of the energy storage device is a charging demand state, and the voltage of the first battery device is greater than the voltage of the second battery device, the second battery device is identified as the target battery device. When the energy demand state of the energy storage device is the discharge demand state, and the voltage of the first battery device is less than the voltage of the second battery device, the second battery device is determined as the target battery device. When the energy demand state of the energy storage device is a discharge demand state, and the voltage of the first battery device is greater than the voltage of the second battery device, the first battery device is identified as the target battery device.

2. The method according to claim 1, characterized in that, Before powering on a battery device other than the target battery device, the method further includes: The requested current of the energy storage device is set to 0.

3. The method according to claim 1, characterized in that, The step of identifying the first battery device as the target battery device includes: if the first battery device is in a powered-on state, then the first battery device is identified as the target battery device; The step of identifying the second battery device as the target battery device includes: if the first battery device is in a powered-on state, then powering off the first battery device and powering on the second battery device, thereby identifying the second battery device as the target battery device.

4. The method according to any one of claims 1 to 3, characterized in that, The preset request current includes a first request current and a second request current, wherein the second request current is less than the first request current; The step of converting energy into energy for the target battery device according to a preset requested current from the energy storage device includes: Based on the first requested current, energy conversion is performed on the target battery device until the voltage difference between the voltage of the target battery device and the voltage of a battery device other than the target battery device is less than or equal to a first preset voltage threshold. The target battery device is converted into energy according to the second requested current.

5. The method according to claim 4, characterized in that, The battery device other than the target battery device meets at least one of the following power-on conditions: The duration for which the voltage difference between the target battery device and the voltage of a battery device other than the target battery device is less than or equal to the second preset voltage threshold is greater than or equal to the first preset duration; The second preset voltage threshold is less than the first preset voltage threshold; The duration of energy conversion of the target battery device according to the second requested current is greater than or equal to the second preset duration.

6. The method according to any one of claims 1 to 3, characterized in that, Determining that a battery device other than the target battery device meets the power-on conditions includes: The polarization voltage of the target battery device is determined based on the preset requested current of the energy storage device and the voltage of the target battery device. The voltage difference between the voltage of the target battery device and the polarization voltage of the target battery device is determined as the actual voltage of the target battery device; If the voltage difference between the actual voltage of the target battery device and the voltage of a battery device other than the target battery device is less than or equal to a second preset voltage threshold, it is determined that the battery device other than the target battery device meets the power-on condition.

7. The method according to any one of claims 1 to 3, characterized in that, The method further includes: The target requested current for each battery device in the target battery device is determined based on the voltage difference between the voltage of the target battery device and the voltage of battery devices other than the target battery device. The preset requested current is determined based on the number of battery devices in the target battery device and the target requested current for each battery device in the target battery device.

8. The method according to any one of claims 1 to 3, characterized in that, The preset voltage includes a first preset voltage or a second preset voltage; the step of converting energy for all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches the preset voltage includes: When the energy demand state of the energy storage device is the charging demand state, all battery devices in the energy storage device are charged until the voltage of any cell in each energy storage device of all battery devices reaches the first set voltage. When the energy demand state of the energy storage device is the discharge demand state, all battery devices in the energy storage device are discharged until the voltage of any cell in any battery device in the energy storage device reaches the second set voltage.

9. The method according to claim 8, characterized in that, Charging all battery devices in the energy storage device until the voltage of any cell in each energy storage device reaches the first preset voltage includes: Obtain the charging request current of the energy storage device, and charge the battery device that is in the powered-on state according to the charging request current of the energy storage device. If the voltage of any cell in any of the battery devices that is powered on reaches the first set voltage, the charging current of the energy storage device is controlled to be 0, the battery device is powered off, and the process proceeds to the step of obtaining the charging request current of the energy storage device, until all battery devices are powered off.

10. The method according to claim 9, characterized in that, The method further includes: When all battery devices are powered off, power is applied to all battery devices after a preset waiting time, starting from the end time when all battery devices are powered off.

11. The method according to claim 9, characterized in that, The step of obtaining the charging request current of the energy storage device includes: The number of battery devices in the powered-on state and the characteristic voltage of the battery devices in the powered-on state are obtained. Based on the characteristic voltage of the battery device in the powered-on state, determine the target charging current for each of the battery devices in the powered-on state. The charging request current of the energy storage device is determined based on the number of battery devices that are in the powered-on state and the target charging current of each battery device in the powered-on state.

12. The method according to claim 8, characterized in that, Discharging all battery devices in the energy storage device until the voltage of any cell in any battery device in the energy storage device reaches the second set voltage includes: Obtain the first discharge request current of the energy storage device, and discharge the battery device that is in the powered-on state according to the first discharge request current of the energy storage device. If the voltage of any cell in any battery device that is powered on is less than or equal to a third set voltage, the second discharge request current of the energy storage device is obtained; the third set voltage is greater than the second set voltage, and the second discharge request current is less than the first discharge request current. According to the second discharge request current of the energy storage device, the battery device in the powered-on state is discharged until the voltage of any cell in any battery device is less than or equal to the second set voltage, and the discharge current of the energy storage device is controlled to be 0, and the discharge of all battery devices is completed.

13. The method according to claim 12, characterized in that, The step of obtaining the first discharge request current of the energy storage device includes: The number of battery devices in the powered-on state and the characteristic voltage of the battery devices in the powered-on state are obtained. Based on the characteristic voltage of the battery device in the powered-on state, determine the target discharge current of each of the battery devices in the powered-on state. The first discharge request current of the energy storage device is determined based on the number of battery devices in the powered-on state and the target discharge current of each battery device in the powered-on state.

14. A state-of-charge balancing device for an energy storage device, characterized in that, The state-of-charge equalization device includes: The determination module is used to determine, based on the voltage of each battery device in the energy storage device, the battery device with balanced voltage in the energy storage device as the first battery device, and the battery devices other than the first battery device as the second battery device; and to determine the target battery device based on the voltage of the first battery device, the voltage of the second battery device, and the power demand state of the energy storage device; the target battery device or the battery device other than the target battery device supports power-on. An energy conversion module is used to convert energy into energy for the target battery device that is powered on, based on a preset request current of the energy storage device, until the battery device other than the target battery device meets the power-on conditions. The balancing module is used to power on battery devices other than the target battery device, and when all battery devices in the energy storage device are powered on, to perform energy conversion on all battery devices in the energy storage device until the voltage of any cell in each battery device of at least one battery device in the energy storage device reaches a preset voltage, so as to balance the state of charge of all battery devices. The step of determining the target battery device based on the voltage of the first battery device, the voltage of the second battery device, and the energy demand state of the energy storage device includes at least one of the following: When the energy demand state of the energy storage device is a charging demand state, and the voltage of the first battery device is less than the voltage of the second battery device, the first battery device is identified as the target battery device. When the energy demand state of the energy storage device is a charging demand state, and the voltage of the first battery device is greater than the voltage of the second battery device, the second battery device is identified as the target battery device. When the energy demand state of the energy storage device is the discharge demand state, and the voltage of the first battery device is less than the voltage of the second battery device, the second battery device is determined as the target battery device. When the energy demand state of the energy storage device is a discharge demand state, and the voltage of the first battery device is greater than the voltage of the second battery device, the first battery device is identified as the target battery device.

15. A control device comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 13.

16. An energy storage device, characterized in that, The energy storage device includes the control device as described in claim 15 and a plurality of battery devices connected to the control device.

17. An energy storage system, characterized in that, The energy storage system includes a power conversion device and an energy storage device as described in claim 16, wherein the power conversion device is connected between the energy storage device and the power generation device.

18. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 13.

19. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 13.

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