Protection device for battery management system and battery management system

Abstract

The utility model provides a protection device for a battery management system and the battery management system, the protection device comprises a first-stage protection module and a second-stage protection module, the first-stage protection module is a controllable switch assembly and is configured to cut off a battery loop based on an abnormal working signal of a battery, and the second-stage protection module is configured to cut off the battery loop based on the abnormal working signal of the battery. The abnormal working signals comprise a first type of abnormal working signals and a second type of abnormal working signals; the second-stage protection module comprises an active fuse and a passive fuse which are connected in series with each other, and when the first-stage protection module cannot work normally, the active fuse cuts off the battery loop based on the first type of abnormal working signals, and the passive fuse cuts off the battery loop based on the second type of abnormal working signals. And the passive fuse cuts off the battery loop based on the second type of abnormal working signals.

Description

Technical Field

[0001] This utility model belongs to the field of power electronics, and in particular relates to a protection device and a battery management system for a battery management system. Background Technology

[0002] The statements in this section are merely to provide background information related to this utility model to aid in understanding it, and this background information does not necessarily constitute prior art.

[0003] A Battery Management System (BMS) is an electronic system used to monitor and manage battery cells or battery packs. It typically performs functions such as voltage monitoring, current monitoring, temperature monitoring, battery equalization, charge / discharge control, state estimation, and fault detection. The main purpose of a BMS is to ensure that batteries operate under safe and efficient conditions, thereby extending battery life and maintaining battery performance, and improving battery safety, reliability, and efficiency. It is crucial for applications such as new energy vehicles, energy storage systems, and portable electronic devices.

[0004] The protection design of the Battery Management System (BMS) is crucial for ensuring the safe, stable, and efficient operation of the battery, and is an essential component of the BMS. When a battery cell or battery pack malfunctions (e.g., overcurrent, overvoltage, overheating, or short circuit), the BMS activates protection to cut off the circuit. For example, when the BMS detects that the battery charging voltage exceeds the rated value, it controls the shutdown of the charging MOSFET, thereby cutting off the charging circuit; when the BMS detects that the battery voltage drops below a safe threshold, it controls the shutdown of the discharging MOSFET, thereby cutting off the discharging circuit; when the BMS detects a short circuit in the battery, it controls the shutdown of the discharging MOSFET, thereby cutting off the discharging circuit. In specific applications such as new energy vehicles and energy storage systems, lithium batteries have large capacity and high power. To prevent serious consequences from failures, a dual protection design is usually adopted, i.e., adding a second level of protection. When the first level of protection fails to function properly, the second level of protection is activated. However, the second level of protection in existing BMS technologies requires active fuses with high breaking capacity and corresponding assembly kits, which are therefore expensive and bulky. Utility Model Content

[0005] Therefore, the purpose of this utility model is to overcome the defects of the prior art and provide a protection device for a battery management system, which includes a first-level protection module and a second-level protection module. The first-level protection module is a controllable switch assembly configured to cut off the battery circuit based on an abnormal operating signal of the battery. The abnormal operating signal includes a first type of abnormal operating signal and a second type of abnormal operating signal. The second-level protection module includes an active fuse and a passive fuse connected in series. When the first-level protection module fails to work properly, the active fuse cuts off the battery circuit based on the first type of abnormal operating signal, and the passive fuse cuts off the battery circuit based on the second type of abnormal operating signal.

[0006] According to the protection device of this utility model, preferably, the second type of abnormal working signal is that the current in the battery circuit exceeds a first preset current threshold.

[0007] According to the protection device of this utility model, preferably, the first type of abnormal working signal includes the current in the battery circuit exceeding a second preset current threshold but less than the first preset current threshold.

[0008] According to the protection device of this utility model, preferably, the first type of abnormal working signal also includes an overvoltage signal and an overtemperature signal.

[0009] According to the protection device of this utility model, preferably, the first preset current threshold is 3-7 times the second preset current threshold.

[0010] According to the protection device of this utility model, preferably, the active fuse and the passive fuse are surface mount devices.

[0011] According to the protection device of this utility model, preferably, the active fuse is a three-terminal fuse.

[0012] According to the protection device of this utility model, preferably, the controllable switch assembly is configured to be bidirectional, which selectively cuts off the battery discharge circuit and the battery charging circuit based on the abnormal operating signal.

[0013] According to the protection device of this utility model, preferably, the controllable switch assembly includes a discharge transistor and a charging transistor connected in reverse series, and the discharge transistor and the charging transistor are respectively connected in reverse parallel with diodes.

[0014] This utility model also provides a battery management system, which includes a microcontroller unit, a battery sampling unit, and a protection device according to this utility model, wherein the battery sampling unit is configured to collect battery operating parameters and provide them to the microcontroller unit, and the microcontroller unit provides an abnormal operation signal to the protection device based on the battery operating parameters.

[0015] Compared with existing technologies, the battery management system of this utility model is small in size, inexpensive, and easy to install. Attached Figure Description

[0016] The embodiments of this utility model will be further described below with reference to the accompanying drawings, wherein:

[0017] Figure 1 This is a schematic block diagram of a protection device for a battery management system according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic circuit topology of a first-level protection module for a protection device for a battery management system according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of a battery management system according to an embodiment of the present utility model;

[0020] Figure 4 This is a schematic comparative diagram of the components of a second-level protection module in a prior art protection device for a battery management system and the components of the second-level protection module in the present invention for a battery management system. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the scope of the present utility model.

[0022] This invention provides a protection device for a battery management system (BMS), comprising a first-level protection module and a second-level protection module. The first-level protection module is a controllable switch assembly configured to cut off the battery circuit based on abnormal operating signals from the battery. These abnormal operating signals include first-type and second-type abnormal operating signals. The second-level protection module includes an active fuse and a passive fuse connected in series. When the first-level protection module malfunctions, the active fuse cuts off the battery circuit based on the first-type abnormal operating signal, and the passive fuse cuts off the battery circuit based on the second-type abnormal operating signal. Since passive fuses typically function as short-circuit and overcurrent protectors, the short-circuit and overcurrent protection in this invention is handled by the passive fuse. This reduces the requirement for the breaking capacity of the active fuse (the maximum current that the fuse can safely interrupt at rated voltage), thus reducing the size and cost of the active fuse.

[0023] See Figure 1The diagram shown is a schematic block diagram of a protection device for a BMS according to an embodiment of the present invention. The protection device is connected in the battery circuit and includes a first-level protection module 1 and a second-level protection module 2 connected in series. The first-level protection module 1 is a transistor assembly, including at least one charging transistor and one discharging transistor. It disconnects the battery circuit based on abnormal operating signals (e.g., overvoltage signal, overcurrent signal, overheat signal, short circuit signal, etc.). For example, the charging transistor disconnects the battery charging circuit based on a battery overvoltage signal or a charging overcurrent signal, and the discharging transistor disconnects based on a discharging overcurrent signal, an overheat signal, or a short circuit signal. The battery discharge circuit is disconnected. The second-level protection unit 2 includes an active fuse 201 and a passive fuse 202 connected in series. When the battery management system detects an abnormal operating signal, if the first-level protection unit 1 of the BMS fails to function properly (e.g., a transistor assembly failure), the second-level protection unit 2 disconnects the battery circuit. The active fuse 201 actively disconnects based on a first type of abnormal operating signal (e.g., abnormal operating signals other than excessive current (e.g., greater than 1000A) or a short circuit), while the passive fuse 202 quickly melts for a second type of abnormal operating signal (excessive current or a short circuit). Thus, this invention does not require an active fuse with a strong breaking capacity.

[0024] In one embodiment of this utility model, the active fuse 201 is an intelligent fuse that monitors current, voltage, temperature, and other signals in the circuit in real time using built-in sensors (such as current sensors, voltage sensors, temperature sensors, etc.). When these signals exceed a set upper limit, the active fuse cuts off the circuit to achieve circuit protection. In another embodiment, the active fuse 201 is a three-terminal fuse, with its first and second terminals connected to the battery circuit, and the third terminal serving as a control terminal for receiving control signals from the control unit to cut off the circuit.

[0025] The passive fuse 202 of this invention is based on physical effects. When the current passing through the fuse exceeds its rated value, the fuse wire or fusible body inside the fuse melts due to overheating, thereby cutting off the circuit and providing protection. In this invention, a fast passive fuse is preferably used, such as a fuse using pure silver as the fusible element, which has strong breaking capacity and short breaking time.

[0026] According to another embodiment of this utility model, both the active fuse 201 and the passive fuse 202 adopt SMD packaging (Surface Mount Devices), which can be mounted on a printed circuit board (PCB). SMD packaging has high assembly density, small electronic product size, and light weight. The volume and weight of surface mount components are usually only about 1 / 10 of that of traditional through-hole components; it has high reliability, strong vibration resistance, and low solder joint defect rate; it has good high-frequency characteristics, reducing electromagnetic and radio frequency interference; it is easy to automate, improves production efficiency, and reduces costs by 30% to 50%.

[0027] See Figure 2 The schematic circuit topology of the first-level protection module 1 of the protection device for a BMS according to an embodiment of the present invention is shown. It includes a discharge transistor T1 and a charging transistor T2. The discharge transistor T1 is provided with a diode D1 connected in anti-parallel, and the charging transistor T2 is provided with a diode D2 connected in anti-parallel. The discharge transistor T1 and the charging transistor T2 are connected in reverse series. In the present invention, the reverse series connection of transistors means that the two transistors are connected back-to-back, for example, the sources of the two transistors are connected to each other (common-source structure) or the drains of the two transistors are connected to each other (common-drain structure, such as...). Figure 2 As shown in the diagram, in this configuration, when a forward voltage is applied, one transistor is turned on and the other is turned off; when a reverse voltage is applied, the roles of the on and off transistors are reversed; and the anti-parallel connection of the transistor and diode enables bidirectional current flow, for example in... Figure 2 In the structure shown, the anodes of diodes D1 and D2 are connected to the drains of transistors T1 and T2, respectively. When the transistors are off, the diodes are on. In this embodiment, when the discharge transistor T1 receives abnormal operating signals such as over-temperature or over-current, it turns off. At this time, the discharge circuit is cut off, and the charging circuit is turned on through the charging transistor T2 and diode D1. When the charging transistor T2 receives abnormal operating signals such as battery overvoltage, it turns off. At this time, the charging circuit is cut off, and the discharge circuit is turned on through the discharge transistor T1 and diode D2.

[0028] According to another embodiment of this utility model, the first-level protection module 1 of the protection device for the BMS is implemented using other controllable switching components capable of bidirectional conduction, which selectively disconnects the battery discharge circuit and the battery charging circuit based on the received abnormal operating signal. For example, the controllable switching component includes a first controllable switch and a second controllable switch, with the first controllable switch disposed in the battery discharge circuit and the second controllable switch disposed in the battery charging circuit. In this utility model, the controllable switch is any controllable switching element capable of being turned on / off according to a control signal, including MOSFETs, IGBTs, etc.

[0029] An embodiment of this utility model also provides a battery management system (BMS), see [link to relevant documentation]. Figure 3 The schematic diagram of the battery management system of this embodiment shown includes a microcontroller unit (MCU), a battery sampling unit (SU), and a battery sampling module (SU). Figure 1 The protection device shown provides the voltage of battery B to the power supply port. The positive terminal P+ of the power supply port is electrically connected to the positive terminal of battery B, and the negative terminal P- of the power supply port is electrically connected to the negative terminal of battery B through the protection device. The battery sampling unit SU collects battery operating parameters such as battery voltage V, temperature T, and current I and provides them to the microcontroller unit MCU. Based on the received battery operating parameters, the microcontroller unit MCU provides an abnormal operation signal to the protection device. Preferably, the microcontroller unit MCU compares the battery operating parameters with a preset threshold and provides a cut-off signal to the active fuse 201 of the first-level protection module 1 and the second-level protection module 2 of the protection device based on the comparison result. The specific details of the protection device are the same as those in the previous embodiment and will not be repeated here.

[0030] According to another embodiment of the present invention, the first-level protection module 1 of the protection device for BMS is disposed between the positive terminal P+ of the power supply port and the positive terminal of the battery B, while the second-level protection module 2 is disposed between the negative terminal P- of the power supply port and the negative terminal of the battery B, or vice versa.

[0031] According to another embodiment of this utility model, the active fuse 201 and passive fuse 202 of the second-level protection module 2 are located at different power supply ports. For example, the active fuse 201 is located between the positive terminal P+ of the power supply port and the positive terminal of battery B, while the passive fuse 202 is located between the negative terminal P- of the power supply port and the negative terminal of battery B, or vice versa. In either case, the active fuse 201 and the passive fuse 202 are connected in series in the battery circuit.

[0032] In one embodiment, the battery management system (BMS) includes a current sensor, a voltage sensor, and a temperature sensor. Current sensors, voltage sensors, and temperature sensors known in the art are all applicable to this invention and will not be described further here.

[0033] In another embodiment, the battery management system (BMS) also includes an analog front-end (AFE), an electrically erasable programmable read-only memory (EEPROM), a low-dropout linear regulator (LDO), and a backup unit (SPS). The analog front-end is a monitoring chip with multiple sampling channels that monitors the voltage and temperature of multi-stage series-connected cells in real time and supports battery balancing. The EEPROM is primarily used to store critical information related to the battery, such as configuration parameters, calibration data, and user settings. The low-dropout linear regulator is a key power management component that provides a stable output voltage while allowing for a small difference between the input and output voltages. The backup unit is a backup power supply or backup control unit used to ensure the safe and stable operation of the battery.

[0034] The battery management system of this invention employs a novel dual-protection design. Specifically, it utilizes a weaker breaking capacity active fuse and a stronger breaking capacity fast passive fuse to achieve a second level of protection. If the first-level protection module malfunctions, and the current in the battery circuit exceeds a first preset current threshold (e.g., 1000A), the stronger breaking capacity fast passive fuse melts to achieve the second level of protection. Conversely, if the current in the battery circuit exceeds a second preset current threshold (e.g., 150A-300A) but is less than the first preset current threshold, or the battery voltage exceeds a preset voltage threshold, or the temperature exceeds a preset temperature threshold, the weaker breaking capacity active fuse cuts off to achieve the second level of protection. The preset thresholds in this invention are set according to actual conditions. Specifically, the first preset current threshold is greater than the second preset current threshold; preferably, the first preset current threshold is 3-7 times the second preset current threshold.

[0035] This invention achieves secondary protection through a combination of active and passive fuses, eliminating the need for high-breaking-capacity active fuses. High-breaking-capacity active fuses are expensive and bulky, while the low-breaking-capacity active fuses used in this invention are inexpensive and compact. Therefore, the battery management system of this invention reduces cost and size. Furthermore, high-breaking-capacity active fuses require additional assembly kits and screws for installation, resulting in high volume and labor costs. In contrast, both the active and passive fuses in this invention utilize SMD packaging, allowing for mounting on a PCB, significantly saving on volume and labor costs.

[0036] To demonstrate the effectiveness of this invention, the inventors have provided a schematic comparative diagram of the components of a second-level protection module in a prior art protection device for a battery management system and the components of the second-level protection module in this invention's protection device for a battery management system, as shown below. Figure 4As shown in the figure, 401 is an active fuse with weak breaking capacity according to the present invention, 402 is a passive fuse with strong breaking capacity according to the present invention, 403 is a prior art active fuse with strong breaking capacity, and 404 is an assembly kit for a prior art active fuse. It is clearly seen from the figure that the volume of the combination of the active fuse with weak breaking capacity and the passive fuse with strong breaking capacity of the present invention is much smaller than the volume of the combination of the active fuse with strong breaking capacity and the assembly kit in the prior art. The volume of the second-level protection module in the prior art is approximately tens of times larger than the volume of the second-level protection module of the present invention.

[0037] Furthermore, the inventors compared the installation structure of the second-level protection module of the prior art with that of this invention. The second-level protection module of the prior art requires screws and assembly kits for fixing to the circuit. In contrast, the second-level protection module of this invention uses SMD packaging and is mounted on the PCB. Clearly, the second-level protection module of this invention is smaller and simpler to install.

[0038] In addition, the inventors compared the costs of the prior art's second-level protection module and the second-level protection module of this utility model, as shown in Table 1 below:

[0039] Table 1

[0040] Components Existing technology (RMB) This utility model (RMB) Cost reduction (RMB) Active fuse 70 8 62 Assembly kit / passive fuse 10 5 5 overall 80 13 67

[0041] As can be seen, the cost is reduced by 83.75% by adopting the design of this utility model.

[0042] Furthermore, for existing designs, it is difficult to find suitable active fuses and fuse assembly kits with high breaking capacity on the market. However, for the design of this invention, active fuses with low breaking capacity and fast-acting passive fuses are readily available on the market. The new design effectively solves supply chain issues.

[0043] Although the present invention has been described through preferred embodiments, the present invention is not limited to the embodiments described herein, and includes various changes and variations without departing from the scope of the present invention.

Claims

1. A protection device for a battery management system, characterized in that, The system includes a first-level protection module and a second-level protection module. The first-level protection module is a controllable switch assembly configured to cut off the battery circuit based on an abnormal operating signal from the battery. The abnormal operating signal includes a first type of abnormal operating signal and a second type of abnormal operating signal. The second-level protection module includes an active fuse and a passive fuse connected in series. When the first-level protection module fails to operate normally, the active fuse cuts off the battery circuit based on the first type of abnormal operating signal, and the passive fuse cuts off the battery circuit based on the second type of abnormal operating signal.

2. The protection device according to claim 1, characterized in that, The second type of abnormal operating signal is when the current in the battery circuit exceeds a first preset current threshold.

3. The protection device according to claim 2, characterized in that, The first type of abnormal operating signal includes the current in the battery circuit exceeding the second preset current threshold but being less than the first preset current threshold.

4. The protection device according to claim 3, characterized in that, The first type of abnormal operating signals also includes overvoltage signals and overtemperature signals.

5. The protection device according to claim 3, characterized in that, The first preset current threshold is 3 to 7 times the second preset current threshold.

6. The protective device according to any one of claims 1-5, characterized in that, The active fuse and the passive fuse are surface mount devices.

7. The protective device according to any one of claims 1-5, characterized in that, The active fuse is a three-terminal fuse.

8. The protective device according to any one of claims 1-5, characterized in that, The controllable switch assembly is configured for bidirectional conduction, selectively cutting off the battery discharge circuit and the battery charging circuit based on the abnormal operating signal.

9. The protection device according to claim 8, characterized in that, The controllable switching assembly includes a discharge transistor and a charging transistor connected in reverse series, and each of the discharge transistor and the charging transistor is connected in reverse parallel with a diode.

10. A battery management system, characterized in that, The device includes a microcontroller unit, a battery sampling unit, and a protection device according to any one of claims 1-9, wherein the battery sampling unit is configured to collect battery operating parameters and provide them to the microcontroller unit, and the microcontroller unit provides an abnormal operation signal to the protection device based on the battery operating parameters.

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