Charging and discharging control method and related device

Abstract

The invention discloses a charging and discharging control method and a related device, and relates to the technical field of energy storage, a bidirectional controllable switch is arranged in a charging and discharging loop where an energy storage unit is located, and when the charging and discharging loop is in a charging process, the bidirectional controllable switch in the charging and discharging loop is turned on in a first direction, so that the energy storage unit can be charged, and the energy storage unit can be charged; at the moment, when the charge state of the energy storage unit of any charge-discharge loop is larger than or equal to the preset charge state upper limit threshold, the bidirectional controllable switch in the charge-discharge loop is controlled to be switched off in the first direction, and the energy storage unit is prevented from being overcharged. When the charging and discharging loop is in the discharging process, the bidirectional controllable switch in the charging and discharging loop is switched on in the second direction, so that the energy storage unit is allowed to discharge, and at the moment, the charging state of the energy storage unit of any charging and discharging loop is smaller than or equal to a preset charging state lower limit threshold value; and the bidirectional controllable switch in the charging and discharging loop is controlled to be switched off in the second direction, so that the energy storage unit is prevented from being over-discharged.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a charging and discharging control method and related device. Background Technology

[0002] In the event of a battery module failure such as shutdown / overcharge / overdischarge / overvoltage / overcurrent, or while the module is powered off, the external output of the battery module is disconnected to protect it. For systems with multiple battery modules connected in parallel, the electrical connection between a battery module and the system is disconnected when one module is fully charged or fully discharged, thus preventing overcharging / overdischarging.

[0003] However, disconnecting the battery module when it is overcharged will have a significant impact on system safety and user experience. Therefore, the charging current of the PCS (Power Conversion System) can be limited when the battery module is close to being fully charged, and the discharging current of the PCS can be limited when the battery module is close to being fully discharged.

[0004] However, this method still has the potential to overcharge or over-discharge a battery module, reducing the operational reliability of the battery module. Summary of the Invention

[0005] In view of the above problems, this application provides a charge / discharge control method and related apparatus to reduce the risk of overcharging or over-discharging of battery modules. The specific solution is as follows:

[0006] The first aspect of this application provides a charging and discharging control method, comprising:

[0007] In response to multiple charging and discharging circuits in the energy storage system being in a charging and discharging state, the state of charge of the energy storage unit in each charging and discharging circuit is monitored; wherein, a bidirectional controllable switch is provided in the charging and discharging circuit, and the bidirectional controllable switch in the charging and discharging circuit is turned on in the first direction during the charging process; and the bidirectional controllable switch in the charging and discharging circuit is turned on in the second direction during the discharging process.

[0008] When multiple charging and discharging circuits are in the charging process, in response to the state of charge of the energy storage unit of any charging and discharging circuit being greater than or equal to a preset upper limit threshold of the state of charge, the bidirectional controllable switch in that charging and discharging circuit is controlled to be cut off in the first direction.

[0009] and / or;

[0010] When multiple charging and discharging circuits are in the process of discharging, in response to the state of charge of the energy storage unit of any charging and discharging circuit being less than or equal to a preset state of charge lower threshold, the bidirectional controllable switch in that charging and discharging circuit is controlled to be turned off in the second direction.

[0011] In one possible implementation, the energy storage unit includes a single battery module located in a charging / discharging circuit. In the charging / discharging circuit, a bidirectional controllable switch is disposed inside or outside the battery module. The battery module is equipped with at least one battery cell, and the battery cell in the battery module is connected to the bidirectional controllable switch after being connected.

[0012] The monitoring of the state of charge of the energy storage unit in each charging and discharging circuit includes:

[0013] For each charging / discharging circuit, the state of charge of each cell in the battery module in the charging / discharging circuit is obtained;

[0014] The average state of charge of each cell is taken as the state of charge of the energy storage unit.

[0015] Alternatively, in the case of cell discharge, the minimum state of charge is taken as the state of charge of the energy storage unit.

[0016] When the battery cell is being charged, the maximum state of charge is taken as the state of charge of the energy storage unit.

[0017] In one possible implementation, the energy storage unit includes multiple battery modules connected in parallel. The parallel battery modules are located in the same charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed outside the battery modules. Each battery module is equipped with at least one battery cell. All the battery cells are connected and then connected to the bidirectional controllable switch.

[0018] The monitoring of the state of charge of the energy storage unit in each charging and discharging circuit includes:

[0019] For each charging and discharging circuit, the state of charge of the battery module is determined based on the state of charge of the cells in each battery module in the charging and discharging circuit.

[0020] The average state of charge of each battery module is taken as the state of charge of the energy storage unit.

[0021] Alternatively, when the battery module is discharging, the minimum state of charge is taken as the state of charge of the energy storage unit.

[0022] When the battery module is charging, the maximum state of charge is taken as the state of charge of the energy storage unit.

[0023] In one possible implementation, the charge / discharge control method further includes:

[0024] When multiple charging and discharging circuits are discharged, and the energy storage units in the multiple charging and discharging circuits have an unbalanced state of charge (SOC), a target discharge energy storage unit is determined from all the energy storage units; wherein, the target discharge energy storage unit is: the energy storage unit other than the first energy storage unit; the first energy storage unit is the energy storage unit with the lowest state of charge among all the energy storage units;

[0025] Controlling the bidirectional controllable switch in the charging and discharging circuit where the target discharge energy storage unit is located to be turned on in the second direction, and controlling the bidirectional controllable switch in the charging and discharging circuit where all the energy storage units except the target discharge energy storage unit are located to be turned off in the second direction;

[0026] And / or,

[0027] When charging is performed through multiple charging and discharging circuits, and the energy storage units in the multiple charging and discharging circuits have an imbalance in SOC, a target charging energy storage unit is determined from all the energy storage units; wherein, the target charging energy storage unit is: the energy storage unit other than the second energy storage unit among all the energy storage units; the second energy storage unit is the energy storage unit with the highest state of charge among all the energy storage units;

[0028] The bidirectional controllable switch in the charging and discharging circuit of the target charging energy storage unit is turned on in the first direction, and the bidirectional controllable switch in the charging and discharging circuit of all energy storage units except the target charging energy storage unit is turned off in the first direction.

[0029] In one possible implementation, determining the target discharge energy storage unit from all the said energy storage units includes:

[0030] From all the energy storage units, all of the energy storage units except the first energy storage unit are selected as the target discharge energy storage unit;

[0031] Alternatively, from all the energy storage units, some of the energy storage units other than the first energy storage unit may be selected as the target discharge energy storage unit.

[0032] In one possible implementation, selecting a portion of the energy storage units, excluding the first energy storage unit, from all the energy storage units as the target discharge energy storage unit includes:

[0033] From all the energy storage units, the energy storage units other than the first energy storage unit are identified as pre-selected discharge energy storage units;

[0034] Based on the target discharge power, at least one of the energy storage units with a total output power greater than or equal to the target discharge power is selected from the determined pre-selected discharge energy storage units as the target discharge energy storage unit.

[0035] In one possible implementation, after the bidirectional controllable switch in the charge / discharge circuit controlling the target discharge energy storage unit is turned on in the second direction, the charge / discharge control method further includes:

[0036] During the discharge process of the target discharge energy storage unit, the state of charge of each target discharge energy storage unit is monitored in real time.

[0037] Then return to the step of determining the target discharge energy storage unit from all the energy storage units when discharging in multiple charging and discharging circuits and when there is a SOC imbalance among the energy storage units in the multiple charging and discharging circuits.

[0038] In one possible implementation, determining the target charging energy storage unit from all the said energy storage units includes:

[0039] From all the energy storage units, all of the energy storage units except the second energy storage unit are selected as the target charging energy storage unit;

[0040] Alternatively, from all the energy storage units, a portion of the energy storage units other than the second energy storage unit may be selected as the target charging energy storage unit.

[0041] In one possible implementation, selecting a portion of the energy storage units, excluding the second energy storage unit, from all the energy storage units as the target charging energy storage unit includes:

[0042] From all the energy storage units, the energy storage units other than the second energy storage unit are identified as pre-selected charging energy storage units;

[0043] Based on the target charging power, at least one of the energy storage units with a total input power greater than or equal to the target charging power is selected from the pre-selected energy storage units as the target energy storage unit.

[0044] In one possible implementation, after the bidirectional controllable switch in the charge / discharge circuit controlling the target charging energy storage unit is turned on in the first direction, the charge / discharge control method further includes:

[0045] During the charging process of the target charging energy storage unit, the state of charge of each target charging energy storage unit is monitored in real time.

[0046] Then return to the step of determining the target charging energy storage unit from all the energy storage units when charging in multiple charging and discharging circuits and when there is a SOC imbalance among the energy storage units in the multiple charging and discharging circuits.

[0047] In one possible implementation, the charge / discharge control method further includes:

[0048] Obtain the temperature of the energy storage unit in each of the charging and discharging circuits;

[0049] In response to the temperature of the energy storage unit in any of the charging and discharging circuits being greater than the upper temperature threshold, the bidirectional controllable switch in that charging and discharging circuit is controlled to be cut off in both the first and second directions.

[0050] In response to the temperature of the energy storage unit in any of the charging and discharging circuits being lower than the lower limit threshold, the bidirectional controllable switch in that charging and discharging circuit is controlled to be turned off in the first direction.

[0051] A second aspect of this application provides a charge / discharge controller, the charge / discharge controller including at least one processor and a memory connected to the processor, wherein:

[0052] The memory is used to store computer programs;

[0053] The processor is used to execute the computer program so that the charge / discharge controller can implement the above-described charge / discharge control method.

[0054] A third aspect of this application provides an energy storage system comprising multiple energy storage units, wherein the energy storage units are internally equipped with the aforementioned charge / discharge controller.

[0055] In one possible implementation, the energy storage unit includes a single battery module located in a charging / discharging circuit. In the charging / discharging circuit, a bidirectional controllable switch is disposed inside or outside the battery module. The battery module is equipped with at least one battery cell, and all the battery cells are connected to the bidirectional controllable switch.

[0056] In one possible implementation, the energy storage unit includes multiple battery modules connected in parallel. The parallel battery modules are located in the same charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed outside the battery modules. Each battery module is equipped with at least one battery cell, and the battery cell in the battery module is connected to the bidirectional controllable switch after being connected.

[0057] In one possible implementation, the bidirectional controllable switch is located at the positive output terminal of the battery module;

[0058] Alternatively, the bidirectional controllable switch may be located at the negative output terminal of the battery module;

[0059] Alternatively, the bidirectional controllable switch may be simultaneously located at both the positive and negative output terminals of the battery module.

[0060] In one possible implementation, the bidirectional controllable switch is connected in parallel with a current-absorbing circuit.

[0061] In one possible implementation, the bidirectional controllable switch is connected to an external control device via a manual switch; the manual switch is used to control the connection and disconnection between the bidirectional controllable switch and the external control device.

[0062] A fourth aspect of this application provides an energy storage system, including multiple energy storage units and the aforementioned charge / discharge controller; the charge / discharge controller is communicatively connected to the multiple energy storage units.

[0063] In one possible implementation, the energy storage unit includes a single battery module located in a charging / discharging circuit, in which a bidirectional controllable switch is disposed outside the battery module, and the battery module is configured with at least one battery cell, all of which are connected to the bidirectional controllable switch.

[0064] In one possible implementation, the energy storage unit includes multiple battery modules connected in parallel. The parallel battery modules are located in the same charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed outside the battery modules. Each battery module is equipped with at least one battery cell, and the battery cell in the battery module is connected to the bidirectional controllable switch after being connected.

[0065] By employing the above technical solution, this application provides a charging and discharging control method and related apparatus. In this application, a bidirectional controllable switch is provided in the charging and discharging circuit of an energy storage unit, such as a battery module. During the charging process, the bidirectional controllable switch in the charging and discharging circuit is turned on in the first direction, thereby charging the energy storage unit. During the charging process, in response to the state of charge (SOC) of the energy storage unit in any charging and discharging circuit being greater than or equal to a preset SOC upper limit threshold, the bidirectional controllable switch in that charging and discharging circuit is controlled to be turned off in the first direction to prevent overcharging of the energy storage unit. During the discharging process, the bidirectional controllable switch in the charging and discharging circuit is turned on in the second direction, thereby allowing the energy storage unit to discharge. During the discharging process, in response to the SOC of the energy storage unit in any charging and discharging circuit being less than or equal to a preset SOC upper limit threshold, the bidirectional controllable switch in that charging and discharging circuit is controlled to be turned off in the second direction to prevent over-discharging of the energy storage unit. Through the above-mentioned operations to prevent overcharging and over-discharging of the energy storage unit, the operational reliability of the energy storage unit is improved. Attached Figure Description

[0066] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0067] Figure 1 A schematic diagram of an energy storage system provided in this application;

[0068] Figure 2 A schematic diagram illustrating the configuration of a bidirectional controllable switch provided in this application;

[0069] Figure 3 A schematic diagram illustrating the configuration of another bidirectional controllable switch provided in this application;

[0070] Figure 4 A schematic diagram illustrating the configuration of another bidirectional controllable switch provided in this application;

[0071] Figure 5 A connection diagram of a battery module and a PCS is provided in this application;

[0072] Figure 6 A schematic diagram of another energy storage system provided in this application;

[0073] Figure 7 A schematic diagram of another energy storage system provided in this application;

[0074] Figure 8 A flowchart of a charging and discharging control method provided in this application;

[0075] Figure 9 A flowchart of a method for determining the state of charge provided in this application;

[0076] Figure 10 A flowchart of a switch on / off control method provided in this application;

[0077] Figure 11 A flowchart of another method for controlling the on / off state of a switch provided in this application. Detailed Implementation

[0078] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0079] The embodiments of this application will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0080] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0081] In energy storage systems, battery modules typically contain at least one cell capable of charging and discharging. When multiple cells are present, they can be connected in series, parallel, or a series-parallel configuration. Battery modules may also include a BMS (Battery Management System).

[0082] In the event of a battery module overcharge / overdischarge / overvoltage / overcurrent fault or when the system is powered off, the external output of the battery module is disconnected, thereby protecting the battery module and the energy storage system. For energy storage systems with multiple battery modules connected in parallel, the electrical connection between a battery module and the energy storage system is disconnected when a particular battery module is fully charged / discharged, thereby preventing overcharge / overdischarge.

[0083] However, disconnecting the battery module when it is overcharged can significantly impact system safety and user experience. Therefore, the charging current of the PCS can be limited when the battery module is nearing full charge. Alternatively, the charging state of the battery module can be determined by its SOC (State of Charge) margin, and the charging current of the PCS can be limited when the SOC is close to 100%. Similarly, for battery module discharge scenarios, the discharge current of the PCS can be limited when the SOC of the battery module is close to depletion (e.g., 0%).

[0084] However, this approach, even when configuring only one battery module, still carries the risk of overcharging or over-discharging that module. For example, in a photovoltaic (PV) energy storage system, both PV modules and battery modules are configured. Both output power to the load simultaneously. When the load's power demand decreases, the unreceived electrical energy from the PV modules is stored in the battery module, effectively charging it. This can lead to overcharging when the battery module's state of charge (SOC) is high. Conversely, when the load's power demand increases, the PV modules' output may be insufficient to support the load's energy requirements, necessitating the battery module to discharge. This can lead to over-discharging when the battery module's SOC is low, reducing the module's operational reliability.

[0085] In scenarios involving multiple battery modules connected in parallel, achieving 100% SOC balance among them is difficult. During charging, even with limited charging current from the power consumption control system (PCS), continuing to charge a module with a higher SOC may lead to overcharging, especially when the module is nearing full charge. For example, if five battery modules are connected in parallel to the PCS, and module 5 has a higher SOC, even with limited charging current from the PCS, current may still flow into module 5, causing overcharging. Similarly, in discharging scenarios, even with limited discharging current from the PCS, continuing to discharge a module with a lower SOC may result in over-discharging. Disconnecting a fully charged battery module at this point reduces the actual usable capacity of the energy storage system. When a user needs power from multiple battery modules, the system must reconnect the disconnected modules, resulting in an untimely response. Likewise, seamless charging is not possible for a battery module that has been discharged and disconnected.

[0086] Therefore, in this embodiment, a bidirectional controllable switch can be installed in the charging and discharging circuit where the battery module is located. This bidirectional controllable switch can control the flow of electrical energy between the battery module and external devices (such as energy storage converters). When the battery module is nearing full charge / discharge, the power flow of the battery module can be unidirectional by controlling the on / off operation of the bidirectional controllable switch. By controlling the bidirectional controllable switch, it is possible to allow only the battery module to discharge when it is about to be fully charged, and / or to allow only the battery module to charge when it is about to be fully discharged, thus avoiding overcharging / over-discharging problems.

[0087] Based on the above, one embodiment of this application provides a charging and discharging control method. The executing entity can be a control module, which can be installed in the battery module or an external control device that communicates with the battery module, such as a PCS that is electrically connected to the battery module, or an electrical device (such as a switch control box) in other energy storage systems.

[0088] In one implementation, the structure of the energy storage system can be referenced. Figure 1 As shown. Figure 1 In this energy storage system, multiple battery modules can be included, specifically 1 to N battery modules, where N is a positive integer. Each battery module contains a battery management system (BMS), a bidirectional controllable switch, and a cell pack capable of charging and discharging. The cell pack contains 1 to M cells, where M is a positive integer. The cells can be connected in series, parallel, or series-parallel configurations. The output of the cell pack is connected to one end of the bidirectional controllable switch, and the other end of the switch is connected to an external control device, such as a power control system (PCS).

[0089] The charging and discharging circuit is a single circuit that performs charging and discharging operations on the energy storage unit. Figure 1 The configuration includes a circuit with a bidirectional controllable switch that can serve as a charging / discharging circuit. Figure 1 In this embodiment, each charging and discharging circuit includes a battery module, which is the energy storage unit in that charging and discharging circuit.

[0090] against Figure 1 In the battery module, a cell status detection unit, such as a sensor, embedded in the cell can collect cell information and transmit it to the BMS. The BMS can then use this information to calculate the cell's SOC and the battery module's SOC. Alternatively, the BMS can also use the collected cell information to monitor whether the cell's temperature is normal.

[0091] In one alternative implementation, an output current detection unit 1 can be provided between the battery cell pack and the bidirectional controllable switch to collect the battery output current 1 in order to monitor the output voltage and current of the battery cell pack.

[0092] In one alternative implementation, an output current detection unit 2 can be provided between the bidirectional controllable switch and the PCS to collect the battery output current 2 in order to monitor the output voltage and current of the battery pack.

[0093] The principle of output current detection units 1 and 2 in detecting battery output current can be the same. Output current detection units 1 and 2 can be set selectively or simultaneously, so that when one of them fails, the other can be switched to.

[0094] When the battery module is connected to the PCS via a bidirectional controllable switch, in one implementation, the bidirectional controllable switch is located at the positive output terminal of the battery module. The location of the bidirectional controllable switch can be referenced... Figure 2 As shown. Figure 2 In this design, a bidirectional controllable switch is placed between the positive terminal (BAT+) of the battery module and the positive terminal (PCS+) of the energy storage converter, while no bidirectional controllable switch is placed between the positive terminal (BAT-) of the battery module and the positive terminal (PCS-) of the energy storage converter. The bidirectional controllable switch can be a bidirectional controllable semiconductor switch.

[0095] The bidirectional controllable switch may include at least one pair of switches connected in parallel, and the pair of switches includes a first switch and a second switch connected in reverse series. Figure 3 Only one switch pair is shown, consisting of a first switch (switch K1) and a second switch (switch K2). Switches K1 and K2 can be of the same type. Specifically, switches K1 and K2 can be MOS (Metal-Oxide-Semiconductor Field-Effect Transistor), IGBT (Insulated Gate Bipolar Transistor), etc. Switches K1 and K2 are connected in reverse series, meaning they are connected top-to-bottom.

[0096] Optionally, the first port 1 of switch K1 is connected to BAT+, the second port 2 of switch K1 is connected to the second port 2 of switch K2, and the first port 1 of switch K2 is connected to PCS+.

[0097] like Figure 3 As shown, during battery module charging, switch K1 can be closed, and the bidirectional controllable switch is turned on in the first direction. This first direction can be the direction in which the charging current flows to the battery module, such as the direction from the energy storage inverter to the battery module. Optionally, when switch K1 is on, the charging current can flow from the energy storage inverter to the battery module, allowing charging of the battery cells. When switch K1 is off, the charging current cannot flow from the energy storage inverter to the battery module, and charging of the battery cells is not possible.

[0098] During battery module discharge, switch K2 can be closed, and the bidirectional controllable switch will conduct in the second direction. This second direction can be the direction in which the discharge current flows out of the battery module. Optionally, when switch K2 is on, the discharge current can flow from the battery cells in the battery module to the energy storage converter, allowing the cells to discharge. When switch K2 is off, the discharge current cannot flow from the cells to the energy storage converter, and the cells cannot discharge.

[0099] In one example, a schematic diagram of multiple switch pairs connected in parallel can be found here. Figure 4 , Figure 4 The example below illustrates this with two switch pairs connected in parallel. In this case, current can flow through each switch pair. By setting multiple switch pairs in parallel, the current carrying capacity of the battery can be improved.

[0100] In one implementation, to reduce the current stress when switches K1 and K2 are turned off, a bidirectional controllable switch is used, meaning that switches K1 and K2 can be connected in parallel with a turn-off current absorption circuit. This turn-off current absorption circuit can be a TVS (Transient Voltage Suppressor) transistor, which absorbs the turn-off current, improving reliability.

[0101] In the above embodiments, the bidirectional controllable switch is located at the positive output terminal of the battery module. In another implementation, the bidirectional controllable switch can also be located at the negative output terminal of the battery module; the specific implementation method is similar to the positive terminal setting method.

[0102] In another implementation, to avoid the inability to control the battery module's on / off state when a single bidirectional controllable switch fails, the bidirectional controllable switches can be simultaneously set at both the positive and negative output terminals of the battery module. When both bidirectional controllable switches are functioning normally, one can be used; if one fails, the other functioning bidirectional controllable switch can be used to control the battery module's on / off state. This embodiment improves the reliability of the switches through redundant bidirectional controllable switches.

[0103] In one implementation, such as Figure 5 As shown, the bidirectional controllable switch can also be connected to an external control device via a manual switch. In this case, the manual switch can control the on / off state of the bidirectional controllable switch and the external control device. Specifically, taking the PCS as an example of the external control device, when the user needs to connect the PCS to the battery module's cells, they can press the manual switch. At this time, the battery module's cells are connected to the PCS. When the user needs to disconnect the PCS from the battery module's cells, they can release the manual switch. At this time, the battery module's cells are disconnected from the PCS. It should be noted that... Figure 5 This example uses only one battery module; other battery modules can also be configured with manual switches.

[0104] In the above embodiments, the bidirectional controllable switch is disposed inside the battery module. In one optional implementation, refer to... Figure 6 The bidirectional controllable switch can also be installed in the switch control box outside the battery module. Figure 6In the circuit, the switch control box contains bidirectional controllable switches 1-N, each connected to a battery module 1-N. The switch control box also contains a switch controller, which communicates with the BMS in the battery module to obtain the cell SOC and calculates the SOC of the battery module. Based on the SOC of the battery module, the controller controls the on / off state of the bidirectional controllable switches connected to the switch controller.

[0105] Figure 6 In one implementation, the switch control box is positioned between the battery module and the external control device. Alternatively, the switch control box can be located within the external control device. The specific configuration can be chosen based on actual requirements.

[0106] The above Figure 1 and Figure 6 In one embodiment, the energy storage unit in one charging / discharging circuit is a single battery module. In another implementation, the energy storage unit in one charging / discharging circuit can also be multiple battery modules, specifically as follows... Figure 7 As shown. Figure 7 The example given is a two-way controllable switch located in a switch control box outside the battery module. In an alternative implementation, the switch control box can also be located in an external control device.

[0107] Figure 7 In the circuit, bidirectional controllable switch 1 is connected to battery modules 1-N in parallel, where N is a positive integer. Bidirectional controllable switch 2 is connected to battery modules 1-X in parallel, where X is a positive integer. Other bidirectional controllable switches in the switch control box can also be connected to at least one battery module.

[0108] In this embodiment, the circuit containing a bidirectional controllable switch is called a charging / discharging circuit, and at least one battery module connected to the bidirectional controllable switch can form an energy storage unit in the charging / discharging circuit. Figure 7 and Figure 1 and Figure 6 In contrast, in this embodiment, the number of battery modules in the energy storage unit of one charging / discharging circuit is one or more.

[0109] Figure 7 The connection relationships of other components are described in the above embodiments and will not be repeated here.

[0110] Based on the structure of the aforementioned energy storage system, one embodiment of this application provides a charging and discharging control method, referring to... Figure 8 It can include:

[0111] S11. In response to the multiple charging and discharging circuits in the energy storage system being in a charging and discharging state, monitor the state of charge of the energy storage unit in each charging and discharging circuit.

[0112] The energy storage system is equipped with multiple charging and discharging circuits, each of which is a circuit that performs charging and discharging operations on the energy storage units within the system. Figure 1 For example, Figure 1 It is equipped with N charging and discharging circuits. The charging and discharging circuits can be in a charging and discharging state, which is divided into two states: charging state and discharging state.

[0113] When multiple charging and discharging circuits in an energy storage system are in a charging state, it means that the energy storage units in the energy storage system are being charged using multiple charging and discharging circuits, i.e., multiple charging and discharging circuits are in the charging process.

[0114] When multiple charging and discharging circuits in an energy storage system are in a discharging state, it means that the energy storage units in the energy storage system are being discharged using multiple charging and discharging circuits, i.e., the multiple charging and discharging circuits are in the discharging process.

[0115] The charging and discharging circuit includes a bidirectional controllable switch. During the charging process, the switch is activated in the first direction. During the discharging process, the switch is activated in the second direction. The first direction is the direction in which the charging current flows to the battery module; the second direction is the direction in which the discharging current flows out of the battery module. For specific implementation details, please refer to the above description.

[0116] When the energy storage unit in the charging and discharging circuit, i.e., at least one battery module, begins charging and discharging operations, the on / off states of the first and second switches in the battery module can be configured as needed, and can be either open or closed. In one example, both the first and second switches are closed. That is, when charging and discharging operations are required for the battery module, the first and second switches are closed. Specifically, closing the switches can be achieved by the control module issuing a conduction command to the first and second switches. When the control module is the BMS inside the battery module, the BMS can communicate directly with the switches and can directly issue conduction commands to the first and second switches. When the control module is a PCS or a switch controller in a switch control box, the PCS or switch controller can indirectly communicate with the switches through the BMS inside the battery module. The PCS or switch controller issues a conduction command to the BMS, causing the BMS to indirectly close the first and second switches, thus enabling the two switches to conduct.

[0117] In practical scenarios, for a charging and discharging circuit, one can utilize... Figure 1The cell information acquisition path collects cell information for each cell, such as the cell's State of Charge (SOC). Based on the cell's SOC, the SOC of the battery module containing the cell is obtained, and then the SOC of the energy storage unit is determined based on the SOC of the battery module. The SOC of the energy storage unit refers to a value that characterizes the overall state of charge of the energy storage unit.

[0118] S12. When multiple charging and discharging circuits are in the charging process, in response to the state of charge of the energy storage unit of any charging and discharging circuit being greater than or equal to the preset upper limit threshold of the state of charge, the bidirectional controllable switch in that charging and discharging circuit is controlled to be turned off in the first direction.

[0119] The preset upper limit threshold for the state of charge (SOC) is a threshold indicating whether the energy storage unit is about to be fully charged or has already been fully charged. This threshold can be a factory default value or a value manually configured based on the actual scenario. For example, it can be 100% or a value close to 100%, such as 98% or 99%. During the charging process of the energy storage unit in the charging / discharging circuit, if the SOC is greater than or equal to the upper limit threshold, it indicates that the energy storage unit is nearing or has already been fully charged. Continuing to charge the energy storage unit at this point will lead to overcharging. In this situation, the first switch can be controlled, such as... Figure 3 When switch K1 is open, the bidirectional controllable switch is cut off in the first direction, preventing the energy storage unit from being charged and thus avoiding overcharging. At this time, the second switch in the bidirectional controllable switch of this charging and discharging circuit can be closed, allowing the energy storage unit to discharge. This ensures that the energy storage unit can discharge immediately when needed, achieving timely response to energy storage unit discharge.

[0120] In this embodiment, for the charging and discharging circuit where the state of charge of the energy storage unit is less than the preset upper limit threshold of the state of charge, since the SOC of the energy storage unit is small and there is no risk of overcharging, the bidirectional controllable switch can be controlled to remain on in the first direction to continue charging it.

[0121] In one example, referencing Figure 1In a charging / discharging circuit, the energy storage unit includes only one battery module. For the charging / discharging circuit containing battery module 1, if the state of charge (SOC) of battery module 1 is greater than or equal to a preset SOC upper limit threshold, then switch K1 in the charging / discharging circuit containing battery module 1 can be opened, and battery module 1 stops charging. Switch K2 in the charging / discharging circuit containing battery module 1 can be closed, allowing battery module 1 to discharge. This ensures that battery module 1 can discharge immediately when needed, achieving timely discharge response. For the charging / discharging circuit containing battery module 2, if the SOC of battery module 2 is less than the preset SOC upper limit threshold, then switch K1 in the charging / discharging circuit containing battery module 2 remains closed, and battery module 2 continues charging. The same applies to other battery modules.

[0122] S13. When multiple charging and discharging circuits are in the process of discharging, in response to the state of charge of the energy storage unit of any charging and discharging circuit being less than or equal to the preset state of charge lower threshold, the bidirectional controllable switch in that charging and discharging circuit is controlled to be turned off in the second direction.

[0123] The preset state-of-charge (SOC) lower limit threshold is a threshold indicating whether the energy storage unit is nearing or has already been discharged. This threshold can be a factory default value or a manually configured value based on the actual scenario; for example, it can be 0% or a value close to 0%, such as 1%. During the discharge process of the battery module in the energy storage unit, if the SOC of the energy storage unit is less than or equal to the lower SOC threshold, it indicates that the energy storage unit is nearing or has already been discharged. Continuing to discharge the energy storage unit at this time will lead to over-discharge. In this case, a second switch can be controlled, such as... Figure 3 When switch K2 is open, the bidirectional controllable switch is cut off in the second direction, preventing the energy storage unit from discharging and thus avoiding over-discharge. The first switch in the bidirectional controllable switch can be closed, allowing the energy storage unit to be charged. This enables the energy storage unit to be charged immediately when needed, achieving timely charging response.

[0124] In one implementation, for a charging and discharging circuit where the state of charge of the energy storage unit is greater than a preset state of charge lower limit threshold, since the SOC of the energy storage unit is relatively large and there is currently no risk of over-discharge, a bidirectional controllable switch can be controlled to remain on in the second direction to continue discharging.

[0125] In one example, referencing Figure 1In a charging / discharging circuit, the energy storage unit includes only one battery module. For the charging / discharging circuit containing battery module 1, if the state of charge (SOC) of battery module 1 is less than or equal to a preset SOC threshold, then switch K2 in the charging / discharging circuit containing battery module 1 can be opened, and battery module 1 stops discharging. Switch K1 in the charging / discharging circuit containing battery module 1 can be closed, allowing battery module 1 to be charged. This ensures immediate charging response. For the charging / discharging circuit containing battery module 2, if the SOC of battery module 2 is greater than the preset SOC threshold, then switch K2 in the charging / discharging circuit containing battery module 2 remains closed, and battery module 2 continues discharging. The same applies to other battery modules.

[0126] It should be noted that, for steps S12 and S13 in this embodiment, only step S12 or only step S13 can be executed, or either S12 or S13 can be executed when the corresponding conditions are met. In one implementation, charging control can be performed only when the multiple charging / discharging circuits are charging, according to the principle of "controlling the bidirectional controllable switch in the charging / discharging circuit to be turned off in the first direction in response to the state of charge of the energy storage unit in any charging / discharging circuit being greater than or equal to a preset upper limit threshold of the state of charge." In another implementation, discharging control can be performed only when the multiple charging / discharging circuits are discharging, according to the principle of "controlling the bidirectional controllable switch in the charging / discharging circuit to be turned off in the second direction in response to the state of charge of the energy storage unit in any charging / discharging circuit being less than or equal to a preset upper limit threshold of the state of charge." In another implementation, during the charging process of multiple charging and discharging circuits, charging control is performed according to the principle of "controlling the bidirectional controllable switch in the charging and discharging circuit to be cut off in the first direction in response to the state of charge of the energy storage unit in any charging and discharging circuit being greater than or equal to a preset upper limit threshold of the state of charge". During the discharging process of multiple charging and discharging circuits, discharging control is performed according to the principle of "controlling the bidirectional controllable switch in the charging and discharging circuit to be cut off in the second direction in response to the state of charge of the energy storage unit in any charging and discharging circuit being less than or equal to a preset upper limit threshold of the state of charge".

[0127] In this embodiment, a bidirectional controllable switch is provided in the charging and discharging circuit of the energy storage unit, such as a battery module. During the charging process, the bidirectional controllable switch in the charging and discharging circuit is turned on in the first direction, thereby charging the energy storage unit. During charging, if the state of charge (SOC) of the energy storage unit in any charging or discharging circuit is greater than or equal to a preset SOC upper limit threshold, the bidirectional controllable switch in that charging or discharging circuit is turned off in the first direction to prevent overcharging of the energy storage unit. During discharging, the bidirectional controllable switch in the charging and discharging circuit is turned on in the second direction, thereby allowing the energy storage unit to discharge. During discharging, if the SOC of the energy storage unit in any charging or discharging circuit is less than or equal to a preset SOC upper limit threshold, the bidirectional controllable switch in that charging or discharging circuit is turned off in the second direction to prevent over-discharging of the energy storage unit. By implementing these measures to prevent overcharging and over-discharging of the energy storage unit, the operational reliability of the energy storage unit is improved.

[0128] Furthermore, the unidirectional current flow control scheme for the energy storage unit based on a bidirectional controllable switch in this embodiment achieves overcharge and over-discharge protection for the energy storage unit and balanced management of multiple battery modules in parallel by limiting the current direction. When the SOC of the energy storage unit approaches the upper or lower limit, the corresponding charging or discharging path is cut off by the switch to prevent extreme conditions.

[0129] Alternatively, the switch can be composed of MOSFETs. After configuring the switch in the charging and discharging circuit, it can be combined with a turn-off current absorption circuit to improve reliability. This solution is simple in design, low in cost, suitable for series or parallel systems, and can achieve dynamic power distribution, improving system safety and user experience.

[0130] Based on any of the above embodiments, in one implementation, the energy storage unit includes a single battery module located in a charging / discharging circuit. A bidirectional controllable switch is disposed inside or outside the battery module within the charging / discharging circuit. The battery module contains at least one battery cell, and all battery cells are connected to the bidirectional controllable switch. For specific structure details, please refer to [reference needed]. Figure 1 or Figure 6 As shown.

[0131] At this time, refer to Figure 9 Monitoring the state of charge of the energy storage units in each charging and discharging circuit can include:

[0132] S21. For each charging / discharging circuit, obtain the state of charge of each cell in the battery module in the charging / discharging circuit.

[0133] In practical implementation, for each cell in the battery module of each charging and discharging circuit, the SOC of the cell can be calculated using the ampere-hour integration method (coulomb counting method) during the dynamic charging and discharging process. The SOC of the cell in its static state can be calculated using the open circuit voltage method (OCV). The two calculated SOCs are then fused to obtain the final SOC of the cell, thereby improving the accuracy of the cell SOC calculation.

[0134] S22. The average value of the state of charge of each cell is taken as the state of charge of the energy storage unit.

[0135] After obtaining the SOC of each cell in the battery module in the charging and discharging circuit, the average value of the state of charge of each cell can be used as the SOC of the energy storage unit. The SOC of the energy storage unit can represent the average state of the cell SOC.

[0136] In another implementation, monitoring the state of charge of the energy storage unit in each charge / discharge circuit can include:

[0137] For each charge / discharge circuit, the state of charge (SOC) of each cell in the battery module is obtained. When a cell is discharging, the minimum SOC is used as the SOC of the energy storage unit to avoid over-discharging of the cell with the lowest SOC. When a cell is charging, the maximum SOC is used as the SOC of the energy storage unit to avoid overcharging of the cell with the highest SOC.

[0138] Based on any of the above embodiments, the energy storage unit includes multiple battery modules connected in parallel. These parallel battery modules are located in the same charging / discharging circuit. A bidirectional controllable switch is disposed outside the battery modules in the charging / discharging circuit. Each battery module contains at least one battery cell, and the battery cell in the battery module is connected to the bidirectional controllable switch. For specific structure details, please refer to [reference needed]. Figure 7 As shown.

[0139] At this point, the state of charge of the energy storage unit in each charging and discharging circuit can be monitored in various ways, for example:

[0140] In one possible implementation, for each charging and discharging circuit, the state of charge (SOC) of the battery module can be determined based on the SOC of the cells in each battery module in the charging and discharging circuit, and the average SOC of each battery module can be used as the SOC of the energy storage unit.

[0141] In this embodiment, the state of charge (SOC) of the battery module is determined based on the SOC of the cells in each battery module within the charging and discharging circuit, as described above. After knowing the SOC of each battery module, to consider the average SOC of the battery modules, the average SOC of each battery module can be used as the SOC of the energy storage unit.

[0142] For example, if there are three battery modules with states of charge of 50%, 70%, and 60% respectively, then the state of charge of the energy storage unit is (50%+70%+60%) / 3=60%.

[0143] In one possible implementation, monitoring the state of charge of the energy storage unit in each charging and discharging circuit can also be done as follows:

[0144] For each charging and discharging circuit, the state of charge (SOC) of the battery module is determined based on the SOC of the cells in each battery module within the charging and discharging circuit. When the battery module is discharging, the minimum SOC is taken as the SOC of the energy storage unit; when the battery module is charging, the maximum SOC is taken as the SOC of the energy storage unit.

[0145] In this embodiment, the state of charge (SOC) of the battery module is determined based on the SOC of the cells in each battery module within the charging and discharging circuit, as described above. Once the SOC of each battery module is known, the SOC of the energy storage unit can be determined from the perspective of its maximum charging and discharging capacity.

[0146] For example, there are three battery modules with states of charge of 50%, 70%, and 60%, respectively. When the battery modules are discharging, the state of charge of the energy storage unit is set to 50%, and when the battery modules are charging, the state of charge of the energy storage unit is set to 70%.

[0147] In this embodiment, different methods are used to determine the state of charge of the energy storage unit when the structure of the energy storage system is different, so that bidirectional controllable switching can be controlled based on the determined state of charge.

[0148] Based on any of the above embodiments, in one implementation, the charge / discharge control method in this embodiment can also achieve SOC balancing among energy storage units. Optionally, in one implementation, referring to... Figure 10 The charging and discharging control method also includes:

[0149] S31. When discharging in multiple charging and discharging circuits, and when there is an imbalance in the SOC of the energy storage units in the multiple charging and discharging circuits, determine the target discharge energy storage unit from all the energy storage units.

[0150] The target discharge energy storage unit is the energy storage unit other than the first energy storage unit among all energy storage units, and the first energy storage unit is the energy storage unit with the lowest state of charge among all energy storage units.

[0151] Optionally, during the discharge process, to avoid over-discharging of energy storage units with lower SOCs, the energy storage system prioritizes the discharge of energy storage units with higher SOCs. During the charging process, to avoid overcharging of energy storage units with higher SOCs, the energy storage system prioritizes the charging of energy storage units with lower SOCs. Therefore, in this embodiment, suitable target discharge energy storage units and target charging energy storage units need to be selected separately during the charging and discharging processes of the energy storage system. This embodiment describes the charging and discharging scenarios separately.

[0152] During the discharge process of an energy storage system, if the State of Charge (SOC) of multiple energy storage units is balanced, the difference in SOC between the units is small, and the probability of any one unit being over-discharged is low. Therefore, all energy storage units can be discharged, or specific units can be selected for discharge based on discharge requirements. Conversely, if the SOC of multiple energy storage units is unbalanced, the difference in SOC between the units is large, and the probability of any one unit being over-discharged is high. Therefore, it is necessary to select a suitable target energy storage unit for discharge.

[0153] Determining whether the State of Charge (SOC) is balanced among multiple energy storage units can include:

[0154] For each energy storage unit in the energy storage system, the State of Charge (SOC) of each unit can be obtained as described above. Then, the largest and smallest SOCs are selected, and the difference between them is calculated. The larger the difference, the greater the SOC difference among the multiple energy storage units. If the difference exceeds a set upper limit, it indicates an imbalance in the SOC among the multiple energy storage units. Conversely, the smaller the difference, the smaller the SOC difference among the multiple energy storage units, and the closer their SOCs are. If the difference is less than or equal to a set lower limit, it indicates a balanced SOC among the multiple energy storage units.

[0155] When an energy storage system discharges and multiple energy storage units have an imbalance in their State of Charge (SOC), discharging the energy storage unit with the lowest SOC carries a significant risk of it being completely depleted. Therefore, to protect the energy storage unit with the lowest SOC, it can be designated as the primary energy storage unit, and the remaining energy storage units (excluding the primary unit) can be designated as target discharge energy storage units. The number of target discharge energy storage units can be determined based on the actual configuration.

[0156] In one implementation, when determining the target discharge energy storage unit from all energy storage units, all energy storage units except the first energy storage unit can be selected as the target discharge energy storage unit. That is, in this embodiment, the energy storage unit with the lowest SOC is preferentially avoided from over-discharging, and all other remaining energy storage units are selected as the target discharge energy storage unit.

[0157] In one implementation, after determining the first energy storage unit, the maximum total discharge power of all other energy storage units in the energy storage system, excluding the first energy storage unit, can be calculated. This maximum total discharge power is the sum of the discharge powers of all other energy storage units excluding the first energy storage unit. In this embodiment, calculating the maximum total discharge power of all other energy storage units excluding the first energy storage unit is to determine whether all remaining energy storage units can provide the target discharge power without using the first energy storage unit for discharge operations. The target discharge power of the energy storage system is related to the load demand power and can be determined based on the load demand power and the discharge capacity that the energy storage system can provide. If the load demand power is within the maximum discharge power that the energy storage system can provide, the target discharge power of the energy storage system is equal to the load demand power.

[0158] After calculating the maximum total discharge power, if the maximum total discharge power is greater than the discharge target power, it means that without using the first energy storage unit for discharge operation, all other remaining energy storage units can also provide the discharge target power. In this case, all other energy storage units except the first energy storage unit can be used as the target discharge energy storage units.

[0159] In another implementation, when selecting the target discharge energy storage unit, a portion of the energy storage units other than the first energy storage unit can be selected as the target discharge energy storage unit. In this embodiment, compared to the above embodiment designed to avoid over-discharge of the energy storage unit with the lowest SOC, this embodiment aims to avoid over-discharge of multiple energy storage units with lower SOCs. Therefore, instead of selecting all energy storage units except the first energy storage unit as the target discharge energy storage unit, it selects a portion of the energy storage units other than the first energy storage unit as the target discharge energy storage unit.

[0160] In one implementation, when selecting a portion of the energy storage units other than the first energy storage unit from all the energy storage units as target discharge energy storage units, the energy storage units other than the first energy storage unit can be determined as pre-selected discharge energy storage units. Based on the discharge target power, at least one energy storage unit with a total output power greater than or equal to the discharge target power from the determined pre-selected discharge energy storage units can be selected as the target discharge energy storage unit.

[0161] In practical implementation, each energy storage unit except the first energy storage unit can be designated as a pre-selected discharge energy storage unit. Then, for each pre-selected discharge energy storage unit, the discharge power of the energy storage units is summed in descending order of their State of Charge (SOC). This determines the minimum number of energy storage units required to ensure that the sum of the discharge power exceeds the target discharge power. For example, in an energy storage system with five energy storage units (units 1, 2, 3, 4, and 5), each with a discharge power of 10 kW, and SOCs of 98%, 96%, 60%, 40%, and 30% for units 1, 2, 3, 4, and 5, respectively, the current target discharge power is 25 kW.

[0162] During discharge operations, priority is given to energy storage units with higher State of Charge (SOC) and whose summed discharge power exceeds the target discharge power. This aims to reduce the SOC gap between energy storage units and prevent energy storage units with lower SOC from having excessively low charge levels. The discharge power is then summed according to SOC from highest to lowest. As mentioned above, the SOC of energy storage units 1, 2, 3, 4, and 5 decreases sequentially. Therefore, the power can be summed in the order of energy storage units 1, 2, 3, 4, and 5. The discharge power of energy storage unit 1 is 10KW, which is less than the target discharge power of 25KW, thus not meeting the discharge requirement. The sum of the discharge power of energy storage units 1 and 2 is 20KW, which is also less than the target discharge power of 25KW, still not meeting the discharge requirement. The sum of the discharge power of energy storage units 1, 2, and 3 is 30KW, which is greater than the target discharge power of 25KW, thus meeting the discharge requirement. Therefore, energy storage units 1, 2, and 3 are the minimum number of energy storage units required to make the sum of their discharge power greater than the target discharge power. Thus, energy storage units 1, 2, and 3 are determined as the target discharge energy storage units with a total output power greater than or equal to the target discharge power. In other words, although there are five energy storage units in the energy storage system, only energy storage units 1, 2 and 3 need to be used for discharge operations to meet the discharge target power. Since energy storage units 4 and 5 have lower SOCs compared to energy storage units 1, 2 and 3, the discharge operations of energy storage units 4 and 5 can be stopped to avoid over-discharge problems caused by the low SOC of these two energy storage units during discharge.

[0163] It should be noted that the above embodiments select the target discharge energy storage unit based on power parameters. In an alternative implementation, the target discharge energy storage unit can also be selected based on current parameters. Whether power or current is used can be determined according to the actual configuration.

[0164] S32. Controlling the bidirectional controllable switch in the charging / discharging circuit where the target discharge energy storage unit is located to be turned on in the second direction, and controlling the bidirectional controllable switch in the charging / discharging circuit where all energy storage units except the target discharge energy storage unit are located to be turned off in the second direction.

[0165] In this embodiment, after identifying the target discharge energy storage unit, the switch K2 in the bidirectional controllable switch of the target discharge energy storage unit is closed, thereby controlling the bidirectional controllable switch in the target discharge energy storage unit to conduct in the second direction, and the target discharge energy storage unit begins to discharge. Furthermore, the bidirectional controllable switch in the target discharge energy storage unit can be either open or closed in the first direction, depending on the charging requirements.

[0166] In this embodiment, only the target discharge energy storage unit needs to be used for discharge operations. The non-target discharge energy storage units—that is, all energy storage units except the target discharge energy storage unit—do not need to discharge. Therefore, switch K2 in the non-target discharge energy storage units can be disconnected, controlling the bidirectional controllable switch in the non-target discharge energy storage unit to be cut off in the second direction, preventing discharge operations. Additionally, switch K1 connected to the non-target discharge energy storage unit can be in a conducting state at this time. If the energy storage system transitions from a discharging state to a charging state, the non-target discharge energy storage unit can be charged promptly.

[0167] Taking the above example of identifying energy storage units 1, 2, and 3 as the target discharge energy storage units, the bidirectional controllable switch in the charge / discharge circuit containing energy storage units 1, 2, and 3 is turned on in the second direction, while the bidirectional controllable switch in the charge / discharge circuit containing energy storage units 4 and 5 is turned off in the second direction, causing energy storage units 4 and 5 to stop discharging. If the target discharge power increases, the second switch of energy storage units 4 and 5 can be closed as needed, allowing them to continue discharging. At this time, the first switch connected to energy storage units 4 and 5 can be in a conducting state. If the energy storage system transitions from a discharging state to a charging state, energy storage units 4 and 5 can be charged in a timely manner.

[0168] In this embodiment, since energy storage units with higher SOC are preferentially used for discharge operations, the SOC of these units gradually decreases, reducing the SOC difference between the various energy storage units and achieving SOC balance. As discharge operations continue, there may be situations where the total output power of the currently discharging energy storage units cannot meet the discharge target power. In this case, the target discharge energy storage unit is selected again and executed sequentially until all energy storage units have performed discharge operations.

[0169] Furthermore, when a storage unit with a high State of Charge (SOC) is discharged, the SOC gradually decreases, potentially leading to a situation where its SOC is too low to be suitable as a target discharge storage unit. Continuing to use this unit for discharge could result in over-discharge. To avoid this problem, one implementation involves real-time monitoring of the State of Charge (SOC) of each target discharge storage unit during the discharge process. In cases where there is an imbalance in the SOC of storage units across multiple charge / discharge loops, the target discharge storage unit is determined from all available units. In other words, the selected target discharge storage unit is updated in real-time based on the SOC of each storage unit, and the discharge operation is then performed using the target discharge storage unit.

[0170] In this embodiment, when the energy storage system is discharging, the second switch of the energy storage unit with the lowest or lower SOC is disconnected to stop the discharge, thus avoiding the problem of excessively low SOC or even over-discharge caused by the discharge operation. However, since the first switch connected to the energy storage unit can be in the on state, if the energy storage system changes from the discharge state to the charging state, the energy storage unit can be charged in time to improve its SOC.

[0171] The above embodiments describe an example of discharging an energy storage system. Another implementation, an embodiment of charging an energy storage system, can be found by referring to [the above examples]. Figure 11 As shown. The charge / discharge control method also includes:

[0172] S41. When charging in multiple charging and discharging circuits, and when there is an imbalance in the SOC of the energy storage units in the multiple charging and discharging circuits, determine the target charging energy storage unit from all the energy storage units.

[0173] The target charging energy storage unit is the energy storage unit other than the second energy storage unit among all energy storage units, and the second energy storage unit is the energy storage unit with the highest state of charge among all energy storage units.

[0174] In this embodiment, the charging of the energy storage system is similar to the discharging embodiment described above. It also requires determining the target charging energy storage unit from among multiple energy storage units when there is a SOC imbalance. The explanation of the SOC imbalance is provided above.

[0175] When determining the target charging energy storage unit from multiple energy storage units, the implementation method is similar to that for determining the target discharging energy storage unit. In one implementation, all energy storage units except the second energy storage unit are selected as the target charging energy storage unit.

[0176] In practical scenarios, when charging an energy storage system, the target energy storage unit can be selected to avoid overcharging the energy storage unit with the highest SOC. In this case, the second energy storage unit with the highest SOC can be selected, and then the maximum total charging power of all other energy storage units in the system, excluding the second energy storage unit, can be calculated. This maximum total charging power is the sum of the charging power of all other energy storage units except the second energy storage unit.

[0177] In this embodiment, the calculation of the maximum total charging power of all energy storage units other than the second energy storage unit is to determine whether the remaining energy storage units can be charged using the above-mentioned target charging power without charging the second energy storage unit.

[0178] If the maximum total charging power is greater than the target charging power, it means that even if the second energy storage unit is not charged, the other remaining energy storage units can still be charged using the target charging power. In this case, all energy storage units other than the second energy storage unit are taken as the target charging energy storage units.

[0179] In another implementation, some energy storage units other than the second energy storage unit can be selected as target charging energy storage units from all energy storage units.

[0180] Optionally, the above embodiments are designed to avoid overcharging of the energy storage unit with the highest SOC. In one optional implementation, the target charging energy storage unit is selected to avoid overcharging of multiple energy storage units with high SOC. In one implementation, when selecting a portion of the energy storage units other than the second energy storage unit from all the energy storage units as the target charging energy storage unit, it can be done as follows: from all the energy storage units, determine the energy storage units other than the second energy storage unit as pre-selected charging energy storage units; based on the charging target power, select at least one energy storage unit from the determined pre-selected charging energy storage units whose total input power is greater than or equal to the charging target power as the target charging energy storage unit.

[0181] In specific implementation, each energy storage unit other than the second energy storage unit is determined as a pre-selected charging energy storage unit. For the pre-selected charging energy storage units in the energy storage system, when selecting the target charging energy storage unit that can be charged with the target charging power, the charging power of the energy storage units can be summed in order of SOC from low to high to determine the minimum number of energy storage units that make the summed charging power greater than or equal to the target charging power. The determined energy storage units are used as the target charging energy storage units. The specific implementation is the same as the discharge operation described above.

[0182] It should be noted that in this embodiment, the target charging energy storage units are selected in order of SOC from low to high in order to prioritize charging the energy storage units with lower SOC, so as to shorten the SOC gap between energy storage units and avoid the energy storage units with higher SOC from having excessive charge.

[0183] S42. Controlling the bidirectional controllable switch in the charging and discharging circuit where the target charging energy storage unit is located to be turned on in the first direction, and controlling the bidirectional controllable switch in the charging and discharging circuit where all energy storage units except the target charging energy storage unit are located to be turned off in the first direction.

[0184] In this embodiment, after selecting the target charging energy storage unit, the first switch in the target charging energy storage unit can be closed to control the bidirectional controllable switch in the target charging energy storage unit to conduct in the first direction, at which time the target charging energy storage unit can be charged. In an optional implementation, if the energy storage units other than the target charging energy storage unit do not need to be charged, the first switches in the energy storage units other than the target charging energy storage unit can be opened to control the bidirectional controllable switches in the energy storage units other than the target charging energy storage unit to be cut off in the first direction, that is, no charging operation is performed on the non-target charging energy storage units at this time. The second switch of the non-target charging energy storage unit can be opened or closed. When there is a charging demand later, the closed second switch allows the non-target charging energy storage unit to directly discharge.

[0185] It should be noted that during the charging process, the State of Charge (SOC) of the energy storage unit being charged will continuously increase. This could lead to a situation where the selected target energy storage unit may include the one with the highest SOC. Therefore, in this embodiment, during the charging process of the target energy storage unit, the state of charge of each target energy storage unit is monitored in real time. When charging in multiple charging / discharging loops, and where there is an imbalance in the SOC of the energy storage units in these loops, the step of determining the target energy storage unit from all energy storage units is executed. In other words, by continuously adjusting the target energy storage unit, charging operations are performed on the lower SOC units, ultimately achieving SOC balance.

[0186] Furthermore, in this embodiment, since charging operations are prioritized for energy storage units with lower SOCs, the SOC of these units gradually increases, approaching the higher SOC, thus reducing the SOC difference between the various energy storage units and achieving SOC balance. As charging operations continue, there may come a point where the maximum total charging power of the currently charging energy storage units no longer exceeds the target charging power. In this case, the target charging energy storage units are selected again, and the process is repeated sequentially until all energy storage units are fully charged.

[0187] In this embodiment, when the energy storage system is charging, the first switch of the energy storage unit with the highest or relatively high SOC is disconnected to stop charging, thus avoiding excessive SOC or even overcharging caused by the charging operation. However, since the connected second switch can be in the conducting state, if the energy storage system switches from the charging state to the discharging state, the energy storage unit can be discharged in time.

[0188] It should be noted that the above embodiments describe the discharge and charging processes of the energy storage system. In the implementation scenario, the energy storage system discharge operation can operate according to the control logic described above, while the energy storage system charging operation can operate according to other control logic. Alternatively, the energy storage system charging operation can operate according to the control logic described above, while the energy storage system discharge operation can operate according to other control logic. Or, the energy storage system discharge operation can operate according to the control logic described above, and the energy storage system charging operation can also operate according to the control logic described above, that is:

[0189] The charge / discharge control methods also include:

[0190] When discharging through multiple charging and discharging loops, and when there is an imbalance in the state of charge (SOC) of the energy storage units in the multiple charging and discharging loops, the target discharge energy storage unit is determined from all the energy storage units. The target discharge energy storage unit is the energy storage unit other than the first energy storage unit. The first energy storage unit is the energy storage unit with the lowest state of charge among all the energy storage units.

[0191] The bidirectional controllable switch in the charging and discharging circuit where the target discharge energy storage unit is located is turned on in the second direction, and the bidirectional controllable switch in the charging and discharging circuit where all energy storage units except the target discharge energy storage unit are located is turned off in the second direction.

[0192] And / or,

[0193] When charging in a multi-channel charging and discharging loop, and when there is an imbalance in the state of charge (SOC) of the energy storage units in the multi-channel charging and discharging loop, the target charging energy storage unit is determined from all the energy storage units. The target charging energy storage unit is the energy storage unit other than the second energy storage unit. The second energy storage unit is the energy storage unit with the highest state of charge among all the energy storage units.

[0194] The bidirectional controllable switch in the charging and discharging circuit of the target charging energy storage unit is turned on in the first direction, and the bidirectional controllable switch in the charging and discharging circuit of all energy storage units except the target charging energy storage unit is turned off in the first direction.

[0195] The specific configuration can be determined based on actual needs.

[0196] In addition, in a practical scenario, in one implementation, when the SOC of the energy storage unit has not reached the upper or lower SOC threshold, the above-mentioned SOC balancing operation during charging and discharging can be used to control the first and second switches to achieve SOC balancing among the energy storage units. When the SOC of the energy storage unit reaches the upper or lower SOC threshold, in order to protect the energy storage unit and avoid overcharging or over-discharging, the corresponding switch of the energy storage unit will be disconnected.

[0197] In addition to using SOC to control the first and second switches, since SOC is related to voltage, voltage can also be used to control the first and second switches, with similar implementation details.

[0198] In summary, this embodiment proposes a unidirectional / bidirectional current flow control algorithm for energy storage units based on a bidirectional controllable switch. When the voltage or SOC of the energy storage unit approaches or reaches a set upper limit (e.g., SOC ≥ 99%), the bidirectional controllable switch limits the power flow of the energy storage unit to be cut off in the charging direction, while the discharging direction operates normally. When the voltage or SOC of the energy storage unit approaches or reaches a set lower limit (e.g., SOC ≤ 1%), the bidirectional controllable switch is cut off in the discharging direction, while the charging direction is normally open. This achieves safe charging and discharging management of the energy storage unit near the upper and lower SOC limits, and also meets the requirements for immediate use. Similarly, for energy storage systems, SOC balancing control can also be achieved through unidirectional current control. The entire scheme achieves overcharge and over-discharge protection and parallel balancing management of the energy storage unit by limiting the current direction. The scheme is simple, reliable, and low-cost, and is applicable to systems that expand energy storage units in series or in parallel.

[0199] Based on any of the above embodiments, the charge / discharge control method further includes:

[0200] The temperature of the energy storage unit in each charging / discharging circuit is acquired. In response to the temperature of any energy storage unit in any charging / discharging circuit exceeding a certain upper temperature threshold, the bidirectional controllable switch in that charging / discharging circuit is controlled to be turned off in both the first and second directions. In response to the temperature of any energy storage unit in any charging / discharging circuit being lower than a certain lower temperature threshold, the bidirectional controllable switch in that charging / discharging circuit is controlled to be turned off in the first direction.

[0201] The temperature of the energy storage unit can be the temperature of the battery cells in the battery module within the energy storage unit, and this temperature can be determined by... Figure 1 In this embodiment, in order to monitor the cell temperature, an upper temperature threshold and a lower temperature threshold can be manually set. The upper temperature threshold is a high temperature threshold, and the lower temperature threshold is a low temperature threshold.

[0202] If the temperature of the energy storage unit exceeds the upper temperature threshold, it indicates that the current cell temperature is too high and the cell is abnormal. At this time, both the first and second control switches are disconnected, and the bidirectional controllable switch is cut off in both the first and second directions, so that the cell is neither allowed to charge nor discharge, in order to protect the cell.

[0203] If the temperature of the energy storage unit is lower than the lower limit threshold, it indicates that the current cell temperature is too low and it is not suitable to continue charging. However, it is possible to discharge the cell. In this case, the first switch can be opened, the bidirectional controllable switch can be closed in the first direction, and the second switch can remain closed.

[0204] In this embodiment, based on the judgment result of whether the temperature of the energy storage unit is too high, the first switch and the second switch are controlled to operate to better protect the battery cell.

[0205] It should be noted that this embodiment is applicable to any energy storage unit. It only requires judging the output voltage, SOC or temperature of the energy storage unit, controlling the bidirectional controllable switch to cut off in one direction, limiting the power flow of the battery module in one direction, and ensuring the reliable operation of the system.

[0206] Based on the embodiments of the above-described charge / discharge control method, another embodiment of this application provides a charge / discharge controller as described above, the charge / discharge controller including at least one processor and a memory connected to the processor, wherein:

[0207] Memory is used to store computer programs;

[0208] The processor is used to execute computer programs so that the charge / discharge controller can implement the above-described charge / discharge control method.

[0209] Based on the above-described embodiments of the charge / discharge controller, another embodiment of this application provides an energy storage system including multiple energy storage units, each of which houses the aforementioned charge / discharge controller. Specifically, the charge / discharge controller may be a BMS (Battery Management System).

[0210] In one implementation, the energy storage unit includes a single battery module located in a charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed inside or outside the battery module. The battery module is equipped with at least one battery cell, and all the battery cells are connected to the bidirectional controllable switch.

[0211] Alternatively, the energy storage unit includes multiple battery modules connected in parallel. The parallel battery modules are located in the same charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is set outside the battery module. Each battery module is equipped with at least one battery cell, and the battery cell in the battery module is connected to the bidirectional controllable switch.

[0212] In one implementation, a bidirectional controllable switch is located at the positive output terminal of the battery module;

[0213] Alternatively, a two-way controllable switch may be installed at the negative output terminal of the battery module;

[0214] Alternatively, a bidirectional controllable switch may be simultaneously installed at both the positive and negative output terminals of the battery module.

[0215] In one implementation, a bidirectional controllable switch is connected in parallel with a current-absorbing circuit for interruption.

[0216] In one implementation, the bidirectional controllable switch is connected to an external control device via a manual switch; the manual switch is used to control the connection and disconnection between the bidirectional controllable switch and the external control device.

[0217] Based on the above-described embodiments of the charge / discharge controller, another embodiment of this application provides an energy storage system including multiple energy storage units and the aforementioned charge / discharge controller, wherein the charge / discharge controller is communicatively connected to the multiple energy storage units. The charge / discharge controller can be an external control device that communicates with the battery modules in the energy storage units, such as a PCS electrically connected to the battery modules, or other electrical equipment in the energy storage system (such as a switch control box).

[0218] In one implementation, the energy storage unit includes a single battery module located in a charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed outside the battery module. The battery module is equipped with at least one battery cell, and all the battery cells are connected to the bidirectional controllable switch.

[0219] Alternatively, the energy storage unit includes multiple battery modules connected in parallel. The parallel battery modules are located in the same charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is set outside the battery module. Each battery module is equipped with at least one battery cell, and the battery cell in the battery module is connected to the bidirectional controllable switch after being connected.

[0220] It should be noted that the explanations of the various components and methods in this embodiment are provided in the corresponding descriptions above.

[0221] This application also provides a computer program product including computer-readable instructions, which, when executed on an electronic device, cause the electronic device to implement any of the charging and discharging control methods provided in this application.

[0222] This application also provides a computer-readable storage medium that carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any of the charging and discharging control methods provided in this application.

[0223] It should also be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. In addition, in the accompanying drawings of the device embodiments provided in this application, the connection relationship between modules indicates that they have a communication connection, which can be implemented as one or more communication buses or signal lines.

[0224] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware, or it can be implemented by special-purpose hardware including application-specific integrated circuits, special-purpose CPUs, special-purpose memory, special-purpose components, etc. Generally, any function performed by a computer program can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be diverse, such as analog circuits, digital circuits, or special-purpose circuits. However, for this application, software program implementation is more often the preferred implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium, such as a computer floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk, or optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, training equipment, or network device, etc.) to execute the methods of the various embodiments of this application.

[0225] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product.

[0226] A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions may be transmitted from one website, computer, training device, or data center to another website, computer, training device, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can store or a data storage device such as a training device or data center that integrates one or more available media. The available medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

Claims

1. A charging and discharging control method, characterized in that, include: In response to multiple charging and discharging circuits in the energy storage system being in a charging and discharging state, the state of charge of the energy storage unit in each charging and discharging circuit is monitored; wherein, a bidirectional controllable switch is provided in the charging and discharging circuit, and the bidirectional controllable switch in the charging and discharging circuit is turned on in the first direction during the charging process; and the bidirectional controllable switch in the charging and discharging circuit is turned on in the second direction during the discharging process. When multiple charging and discharging circuits are in the charging process, in response to the state of charge of the energy storage unit of any charging and discharging circuit being greater than or equal to a preset upper limit threshold of the state of charge, the bidirectional controllable switch in that charging and discharging circuit is controlled to be cut off in the first direction. and / or; When multiple charging and discharging circuits are in the process of discharging, in response to the state of charge of the energy storage unit of any charging and discharging circuit being less than or equal to a preset state of charge lower threshold, the bidirectional controllable switch in that charging and discharging circuit is controlled to be turned off in the second direction.

2. The charging and discharging control method according to claim 1, characterized in that, The energy storage unit includes a single battery module, which is located in a charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed inside or outside the battery module. The battery module is equipped with at least one battery cell, and all the battery cells are connected to the bidirectional controllable switch. The monitoring of the state of charge of the energy storage unit in each charging and discharging circuit includes: For each charging / discharging circuit, the state of charge of each cell in the battery module in the charging / discharging circuit is obtained; The average state of charge of each cell is taken as the state of charge of the energy storage unit. Alternatively, in the case of cell discharge, the minimum state of charge is taken as the state of charge of the energy storage unit. When the battery cell is being charged, the maximum state of charge is taken as the state of charge of the energy storage unit.

3. The charging and discharging control method according to claim 1, characterized in that, The energy storage unit includes multiple battery modules connected in parallel. The parallel battery modules are located in the same charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed outside the battery module. Each battery module is equipped with at least one battery cell, and the battery cell in the battery module is connected to the bidirectional controllable switch after being connected. The monitoring of the state of charge of the energy storage unit in each charging and discharging circuit includes: For each charging and discharging circuit, the state of charge of the battery module is determined based on the state of charge of the cells in each battery module in the charging and discharging circuit. The average state of charge of each battery module is taken as the state of charge of the energy storage unit. Alternatively, when the battery module is discharging, the minimum state of charge is taken as the state of charge of the energy storage unit. When the battery module is charging, the maximum state of charge is taken as the state of charge of the energy storage unit.

4. The charging and discharging control method according to claim 1, characterized in that, The charging and discharging control method further includes: When multiple charging and discharging circuits are discharged, and the energy storage units in the multiple charging and discharging circuits have an unbalanced state of charge (SOC), a target discharge energy storage unit is determined from all the energy storage units; wherein, the target discharge energy storage unit is: the energy storage unit other than the first energy storage unit; the first energy storage unit is the energy storage unit with the lowest state of charge among all the energy storage units; Controlling the bidirectional controllable switch in the charging and discharging circuit where the target discharge energy storage unit is located to be turned on in the second direction, and controlling the bidirectional controllable switch in the charging and discharging circuit where all the energy storage units except the target discharge energy storage unit are located to be turned off in the second direction; And / or, When charging is performed through multiple charging and discharging circuits, and the energy storage units in the multiple charging and discharging circuits have an imbalance in SOC, a target charging energy storage unit is determined from all the energy storage units; wherein, the target charging energy storage unit is: the energy storage unit other than the second energy storage unit among all the energy storage units; the second energy storage unit is the energy storage unit with the highest state of charge among all the energy storage units; The bidirectional controllable switch in the charging and discharging circuit of the target charging energy storage unit is turned on in the first direction, and the bidirectional controllable switch in the charging and discharging circuit of all energy storage units except the target charging energy storage unit is turned off in the first direction.

5. The charging and discharging control method according to claim 4, characterized in that, The step of determining the target discharge energy storage unit from all the energy storage units includes: From all the energy storage units, all of the energy storage units except the first energy storage unit are selected as the target discharge energy storage unit; Alternatively, from all the energy storage units, some of the energy storage units other than the first energy storage unit may be selected as the target discharge energy storage unit.

6. The charging and discharging control method according to claim 5, characterized in that, The step of selecting a portion of the energy storage units, excluding the first energy storage unit, from all the energy storage units as the target discharge energy storage units includes: From all the energy storage units, the energy storage units other than the first energy storage unit are identified as pre-selected discharge energy storage units; Based on the target discharge power, at least one of the energy storage units with a total output power greater than or equal to the target discharge power is selected from the determined pre-selected discharge energy storage units as the target discharge energy storage unit.

7. The charging and discharging control method according to any one of claims 4-6, characterized in that, After the bidirectional controllable switch in the charge / discharge circuit controlling the target discharge energy storage unit is turned on in the second direction, the charge / discharge control method further includes: During the discharge process of the target discharge energy storage unit, the state of charge of each target discharge energy storage unit is monitored in real time. Then return to the step of determining the target discharge energy storage unit from all the energy storage units when discharging in multiple charging and discharging circuits and when there is a SOC imbalance among the energy storage units in the multiple charging and discharging circuits.

8. The charging and discharging control method according to claim 4, characterized in that, The step of determining the target charging energy storage unit from all the energy storage units includes: From all the energy storage units, all of the energy storage units except the second energy storage unit are selected as the target charging energy storage unit; Alternatively, from all the energy storage units, a portion of the energy storage units other than the second energy storage unit may be selected as the target charging energy storage unit.

9. The charging and discharging control method according to claim 8, characterized in that, The step of selecting a portion of the energy storage units, excluding the second energy storage unit, from all the energy storage units as the target charging energy storage unit includes: From all the energy storage units, the energy storage units other than the second energy storage unit are identified as pre-selected charging energy storage units; Based on the target charging power, at least one of the energy storage units with a total input power greater than or equal to the target charging power is selected from the pre-selected energy storage units as the target energy storage unit.

10. The charging and discharging control method according to claim 8 or 9, characterized in that, After the bidirectional controllable switch in the charging and discharging circuit controlling the target charging energy storage unit is turned on in the first direction, the charging and discharging control method further includes: During the charging process of the target charging energy storage unit, the state of charge of each target charging energy storage unit is monitored in real time. Then return to the step of determining the target charging energy storage unit from all the energy storage units when charging in multiple charging and discharging circuits and when there is a SOC imbalance among the energy storage units in the multiple charging and discharging circuits.

11. The charging and discharging control method according to claim 1, characterized in that, The charging and discharging control method further includes: Obtain the temperature of the energy storage unit in each of the charging and discharging circuits; In response to the temperature of the energy storage unit in any of the charging and discharging circuits being greater than the upper temperature threshold, the bidirectional controllable switch in that charging and discharging circuit is controlled to be cut off in both the first and second directions. In response to the temperature of the energy storage unit in any of the charging and discharging circuits being lower than the lower limit threshold, the bidirectional controllable switch in that charging and discharging circuit is controlled to be turned off in the first direction.

12. A charge / discharge controller, characterized in that, The charge / discharge controller includes at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs; The processor is configured to execute the computer program to enable the charge / discharge controller to implement the charge / discharge control method as described in any one of claims 1-11.

13. An energy storage system, characterized in that, It includes multiple energy storage units, and each energy storage unit is equipped with a charge / discharge controller as described in claim 12.

14. The energy storage system according to claim 13, characterized in that, The energy storage unit includes a single battery module located in a charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed inside or outside the battery module. The battery module is equipped with at least one battery cell, and all the battery cells are connected to the bidirectional controllable switch.

15. The energy storage system according to claim 13, characterized in that, The energy storage unit includes multiple battery modules connected in parallel. The parallel battery modules are located in the same charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed outside the battery module. Each battery module is equipped with at least one battery cell, and the battery cell in the battery module is connected to the bidirectional controllable switch after being connected.

16. The energy storage system according to claim 14 or 15, characterized in that, The bidirectional controllable switch is located at the positive output terminal of the battery module. Alternatively, the bidirectional controllable switch may be located at the negative output terminal of the battery module; Alternatively, the bidirectional controllable switch may be simultaneously located at both the positive and negative output terminals of the battery module.

17. The energy storage system according to claim 13, characterized in that, The bidirectional controllable switch is connected in parallel with a current absorption circuit for interruption.

18. The energy storage system according to claim 13, characterized in that, The bidirectional controllable switch is connected to an external control device via a manual switch; the manual switch is used to control the connection and disconnection between the bidirectional controllable switch and the external control device.

19. An energy storage system, characterized in that, It includes multiple energy storage units and a charge / discharge controller as described in claim 12; the charge / discharge controller is communicatively connected to the multiple energy storage units.

20. The energy storage system according to claim 19, characterized in that, The energy storage unit includes a single battery module located in a charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed outside the battery module. The battery module is equipped with at least one battery cell, and all the battery cells are connected to the bidirectional controllable switch.

21. The energy storage system according to claim 19, characterized in that, The energy storage unit includes multiple battery modules connected in parallel. The parallel battery modules are located in the same charging and discharging circuit. In the charging and discharging circuit, a bidirectional controllable switch is disposed outside the battery module. Each battery module is equipped with at least one battery cell, and the battery cell in the battery module is connected to the bidirectional controllable switch after being connected.

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