Battery management system and energy storage device

Abstract

The utility model discloses a battery management system and an energy storage device, and relates to the technical field of battery management systems, and the battery management system comprises a control module, a voltage converter and a dry node module. The first input end of the voltage converter is connected with the first output end of the control module. The dry node module is connected between the second output end of the control module and the second input end of the voltage converter. And the dry node module is used for closing the charging and discharging function of the voltage converter so as to cut off a charging and discharging loop between the battery managed by the battery management system and equipment powered by the battery through the voltage converter. According to the utility model, on the basis of ensuring a simple system structure and low cost, the control reliability of the battery management system to the charging and discharging process of the battery is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of battery management systems, in particular to a battery management system and an energy storage device. Background Art

[0002] In the current Battery Management System (BMS), in order to simplify the structure and reduce costs, a common practice is to use the switch tube or switching element in the voltage converter (Direct Current-to-Direct Current Converte, DC-DC) as the control component of the battery's charge and discharge circuit (that is, the charge and discharge circuit between the battery and the device powered by the battery through the voltage converter). This eliminates the need to design a separate charge and discharge switch in the battery management system.

[0003] Although this approach effectively reduces system complexity and cost, it also introduces a potential risk: the system is prone to communication failure, data loss, and other reasons, which may cause the voltage converter's switch tube or switching element to be unable to cut off the battery's charge and discharge circuit, thereby causing the battery management system's control reliability of the battery charging and discharging process to deteriorate. Utility Model Content

[0004] The main purpose of the utility model is to provide a battery management system, aiming to improve the control reliability of the battery management system over the battery charging and discharging process on the basis of ensuring the simplicity of the system structure and low cost.

[0005] To achieve the above objectives, the present invention provides a battery management system, which includes:

[0006] Control module;

[0007] a voltage converter, wherein a first input terminal of the voltage converter is connected to a first output terminal of the control module;

[0008] A dry node module, which is connected between the second output end of the control module and the second input end of the voltage converter, and is used to turn off the charging and discharging function of the voltage converter to cut off the charging and discharging circuit between the battery managed by the battery management system and the device powered by the battery through the voltage converter.

[0009] In one embodiment, the dry node module is a relay;

[0010] One end of the relay is connected to the second output end of the control module, and the other end of the relay is connected to the second input end of the voltage converter.

[0011] In one embodiment, the battery management system further includes a trip unit;

[0012] The control end of the trip unit is connected to the control module, the first trip end of the trip unit is connected to the battery managed by the battery management system, and the second trip end of the trip unit is connected to the voltage converter;

[0013] The trip device is used to cut off the input and output circuit between the battery and the voltage converter.

[0014] In one embodiment, the battery management system further includes a trip unit;

[0015] The trip unit is mounted on the chassis where the battery management system is located, and is used to cut off the input and output circuits between the battery and the voltage converter.

[0016] In one embodiment, the trip unit is a shunt trip unit.

[0017] In one embodiment, the battery management system further includes a battery voltage acquisition module, a battery temperature acquisition module, and a battery current acquisition module;

[0018] The sampling end of the battery voltage acquisition module, the sampling end of the battery temperature acquisition module, and the sampling end of the battery current acquisition module are connected to the battery, and the output end of the battery voltage acquisition module, the output end of the battery temperature acquisition module, and the output end of the battery current acquisition module are connected to the input end of the control module.

[0019] In one embodiment, the battery voltage acquisition module is a voltage sensor, the battery temperature acquisition module is a temperature sensor, and the battery current acquisition module is a current sensor.

[0020] In one embodiment, the voltage converter includes a high voltage input and output unit, a low voltage input and output unit, a capacitor, an inductor, a first transformer, and a second transformer;

[0021] The high-voltage input-output unit is connected to one end of the capacitor, the other end of the capacitor is connected to one end of the inductor, the other end of the inductor is connected to the first end of the secondary coil of the first transformer, the second end of the secondary coil of the first transformer is connected to the first end of the secondary coil of the second transformer, and the second end of the secondary coil of the second transformer is connected to the high-voltage input-output unit;

[0022] The first end of the primary coil of the first transformer is respectively connected to the first end of the primary coil of the second transformer and the low-voltage input and output unit, and the second end of the primary coil of the first transformer is respectively connected to the second end of the primary coil of the second transformer and the low-voltage input and output unit.

[0023] In one embodiment, the high-voltage input-output unit includes a switch element, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, and a first fuse; and the low-voltage input-output unit includes a fifth switch tube, a sixth switch tube, a seventh switch tube, an eighth switch tube, and a second fuse;

[0024] One end of the switching element is connected to the first fuse, the other end of the switching element is respectively connected to the drain of the first switching tube and the drain of the second switching tube, the source of the second switching tube is respectively connected to the drain of the third switching tube and one end of the capacitor, the source of the first switching tube is respectively connected to the second end of the secondary coil of the second transformer and the drain of the fourth switching tube, and the source of the third switching tube is connected to the source of the fourth switching tube;

[0025] The first end of the primary coil of the first transformer is respectively connected to the first end of the primary coil of the second transformer, the source of the fifth switching tube, and the drain of the sixth switching tube; the second end of the primary coil of the first transformer is respectively connected to the second end of the primary coil of the second transformer, the source of the seventh switching tube, and the drain of the eighth switching tube; the drain of the fifth switching tube and the drain of the seventh switching tube are connected to the second fuse; and the source of the sixth switching tube is connected to the source of the eighth switching tube.

[0026] In addition, to achieve the above-mentioned purpose, the present invention also provides an energy storage device, which includes a chassis, a battery and the above-mentioned battery management system, the battery and the battery management system are both installed in the chassis, and the battery management system is connected to the battery.

[0027] The utility model provides a battery management system, which includes a control module, a voltage converter and a dry node module; the first input end of the voltage converter is connected to the first output end of the control module, and the dry node module is connected between the second output end of the control module and the second input end of the voltage converter; the dry node module is used to turn off the charge and discharge function of the voltage converter to cut off the charge and discharge circuit between the battery managed by the battery management system and the equipment powered by the battery through the voltage converter.

[0028] Therefore, the present invention sets a dry node module between the control module and the voltage converter for shutting down the charge and discharge function of the voltage converter. Thus, when the control module fails to control the communication of the voltage converter, that is, when the switch tube or switch element of the voltage converter cannot cut off the charge and discharge circuit of the battery, the dry node module can be used to shut down the charge and discharge function of the voltage converter, so that the voltage converter no longer inputs and outputs electrical signals with the device powered by the battery, thereby cutting off the charge and discharge circuit between the battery managed by the battery management system and the device powered by the battery through the voltage converter, so as to improve the control reliability of the battery management system over the battery charging and discharging process while ensuring the simplicity and low cost of the system structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0030] Figure 1 A schematic structural diagram of a conventional battery management system provided in an embodiment of the present utility model;

[0031] Figure 2 A schematic structural diagram of a conventional battery management system for implementing the battery management system on a high-voltage battery pack provided by an embodiment of the present invention;

[0032] Figure 3 A schematic structural diagram of another conventional battery management system when implementing the battery management system provided by an embodiment of the present utility model on a high-voltage battery pack;

[0033] Figure 4 A schematic structural diagram of a battery management system provided in the first embodiment of the present utility model;

[0034] Figure 5 A schematic diagram of the internal structure of a voltage converter provided by the first embodiment of the present utility model;

[0035] Figure 6 A schematic diagram of the circuit structure of a voltage converter provided in the first embodiment of the present utility model;

[0036] Figure 7 A schematic structural diagram of a battery management system provided in a second embodiment of the present invention;

[0037] Figure 8 This is a structural diagram of a battery management system provided in the third embodiment of the present utility model.

[0038] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments.

[0039] Description of Figure Numbers:

[0040] 10. Control module; 20. Voltage converter; 30. Dry node module; 40. Battery voltage acquisition module; 50. Battery temperature acquisition module; 60. Battery current acquisition module; 21. High-voltage input and output unit; 22. Low-voltage input and output unit; A1. Trip unit; a1. Trip unit electromagnetic coil; a2. Trip unit free tripping mechanism; a3. Transmission mechanism; K1. Switch element; M1-M8. Switch tube; B1-B2. Fuses; T1-T2. Transformer 101, primary coil of the first transformer; 102, secondary coil of the first transformer; 201, primary coil of the second transformer; 202, secondary coil of the second transformer; C1, capacitor; L1, inductor; 100, battery; SW1-SW2, charge and discharge switches; P+, positive electrode on the low-voltage side of the voltage converter; P-, negative electrode on the low-voltage side of the voltage converter; PHV+, positive electrode on the high-voltage side of the voltage converter; PHV-, negative electrode on the high-voltage side of the voltage converter. DETAILED DESCRIPTION

[0041] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] It should be noted that the descriptions of "first", "second", etc. in this utility model are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0044] Please refer to Figure 1The battery management system generally comprises a control module 10, a first charge / discharge switch SW1, and a second charge / discharge switch SW2. The first charge / discharge switch SW1 and the second charge / discharge switch SW2 are used to disconnect the charge / discharge circuit of the battery 100 managed by the battery management system (i.e., the charge / discharge circuit between the battery 100 and the device it powers).

[0045] On this basis, in order to realize the application of battery management system on high voltage battery pack, it is usually Figure 1 Based on the system architecture shown, a voltage converter 20 is added to obtain Figure 2 Considering that the voltage converter 20 generally carries a switch tube or switch element that can be used to cut off the charge and discharge circuit of the battery 100, in order to simplify the system structure and reduce costs, a common practice is to use the switch tube or switch element in the voltage converter 20 as a control component of the charge and discharge circuit of the battery 100 (that is, the charge and discharge circuit between the battery 100 and the device powered by the battery 100 through the voltage converter 20), thereby eliminating the need to design a separate charge and discharge switch in the battery management system. For details, please refer to Figure 3 .

[0046] Although this approach effectively reduces system complexity and cost, it also introduces a potential risk: the system is prone to communication failure, data loss, and other reasons, which may cause the voltage converter's switch tube or switching element to be unable to cut off the battery's charge and discharge circuit, thereby causing the battery management system's control reliability of the battery charging and discharging process to deteriorate.

[0047] Based on this, the present invention provides a battery management system. In the first embodiment of the present invention, please refer to Figure 4 The battery management system may include: a control module 10, a voltage converter 20 and a dry node module 30; the first input end of the voltage converter 20 is connected to the first output end of the control module 10, and the dry node module 30 is connected between the second output end of the control module 10 and the second input end of the voltage converter 20; the dry node module 30 is used to turn off the charge and discharge function of the voltage converter 20, so as to cut off the charge and discharge circuit between the battery 100 managed by the battery management system and the device powered by the battery 100 through the voltage converter 20.

[0048] It should be noted that the control module 10 may be a microcontroller unit (MCU), a controller, or other control chip or control circuit with control functions, and this embodiment does not specifically limit this. When the control module 10 is normally controlling the communication with the voltage converter 20, the control module 10 outputs a charge-discharge circuit disconnection signal to the voltage converter 20 to control the disconnection of the corresponding switching element or switch in the voltage converter 20, thereby disconnecting the charge-discharge circuit between the battery 100 managed by the battery management system and the device powered by the battery 100 through the voltage converter 20.

[0049] Additionally, it should be noted that the dry node module 30 may be a relay. In the event that the control module 10 fails to control the communication with the voltage converter 20, i.e., in the event that the switch tube or switch element of the voltage converter 20 is unable to disconnect the charge and discharge circuit of the battery 100, the state of the relay will change (either from a closed state to an open state or from an open state to a closed state), thereby stopping the charge and discharge functions of the voltage converter 20 and shutting down the charge and discharge functions of the voltage converter 20. Consequently, the voltage converter 20 will no longer input or output electrical signals to and from the device powered by the battery 100. Consequently, the charge and discharge circuit between the battery 100 and the device powered by the battery 100 through the voltage converter 20 will be disconnected due to the voltage converter 20 interrupting the input and output of electrical signals to and from the device powered by the battery 100.

[0050] In this embodiment, a dry node module 30 for shutting down the charge and discharge function of the voltage converter is provided between the control module 10 and the voltage converter 20. Thus, when the control module 10 fails to control the communication of the voltage converter 20, that is, when the switch tube or switch element of the voltage converter 20 cannot cut off the charge and discharge circuit of the battery 100, the dry node module 30 can be used to shut down the charge and discharge function of the voltage converter 20, so that the voltage converter 20 no longer inputs and outputs electrical signals with the device powered by the battery 100, thereby cutting off the charge and discharge circuit between the battery 100 managed by the battery management system and the device powered by the battery 100 through the voltage converter 20, so as to improve the control reliability of the battery management system over the battery charge and discharge process while ensuring the simplicity and low cost of the system structure.

[0051] In one possible implementation, please refer to Figure 5 , the voltage converter 20 may include a high voltage input and output unit 21, a low voltage input and output unit 22, a capacitor C1, an inductor L1, a first transformer T1 and a second transformer T2;

[0052] The high-voltage input-output unit 21 is connected to one end of the capacitor C1, the other end of the capacitor C1 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to the first end of the secondary coil 102 of the first transformer T1, the second end of the secondary coil 102 of the first transformer T1 is connected to the first end of the secondary coil 202 of the second transformer T2, and the second end of the secondary coil of the second transformer T2 is connected to the high-voltage input-output unit 21;

[0053] The first end of the primary coil 101 of the first transformer T1 is respectively connected to the first end of the primary coil 201 of the second transformer T2 and the low-voltage input-output unit 22, and the second end of the primary coil 101 of the first transformer T1 is respectively connected to the second end of the primary coil 201 of the second transformer T2 and the low-voltage input-output unit 22.

[0054] In the figure, PHV+ is the positive electrode on the high-voltage side of the voltage converter 20, PHV- is the negative electrode on the high-voltage side of the voltage converter 20; P+ is the positive electrode on the low-voltage side of the voltage converter 20, and P- is the negative electrode on the low-voltage side of the voltage converter 20.

[0055] It should be noted that the high voltage input and output unit 21 is used to implement high voltage input and output, and the low voltage input and output unit 22 is used to implement low voltage input and output. This embodiment does not specifically limit the structural composition of the high voltage input and output unit 21 and the low voltage input and output unit 22.

[0056] For example, please refer to Figure 6 The high-voltage input-output unit 21 may include a switch element K1, a first switch tube M1, a second switch tube M2, a third switch tube M3, a fourth switch tube M4, and a first fuse B1; the low-voltage input-output unit 22 may include a fifth switch tube M5, a sixth switch tube M6, a seventh switch tube M7, an eighth switch tube M8, and a second fuse B2;

[0057] One end of the switch element K1 is connected to the first fuse B1, and the other end of the switch element K1 is respectively connected to the drain of the first switch transistor M1 and the drain of the second switch transistor M2. The source of the second switch transistor M2 is respectively connected to the drain of the third switch transistor M3 and one end of the capacitor C1. The source of the first switch transistor M1 is respectively connected to the second end of the secondary winding 202 of the second transformer T2 and the drain of the fourth switch transistor M4. The source of the third switch transistor M3 is connected to the source of the fourth switch transistor M4.

[0058] A first end of the primary coil 101 of the first transformer T1 is respectively connected to a first end of the primary coil 201 of the second transformer T2, the source of the fifth switch M5, and the drain of the sixth switch M6. A second end of the primary coil 101 of the first transformer T1 is respectively connected to a second end of the primary coil 201 of the second transformer T2, the source of the seventh switch M7, and the drain of the eighth switch M8. The drain of the fifth switch M5 and the drain of the seventh switch M7 are connected to the second fuse B2. The source of the sixth switch M6 is connected to the source of the eighth switch M8.

[0059] Among them, the switching elements and switching tubes in this example both refer to controllable switches with opening and closing functions; the switching elements can be relays, thyristors, etc., and the switching tubes can be MOS tubes, triodes, IGBTs (Insulated Gate Bipolar Transistors), etc. This embodiment does not make specific limitations on this.

[0060] It should be noted that when the switching element or switch tube in the voltage converter 20 is used to cut off the charge and discharge circuit between the battery 100 and the device powered by the battery 100 through the voltage converter 20, the charge and discharge circuit between the battery 100 and the device powered by the battery 100 through the voltage converter 20 can be cut off by controlling the switch element K1 to be disconnected, or controlling the first switch tube M1, the second switch tube M2, the third switch tube M3 and the fourth switch tube M4 to be disconnected, or controlling the fifth switch tube M5, the sixth switch tube M6, the seventh switch tube M7 and the eighth switch tube M8 to be disconnected.

[0061] Based on the above first embodiment, a second embodiment of the battery management system of the present utility model is proposed. In the second embodiment, please refer to Figure 7 The battery management system may further include a trip unit A1; the control end of the trip unit A1 is connected to the control module 10, the first trip end of the trip unit A1 is connected to the battery 100 managed by the battery management system, and the second trip end of the trip unit A1 is connected to the voltage converter 20; the trip unit A1 is used to cut off the input and output circuits between the battery 100 and the voltage converter 20.

[0062] It should be noted that trip unit A1 is a device mechanically connected to the circuit breaker. Its primary function is to release the retaining mechanism and automatically disconnect the circuit breaker. Trip unit A1 can be a shunt trip unit, an electromagnetic trip unit, or another type of trip unit, and this embodiment does not specifically limit this.

[0063] Among them, when the release A1 is a shunt release, its working principle for cutting off the input and output circuit between the battery 100 and the voltage converter 20 is as follows: when it is necessary to cut off the input and output circuit between the battery 100 and the voltage converter 20, the electromagnetic coil of the shunt release (i.e. Figure 6 A set voltage will be applied to a1 in the circuit to generate electromagnetic force to attract the armature, thereby driving the free tripping mechanism (i.e. Figure 6 a2) connected to the transmission mechanism (ie Figure 6 a3) in the figure is activated to push the free tripping mechanism in the shunt release to release the main contacts, so that the main contacts are disconnected, thereby cutting off the input and output circuit between the battery 100 and the voltage converter 20. The battery 100 no longer inputs and outputs electrical signals to and from the voltage converter 20.

[0064] It is understandable that the first embodiment described above essentially disconnects the charge and discharge circuits between the battery 100 managed by the battery management system and the device powered by the battery 100 through the voltage converter 20 by disconnecting the input and output circuits between the voltage converter 20 and the device. However, the input and output circuits between the battery 100 and the voltage converter 20 are not disconnected, so the battery 100 continues to transmit and receive electrical signals with the voltage converter 20, which poses certain safety risks to the battery management system. Therefore, this embodiment provides a trip device A1 in the battery management system that can disconnect the input and output circuits between the battery 100 and the voltage converter 20. This physically isolates the battery 100 and the voltage converter 20, completely blocking the transmission of electrical signals between the battery 100 and the voltage converter 20, thereby eliminating potential safety risks and improving the safety of the battery management system.

[0065] In other embodiments, the trip unit A1 may also be installed on the chassis where the battery management system is located, so that the user can manually trigger the free tripping mechanism of the trip unit A1 to disconnect, thereby cutting off the input and output circuits between the battery 100 and the voltage converter 20 .

[0066] Based on the above first embodiment and / or second embodiment, a third embodiment of the battery management system of the present utility model is proposed. In the third embodiment, please refer to Figure 8 The battery management system may further include a battery voltage acquisition module 40, a battery temperature acquisition module 50, and a battery current acquisition module 60; the sampling ends of the battery voltage acquisition module 40, the sampling ends of the battery temperature acquisition module 50, and the sampling ends of the battery current acquisition module 60 are connected to the battery 100, and the output ends of the battery voltage acquisition module 40, the output ends of the battery temperature acquisition module 50, and the output ends of the battery current acquisition module 60 are connected to the input end of the control module 10.

[0067] It should be noted that the battery voltage acquisition module 40 is used to acquire the real-time voltage value of the battery 100. The battery voltage acquisition module 40 may be a voltage sensor, a sampling resistor, or other device capable of acquiring voltage. The battery temperature acquisition module 50 is used to acquire the real-time temperature value of the battery 100. The battery temperature acquisition module 50 may be a temperature sensor or other device capable of acquiring temperature. The battery current acquisition module 60 is used to acquire the real-time current value of the battery 100. The battery current acquisition module 60 may be a current sensor, a sampling resistor, or other device capable of acquiring current. This embodiment does not specifically limit the structures of the battery voltage acquisition module 40, the battery temperature acquisition module 50, and the battery current acquisition module 60.

[0068] The present invention also provides an energy storage device, comprising a chassis, a battery 100, and the aforementioned battery management system. The battery 100 and the battery management system are both mounted within the chassis, and the battery management system is connected to the battery 100. The structure of the battery management system can be referenced from the aforementioned embodiments and will not be further described here. As the energy storage device of this embodiment incorporates all the technical solutions of all the aforementioned battery management system embodiments and achieves the same technical effects, further description will not be given here.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A battery management system, characterized in that: The battery management system includes: Control module; a voltage converter, wherein a first input terminal of the voltage converter is connected to a first output terminal of the control module; A dry node module, which is connected between the second output end of the control module and the second input end of the voltage converter, and is used to turn off the charging and discharging function of the voltage converter to cut off the charging and discharging circuit between the battery managed by the battery management system and the device powered by the battery through the voltage converter.

2. The battery management system according to claim 1, wherein: The dry node module is a relay; One end of the relay is connected to the second output end of the control module, and the other end of the relay is connected to the second input end of the voltage converter.

3. The battery management system according to claim 1, wherein: The battery management system further includes a trip unit; The control end of the trip unit is connected to the control module, the first trip end of the trip unit is connected to the battery managed by the battery management system, and the second trip end of the trip unit is connected to the voltage converter; The trip device is used to cut off the input and output circuit between the battery and the voltage converter.

4. The battery management system according to claim 1, wherein: The battery management system further includes a trip unit; The trip unit is mounted on the chassis where the battery management system is located, and is used to cut off the input and output circuits between the battery and the voltage converter.

5. The battery management system according to claim 3 or 4, characterized in that: The release is a shunt release.

6. The battery management system according to any one of claims 1 to 4, characterized in that: The battery management system also includes a battery voltage acquisition module, a battery temperature acquisition module and a battery current acquisition module; The sampling end of the battery voltage acquisition module, the sampling end of the battery temperature acquisition module, and the sampling end of the battery current acquisition module are connected to the battery, and the output end of the battery voltage acquisition module, the output end of the battery temperature acquisition module, and the output end of the battery current acquisition module are connected to the input end of the control module.

7. The battery management system according to claim 6, characterized in that: The battery voltage acquisition module is a voltage sensor, the battery temperature acquisition module is a temperature sensor, and the battery current acquisition module is a current sensor.

8. The battery management system according to any one of claims 1 to 4, characterized in that: The voltage converter includes a high voltage input and output unit, a low voltage input and output unit, a capacitor, an inductor, a first transformer and a second transformer; The high-voltage input-output unit is connected to one end of the capacitor, the other end of the capacitor is connected to one end of the inductor, the other end of the inductor is connected to the first end of the secondary coil of the first transformer, the second end of the secondary coil of the first transformer is connected to the first end of the secondary coil of the second transformer, and the second end of the secondary coil of the second transformer is connected to the high-voltage input-output unit; The first end of the primary coil of the first transformer is respectively connected to the first end of the primary coil of the second transformer and the low-voltage input and output unit, and the second end of the primary coil of the first transformer is respectively connected to the second end of the primary coil of the second transformer and the low-voltage input and output unit.

9. The battery management system according to claim 8, characterized in that: The high-voltage input-output unit includes a switch element, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and a first fuse; the low-voltage input-output unit includes a fifth switch tube, a sixth switch tube, a seventh switch tube, an eighth switch tube and a second fuse; One end of the switching element is connected to the first fuse, the other end of the switching element is respectively connected to the drain of the first switching tube and the drain of the second switching tube, the source of the second switching tube is respectively connected to the drain of the third switching tube and one end of the capacitor, the source of the first switching tube is respectively connected to the second end of the secondary coil of the second transformer and the drain of the fourth switching tube, and the source of the third switching tube is connected to the source of the fourth switching tube; The first end of the primary coil of the first transformer is respectively connected to the first end of the primary coil of the second transformer, the source of the fifth switching tube, and the drain of the sixth switching tube; the second end of the primary coil of the first transformer is respectively connected to the second end of the primary coil of the second transformer, the source of the seventh switching tube, and the drain of the eighth switching tube; the drain of the fifth switching tube and the drain of the seventh switching tube are connected to the second fuse; and the source of the sixth switching tube is connected to the source of the eighth switching tube.

10. An energy storage device, characterized in that: The energy storage device includes a chassis, a battery, and a battery management system according to any one of claims 1 to 9; the battery and the battery management system are both installed in the chassis, and the battery management system is connected to the battery.

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