An energy storage system and a control method of an energy storage system

Abstract

The application discloses an energy storage system and a control method thereof, which are used for isolating a fault source, avoiding expansion of a fault range and improving safety of the energy storage system. The energy storage system comprises at least one battery cluster and a controller. Each battery cluster comprises a direct-current-direct-current converter and a plurality of battery units. The plurality of battery units are connected in series and connected to the direct-current-direct-current converter, so that the battery cluster can obtain charging power or output discharging power through the direct-current-direct-current converter. Each battery unit comprises a battery cell and an optimizer. The optimizer of each battery unit is used for bypassing or series conduction control of the battery cell belonging to the same battery unit. The controller is connected with each battery unit. When a fault of a certain battery unit is detected, the optimizer of the fault battery unit is controlled to bypass the battery cell belonging to the fault battery unit.

Description

Technical Field

[0001] This application relates to the field of energy technology, and in particular to an energy storage system and a control method for the energy storage system. Background Technology

[0002] Energy storage systems can store and release electrical energy between the generation side, the grid side, and the user side, and have functions such as peak shaving and valley filling, peak regulation and frequency regulation, and grid connection with new energy generation.

[0003] To ensure the safety of energy storage systems, fault detection is required during operation, and regular safety maintenance is necessary.

[0004] Currently, most fault detection methods for energy storage systems involve installing temperature and smoke detectors in the prefabricated energy storage compartment. Temperature detectors monitor the temperature of the compartment and shut down the system when it exceeds a pre-set temperature. Smoke detectors detect fires within the compartment and shut down the system when an alarm is triggered. When an energy storage system malfunctions, the temperature of the prefabricated compartment rises, potentially leading to a fire. In practical use, when the temperature detector detects a temperature exceeding the pre-set value and the smoke alarm sounds, the system shuts down and fire suppression systems are activated to extinguish the fire, ensuring the safety of the energy storage system and connected equipment. However, when a battery in the energy storage system malfunctions, the battery temperature takes time to rise. Before the temperature detector detects the compartment temperature exceeding the pre-set value, other components connected to the faulty battery may already be damaged, potentially causing complete failure of the energy storage device, resulting in serious safety hazards and economic losses. Summary of the Invention

[0005] This application provides an energy storage system and a fault detection method for the energy storage system, which is used to isolate the fault source, prevent the fault range from expanding, and improve the safety of the energy storage system.

[0006] In a first aspect, this application provides an energy storage system comprising: at least one battery cluster and a controller.

[0007] Each battery cluster includes a DC-DC converter and multiple battery cells. These battery cells are connected in series with the DC-DC converter, allowing the battery cluster to obtain charging power or output discharging power through the converter. Each battery cell includes a cell and an optimizer. The optimizer in each battery cell is used to bypass or control the series conduction of cells belonging to the same battery cell. A controller is connected to each battery cell and, when a fault is detected in a battery cell, controls the optimizer of the faulty battery cell to bypass the cells belonging to that cell. The faults include cell circuit faults, cell overcharging, cell over-discharging, and other fault types that may cause safety hazards or damage to the cell. Cell short circuits include various possible serious internal short-term increases in temperature or volume within the battery; although the specific names may differ, they all fall within the scope of cell open circuit faults.

[0008] In this embodiment, the controller can monitor the operating status of each battery cell. When a faulty battery cell is detected, the controller can control the optimizer in the faulty battery cell to bypass the cells in the faulty battery cell, thereby disconnecting the cells in the faulty battery cell from the power transmission path of the battery cluster to which the faulty battery cell belongs. This isolates the fault source, prevents the fault range of the energy storage system from expanding, and ensures the safety of the energy storage system.

[0009] In one possible implementation, the controller includes a system-level controller.

[0010] Specifically, the system-level controller is used to: when a fault is detected in a certain battery cell, control the optimizer of the faulty battery cell to bypass the cell to which the faulty battery cell belongs.

[0011] The energy storage system described above can be centrally controlled using a system-level controller.

[0012] In one possible implementation, the controller includes at least one cluster-level controller. Each cluster-level controller corresponds to each battery cluster.

[0013] Each cluster-level controller is connected to the battery cells in the corresponding battery cluster. When a fault is detected in a battery cell in the corresponding battery cluster, the controller controls the optimizer of the faulty battery cell to bypass the cell to which the faulty battery cell belongs.

[0014] Using the above-mentioned energy storage system, cluster-level controllers can be used to detect and control individual battery clusters, thereby enabling each battery cluster to work independently without affecting each other.

[0015] In one possible implementation, the controller includes a system-level controller and a cluster-level controller.

[0016] The system-level controller is used to detect the fault status of each battery cell; each cluster-level controller corresponds to each battery cluster and is connected to the battery cells in the corresponding battery cluster. When it is determined that a battery cell in the corresponding battery cluster has failed, the optimizer of the failed battery cell is controlled to bypass the cell to which the failed battery cell belongs.

[0017] Using the above-mentioned energy storage system, centralized monitoring can be performed using a system-level controller, and individual battery clusters can be controlled using a cluster-level controller.

[0018] In one possible implementation, after the controller controls the optimizer of the faulty battery cell to bypass the cell to which the faulty battery cell belongs, it is also used to: control other battery cells to discharge to a safe range, and control the DC-DC converter in the battery cluster to which the faulty battery cell belongs to turn off, so as to isolate the battery cluster to which the faulty battery cell belongs from other battery clusters. Other battery cells are the battery cells in the battery cluster to which the faulty battery cell belongs, excluding the faulty battery cell. Other battery clusters are the battery clusters in the energy storage system excluding the battery cluster to which the faulty battery cell belongs.

[0019] By using the above-mentioned energy storage system, other battery cells in the battery cluster to which the faulty battery cell belongs can be discharged, and the DC-DC converter in the battery cluster can be turned off, thereby achieving isolation between battery clusters and further improving the safety of the energy storage system.

[0020] In one possible implementation, the controller is specifically used to: when the battery cluster to which the faulty battery cell belongs is in a discharging state, directly output the electrical energy of other battery cells to the target device through a DC-DC converter.

[0021] In one possible implementation, the controller is specifically used to: adjust other battery cells to a discharging state when the battery cluster to which the faulty battery cell belongs is in a charging or standby state, and output the electrical energy of the other battery cells to the target device through a DC-DC converter.

[0022] In one possible implementation, a DC-DC converter is used to convert charging power into charging voltage to charge connected battery cells; or to convert the voltages of multiple battery cells belonging to the same battery cluster into discharging power and output it.

[0023] Using the above-mentioned energy storage system, a DC-to-DC converter can be used to regulate the voltage of the electrical energy input to the battery cluster and the electrical energy output from the battery cluster, thereby achieving voltage adaptation.

[0024] Secondly, this application provides a control method for an energy storage system, which can be applied to the energy storage system provided in the first aspect of this application and any possible design. Specifically, the control method may include the following steps: detecting the fault state of each battery cell; when a fault is detected in a battery cell, controlling the optimizer of the faulty battery cell to bypass the cell to which the faulty battery cell belongs. The fault includes cell short circuit, overcharge, or over-discharge.

[0025] Using the above method, the controller can monitor the operating status of each battery cell. When a faulty battery cell is detected, the controller can control the optimizer in the faulty battery cell to bypass the cells in the faulty battery cell, thereby disconnecting the cells in the faulty battery cell from the power transmission path of the battery cluster to which the faulty battery cell belongs. This isolates the fault source, prevents the fault range of the energy storage system from expanding, and ensures the safety of the energy storage system.

[0026] In one possible implementation, after the optimizer of the faulty battery cell bypasses the cell to which the faulty battery cell belongs, the method further includes: controlling other battery cells to discharge to a safe range, and controlling the DC-DC converter in the battery cluster to which the faulty battery cell belongs to turn off, so as to isolate the battery cluster to which the faulty battery cell belongs from other battery clusters. The other battery cells are the battery cells in the battery cluster to which the faulty battery cell belongs, excluding the faulty battery cell. The other battery clusters are the battery clusters in the energy storage system excluding the battery cluster to which the faulty battery cell belongs.

[0027] Using the above method, other battery cells in the battery cluster to which the faulty battery cell belongs can be discharged, and the DC-DC converter in the battery cluster can be turned off, thereby achieving isolation between battery clusters and further improving the safety of the energy storage system.

[0028] In one possible implementation, controlling other battery cells to discharge to a safe range includes: when the battery cluster to which the faulty battery cell belongs is in a discharging state, directly outputting the electrical energy of other battery cells to the target device via a DC-DC converter until the remaining charge of the other battery cells is within a safe range.

[0029] In one possible implementation, controlling other battery cells to discharge to a safe range includes: when the battery cluster to which the faulty battery cell belongs is in a charging or standby state, adjusting other battery cells to a discharging state, and outputting the electrical energy of other battery cells to the target device through a DC-DC converter until the remaining charge of other battery cells is within a safe range. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of a photovoltaic energy storage system provided in an embodiment of this application;

[0031] Figure 2 A schematic diagram of the structure of a prefabricated energy storage cabin provided in this application embodiment;

[0032] Figure 3 This is a schematic diagram of the structure of an energy storage system provided in an embodiment of this application;

[0033] Figure 4 This is a schematic diagram of the structure of an optimizer provided in an embodiment of this application;

[0034] Figure 5 A flowchart illustrating a control method for an energy storage system provided in this application embodiment. Figure 1 ;

[0035] Figure 6 A flowchart illustrating a control method for an energy storage system provided in this application embodiment. Figure 2 . Detailed Implementation

[0036] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0037] The specific operational methods in the method embodiments can also be applied to the device embodiments or system embodiments. It should be noted that in the description of this application, "at least one" refers to one or more, where "multiple" refers to two or more. Therefore, in the embodiments of this invention, "multiple" can also be understood as "at least two". "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, it should be understood that in the description of this application, terms such as "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or order.

[0038] It should be noted that in the embodiments of this application, "connection" refers to an electrical connection or a communication connection. An electrical connection can be a direct or indirect connection between two electrical components, and a communication connection can be communication between two communication devices. For example, A and B can be connected directly, or they can be indirectly connected through one or more other electrical components, such as A and B being connected. Alternatively, A can be directly connected to C, and C can be directly connected to B, with A and B connected through C.

[0039] It should be noted that the switch in the embodiments of this application can be one or more of various types of switching devices, such as relays, metal oxide semiconductor field effect transistors (MOSFETs), bipolar junction transistors (BJTs), insulated gate bipolar transistors (IGBTs), gallium nitride field effect transistors (GaN), and silicon carbide (SiC) power transistors. These will not be listed individually in the embodiments of this application. Each switching device can include a first electrode, a second electrode, and a control electrode, wherein the control electrode is used to control the switching device to be turned on or off. When the switching device is on, current can be transmitted between the first electrode and the second electrode; when the switching device is off, no current can be transmitted between the first electrode and the second electrode. Taking a MOSFET as an example, the control electrode of the switching device is the gate, the first electrode of the switching device can be the source of the switching device, and the second electrode can be the drain of the switching device; alternatively, the first electrode can be the drain of the switching device, and the second electrode can be the source of the switching device.

[0040] The energy storage system provided in this application can be adapted to different application scenarios, such as photovoltaic energy storage system application scenarios and power supply system application scenarios. This application will take the photovoltaic energy storage system scenario as an example for explanation. Figure 1 This is a schematic diagram of the application scenario of the energy storage system provided in this application.

[0041] In photovoltaic and energy storage system application scenarios, such as Figure 1 As shown, a photovoltaic-storage system can include photovoltaic modules, an energy storage converter, an energy storage system, and a grid-connected inverter. The photovoltaic modules convert solar energy into direct current (DC) electricity and output it to the grid-connected inverter. The grid-connected inverter converts the DC electricity into alternating current (AC) electricity and transmits it to the grid, thus enabling the photovoltaic-storage system to connect to the grid. The energy storage system can store a portion of the electricity output from the photovoltaic inverter when the electricity generated by the photovoltaic modules exceeds the grid's demand, and it can also supply the stored electricity to the grid when the electricity output from the photovoltaic modules is insufficient to meet the grid's demand. The energy storage converter can convert the grid voltage to the supply voltage of the energy storage system, or convert the voltage stored in the energy storage system to the grid voltage and output it to the grid.

[0042] In one possible implementation, the energy storage converter can be connected to the photovoltaic modules. When the electricity generated by the photovoltaic modules exceeds the grid's demand for electricity, a portion of the electricity generated by the photovoltaic modules is voltage-converted and output to the energy storage converter for storage. When the electricity generated by the photovoltaic modules cannot meet the grid's demand for electricity, the electricity stored in the energy storage system is voltage-converted and output to the grid through a grid-connected inverter to meet the grid's demand for electricity.

[0043] In practical applications, as the proportion of electricity generated by photovoltaic-energy storage systems transmitted to the grid increases, the number of battery modules in the energy storage system gradually increases, and the output power of the energy storage system also gradually increases. Once the energy storage system fails, it directly affects the efficiency of the photovoltaic-energy storage system, and in severe cases, the entire photovoltaic-energy storage system cannot operate. Therefore, energy storage systems need to have high safety. To improve the safety of energy storage systems, fault detection is required during operation, and regular safety maintenance is necessary. The faults include cell circuits, cell overcharging or over-discharging, and other fault types that may cause safety hazards or damage to the cells. Among them, cell short circuits include various possible serious internal battery short-term overheating or temperature rise faults. Although the specific names may differ, they all fall within the scope of cell open circuit faults.

[0044] like Figure 2 The diagram shown illustrates a fault detection method for an energy storage system. (See also...) Figure 2 As shown, the energy storage system can be installed inside the prefabricated energy storage compartment, with temperature detectors, smoke detectors, and fire extinguishing devices installed at multiple locations within the compartment.

[0045] Specifically, both temperature detectors and smoke detectors are connected to the fire extinguishing system. The temperature detectors have a specific temperature detection range within the prefabricated energy storage compartment, capable of detecting temperatures within that range. The smoke detectors can detect whether a fire has broken out within the prefabricated energy storage compartment, and the fire extinguishing system can extinguish the fire if it does occur.

[0046] Specifically, when a battery in the energy storage system malfunctions, it generates a large amount of heat, causing thermal runaway in the system. Over time, the heat generated by the battery causes the ambient temperature to rise, potentially leading to a fire. When a temperature detector detects that the temperature within its detection range has reached a first set value, and a smoke detector detects a fire in the prefabricated energy storage compartment, the system is shut down, and a fire extinguishing device is activated to extinguish the fire in the compartment. This ensures the safety of the energy storage system and the normal operation of other devices connected to it. It should be noted that this embodiment shows only one temperature detector, but the number of temperature detectors in this embodiment is not limited to this.

[0047] In actual use, before the ambient temperature caused by the faulty battery reaches the first set value, multiple devices connected to the faulty battery may have already been damaged, which increases the scope of the energy storage system's failure. In severe cases, it may even cause the entire energy storage system to fail, posing serious safety hazards and causing serious economic losses.

[0048] To address the aforementioned issues, this application provides an energy storage system and a control method for the energy storage system, which is used to isolate fault sources, prevent the fault range from expanding, and improve the safety of the energy storage system.

[0049] like Figure 3 The image shows an energy storage system provided in an embodiment of this application. See also... Figure 3 As shown, the energy storage system 30 includes at least one battery cluster 31 and a controller 32.

[0050] Each battery cluster 31 includes a direct current to direct current (DC / DC) converter 311 and multiple battery cells 312. The multiple battery cells 312 are connected in series and then connected to the DC / DC converter 311, so that the battery cluster 31 can obtain charging power or output discharging power through the DC / DC converter 311.

[0051] Specifically, each battery cell 312 includes a cell 3121 and an optimizer 3122. The optimizer 3122 of each battery cell 312 is used to perform bypass or series conduction control on the cells 3121 belonging to the same battery cell 312.

[0052] The controller 32 is connected to each battery cell 312. When the controller 32 detects that a battery cell 312 has failed, it controls the optimizer 3122 of the failed battery cell to bypass the cell 3121 to which the failed battery cell belongs.

[0053] In actual use, there are many reasons for short circuits in the battery cells, such as external high temperature and battery cell manufacturing, which will not be described in detail here.

[0054] In this application, the energy storage system 30 may further include an input / output terminal, which can be connected to a power supply and / or a load. When the input / output terminal of the energy storage system 30 is connected to a power supply, the energy storage system 30 is in a charging state, and the energy storage system 30 can receive and store the electrical energy output by the power supply through the input / output terminal. When the input / output terminal of the energy storage system 30 is connected to a load or a power grid, the energy storage system 30 is in a discharging state, and the energy storage system 30 can output the stored electrical energy to the load or the power grid through the input / output terminal, thereby supplying power to the load or the power grid. When the energy storage system 30 does not store electrical energy output by the power supply and does not output the stored electrical energy to the load or the power grid, the energy storage system 30 is in a standby state.

[0055] In actual use, the energy storage system 30 also includes a DC bus. Each battery cluster 31 in the energy storage system 30 can be connected to the input / output terminal through the DC bus, that is, multiple battery clusters 31 are connected in parallel.

[0056] Specifically, when the energy storage system 30 is in a charging state, some or all of the battery clusters 31 in the energy storage system 30 operate in a charging state. Similarly, when the energy storage system 30 is in a discharging state, some or all of the battery clusters 31 in the energy storage system 30 operate in a discharging state. The controller 32 can control the battery clusters 31 to switch between charging, discharging, or standby states, and control the charging power of each battery cluster 31 when it is in a charging state, or the discharging power of each battery cluster 31 when it is in a discharging state.

[0057] In practical applications, the energy storage system 30 can be fixedly connected to the power supply and the load. In another implementation, the energy storage system 30 can be configured as a flexible and detachable device. For example, the energy storage system 30 may have a fixed interface through which the power supply and the load can be connected. In this case, the energy storage system 30 is a device independent of the power supply and the load.

[0058] Using the energy storage system 30 provided in this application embodiment, the optimizer 3122 in each battery cell 312 can realize bypass and series conduction control of the cell 3121. The controller 32 can perform fault detection on the battery cells 312 in each battery cluster 31. When the controller 32 detects a faulty battery cell 312, the controller 32 issues a fault alarm and controls the optimizer 3122 in the battery cell 312 to bypass the cell 3121 in the faulty battery cell 312. This isolates the faulty battery cell 312 from the power transmission path before it causes thermal runaway, preventing the fault range from expanding and ensuring the safety of the energy storage system 30.

[0059] It should be understood that when the cell 3121 in the faulty battery cell 312 is bypassed by the optimizer 3122, the cell 3121 in the faulty battery cell 312 cannot receive electrical energy from the power transmission path or output the stored electrical energy, thereby disconnecting the electrical connection between the faulty cell 3121 and other battery cells 312. This achieves isolation of the fault source, avoids damage to other battery cells 312 in the battery cluster 31 to which the faulty battery cell 312 belongs, further reduces the number of faulty devices in the energy storage system 30, and lowers the maintenance cost of the energy storage system 30. Here, "other battery cells 312" refers to the battery cells 312 in the battery cluster 31 to which the faulty battery cell 312 belongs, excluding the faulty battery cell 312.

[0060] The following is a detailed description of the battery cluster 31 and controller 32 in the energy storage system 30.

[0061] I. Battery Cluster 31

[0062] Each battery cluster 31 includes a DC / DC converter 311 and multiple battery cells 312 connected in series.

[0063] The DC / DC converter 311 is used to charge multiple battery cells 312 connected in series and to output the electrical energy stored in the multiple battery cells 312 connected in series. The first terminal of the DC / DC converter 311 can be connected to a DC bus, and the second terminal of the DC / DC converter 311 is connected to multiple battery cells 312 connected in series, so that the battery cluster 31 can obtain charging power or output discharging power through the DC / DC converter 311.

[0064] Specifically, when the battery cluster 31 receives charging power, the first terminal of the DC / DC converter 311 is the input terminal, and the second terminal of the DC / DC converter 311 is the output terminal. The DC / DC converter 311 receives charging power from the DC bus through the first terminal, converts the received charging power into a charging voltage, and charges the multiple battery cells 312 connected in series in the battery cluster 31 through the second terminal. When the battery cluster 31 outputs discharging power, the first terminal of the DC / DC converter 311 is the output terminal, and the second terminal of the DC / DC converter 311 is the input terminal. The DC / DC converter 311 converts the voltage of the multiple battery cells 312 connected in series into discharging power through the second terminal, and outputs the discharging power to the DC bus through the second terminal.

[0065] In actual use, the voltage of the DC bus may differ from the voltage of the multiple battery cells 312 connected in series. Therefore, the voltage on the DC bus cannot directly charge the cells 3121 in the series-connected battery cells 312. Thus, the DC / DC converter 311 can regulate the voltage input from the DC bus to the battery cluster 31, and also regulate the voltage output from the multiple battery cells 312 connected in series in the battery cluster 31 to the DC bus, thereby achieving voltage matching between the battery cluster 31 and the DC bus.

[0066] Multiple battery cells 312 connected in series are devices for storing electrical energy in the battery cluster 31. The multiple battery cells 312 connected in series are connected to a DC / DC converter 311 so that the battery cluster 31 can obtain charging power or output discharging power through the DC / DC converter 311.

[0067] In practical use, after receiving the charging voltage output from the connected DC / DC converter 311, the multiple battery cells 312 connected in series divide the charging voltage to obtain multiple sub-charging voltages. Each battery cell 312 receives one sub-charging voltage and stores the electrical energy carried in the sub-charging voltage, thereby charging the battery cell 312. Similarly, when the battery cluster 31 outputs discharge power, each battery cell 312 outputs a sub-discharge voltage. The multiple sub-discharge voltages are superimposed to form a discharge voltage, which is converted into discharge power by the DC / DC converter 311 and then output to the DC bus.

[0068] Specifically, each battery cell 312 may include a cell 3121 and an optimizer 3122.

[0069] Specifically, the optimizer 3122 of each battery cell 312 is used to perform bypass or series conduction control on the cells 3121 belonging to the same battery cell 312.

[0070] Specifically, when the optimizer 3122 performs series conduction control on the cells 3121 belonging to the same battery cell 312, the cells 3121 of the same battery cell 312 can receive charging power output from the DC / DC converter 311, or output stored electrical energy through the DC / DC converter 311. When the optimizer 3122 performs bypass control on the cells 3121 belonging to the same battery cell 312, the cells 3121 of the same battery cell 312 are disconnected from other battery cells 312 and the DC / DC converter 311. The other battery cells are the battery cells 312 in the same battery cluster 31 to which this battery cell belongs, excluding this battery cell.

[0071] Specifically, each battery cell 312 has an optimizer 3122 connected to a controller 32. When the controller 32 detects a fault in a battery cell 312, it can send a control signal to the optimizer 3122 in the faulty battery cell 312. The control signal can control the optimizer 3122 to bypass the cell 3121 to which the faulty battery cell 312 belongs.

[0072] In practical use, the optimizer 3122 can be a switching circuit, and the control signal used to control the optimizer 3122 to bypass the cell 3121 is the drive signal of the switching circuit. The first terminal of the optimizer 3122 is connected in series with other battery cells 312, and the second terminal of the optimizer 3122 is connected to the cell 3121 belonging to the same battery cell 312.

[0073] In this circuit, the first terminal of the first terminal of the switch circuit is the terminal of the battery cell 312 that receives a high level, the second terminal of the first terminal of the switch circuit is the terminal of the battery cell 312 that receives a low level, the first terminal of the second terminal of the switch circuit is connected to the positive terminal of the battery cell 3121, and the second terminal of the second terminal of the switch circuit is connected to the negative terminal of the battery cell 3121.

[0074] Specifically, when the switching circuit does not receive a control signal, the first terminal of the first end of the switching circuit is connected to the first terminal of the second end, and the second terminal of the first end of the switching circuit is connected to the second terminal of the second end. At this time, the cell 3121 is connected in series with other battery units 312. When the switching circuit receives a control signal, the first terminal of the first end of the switching circuit is connected to the second terminal of the first end, thereby isolating the cell 3121 from the power transmission path formed by multiple battery units 312 connected in series.

[0075] In a specific implementation, a switch is connected to the first endpoint of the first terminal of the first terminal and the first endpoint of the second terminal of the first terminal of the switching circuit, and a switch is connected between the first endpoint of the first terminal and the second endpoint of the first terminal of the switching circuit. The controller 32 can control the optimizer 3122 to perform bypass or series conduction control on the battery cell 3121 by sending a corresponding drive signal to the switch in the switching circuit.

[0076] Optionally, optimizer 3122 is Figure 4 The step-down switching circuit shown has a high-level drive signal sent by controller 32.

[0077] Specifically, switch T1 can be in a continuously conducting state. When controller 32 sends a low-level drive signal to switch T2, switch T2 is turned off, and the first terminal of optimizer 3122 forms a power transmission path with cell 3121. At this time, cell 3121 can be connected in series with other battery units 312 through the first terminal of optimizer 3122, thereby realizing the series conduction control of cell 3121. When controller 32 sends a high-level drive signal to switch T2, switch T2 is turned on. When power is transmitted on the power transmission path formed by multiple series-connected battery units 312, the transmitted power returns directly to the power transmission path through switch T2 without passing through cell 3121, thus bypassing cell 3121. At this time, cell 3121 is disconnected from other battery units 312, thereby realizing bypass control of cell 3121.

[0078] It should be understood that the above description of the optimizer 3122 is for illustrative purposes only. In actual use, the optimizer 3122 can also adopt other circuit structures. For example, the optimizer 3122 can be a boost switch circuit or a buck-boost switch circuit. By controlling the drive signal of the switch in the control circuit, the optimizer 3122 can be controlled to bypass or connect in series with the battery cell 3121.

[0079] II. Controller 32

[0080] The controller 32 is connected to the battery cell 312 in each battery cluster 31. The controller 32 can perform fault detection on each battery cell 312, and when a fault is detected in a battery cell 312, it will issue a fault alarm and control the optimizer 3122 of the faulty battery cell 312 to bypass the cell 3121 to which the faulty battery cell 312 belongs.

[0081] Specifically, the controller 32 determines the standard values ​​of the operating parameters of the battery unit 312 under the current operating state of the energy storage system 30, and compares the standard values ​​with the actual operating parameters of the battery unit 312. When the difference between the operating parameters of the battery unit 312 and the calculated standard values ​​is greater than or equal to a set value, the controller determines that the battery unit 312 is operating abnormally, and identifies the abnormally operating battery unit 312 as a faulty battery unit 312. The set value can be 2% of the standard operating parameter value.

[0082] Optionally, if the current energy storage system 30 is in a charging state, the standard charging current curve and / or standard charging voltage curve of each battery cell 312 can be determined according to the charging power. If the current curve in the operating parameters of the battery cell 312 does not match the standard charging current curve, or the voltage curve in the operating parameters of the battery cell 312 does not match the standard charging voltage curve, it can be determined that the battery cell 312 is operating abnormally and has failed.

[0083] In actual use, due to fluctuations in the detection accuracy of the controller 32 and the transmitted power, to avoid detection errors, after determining that the battery unit 312 is malfunctioning, the duration of the malfunction is recorded. When the duration of the malfunction reaches a preset time range, the battery unit 312 is considered to have failed. The preset time range can be set according to the safety operation requirements of the energy storage system 30. For example, the preset time range can be 1 to 3 seconds.

[0084] In this application, after determining that a battery cell 312 has failed, the controller 32 sends a control signal to the optimizer 3122 in the failed battery cell 312 to control the optimizer 3122 to perform bypass control on the cell 3121 in the failed battery cell 3122.

[0085] In one possible implementation, controller 32 includes a system-level controller.

[0086] Specifically, the system-level controller is connected to each battery cell 312. The system-level controller is used to perform fault detection on each battery cell 312, and when a fault is detected in a battery cell 312, to control the optimizer 3122 of the faulty battery cell 312 to bypass the cell 3121 to which the faulty battery cell 312 belongs. Optionally, this system-level controller can be a battery management system (BMS).

[0087] In one possible implementation, controller 32 includes at least one cluster-level controller. Each cluster-level controller corresponds to each battery cluster 31. Each cluster-level controller is connected to a battery cell 312 in the corresponding battery cluster 31.

[0088] Specifically, each cluster-level controller is used to detect the fault status of each battery cell 312 in the corresponding battery cluster 31. When a fault is detected in a battery cell 312 in the corresponding battery cluster 31, the optimizer 3122 of the faulty battery cell 312 is controlled to bypass the cell 3121 to which the faulty battery cell 312 belongs.

[0089] In one possible implementation, controller 32 includes a system-level controller and a cluster-level controller. The system-level controller can be connected to each battery cluster 31 and detect the fault status of battery cells 312 in each battery cluster 31.

[0090] Each cluster-level controller corresponds to each battery cluster 31. Each cluster-level controller is connected to the system-level controller and the battery cell 312 in the corresponding battery cluster 31. When it is determined that a battery cell 312 in the corresponding battery cluster 31 has failed, the optimizer 3122 of the faulty battery cell 312 is controlled to bypass the cell 3121 to which the faulty battery cell 312 belongs.

[0091] It should be noted that when the cell 3121 in the faulty battery cell 312 is bypassed by the optimizer 3122, the cell 3121 in the faulty battery cell 312 can be isolated from the power transmission path formed by multiple battery cells 312 connected in series. To prevent the chemical reaction generated by the cell 3121 in the faulty battery cell from damaging other connected battery cells 312, for example, a short circuit in the cell 3121 in the faulty battery cell 312 can break down the switch in the optimizer 3122, allowing the cell 3121 in the faulty battery cell 312 to reconnect to the power transmission path. After the controller 32 controls the optimizer 3122 of the faulty battery cell 312 to bypass the cell 3121 of the faulty battery cell 312, it can also control other battery cells 312 to discharge to a safe range and control the DC / DC converter 311 in the battery cluster 31 to which the faulty battery cell 312 belongs to turn off, so as to isolate the battery cluster 31 to which the faulty battery cell 312 belongs from other battery clusters 31. Among them, other battery units 312 are battery units 312 other than the faulty battery unit 312 in the battery cluster 31 to which the faulty battery unit 312 belongs, and other battery clusters 31 are battery clusters 31 in the energy storage system 30 other than the battery cluster 31 to which the faulty battery unit 312 belongs.

[0092] Optionally, the controller 32 sets the discharge power of the battery cluster 31 to which the faulty battery cell 312 belongs to the maximum discharge power to accelerate the speed at which other battery cells 312 enter the safe zone.

[0093] It should be understood that when other battery cells 312 discharge to a safe range, all other battery cells 312 are in a low-energy state, thereby ensuring the maximum safety of the energy storage system 30.

[0094] Optionally, to improve the safety of the energy storage system 30, the safety range can be equal to zero and less than 10% of the storage capacity of the battery cell 312.

[0095] In actual use, before the controller 32 controls the other battery cells 312 in the battery cluster 31 to which the faulty battery cell 312 belongs to discharge to a safe range, it needs to first determine the operating status of the battery cluster 31 and control the discharge mode of the stored electrical energy of the other battery cells 312 according to the current operating status of the battery cluster 31.

[0096] In one possible implementation, when the battery cluster 31 to which the faulty battery cell 312 belongs is in a discharging state, the DC / DC converter 311 directly outputs the electrical energy of other battery cells 312 to the target device until the remaining charge of the other battery cells 312 is within a safe range. The target device can be any of the following: the power grid, electrical equipment, or other battery clusters in an energy storage system.

[0097] In one possible implementation, when the battery cluster to which the faulty battery cell belongs is in a charging or standby state, other battery cells 312 are adjusted to a discharging state, and the electrical energy of other battery cells 312 is output to the target device through a DC / DC converter 311 until the remaining power of other battery cells 312 is within a safe range.

[0098] In practical use, the optimizer 3122 can be a switching circuit composed of devices such as switching transistors, diodes, inductors, and capacitors. The operating state of the optimizer 3122 can be achieved by adjusting the operating state of these devices (such as switching transistors).

[0099] In this application, the operating state of the above-mentioned device can be adjusted by the controller 32.

[0100] In actual use, the controller 32 can be connected to the control electrode of the switch in the optimizer 3122, and by providing a drive signal to the switch in the optimizer 3122, it can control the conduction time and conduction duration of the switch tube, thereby adjusting the working state of the optimizer 3122, so as to control the optimizer 3122 to bypass or series conduction control of the cells 3121 belonging to the same battery unit 312.

[0101] Specifically, if the switch in optimizer 3122 is a MOSFET, the controller 32 can be connected to the gate of the MOSFET, thereby enabling optimizer 3122 to bypass or connect the cells 3121 belonging to the same battery cell 312 by controlling the on / off state of the MOSFET; if the switch in optimizer 3122 is a BJT, the controller 32 can be connected to the base of the BJT, thereby enabling optimizer 3122 to bypass or connect the cells 3121 belonging to the same battery cell 312 by controlling the on / off state of the BJT.

[0102] In a specific implementation, the controller 32 can be any of the following: a microcontroller unit (MCU), a central processing unit (CPU), a field-programmable gate array (FPGA), or a digital signal processor (DSP). Of course, the specific form of the controller 32 is not limited to the examples mentioned above.

[0103] Based on the energy storage system 30 provided in the embodiments of this application, this application also provides a control method for the energy storage system, which can be executed by the controller 32 in the energy storage system 30. The control method for the energy storage system provided in the embodiments of this application can detect faults in battery cells during the operation of the energy storage system and isolate the fault source to prevent the fault range from expanding and ensure the safety of the energy storage system. Figure 5 As shown, the control method for an energy storage system may include the following steps:

[0104] Step 501: Detect the fault status of each battery cell.

[0105] In practical use, the controller can monitor the operating parameters of each battery cell and use these parameters for fault diagnosis. These operating parameters can be electrical parameters generated during the battery cell's operation, and may include one or more of the following: voltage, current, and power values.

[0106] Specifically, the process by which the controller uses operating parameters to determine the fault state of the battery cell can be found in the aforementioned description of the controller, and will not be repeated here.

[0107] Step 502: When a fault is detected in a battery cell, the optimizer of the faulty battery cell bypasses the cells belonging to the faulty battery cell. Specifically, when the controller detects a fault in a battery cell, it sends a fault alarm and sends a control signal to the optimizer in the faulty battery cell to control the optimizer to bypass the cells in the faulty battery cell. When the cells in the faulty battery cell are bypassed, the cells in the faulty battery cell are isolated from the power transmission path in the battery cluster, thereby achieving isolation of the fault source.

[0108] In one possible implementation, after the optimizer of the faulty battery cell bypasses the cell to which the faulty battery cell belongs, the method further includes: controlling other battery cells to discharge to a safe range, and controlling the DC-DC converter in the battery cluster to which the faulty battery cell belongs to turn off, so as to isolate the battery cluster to which the faulty battery cell belongs from other battery clusters. The other battery cells are the battery cells in the battery cluster to which the faulty battery cell belongs, excluding the faulty battery cell. The other battery clusters are the battery clusters in the energy storage system excluding the battery cluster to which the faulty battery cell belongs.

[0109] In one possible implementation, controlling other battery cells to discharge to a safe range includes: when the battery cluster to which the faulty battery cell belongs is in a discharging state, directly outputting the electrical energy of other battery cells to the target device via a DC-DC converter until the remaining charge of the other battery cells is within a safe range.

[0110] In one possible implementation, controlling other battery cells to discharge to a safe range includes: adjusting other battery cells to a discharging state when the battery cluster to which the faulty battery cell belongs is in a charging or standby state, and outputting the electrical energy of the other battery cells to the target device via a DC-DC converter, until the remaining charge of the other battery cells is within a safe range.

[0111] See the foregoing description, Figure 6 An exemplary control method for an energy storage system is illustrated. The controller can be the subject executing the control method, which specifically includes the following steps:

[0112] Step 601: Detect the fault status of each battery cell and proceed to step 602.

[0113] Step 602: When a fault is detected in a battery cell, the optimizer of the faulty battery cell bypasses the cell to which the faulty battery cell belongs, and then executes step 603.

[0114] Step 603: Determine whether the battery cluster to which the faulty battery cell belongs is in a discharging state. If yes, proceed to step 604; otherwise, proceed to step 606.

[0115] Step 604: Directly output the electrical energy from other battery cells to the target device via a DC / DC converter, and then execute step 605. The other battery cells are those outside the faulty battery cell within the battery cluster to which the faulty battery cell belongs.

[0116] Step 605: Check whether the remaining power of other battery modules is within a safe range. If yes, proceed to step 606; otherwise, return to step 604.

[0117] Step 606: Adjust the other battery cells to a discharge state and proceed to step 607.

[0118] Step 607: Output electrical energy from other battery cells to the target device via a DC / DC converter, and then execute step 608.

[0119] Step 608: Check if the remaining power of other battery cells is within a safe range. If yes, proceed to step 609; otherwise, return to step 607.

[0120] Step 609: Turn off the DC / DC converter in the battery cluster to which the faulty battery cell belongs.

[0121] In one possible implementation, when the controller detects a fault in a battery cell, it first confirms whether the battery cluster to which the faulty battery cell belongs is in a discharging state, and then controls the optimizer of the faulty battery cell to bypass the cell to which the faulty battery cell belongs.

[0122] Based on the above embodiments, this application also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a computer, it causes the computer to perform the control method of the energy storage system provided in the above embodiments.

[0123] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0124] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0125] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0126] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0127] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. An energy storage system, characterized in that, Includes at least one battery cluster and a controller; Each battery cluster includes a DC-DC converter and multiple battery cells. The multiple battery cells are connected in series and then connected to the DC-DC converter, so that the battery cluster can obtain charging power or output discharging power through the DC-DC converter. Each battery cell includes a cell and an optimizer. The optimizer of each battery cell is used to bypass or series conduction control of the cells belonging to the same battery cell. The controller is connected to each battery cell. When the controller detects a fault in a battery cell, it controls the optimizer of the faulty battery cell to bypass the cell to which the faulty battery cell belongs. The fault includes short circuit, over-discharge, or overcharge of the cell. After the controller controls the optimizer of the faulty battery cell to bypass the cell to which the faulty battery cell belongs, it is also used to: control other battery cells to discharge to a safe range, and control the DC-DC converter in the battery cluster to which the faulty battery cell belongs to turn off, so as to isolate the battery cluster to which the faulty battery cell belongs from other battery clusters. The other battery cells are the battery cells in the battery cluster to which the faulty battery cell belongs, excluding the faulty battery cell. The other battery clusters are the battery clusters in the energy storage system excluding the battery cluster to which the faulty battery cell belongs.

2. The energy storage system as described in claim 1, characterized in that, The controller includes a system-level controller; The system-level controller is specifically used to: when a fault is detected in a certain battery cell, control the optimizer of the faulty battery cell to bypass the cell to which the faulty battery cell belongs.

3. The energy storage system as described in claim 1, characterized in that, The controller includes at least one cluster-level controller; Each cluster-level controller corresponds to each battery cluster; Each cluster-level controller is connected to the battery cells in the corresponding battery cluster. When a fault is detected in a battery cell in the corresponding battery cluster, the controller controls the optimizer of the faulty battery cell to bypass the cell to which the faulty battery cell belongs.

4. The energy storage system as described in claim 1, characterized in that, The controller includes a system-level controller and a cluster-level controller; The system-level controller is used to detect the fault status of each battery cell; Each cluster-level controller corresponds to each battery cluster, and each cluster-level controller is connected to the battery cells in the corresponding battery cluster. When it is determined that a battery cell in the corresponding battery cluster has failed, the controller controls the optimizer of the failed battery cell to bypass the cell to which the failed battery cell belongs.

5. The energy storage system as described in claim 1, characterized in that, The controller is specifically used to: when the battery cluster to which the faulty battery cell belongs is in a discharging state, directly output the electrical energy of the other battery cells to the target device through the DC-DC converter.

6. The energy storage system as described in claim 1, characterized in that, The controller is specifically used to: adjust the other battery cells to a discharging state when the battery cluster to which the faulty battery cell belongs is in a charging state or a standby state, and output the electrical energy of the other battery cells to the target device through the DC-DC converter.

7. The energy storage system according to any one of claims 1-6, characterized in that, The DC-DC converter is used to convert the charging power into a charging voltage to charge the connected battery cells; or to convert the voltage of multiple battery cells belonging to the same battery cluster into the discharging power and output it.

8. A control method for an energy storage system, characterized in that, The control method, applied to the energy storage system according to any one of claims 1-7, comprises: Detect the fault status of each battery cell; When a fault is detected in a battery cell, the optimizer of the faulty battery cell is controlled to bypass the cell to which the faulty battery cell belongs. The fault includes short circuit, overcharge or over-discharge of the cell. After the optimizer controlling the faulty battery cell bypasses the cell to which the faulty battery cell belongs, the method further includes: controlling other battery cells to discharge to a safe range, and controlling the DC-DC converter in the battery cluster to which the faulty battery cell belongs to turn off, so as to isolate the battery cluster to which the faulty battery cell belongs from other battery clusters. The other battery cells are the battery cells in the battery cluster to which the faulty battery cell belongs, excluding the faulty battery cell. The other battery clusters are the battery clusters in the energy storage system excluding the battery cluster to which the faulty battery cell belongs.

9. The method as described in claim 8, characterized in that, Controlling other battery cells to discharge to a safe range includes: When the battery cluster to which the faulty battery cell belongs is in a discharging state, the power of the other battery cells is directly output to the target device through the DC-DC converter until the remaining power of the other battery cells is within the safe range.

10. The method as described in claim 8, characterized in that, Controlling other battery cells to discharge to a safe range includes: When the battery cluster to which the faulty battery cell belongs is in a charging or standby state, the other battery cells are adjusted to a discharging state, and the power of the other battery cells is output to the target device through the DC-DC converter until the remaining power of the other battery cells is within the safe range.

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