Battery pack having cut-off protection function, and energy storage system

Abstract

Provided in the present application are a battery pack having a cut-off protection function, and an energy storage system. The battery pack comprises: a battery module, which is composed of a plurality of single cells; a breaking device, which is connected in series to the battery module; and a current sensor and a controller, wherein a first end of the current sensor is connected to a positive output end of the battery pack, and a second end of the current sensor is connected to a negative output end of the battery pack, such that the current difference between the positive output end and negative output end of the battery pack is measured; and the controller is used for controlling the breaking device to disconnect when the current difference measured by the current sensor is greater than a first threshold value, such that when a cell in the battery pack has a ground short-circuit fault, the fault can be quickly cut off, thereby ensuring the safe operation of the whole energy storage system.

Description

A battery pack and energy storage system with disconnection protection function

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on December 8, 2023, with application number 202311691834.7 and invention name “A battery pack and energy storage system with disconnection protection function”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of energy technology, and in particular to a battery pack and energy storage system with a disconnection protection function. Background Art

[0003] As the proportion of renewable energy sources increases, battery energy storage systems are becoming increasingly important to address the intermittent and unstable nature of large-scale photovoltaic and wind power generation, and their proportion is also increasing. Limited by the size of battery cells and battery modules, battery energy storage systems are generally composed of multiple battery modules connected in series and then in parallel. Placing multiple battery modules together can easily lead to safety hazards. Furthermore, due to the inevitable defects in the incoming materials and processing of battery cells, these defects can cause these cells to experience abnormalities during use, such as leakage and failure. These abnormalities can cause the cells to short to ground. Therefore, designing a safe protection solution to prevent the spread of faults, such as short-circuiting to ground, is crucial. Summary of the Invention

[0004] To address the above issues, the present application provides a battery pack and energy storage system with a disconnection protection function, which can quickly cut off the fault in the event of a battery pack failure (for example, a short circuit failure of the battery cell to ground) to ensure the safe operation of the energy storage system.

[0005] In a first aspect, an embodiment of the present application provides a battery pack, which includes a battery module, a disconnecting device, a first current sensor and a first controller, wherein the battery module includes a plurality of single cells connected in series, the disconnecting device is connected in series with the battery module, the first end of the first current sensor is connected to the positive output end of the battery pack, the second end of the first current sensor is connected to the negative output end of the battery pack, the first current sensor is used to detect the current difference between the positive output end and the negative output end of the battery pack, and the first controller is used to control the disconnecting device to disconnect when the current difference detected by the first current sensor is greater than a first threshold value.

[0006] When two battery packs within the same battery cluster experience a short-circuit to ground fault, it is equivalent to multiple battery cells connected in series without a load. Since the voltage of multiple battery cells connected in series is very high, it is very easy to cause a fire hazard due to voltage breakdown. At this time, due to the existence of two current loops within the energy storage unit cluster, the current magnitudes at both ends of the two battery packs experiencing the short-circuit to ground fault are different, that is, there is a current difference at both ends of the two battery packs experiencing the short-circuit to ground fault. At this time, when the current difference detected by the first current sensor within the faulty battery pack is greater than the first threshold, the first controller within the battery pack controls the disconnect device within the battery pack to disconnect, thereby disconnecting the faulty circuit within the energy storage unit cluster, avoiding the risk of fire caused by voltage breakdown.

[0007] It should be understood that the embodiments of the present application do not limit the specific location of the disconnect device in the battery pack. That is, the disconnect device can be connected in series with either the negative electrode of the battery module or the positive electrode of the battery module. In either case, the first controller in one of the two battery packs experiencing a short-to-ground fault can trigger a protection mechanism, controlling the disconnect device in the same battery pack to disconnect, thereby breaking the fault circuit within the energy storage cell cluster and avoiding the risk of fire due to voltage breakdown.

[0008] Optionally, the first controller and the first current sensor may be integrated on a circuit board. In other words, the first current sensor may be an intelligent current sensor having a logic judgment function and a control function.

[0009] Optionally, the first controller may be provided independently of the first current sensor. The first controller may be a separate controller or may be integrated into other devices in the battery pack.

[0010] Optionally, the first current sensor may be a residual current operated protective device (RCD).

[0011] Optionally, the disconnecting device may be a switch, an exploding fuse, a contactor, a relay, a circuit breaker, an insulated gate bipolar transistor (IGBT), or a metal oxide semiconductor field effect transistor (MOSFET).

[0012] Optionally, the battery pack further includes a second current sensor and a second controller, wherein the second current sensor, the battery module, and the disconnect device are connected in series. The second current sensor is configured to detect a current flowing therethrough, and the second controller is configured to control the disconnect device to disconnect if the current detected by the second current sensor exceeds a second threshold.

[0013] When two battery packs within the same battery cluster experience a short-circuit to ground fault, it's equivalent to connecting multiple battery cells in series without a load. Because the voltage across multiple battery cells in series is very high, voltage breakdown can easily lead to a fire hazard. At this point, the current in the current loop surges. That is, compared to the current loop when the battery pack is operating normally, the current in the fault current loop surges when the battery pack fails. This also means that the current flowing through the second current sensor surges. When the current detected by the second current sensor within the battery pack exceeds a second threshold, the disconnect device within the same battery pack is controlled to disconnect, breaking the fault loop and thus avoiding the risk of fire due to voltage breakdown.

[0014] By simultaneously installing a first current sensor and a second current sensor in the battery pack, the system detects short-circuit faults to ground using two different detection methods. This allows for more reliable and accurate fault detection, enabling timely disconnection and protection, ensuring the safe operation of the energy storage system. Furthermore, if either the first or second current sensor fails, the other current sensor can still detect short-circuit faults in multiple battery packs, further improving system reliability.

[0015] It should be understood that the second current sensor and the disconnect device need to be connected in series on the same side of the battery module to achieve detection and disconnection protection for battery cell short-circuit faults. Optionally, the second current sensor and the disconnect device can both be connected in series to the negative electrode of the battery module, or the second current sensor and the disconnect device can both be connected in series to the positive electrode of the battery module.

[0016] Optionally, the second current sensor may be connected in series between the battery module and the disconnecting device, and the disconnecting device may also be connected in series between the battery module and the second current sensor.

[0017] Optionally, the second controller and the second current sensor are integrated on a circuit board. In other words, the second current sensor can be an intelligent current sensor with logic judgment function and control function.

[0018] Optionally, the second controller may be provided independently of the second current sensor. The second controller may be a separate controller or may be integrated into other devices in the battery pack.

[0019] Optionally, the first controller and the second controller may be two independent controllers, for example, the first controller and the second controller may be integrated into different devices or circuit boards, for example, the first controller and the second controller may be integrated into a first current controller and a second current controller, respectively.

[0020] Optionally, the first controller and the second controller may be the same controller, that is, the same controller performs the functions of the first controller and the second controller. For example, the functions of the first controller and the second controller may be performed by a BMS.

[0021] Optionally, only one of the first current sensor and the second current sensor is in operation at the same time, so as to save electric energy while improving system reliability.

[0022] Optionally, when the first controller and the second controller are two independent controllers, it is also possible to control only one of the first controller and the second controller to be in operation at the same time, so as to save electric energy while improving system reliability.

[0023] Optionally, a competition signal can be set to ensure that only one of the first and second current sensors is in operation at the same time. Specifically, the operation state of the second current sensor can be controlled based on the operation state of the first current sensor. When the first current sensor is in operation, the second current sensor is controlled to stop operation; when the first current sensor is in non-operational state, the second current sensor is controlled to operate.

[0024] Since, under normal circumstances, the first current sensor has higher accuracy, faster response, and better effect in detecting battery cell short-circuit faults than the second current sensor, setting the priority of the first current sensor higher than that of the second current sensor is beneficial to improving the detection effect of battery cell short-circuit faults.

[0025] Optionally, when the functions of the first controller and the second controller are implemented by a centralized controller (e.g., a BMS) (herein, the centralized controller is referred to as the first controller), the first controller is further configured to, when the first current sensor is in an operating state, control the second current sensor to be inoperative. Exemplarily, the first controller may send a first control signal to the second current sensor, the first control signal being configured to instruct the second current sensor to be inoperative.

[0026] Optionally, when the first controller and the second controller are two independent controllers, and the first controller and the second controller are used to control the first current sensor and the second current sensor respectively, the operation switching between the first current sensor and the second current sensor can be controlled by the first controller. Specifically, the first controller is also used to send a second control signal to the second controller when the first current sensor is in an operating state, and the second control signal is used to indicate that the second current sensor is not working, and the second controller is used to control the second current sensor to not work according to the second control signal.

[0027] Optionally, the second current sensor is powered by a battery module in the same battery pack. In this case, no external power supply is required to achieve ground short-circuit fault detection and disconnection protection. This ensures that even when the energy storage system is disconnected from the AC grid or the AC grid connected to the energy storage system is dead, the battery cell ground short-circuit fault can still be detected.

[0028] Optionally, when the second controller is integrated into the second current sensor, the second controller can also be powered by the same battery module in the same battery pack. That is, the same battery module can be used to power both the second current sensor and the second controller. This ensures that even when the energy storage system is disconnected from the AC grid or the AC grid connected to the energy storage system is dead, a cell-to-ground short circuit fault can still be detected and disconnected for protection.

[0029] Optionally, the first current sensor may be any one of a Hall sensor, a tunnel magnetoresistance sensor (TMR), an anisotropic magnetoresistance sensor (AMR), and a giant magnetoresistance sensor (GMR).

[0030] In a second aspect, the present application provides an energy storage system, which may include at least one energy storage unit cluster and a DC / AC converter, wherein the energy storage unit cluster includes at least two battery packs as described in any one of the first aspects, at least two battery packs are connected in series, and the energy storage unit cluster is connected to an AC power grid or a load through a DC / AC converter.

[0031] Optionally, the energy storage unit cluster further includes an auxiliary source, and two ends of the auxiliary source are respectively connected to the positive output end and the negative output end of the energy storage unit cluster.

[0032] Optionally, the first current sensor is powered by the auxiliary source.

[0033] Optionally, when the first controller is integrated into the first current sensor, the first controller is powered by the auxiliary source.

[0034] When the energy storage system is connected to the AC grid and the AC grid is powered, the cluster-level auxiliary source is also powered. The cluster-level auxiliary source is used to power the first current sensor and / or the first controller, thereby ensuring the normal operation of the first current sensor and / or the first controller.

[0035] The technical effects that can be achieved by any possible design in the second aspect can be referred to the technical effects that can be achieved by any possible design in the first aspect, and will not be repeated here. These and other aspects of the present application will be more concise and easy to understand in the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0037] Figure 1 is a schematic diagram of the structure of a battery cluster in an industrial and commercial scenario;

[0038] Figure 2 is a schematic diagram of the structure of a battery cluster in a power station scenario;

[0039] FIG3 is a schematic structural diagram of an energy storage system provided in an embodiment of the present application;

[0040] FIG4 is a schematic structural diagram of another energy storage system provided in an embodiment of the present application;

[0041] FIG5 is a schematic structural diagram of another energy storage system provided in an embodiment of the present application;

[0042] FIG6 is a schematic structural diagram of another energy storage system provided in an embodiment of the present application;

[0043] FIG7 is a schematic structural diagram of an energy storage unit cluster provided in an embodiment of the present application;

[0044] FIG8 is a schematic diagram of a current loop of an energy storage system in normal operation according to an embodiment of the present application;

[0045] FIG9 is a schematic diagram of a current loop in an energy storage system provided by an embodiment of the present application when two or more battery packs have a short circuit to ground fault;

[0046] FIG10 is a schematic diagram of a current loop in another energy storage system provided by an embodiment of the present application when two or more battery packs have a short circuit to ground fault;

[0047] FIG11 is a schematic structural diagram of another energy storage unit cluster provided in an embodiment of the present application;

[0048] FIG12 is a schematic diagram of a current loop of another energy storage system provided in an embodiment of the present application under normal operating conditions;

[0049] FIG13 is a schematic diagram of a current loop in another energy storage system provided by an embodiment of the present application when two or more battery packs have a short circuit to ground fault;

[0050] FIG14 is a schematic diagram of a current loop in another energy storage system provided by an embodiment of the present application when two or more battery packs have a short circuit to ground fault. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the present application clearer, the embodiments of the present invention are described below in conjunction with the drawings in the embodiments of the present invention. In the following description, specific aspects of the embodiments of the present invention or drawings in which specific aspects of the embodiments of the present invention can be used are shown. It should be understood that the embodiments of the present invention can be used in other aspects and may include structural or logical changes not depicted in the drawings. Therefore, the following detailed description should not be understood in a restrictive sense, and the scope of the present invention is defined by the appended claims.

[0052] It should be noted that, in the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in this article is merely a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two, and “at least one” and “one or more” refer to one, two or more. The singular expressions “a”, “an”, “said”, “the” and “this” are intended to also include expressions such as “one or more”, unless there is a clear indication to the contrary in the context.

[0053] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0054] In the description of the embodiments of the present application, the terms "up", "down", "left", "right", "vertical", "horizontal", etc. indicate orientations or positional relationships that are defined relative to the orientations or positions of the components schematically placed in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative descriptions and clarifications, rather than indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. They may change accordingly according to changes in the orientation of the components placed in the drawings, and therefore cannot be understood as limitations on the present application.

[0055] In the embodiments of the present application, the same reference numerals are used to represent the same component or the same part. In addition, the various parts in the drawings are not drawn to scale, and the sizes and dimensions of the parts shown in the drawings are only exemplary and should not be understood as limiting the present application.

[0056] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," "connected," "configured," and the like should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, detachable fixation, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; they may refer to internal connections between two devices or interactions between two devices, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0057] It should be noted that when a device is referred to as being "fixed to," "disposed on," or "configured on" another device, it may be directly on the other device or there may be a central device. When a device is considered to be "connected to" another device, it may be directly connected to the other device or there may be a central device. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0058] The terms used in the embodiments of the present invention are only used to explain the specific embodiments of the present invention and are not intended to limit the present invention.

[0059] As the proportion of renewable energy sources increases, battery energy storage systems are becoming increasingly important to address the intermittent and unstable nature of large-scale photovoltaic and wind power generation, and their proportion is also increasing. Limited by the size of battery cells and battery modules, battery energy storage systems are generally composed of multiple battery modules connected in series and then in parallel. Placing multiple battery modules together can easily lead to safety hazards. Furthermore, due to the inevitable defects in the incoming materials and processing of battery cells, these defects can cause these cells to experience abnormalities during use, such as leakage and failure. These abnormalities can cause the cells to short to ground. Therefore, designing a safe protection solution to prevent the spread of faults, such as short-circuiting to ground, is crucial.

[0060] In an energy storage system, if a short-circuit occurs to the ground in a single battery pack, it will have little impact on the operation of the entire energy storage system. However, if a short-circuit occurs to the ground in two or more battery packs, it is easy to cause a fire risk due to voltage breakdown, seriously endangering the safe operation of the entire energy storage system.

[0061] In view of the potential failure possibility of the energy storage system, that is, the inevitable possibility of the battery cells in the battery pack short-circuiting to the ground, the existing technology adopts various methods to ensure the safe operation of the energy storage system.

[0062] For example, in the prior art, a common fuse is usually configured in the battery pack, and a cluster-level high-voltage common fuse is configured in the cluster control box. The common fuse in the battery pack and the high-voltage common fuse in the cluster control box will melt when the current passing through them is greater than a threshold, thereby disconnecting and protecting against differential mode faults caused by failure of components such as power converters.

[0063] In addition, the cluster control box is also equipped with a cluster-level insulation impedance detection function and a cluster-level switch. When the battery cell insulation to the ground fails due to battery cell leakage, foreign matter entering the PACK, etc., the insulation impedance detection circuit can identify the insulation impedance abnormality before the system is powered on and control the cluster-level switch to disconnect for disconnection protection. However, during the power-on operation of the system, the insulation impedance detection circuit cannot identify the abnormality, so it cannot play an effective protective role during the power-on operation of the system.

[0064] In addition, the cluster control box is also equipped with a residual current operated protective device (RCD). Figure 1 is a schematic diagram of the structure of a battery cluster in an industrial and commercial scenario. For industrial and commercial scenarios, the AC side of the power converter is grounded. Therefore, when a single-point insulation failure occurs in a battery pack (i.e., a short-circuit to ground occurs in a battery cell in a single battery pack), the cluster-level RCD can detect the fault current and trigger the cluster-level switch for disconnection protection. However, if two or more battery cells in the same battery pack experience a short-circuit to ground, even if the cluster-level switch is disconnected, there is still a risk of fire due to voltage breakdown between the two battery packs experiencing a short-circuit to ground. Therefore, if two or more battery cells in the same battery pack experience a short-circuit to ground, disconnecting the cluster-level switch will not effectively prevent fire and other hazards. Figure 2 is a schematic diagram of the structure of a battery cluster in a power plant scenario. For power plant scenarios, the AC side of the power converter is not grounded. Therefore, whether a single-point short-to-ground fault occurs in a battery pack or multiple-point short-to-ground faults occur in a battery pack (i.e., cells in multiple battery packs are short-circuited to ground), the cluster-level RCD cannot detect the fault current and cannot trigger the cluster-level switch for disconnect protection. Furthermore, in scenarios where the energy storage system is not powered (such as transportation and storage), the cluster-level RCD cannot detect cell-to-ground shorts within the pack and cannot trigger disconnect protection.

[0065] To address the above issues, the present application provides a battery pack and energy storage system that can quickly cut off the fault and ensure the safe operation of the energy storage system when a short circuit to ground occurs in the battery cells of two or more battery packs in a battery cluster.

[0066] First, the energy storage system provided by the embodiment of the present application is introduced. Figures 3 to 6 are schematic structural diagrams of four energy storage systems provided by the embodiment of the present application. Referring to Figures 3 to 6, the energy storage system provided by the embodiment of the present application includes one or more energy storage unit clusters (two energy storage unit clusters are shown in the figure, battery cluster 1 and battery cluster 2), and an energy storage unit cluster may include at least two battery packs (each battery cluster in the figure includes N battery packs), and the battery packs are connected in series with each other. In other words, an energy storage unit cluster can be composed of at least two battery packs connected in series. The internal structure of the battery pack will be described in detail below.

[0067] It should be noted that the energy storage system provided in the embodiment of the present application involves a multi-layer structure, the first layer is called an energy storage system or a battery energy storage system, the second layer is called an energy storage unit cluster or a battery cluster, the third layer is called a battery pack or PACK, and the fourth layer is called a battery module. The different names of the same layer structure mentioned above have the same meaning in the embodiment of the present application, and are all used to refer to this specific layer structure. The embodiment of the present application does not distinguish between them. A battery module can be composed of multiple battery cells connected in series, a battery pack can include a battery module, a battery management unit (BMU) and an optimizer, a battery cluster can include multiple battery packs connected in series, and an energy storage system can include multiple battery clusters connected in parallel. As shown in Figures 3 to 6, in the energy storage system provided in the present application, one or more energy storage unit clusters can be illustrated by taking battery clusters 1 to 2 as examples, where battery cluster 1 can be composed of PACK11 to PACK1n connected in series, and battery cluster 2 can be composed of PACK21 to PACK2n connected in series, where n is an integer.

[0068] In one possible implementation, each battery cluster in the energy storage system can be coupled to a DC bus via a direct current (DC) / direct current converter (DC / DC converter). One battery cluster is coupled to the DC bus via a DC / DC converter. As shown in FIG3 , battery cluster 1 can be coupled to the DC bus via converter DC / DC1, and battery cluster 2 can be coupled to the DC bus via converter DC / DC2. Each battery cluster is coupled to the DC bus via a DC / DC converter to achieve simple parallel expansion of multiple battery clusters, which can increase the energy storage capacity of the energy storage system. The DC / DC converter can also achieve flexible control of the energy of a single battery cluster and rapid switching of a single battery cluster under abnormal operating conditions, thus having strong applicability. After multiple battery clusters are connected in parallel, they can share a single alternating current (AC) inverter (DC / AC converter) to convert DC power into AC power and exchange energy with the AC power grid.

[0069] Here, the DC / DC converter can be a bidirectional DC / DC converter, and the circuit topology of the bidirectional DC / DC converter can be either isolated or non-isolated. The step-up ratio of the bidirectional DC / DC converter is determined by the DC bus voltage and the port voltage of the battery cluster. Taking battery cluster 1 as an example, since the port voltage of a battery varies with its energy storage capacity, the port voltage of battery cluster 1 varies with the number of battery packs connected in series within battery cluster 1. A large change in the number of battery packs connected in series within battery cluster 1 will also result in a large change in the port voltage of battery cluster 1. For example, assuming the port voltage of a battery pack is 50V, when two battery packs are connected in series within battery cluster 1, the port voltage of battery cluster 1 is 100V. When 30 battery packs are connected in series within battery cluster 1, the port voltage of battery cluster 1 is 1500V, which is the upper limit voltage of the low-voltage system. Therefore, the port voltage of battery cluster 1 can have a wide output voltage range, such as 100V to 1500V. To match the voltage range of the battery cluster 1's ports, converter DC / DC1 typically utilizes a non-isolated circuit topology and can be designed with a wide range of input / output capabilities, allowing for flexible adaptation to varying input / output voltages. The bidirectional DC / DC converter (including converters DC / DC1 and DC / DC2) can utilize circuit topologies such as a boost circuit, a flying capacitor boost circuit, a flying capacitor multilevel circuit, a positive and negative symmetrical three-level boost circuit, or a four-switch buck-boost circuit, depending on the specific application scenario. The boost ratio of converter DC / DC1 is determined by the DC bus voltage and the port voltage of battery cluster 1, depending on the specific application scenario.

[0070] In some feasible implementations, to manage individual battery clusters, a centralized monitoring system (BCU) can be added for each battery cluster, with each battery cluster corresponding to a corresponding BCU. For example, battery cluster 1 can correspond to BCU1 in DC / DC converter 1, and battery cluster 2 can correspond to BCU2 in DC / DC converter 2. Each battery cluster's BCU can be connected to each battery pack in the cluster via a control bus. The BCU can exchange information with each battery pack in the cluster in real time, enabling real-time, unified monitoring of the battery packs in each cluster, thus enabling flexible control of the energy storage system and providing high applicability. Optionally, when the BCU is implemented as a standalone circuit module, the BCU corresponding to each battery cluster can exchange information with the controller in the DC / DC converter, while the BCU is connected to each battery pack in the cluster via a control bus. In specific implementations, the BCU and battery packs can exchange information via wireless communication, DC power carrier communication, or other methods, depending on the actual application scenario, providing flexible operation and high applicability. Optionally, when the centralized monitoring system BCU of a single battery cluster is integrated as a separate circuit board or circuit module in the DC / DC converter to which the battery cluster is connected, the system structure of the energy storage system can be simplified. At the same time, since a single battery cluster is usually installed close to the DC / DC converter, integrating the centralized monitoring system of a single battery cluster into the DC / DC converter is conducive to the connection of the control bus.

[0071] Optionally, in some feasible implementations, to monitor and control the battery pack status, a battery management unit (BMU) may be added to the battery pack of each battery cluster. The BMU may include a module battery management system (mBMS) and corresponding sampling control modules, communication modules, power supply modules, and switch bridge arm drive control circuits, etc., to monitor and control the status of each energy storage element group (i.e., each battery pack) in the battery pack. The battery cluster's centralized monitoring system (BCU) communicates with the battery management unit (BMS) in the battery pack to jointly monitor and control the battery pack status.

[0072] In one possible implementation, each battery cluster can be configured with a separate DC / AC converter. That is, multiple battery clusters do not share a common DC / AC converter; instead, the battery clusters directly output converted AC power to the AC grid. As shown in Figure 4, battery cluster 1 can be coupled to the AC grid via converters DC / DC1 and DC / AC1, while battery cluster 2 can be coupled to the AC grid via converters DC / DC2 and DC / AC2. Each battery cluster is coupled to the AC grid via DC / DC and DC / AC converters, enabling simple parallel expansion of multiple battery clusters. This increases the energy storage system's storage capacity and allows for energy exchange with the AC grid.

[0073] In one possible implementation, each battery cluster can be equipped with a cluster control box for unified control of the individual battery clusters. The cluster control box can contain cluster-level fuses, cluster-level insulation impedance detectors, cluster-level switches, and other devices to enable cluster-level management and protection. As shown in Figure 5, battery cluster 1 can be coupled to the DC bus via cluster control box 1, and battery cluster 2 can be coupled to the DC bus via cluster control box 2. Each battery cluster can be coupled to the DC bus via the cluster control box to enable simple parallel expansion of multiple battery clusters, increasing the energy storage capacity of the energy storage system. When multiple battery clusters are connected in parallel, they can share a common DC / AC converter to convert DC power into AC power and exchange energy with the AC grid.

[0074] In one possible implementation, each battery cluster can be equipped with a cluster control box and a separate DC / AC converter. That is, multiple battery clusters do not share a common DC / AC converter; instead, the battery clusters directly output converted AC power to the AC grid. As shown in Figure 6, the power output of battery cluster 1 after passing through cluster control box 1 can be coupled to the AC grid via converter DC / AC1. The power output of battery cluster 2 after passing through cluster control box 2 can be coupled to the AC grid via converter DC / AC2. Each battery cluster is coupled to the AC grid via a DC / AC converter, enabling simple parallel expansion of multiple battery clusters. This increases the energy storage system's storage capacity and allows for energy exchange with the AC grid.

[0075] Next, the internal structure of the battery pack provided in the embodiment of the present application is introduced. Figure 7 is a structural schematic diagram of an energy storage unit cluster provided in the embodiment of the present application, and the energy storage unit cluster includes a plurality of battery packs connected in series and a cluster control box. As shown in Figure 7, each battery pack in the embodiment of the present application includes a battery module, a disconnecting device (a switch is taken as an example in Figure 7), a first current sensor (RCD is taken as an example in Figure 7) and a first controller (not shown in Figure 7). Exemplarily, the energy storage unit cluster shown in Figure 7 includes PACK1...PACKn-1, PACKn, wherein PACK1 includes battery module 1, disconnecting device 1 and RCD1, and PACKn includes battery module n, disconnecting device n and RCDn.

[0076] The battery module includes multiple single cells, which are connected in series to expand the capacity of the battery pack. It should be understood that the number of single cells in the battery module can be flexibly set according to actual needs.

[0077] Wherein, the disconnecting device is connected in series with the battery module. In FIG7 , the disconnecting device is connected in series with the negative electrode of the battery module. It should be understood that the disconnecting device can also be connected in series with the positive electrode of the battery module. The embodiment of the present application does not limit the relative position of the disconnecting device and the battery module. The disconnecting device in the embodiment of the present application is a controllable disconnecting device, that is, the disconnecting device disconnects under the control of a control signal, thereby disconnecting the current path in the battery pack. Exemplarily, the disconnecting device can be a switch, an explosive fuse, a contactor, a relay, a circuit breaker, an insulated gate bipolar transistor (IGBT), or a metal-oxide semiconductor field effect transistor (MOSFET). When the disconnecting device is a switch, the switch can be disconnected under the control of a control signal, thereby disconnecting the current path in the battery pack. When the disconnecting device is an explosive fuse, the explosive fuse can be disconnected under the control of a control signal, thereby disconnecting the current path in the battery pack. It should be understood that any device that can be disconnected according to a control signal can be used as the controllable disconnecting device in the embodiments of the present application, and the controllable disconnecting device can be flexibly selected according to actual needs.

[0078] Wherein, the first end of the first current sensor is connected to the positive output end of the battery pack, and the second end of the first current sensor is connected to the negative output end of the battery pack, thereby detecting the current difference between the positive output end and the negative output end of the battery pack. In one possible implementation, the first current sensor can be a device for detecting the current difference. In another possible implementation, the first current sensor can also be a circuit for detecting the current difference. Exemplarily, the first current sensor can be a residual current operated protective device (RCD). It should be understood that any sensor that can be connected to the two ends of the battery pack and obtain the current difference between the two ends can be used as the first current sensor in the embodiment of the present application, and the first current sensor can be flexibly selected according to actual needs.

[0079] In which, the first controller is used to control the above-mentioned disconnecting device to disconnect when the current difference between the positive output terminal and the negative output terminal of the battery pack is greater than a first threshold value, that is, the first controller always controls the above-mentioned disconnecting device to disconnect when the current difference detected by the first current sensor is greater than the first threshold value.

[0080] In one possible implementation, the first controller and the first current sensor can be integrated on a single circuit board. In other words, the first current sensor can be an intelligent current sensor with both logic and control functions. In another possible implementation, the first controller can be independent of the first current sensor. The first controller can be a separate controller or integrated into other components within the battery pack. In another possible implementation, the first controller can also be the battery management system (BMS) within the battery pack.

[0081] In one possible implementation, the energy storage unit cluster provided in the embodiments of the present application may not be provided with a cluster control box. In another possible implementation, a cluster control box may also be provided on the energy storage unit side provided in the embodiments of the present application. The cluster control box may be provided with a cluster-level fuse, a cluster-level switch, or a cluster-level insulation impedance detection circuit. For example, an RCD may be provided in the cluster control box to detect the current difference between the positive and negative output terminals of the battery cluster, further improving the safety of the energy storage system. Alternatively, based on cost considerations, after providing the first current sensor in the battery pack, the RCD may no longer be provided in the cluster control box.

[0082] Next, the working principle of the energy storage unit cluster shown in FIG7 provided in an embodiment of the present application is described.

[0083] Figure 8 is a schematic diagram of the current loop of the energy storage system shown in Figure 7 under normal operation. As shown in Figure 8, when the energy storage system is operating normally, the currents at both ends of a battery pack within the energy storage unit cluster should be approximately equal. That is, when the energy storage system is operating normally, there is no current difference at both ends of the battery pack, or only a slight current difference. Therefore, by properly setting the first threshold, when the energy storage system is operating normally, the current difference detected by the first current sensor will not exceed the first threshold, and the disconnect device will be in the closed state.

[0084] FIG9 is a schematic diagram of the current loop in the case where two or more battery packs in the energy storage system shown in FIG7 have a short circuit to ground fault. As shown in FIG9 , the battery cells in battery pack 1 and battery pack n-1 both have a short circuit to ground fault. At this time, due to the presence of two grounding points, it is equivalent to multiple battery cells connected in series without load. Since the voltage of multiple battery cells connected in series is very large, it is very easy to cause a fire hazard due to voltage breakdown. At this time, due to the presence of two current loops in the energy storage unit cluster, the current magnitudes at both ends of the two battery packs that have a short circuit to ground fault are different, that is, there is a current difference at both ends of the two battery packs that have a short circuit to ground fault. In an embodiment of the present application, when the current difference detected by the first current sensor in the battery pack that has a short circuit to ground fault is greater than the first threshold value, the disconnecting device in the same battery pack is controlled to disconnect, thereby disconnecting the fault circuit in the energy storage unit cluster. Taking Figure 9 as an example, a disconnect device is connected in series with the negative terminal of the battery module. When a short-circuit fault occurs to ground in the cells of PACK1 and PACKn-1, a current difference occurs between the positive and negative output terminals of PACK1. The current difference detected by the first current sensor in PACK1 exceeds a first threshold, triggering the first controller in PACK1 to disconnect disconnect device 1. Disconnecting disconnect device 1 can open the fault circuit in Figure 9 and prevent the risk of fire caused by voltage breakdown.

[0085] FIG10 is a schematic diagram of the current loop in the event of a short-circuit to ground fault in two or more battery packs in another energy storage system provided by an embodiment of the present application. The difference between FIG10 and FIG9 is that the disconnect device in FIG9 is connected in series with the negative electrode of the battery module, while the disconnect device in FIG10 is connected in series with the positive electrode of the battery module. As shown in FIG10, when a short-circuit to ground fault occurs in the battery cells in PACK1 and PACKn-1, a current difference exists between the positive output terminal and the negative output terminal of PACK n-1. The current difference detected by the first current sensor in PACK n-1 is greater than the first threshold value, thereby triggering the first controller in PACK n-1 to control the disconnect device n-1 to disconnect. The disconnection of disconnect device n-1 can disconnect the fault circuit in FIG10 to avoid the risk of fire caused by voltage breakdown. It can be seen that whether the disconnect device is connected in series with the positive electrode of the battery module or the negative electrode of the battery module, it can play a disconnection protection role, and the embodiments of the present application are not limited to this.

[0086] FIG11 is a schematic diagram of the structure of another energy storage unit cluster provided in an embodiment of the present application. As shown in FIG11 , in one possible implementation, the battery pack provided in an embodiment of the present application further includes a second current sensor (TMR as an example in FIG11 ) and a second controller (not shown in FIG11 ). The disconnecting device in FIG11 is an exploding fuse as an example. Exemplarily, the energy storage unit cluster shown in FIG11 includes PACK1…PACKn-1, PACKn, where PACK1 includes battery module 1, disconnecting device 1, TMR1, and RCD1, and PACKn includes battery module n, disconnecting device n, TMRn, and RCDn.

[0087] Among them, the second current sensor is connected in series with the battery module and the disconnecting device in the battery pack. In Figure 11, the second current sensor is connected in series between the negative pole of the battery module and the disconnecting device. It should be understood that the second current sensor can also be connected in series with the positive pole of the battery module. The second current sensor is used to detect the magnitude of the current passing through the series circuit. In one possible implementation, the second current sensor can be a device for detecting current. In another possible implementation, the second current sensor can also be a circuit for detecting current. Exemplarily, the first current sensor can be any one of a Hall sensor, a tunnel magnetoresistance sensor (TMR), an anisotropic magnetoresistance sensor (AMR), and a giant magnetoresistance sensor (GMR). It should be understood that the above examples are merely exemplary. Any sensor that can be connected in series in a circuit and detect the current passing through can be used as the second current sensor in the embodiment of the present application, and the second current sensor can be flexibly selected according to actual needs.

[0088] It should be noted that the second current sensor and the disconnecting device need to be connected in series on the same side of the battery module in order to realize the detection and disconnection protection functions of the battery cell short-circuit fault. Exemplarily, the second current sensor and the disconnecting device can both be connected in series to the negative pole of the battery module, and the second current sensor and the disconnecting device can also both be connected in series to the positive pole of the battery module. The embodiments of the present application do not limit the relative position relationship between the second current sensor and the disconnecting device. Exemplarily, in one possible implementation, one end of the TMR is connected to the positive output terminal of the battery module, the other end of the TMR is connected to one end of the disconnecting device, and the other end of the disconnecting device is connected to the positive output terminal of the battery pack. In another possible implementation, one end of the disconnecting device is connected to the positive output terminal of the battery module, the other end of the disconnecting device is connected to one end of the TMR, and the other end of the TMR is connected to the positive output terminal of the battery pack. In another possible implementation, one end of the TMR is connected to the negative output terminal of the battery module, the other end of the TMR is connected to one end of the disconnecting device, and the other end of the disconnecting device is connected to the negative output terminal of the battery pack. In another possible implementation, one end of the disconnect device is connected to the negative output end of the battery module, the other end of the disconnect device is connected to one end of the TMR, and the other end of the TMR is connected to the negative output end of the battery pack.

[0089] The second controller is used to control the disconnecting device in the battery pack to disconnect when the current detected by the second current sensor is greater than a second threshold value.

[0090] In one possible implementation, the second controller and the second current sensor are integrated on a single circuit board. In other words, the second current sensor can be an intelligent current sensor with both logic and control functions. In another possible implementation, the second controller can be independent of the second current sensor. The second controller can be a separate controller or integrated into other components within the battery pack. In another possible implementation, the second controller can also be the battery management system within the battery pack.

[0091] In one possible implementation, the first controller and the second controller may be two independent controllers. For example, the first controller and the second controller may be integrated into different devices or circuit boards. For example, the first controller and the second controller may be integrated into a first current controller and a second current controller, respectively. In one possible implementation, the first controller and the second controller may be the same controller, that is, the same controller performs the functions of the first controller and the second controller. For example, the functions of the first controller and the second controller may be performed by a BMS.

[0092] Next, the working principle of the energy storage unit cluster shown in FIG11 provided in an embodiment of the present application is described.

[0093] FIG12 is a schematic diagram of the current loop of the energy storage system shown in FIG11 under normal operating conditions. As shown in FIG12 , when the energy storage system is operating normally, the current value in the current loop within the energy storage unit cluster is relatively stable, typically with only slight fluctuations. Therefore, by reasonably setting the second threshold, when the energy storage system is operating normally, the current detected by the second current sensor will not exceed the second threshold, and the disconnect device is in a closed state. FIG13 is a schematic diagram of the current loop in the energy storage system shown in FIG11 when two or more battery packs experience a short-circuit to ground fault. As shown in FIG13 , the cells in battery pack 1 and battery pack n-1 both experience a short-circuit to ground fault. At this time, due to the presence of two or more grounding points, it is equivalent to connecting multiple cells in series without load. At this time, the current in the current loop will surge. That is, compared to the current loop in FIG12 , the current flowing through the second current sensor in the current loop in FIG13 will surge. In an embodiment of the present application, when the current detected by the second current sensor in a battery pack exceeds the second threshold, the disconnect device in the same battery pack is controlled to open. As shown in FIG13 , when a short-circuit fault occurs to the ground in the battery cells of PACK1 and PACKn-1-, the current detected by the second current sensor in PACK1 is greater than the second threshold value, thereby triggering the second controller in PACK1 to control the disconnecting device 1 to disconnect. The disconnection of the disconnecting device 1 can disconnect the fault circuit in FIG13 , thereby avoiding the risk of fire caused by voltage breakdown.

[0094] FIG14 is a schematic diagram of the current loop in the event of a short-circuit to ground fault in two or more battery packs in the energy storage system shown in FIG11 . FIG14 differs from FIG13 in that the second current sensor and disconnect device in FIG13 are connected in series with the negative electrode of the battery module, while the second current sensor and disconnect device in FIG14 are connected in series with the positive electrode of the battery module. As shown in FIG14 , if the second current sensor and disconnect device are connected in series with the positive electrode of the battery module, then when a short-circuit to ground fault occurs in the battery cells of PACK1 and PACKn-1, the current detected by the second current sensor in PACKn-1 exceeds the second threshold, triggering the second controller in PACKn-1 to control disconnect device n-1 to disconnect. Disconnecting disconnect device n-1 can break the fault loop in FIG14 , thereby preventing the risk of fire caused by voltage breakdown. Therefore, whether the disconnect device and the second current sensor are connected in series with the positive electrode of the battery module or the negative electrode of the battery module, both can provide a disconnect protection function, and this embodiment of the present application is not limited to this.

[0095] It should be understood that in one possible implementation, the second current sensor can exist independently of the first current sensor. That is, a second current sensor and a disconnect device are provided in the battery pack. The second current sensor detects a cell-to-ground short-circuit fault and controls the disconnect device to disconnect, thereby providing disconnect protection under fault conditions. In this case, only one set of fault detection and disconnect protection logic is provided in the battery pack.

[0096] In another possible implementation, both a first current sensor and a second current sensor can be installed in the battery pack. Using two different sets of control logic to detect cell-to-ground short-circuit faults, this allows for more reliable and accurate fault detection, prompting timely disconnection and protection, ensuring the safe operation of the energy storage system. Furthermore, if either the first or second current sensor fails, the other set of control logic can still be used to detect multiple battery pack short-circuit faults, further improving system reliability.

[0097] In the embodiment of the present application, it is also possible to control only one of the first current sensor and the second current sensor to be in the operating state at the same time, so as to save energy while improving system reliability. Similarly, when the first controller and the second controller are two independent controllers, it is also possible to control only one of the first controller and the second controller to be in the operating state at the same time, so as to save energy while improving system reliability. It should be noted that the operating state refers to the current sensor or controller being powered on and working normally to realize the detection or control function. The corresponding state to the operating state is the non-operating state. In the non-operating state, the current sensor or controller does not work and does not consume power.

[0098] Specifically, the above functions can be achieved by setting a competition signal. In the embodiment of the present application, the operating state of the second current sensor is controlled according to the operating state of the first current sensor. Specifically, when the first current sensor is in the operating state, the second current sensor is controlled to stop running, and when the first current sensor is in the non-operating state, the second current sensor is controlled to run. Because under normal circumstances, the first current sensor has higher accuracy, faster response and better effect in detecting battery cell short-circuit faults than the second current sensor, therefore, setting the priority of the first current sensor higher than that of the second current sensor is beneficial to improving the detection effect of battery cell short-circuit faults.

[0099] In one possible implementation, when the functions of the first controller and the second controller are implemented by a centralized controller (e.g., a BMS) (herein, the centralized controller is referred to as the first controller), the first controller is further configured to, when the first current sensor is in an operating state, send a first control signal to the second current sensor, the first control signal being used to instruct the second current sensor to be non-operating. For example, before a first moment, the second current sensor is in an operating state, detecting the current passing therethrough in real time. At the first moment, the first current sensor begins operating (e.g., the condition for the first current sensor to begin operating may be that the first current sensor is powered on). Upon detecting that the first current sensor has begun operating, the first controller sends the first control signal to the second sensor. The second sensor stops operating (the second sensor switches to a non-operating state) after receiving the first control signal. As a possible implementation, when the first current sensor is in an operating state, the first controller continuously sends the first control signal to the second current sensor, or the first controller sends the first control signal to the second current sensor at preset time intervals. When the first controller stops sending the first control signal, it indicates that the first current sensor has ceased operating (is no longer in an operating state). At this point, the second sensor no longer receives the first control signal and resumes operation. As another possible implementation, the first controller stops sending the first control signal after sending the first control signal until it detects that the first current sensor has stopped working. Then, the first controller sends a third control signal to the second current sensor, where the third control signal is used to instruct the second current sensor to operate. The second current sensor resumes operation after receiving the third control signal.

[0100] In another possible implementation, when the first controller and the second controller are two independent controllers, and the first controller and the second controller are used to control the first current sensor and the second current sensor respectively, the operation switching between the first current sensor and the second current sensor can be controlled by the first controller. Specifically, the first controller is also used to send a second control signal to the second controller when the first current sensor is in an operating state, and the second control signal is used to indicate that the second current sensor is not working. Exemplarily, before the first moment, the second current sensor is in an operating state and detects the current passing through in real time. At the first moment, the first current sensor starts working (for example, the condition for the first current sensor to start working may be that the first current sensor is powered on). When the first controller detects that the first current sensor starts working, it sends a first control signal to the second controller. After receiving the first control signal, the second controller controls the second current sensor to stop working. As a possible implementation, when the first current sensor is in operation, the first controller continuously sends the first control signal to the second controller, or the first controller sends the first control signal to the second controller at a preset time interval. When the first controller stops sending the first control signal, it indicates that the first current sensor has stopped working (is no longer in operation). At this time, the second controller cannot receive the first control signal, and the second controller controls the second current sensor to restart working. As another possible implementation, the first controller stops sending the first control signal after sending the first control signal until it detects that the first current sensor has stopped working, and then sends a third control signal to the second controller. The third control signal is used to instruct the second current sensor to operate. After receiving the third control signal, the second controller controls the second current sensor to restart working.

[0101] In another possible implementation, when the first controller and the second controller are two independent controllers and are used to control the first current sensor and the second current sensor, respectively, the switching between the first and second current sensors can also be controlled by the second controller. Specifically, the second controller is further used to control the second current sensor to be inoperative when the first current sensor is in an operational state. In this case, the second controller detects the operating state of the first current sensor in real time and controls the operating state of the second current sensor based on the operating state of the first current sensor.

[0102] In the embodiment of the present application, the first current sensor and the second current sensor can also be controlled to work under different circumstances to realize the detection of battery cell faults at all times. Specifically, when the AC grid connected to the energy storage system is powered, the first current sensor can be used to detect the battery cell short-circuit fault. When the AC grid connected to the energy storage system is powered, or when the energy storage system is not connected to the AC grid, the second current sensor can be used to detect the battery cell short-circuit fault. In this way, whether the energy storage system is powered on and running, or when the energy storage system is not powered on during transportation, storage, etc., the battery cell short-circuit fault detection and disconnection protection can be realized.

[0103] In one possible implementation, since the first current sensor generally consumes a large amount of power, the first current sensor can be powered by a cluster-level auxiliary source, and then detect the short-circuit fault of the battery cell to ground when the cluster-level auxiliary source is powered, and control the disconnecting device to perform disconnection protection. Exemplarily, as shown in FIG11 , the cluster-level auxiliary source can be set in a cluster control box, with the first end of the cluster-level auxiliary source connected to the positive output end of the energy storage unit cluster, and the second end of the cluster-level auxiliary source connected to the negative output end of the energy storage unit cluster. Exemplarily, the cluster-level auxiliary source can be powered by a DC bus, or the cluster-level auxiliary source can also be powered directly by an AC power grid.

[0104] When the first controller is integrated into the first current sensor, the first controller can also be powered by the cluster-level auxiliary source. When the first controller is integrated into other devices, or when the first controller is an independent controller, the first controller can also be powered by the cluster-level auxiliary source.

[0105] When the energy storage system is connected to the AC grid and the AC grid is powered, the cluster-level auxiliary source is also powered. The cluster-level auxiliary source is used to power the first current sensor and / or the first controller, thereby ensuring the normal operation of the first current sensor and / or the first controller.

[0106] In one possible implementation, in order to ensure that a cell-to-ground short-circuit fault can still be detected when the energy storage system is not connected to the AC grid or the AC grid connected to the energy storage system is out of power, the above-mentioned second current sensor can be powered by the battery module in the same battery pack, thereby realizing the ground short-circuit fault detection and disconnection protection functions without the need for an external power supply.

[0107] When the second controller is integrated into the second current sensor, it can also be powered by the same battery module in the same battery pack. That is, the same battery module can power both the second current sensor and the second controller. This ensures that even if the energy storage system is disconnected from the AC grid or the AC grid connected to the energy storage system is dead, a cell-to-ground short circuit fault can still be detected and disconnected for protection.

[0108] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A battery pack with a disconnection protection function, characterized in that: The battery pack includes a battery module, a disconnecting device, a first current sensor and a first controller; The battery module includes a plurality of single cells; The disconnecting device is connected in series with the battery module. A first end of the first current sensor is connected to a positive output end of the battery pack, a second end of the first current sensor is connected to a negative output end of the battery pack, and the first current sensor is used to detect a current difference between the positive output end and the negative output end; The first controller is used for controlling the disconnecting device to disconnect when the current difference is greater than a first threshold.

2. The battery pack according to claim 1, characterized in that: The battery pack also includes a second current sensor and a second controller. The second current sensor is connected in series with the battery pack and the disconnecting device. The second current sensor is used to detect the magnitude of the current passing therethrough. The second controller is used to control the disconnecting device to disconnect when the current detected by the second current sensor is greater than a second threshold value.

3. The battery pack according to claim 1 or 2, characterized in that: The battery pack also includes a second current sensor, which is connected in series with the battery module and the disconnecting device. The second current sensor is used to detect the magnitude of the current passing through. The first controller is used to control the disconnecting device to disconnect when the current detected by the second current sensor is greater than a second threshold value.

4. The battery pack according to claim 2 or 3, characterized in that: The second current sensor and the disconnecting device are both connected in series between the battery pack and the positive output terminal of the battery pack, or the second current sensor and the disconnecting device are both connected in series between the battery pack and the negative output terminal of the battery pack.

5. The battery pack according to any one of claims 2 to 4, characterized in that: Only one of the first current sensor and the second current sensor is in operation at the same time.

6. The battery pack according to claim 2, 4 or 5, characterized in that: Only one of the first controller and the second controller is in operation at the same time.

7. The battery pack according to claim 2, 4 or 5, characterized in that: The first controller is further configured to, when the first current sensor is in operation, send a second control signal to the second controller, and the second controller is further configured to control the second current sensor to not operate according to the second control signal.

8. The battery pack according to any one of claims 2, 4 to 7, characterized in that: The second current sensor or the second controller is powered by the battery module.

9. The battery pack according to any one of claims 3 to 5, characterized in that: The first controller is further configured to control the second current sensor when the first current sensor is in an operating state.

10. The battery pack according to any one of claims 2 to 9, characterized in that: The second current sensor is at least one of the following: Hall sensor, tunnel magnetoresistance sensor TMR, anisotropic magnetoresistance sensor AMR, giant magnetoresistance sensor GMR.

11. The battery pack according to any one of claims 1 to 10, characterized in that: The first current sensor is a residual current operated protector (RCD).

12. The battery pack according to any one of claims 1 to 11, characterized in that: The disconnecting device is at least one of the following: Switches, exploding fuses, contactors, relays, circuit breakers, insulated gate bipolar transistors (IGBTs), metal-oxide semiconductor field effect transistors (MOS).

13. An energy storage system with a disconnection protection function, characterized in that: The energy storage system includes at least one energy storage unit cluster and a direct current / alternating current (DC / AC) converter, the energy storage unit cluster includes at least two battery packs as described in any one of claims 1 to 12, the at least two battery packs are connected in series, and the energy storage unit cluster is connected to an AC power grid or a load through the DC / AC converter.

14. The energy storage system according to claim 13, characterized in that: The energy storage unit cluster also includes an auxiliary source, a first end of the auxiliary source is connected to the positive output end of the energy storage unit cluster, and a second end of the auxiliary source is connected to the negative output end of the energy storage unit cluster; the auxiliary source is used to power the first current sensor or the first controller.

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