Vehicle low-voltage lithium battery protection system

Abstract

The invention discloses a low-voltage lithium battery protection system for a vehicle. The low-voltage lithium battery protection system comprises a battery cell module, a PCB adapter plate, a battery management module, a first connector, a flexible flat cable FFC and a second connector, the battery cell module comprises a plurality of single battery cells which are connected in series or in parallel, and the battery cell module is welded to the PCB adapter plate through battery cell tabs extending from the single battery cells; and the PCB adapter plate is connected with the battery management module through the first connector, the flexible flat cable FFC and the second connector. According to the system, accurate acquisition and stable transmission of battery temperature, voltage and current signals are realized, the accuracy of battery state analysis and the effectiveness of protection decision are ensured, and meanwhile, the overall safety and maintainability of the system are improved.

Description

Technical Field

[0001] The present invention relates to the field of low-voltage lithium batteries for vehicles, and more specifically to a low-voltage lithium battery protection system for vehicles. Background Art

[0002] With the rapid development of new energy vehicles and intelligent driving technologies, low-voltage lithium battery systems are increasingly widely used in the field of on-vehicle low-voltage power supply due to their advantages such as high energy density and long cycle life. However, the safety, stability, and life management of lithium batteries highly depend on the performance of the battery management system. Especially in complex on-vehicle working conditions, the high-precision monitoring, dynamic balancing, and multi-level safety protection of battery states have become the core technical challenges.

[0003] In the prior art, the battery module and the battery management system are usually connected by means of a flexible printed circuit board (FPC) plus a busbar, which has problems such as a long design cycle, complex processing technology, and high mold cost, resulting in high production costs. This method has extremely high requirements for the welding process, is prone to solder joint voids, affects the product quality stability, and is difficult to achieve short-term and efficient delivery during mass production. More critically, the FPC solution lacks compatibility after design changes. Once the design scheme is adjusted, it is necessary to re-design and manufacture, further increasing the time and cost burden.

[0004] Secondly, traditional low-voltage lithium battery protection systems mostly adopt a discrete sensor layout and ordinary cable connections, which have technical bottlenecks. For example, temperature detection usually relies on a single or a small number of thermistors, making it difficult to comprehensively capture the temperature distribution characteristics of the battery cell module, resulting in a lag in thermal runaway warning; the temperature drift effect of ordinary resistors in the voltage acquisition circuit will introduce measurement errors, affecting the accuracy of state-of-charge estimation. Moreover, traditional connectors are prone to poor contact due to vibration, and signal transmission is susceptible to electromagnetic interference, resulting in insufficient stability in the on-vehicle environment.

[0005] In addition, the balancing strategies of existing battery management modules mostly adopt fixed threshold triggering or passive balancing modes, which cannot dynamically adjust the priority according to the real-time state of the battery cells, resulting in low balancing efficiency and accelerated deterioration of battery cell consistency. At the same time, the protection mechanism often adopts a single threshold turn-off logic, lacking the ability of hierarchical response, being prone to false triggering due to instantaneous interference or delayed response in extreme working conditions, increasing the risk of battery overcharge / overdischarge.

[0006] Therefore, how to design a low-voltage lithium battery protection system for vehicles to achieve comprehensive acquisition of relevant parameters, improve the anti-interference ability and connection reliability of the signal transmission link, and then achieve intelligent dynamic management and multi-level safety protection is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a low-voltage lithium battery protection system for vehicles. By integrating high-precision sensors, adopting a highly reliable connection architecture and anti-interference design, and implementing intelligent dynamic management and multi-level safety protection strategies, it realizes the accurate acquisition and stable transmission of battery temperature, voltage, and current signals, ensures the accuracy of battery state analysis and the effectiveness of protection decisions, and at the same time improves the overall safety and maintainability of the system.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The present invention provides a low-voltage lithium battery protection system for vehicles, including: a battery cell module, a PCB adapter board, a battery management module, a first connector, a flexible flat cable FFC, and a second connector;

[0010] The battery cell module includes a plurality of series-connected or parallel-connected single battery cells, which are welded to the PCB adapter board through the battery cell tabs extended from the single battery cells;

[0011] The PCB adapter board is connected to the battery management module through the first connector, the flexible flat cable FFC, and the second connector.

[0012] Preferably, first thermistors, second thermistors, third thermistors, and fourth thermistors are symmetrically arranged in the four corner regions of the PCB adapter board for collecting the temperature signals of the battery cell module.

[0013] Preferably, the PCB adapter board is provided with a voltage dividing circuit for collecting the voltage signals of the battery cell module; the voltage dividing circuit includes voltage dividing resistors, and the voltage dividing resistors adopt low-temperature-drift metal film resistors.

[0014] Preferably, the PCB adapter board is provided with a Hall current sensor for collecting the current signals of the battery cell module; the Hall current sensor adopts a closed-loop Hall sensor and supports a multi-threshold trigger mechanism, including a warning threshold and an emergency shutdown threshold.

[0015] Preferably, the flexible flat cable FFC is composed of copper foil conductors and upper and lower layers of polyester insulating materials; the copper foil conductors are arranged in parallel and at regular intervals, and both ends are stamped into flat plugs with guiding protrusions.

[0016] Preferably, the first connector and the second connector adopt an anti-misinsertion structure, are provided with an elastic terminal array, and form full-area contact with the flat plugs at both ends of the flexible flat cable FFC through a vertical crimping method.

[0017] Preferably, the battery management module includes:

[0018] Data acquisition and processing unit: It is used to receive voltage, current and temperature signals from the voltage dividing circuit, Hall current sensor and thermistor, and perform signal denoising and calibration through digital filtering algorithms;

[0019] Dynamic equalization control unit: It is used to analyze the state of charge of individual battery cells in real time through the dynamic priority allocation algorithm, generate equalization instructions and perform current equalization operations;

[0020] Multi-level protection decision-making unit: It is used to determine early warning, current limiting or hardware shutdown actions according to the preset voltage, current and temperature thresholds, combined with the time-sharing trigger logic, and output control signals to the battery cell module and external load;

[0021] Communication interface unit: It is used to support two-way data interaction with the vehicle control system, and transmit battery status, fault codes and system configuration parameters;

[0022] Fault diagnosis and storage unit: It is used to monitor the operating status of each functional unit in real time, record historical fault information in the non-volatile memory, and generate readable alarm signals.

[0023] Preferably, in the dynamic equalization control unit, performing the current equalization operation includes:

[0024] Dynamically allocate equalization priorities according to the voltage deviation and temperature difference of individual battery cells, and use pulse width modulation (PWM) to control the equalization current, and activate the equalization operation in stages at the end of charging and the beginning of discharging.

[0025] Preferably, in the multi-level protection decision-making unit, the time-sharing trigger logic includes:

[0026] First-level protection: When the current exceeds the early warning threshold, trigger the current limiting instruction and send an early warning signal to the communication interface unit;

[0027] Second-level protection: When the current continuously exceeds the emergency shutdown threshold or the temperature is abnormal, directly cut off the main circuit MOSFET;

[0028] Third-level protection: When a serious voltage imbalance or individual fault is detected, start the system-level isolation protection.

[0029] Preferably, the fault diagnosis and storage unit supports classified storage of fault codes, including:

[0030] Sensor failure, communication interruption, equalization timeout, overvoltage / undervoltage, over-temperature / low-temperature fault types;

[0031] Timestamp, environmental parameters and associated battery cell numbers at the time of fault occurrence.

[0032] Through the above technical solutions, compared with the prior art, the technical solutions of the present invention have the following

[0033] Beneficial effects:

[0034] 1. The system integrates a symmetrically distributed four-thermistor network, low-temperature-drift voltage-dividing resistors, and a closed-loop Hall current sensor through a PCB adapter board, achieving precise acquisition of temperature, voltage, and current signals. Multi-dimensional high-precision sensing provides a reliable data basis for battery state analysis, ensuring the accuracy of protection decisions.

[0035] 2. Adopting a combined solution of FFC cables and anti-misplugging connectors, the regular arrangement of copper foil conductors reduces signal crosstalk, and the polyester insulation layer enhances the anti-electromagnetic interference ability. The elastic terminal array of the connector achieves full-area contact through vertical crimping, reducing contact resistance and plugging and unplugging losses compared with traditional plugging methods, and the anti-misplugging structure avoids installation errors. It ensures the stability of signal transmission in a complex vehicle vibration environment and simplifies the modular maintenance process at the same time.

[0036] 3. The battery management module realizes refined control through a dynamic priority balancing algorithm and time-sharing trigger protection logic. The dynamic balancing unit adjusts the PWM balancing strategy in real time according to the voltage / temperature differences of the battery cells, actively balances the states of the battery cells at the key stages of charging and discharging, and delays capacity decay. The multi-level protection adopts a progressive response mechanism, which progresses layer by layer from warning, current limiting to hardware shutdown, avoiding mis-triggering and ensuring fast isolation in extreme cases. It significantly improves the system safety and maintainability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0038] Figure 1 Structural schematic diagram of a vehicle low-voltage lithium battery protection system provided by an embodiment of the present invention;

[0039] Figure 2 Structural schematic diagram of the PCB adapter board provided by an embodiment of the present invention;

[0040] Figure 3 Connection schematic diagram of the connector and the flexible flat cable FFC provided by an embodiment of the present invention;

[0041] Figure 4 Structural schematic diagram of the flexible flat cable FFC provided by an embodiment of the present invention;

[0042] Figure 5 Framework diagram of the battery management module provided by an embodiment of the present invention;

[0043] In the figure, 1 - battery cell module, 2 - PCB adapter board, 3 - battery management module, 4 - first connector, 5 - flexible flat cable FFC, 6 - second connector, 7 - battery cell tab; 11 - first thermistor, 12 - second thermistor, 13 - third thermistor, 14 - fourth thermistor, 21 - voltage dividing circuit, 31 - Hall current sensor, 41 - positive copper busbar, 42 - negative copper busbar; 3a - data acquisition and processing unit, 3b - dynamic equalization control unit, 3c - multi - level protection decision - making unit, 3d - communication interface unit, 3e - fault diagnosis and storage unit. Specific embodiments

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0045] As Figure 1 shown, this embodiment provides a vehicle - used low - voltage lithium - battery protection system, including: a battery cell module 1, a PCB adapter board 2, a battery management module 3, a first connector 4, a flexible flat cable FFC 5, and a second connector 6;

[0046] The battery cell module 1 includes a plurality of series - connected or parallel - connected single battery cells, and the battery cell tabs 7 extended from the single battery cells are welded to the PCB adapter board 2;

[0047] The PCB adapter board 2 is connected to the battery management module 3 through the first connector 4, the flexible flat cable FFC 5, and the second connector 6.

[0048] Here, the battery cell module 1 is directly welded to the PCB adapter board 2 through the battery cell tabs 7 to form a stable electrical connection, avoiding the risk of loosening in traditional wire welding. Through the modular design of the first connector 4, FFC 5, and the second connector 6, the detachable connection between the battery management module 3 and the battery cell module is realized, which is convenient for later maintenance or upgrade. This architecture reduces the assembly complexity while ensuring the reliability of signal transmission, and is especially suitable for vehicle - used low - voltage scenarios with limited space.

[0049] The following further details each structure of the above - mentioned system:

[0050] As Figure 2 shown, in this embodiment, the first thermistor 11, the second thermistor 12, the third thermistor 13, and the fourth thermistor 14 are symmetrically arranged in the four - corner areas of the PCB adapter board 2 to collect the temperature signals of the battery cell module 1.

[0051] The PCB adapter board 2 is provided with a voltage divider circuit 21 for collecting the voltage signal of the battery module 1; the voltage divider circuit includes a voltage divider resistor, and the voltage divider resistor is a low-temperature drift metal film resistor.

[0052] In addition, the PCB adapter board 2 is provided with a Hall current sensor 31 for collecting the current signal of the battery module 1; the Hall current sensor 31 adopts a closed-loop Hall sensor and supports a multi-threshold trigger mechanism, including a warning threshold and an emergency shutdown threshold.

[0053] The PCB adapter board 2 is also provided with a positive copper bus 41 and a negative copper bus 42, which are respectively connected to the positive and negative electrodes of the battery for efficient and stable current transmission. They are made of pure copper material with high conductivity to ensure low resistance and minimum energy loss.

[0054] In this embodiment, the PCB adapter board 2 realizes all-round temperature monitoring of the battery module 1 through the thermistors symmetrically arranged at the four corners, covering the edge and center areas of the battery module, avoiding the local blind area problem of traditional single-point temperature measurement. The thermistor adopts high-precision NTC components, and cooperates with the copper-based heat dissipation design of the PCB adapter board 2 to quickly respond to temperature changes and ensure that the temperature acquisition error is ≤±1°C. In addition, the voltage divider circuit 21 adopts low-temperature drift metal film resistors, and its voltage divider ratio remains stable over the entire temperature range. Combined with differential sampling technology, the voltage acquisition accuracy can reach ±0.1%, which significantly improves the voltage monitoring reliability of the battery module 1.

[0055] The Hall current sensor 31 adopts a closed-loop design and a built-in magnetic balance feedback circuit, which can compensate for external magnetic field interference in real time. Its multi-threshold trigger mechanism supports dynamic adjustment of the warning threshold (such as 120% of the rated current) and the emergency shutdown threshold (such as 150% of the rated current), and achieves fast response through a hardware comparator. It not only improves the accuracy and anti-interference ability of current monitoring, but also effectively avoids the risk of battery damage caused by overcurrent or short circuit through a graded protection mechanism.

[0056] Further, such as Figure 3 As shown, the first connector 4 and the second connector 6 adopt an anti-misinsertion structure; they are both provided with an elastic terminal array 41, which forms full-area contact with the flat plugs at both ends of the flexible flat cable FFC5 by vertical crimping; and the copper foil wires are arranged in parallel and at regular intervals, and the two ends are stamped into flat plugs with guide protrusions.

[0057] Further, such as Figure 4 As shown, a single flexible flat cable FFC5 is composed of a copper foil conductor 51 and two layers of upper and lower polyester insulating materials 52 .

[0058] In this embodiment, the flexible flat cable FFC5 uses high-purity copper foil conductors with a conductor spacing designed to be 0.5 mm. The parallel arrangement effectively reduces signal crosstalk and ensures the stability of signal transmission. The thickness of the upper and lower layers of polyester insulating materials is 0.1 mm, which has excellent high-temperature resistance and anti-aging performance, meeting the stringent requirements of the in-vehicle environment. The guiding protrusions formed by stamping at both ends of the flat plug adopt a trapezoidal structure, which precisely matches the bevel angle of the connector slot, ensuring self-alignment during insertion and reducing problems such as pin bending or poor contact caused by assembly deviation.

[0059] In addition, the first connector 4 and the second connector 6 adopt an anti-misinsertion structure. Through the asymmetric card slot design, it is ensured that the FFC5 can only be inserted unidirectionally, avoiding the risk of signal polarity error or short circuit caused by reverse insertion. The elastic terminal array is made of beryllium copper, and the contact points are gold-plated. When vertically crimped, a constant contact pressure is generated through elastic deformation, and the contact resistance ≤ 5 mΩ, ensuring low loss and high reliability of signal transmission.

[0060] The battery management module 3 in this embodiment, as Figure 5 shown, includes:

[0061] Data acquisition and processing unit 3a: used to receive voltage, current, and temperature signals from the voltage division circuit 21, Hall current sensor 31, and thermistor, and perform signal denoising and calibration through digital filtering algorithms;

[0062] Dynamic equalization control unit 3b: used to analyze the state of charge of individual battery cells in real time through a dynamic priority allocation algorithm, generate equalization instructions, and perform current equalization operations; specifically, performing current equalization operations includes:

[0063] Dynamically allocate equalization priorities according to the voltage deviation and temperature difference of individual battery cells, and use pulse width modulation PWM to control the equalization current, and activate the equalization operation in stages at the end of charging and the beginning of discharging.

[0064] Multi-level protection decision-making unit 3c: used to determine warning, current limiting, or hardware shutdown actions according to preset voltage, current, and temperature thresholds, combined with time-sharing trigger logic, and output control signals to the battery cell module 1 and external loads; the time-sharing trigger logic includes:

[0065] Primary protection: When the current exceeds the warning threshold, trigger a current limiting instruction and send a warning signal to the communication interface unit 3d; Secondary protection: When the current continuously exceeds the emergency shutdown threshold or the temperature is abnormal, directly cut off the main circuit MOSFET; Tertiary protection: When a serious voltage imbalance or individual failure is detected, start the system-level isolation protection.

[0066] Communication interface unit 3d: used to support two-way data interaction with the vehicle control system, and transmit battery status, fault codes, and system configuration parameters;

[0067] Fault diagnosis and storage unit 3e: It is used to monitor the operating status of each functional unit in real time, record historical fault information into a non-volatile memory, and generate a readable alarm signal. It supports classified storage of fault codes, including: sensor failure, communication interruption, equalization timeout, overvoltage / undervoltage, over-temperature / under-temperature fault types; timestamp, environmental parameters and associated cell numbers at the time of fault occurrence.

[0068] In this embodiment, the data acquisition and processing unit of the battery management module collects data through an integrated voltage-dividing circuit, a Hall current sensor and a thermistor, and uses a digital filtering algorithm to denoise and calibrate voltage, current and temperature signals, ensuring the high precision of the input data. The dynamic equalization control unit adopts a dynamic priority allocation algorithm, adjusts the equalization strategy in real time based on the voltage deviation and temperature difference of individual cells, and activates the equalization operation through PWM technology in the late charging stage and the early discharging stage, effectively delaying the battery capacity attenuation and improving the overall service life of the battery pack.

[0069] The multi-level protection decision unit executes hierarchical responses from early warning to emergency shutdown according to preset voltage, current and temperature thresholds, combined with time-sharing trigger logic, ensuring that the system can take appropriate measures quickly in case of anomalies. The communication interface unit realizes two-way data interaction with the vehicle control system, facilitating the monitoring of the battery status and timely adjustment of operating parameters; the fault diagnosis and storage unit records detailed fault information, including types, timestamps and environmental parameters, etc., providing a basis for subsequent analysis and enhancing the maintainability and safety of the system. These designs jointly improve the reliability and adaptability of the battery management system in a complex vehicle-mounted environment.

[0070] Furthermore, the working principle of the above vehicle low-voltage lithium battery protection system is as follows:

[0071] This system collects the temperature, voltage and current signals of the cell module 1 in real time through the thermistor, voltage-dividing circuit and closed-loop Hall current sensor on the PCB adapter board 2. The collected analog signals are transmitted to the data acquisition and processing unit 3a of the battery management module 3 through the flexible flat cable FFC5, and are denoised and calibrated through a digital filtering algorithm to generate high-precision digital signals. The dynamic equalization control unit 3b analyzes the voltage deviation and temperature difference of individual cells based on the calibrated data, dynamically allocates equalization priorities, and activates PWM equalization operations in stages in the late charging stage (SOC>95%) and the early discharging stage (SOC<10%), and actively discharges or charges high-voltage or low-voltage cells through equalization resistors, thereby improving cell consistency and delaying battery capacity attenuation.

[0072] The multi-level protection decision-making unit 3c polls the voltage, current, and temperature threshold status at a cycle of 10 ms. When the current exceeds the warning threshold, the first-level current limiting protection is triggered and a warning signal is sent; if the abnormality persists or the temperature exceeds the limit, the second-level protection is activated to directly cut off the main circuit MOSFET; when the detected voltage difference > 500 mV or a single cell fails, the third-level protection is activated to cut off the total positive / negative relay to achieve system-level isolation. At the same time, the fault diagnosis and storage unit 3e records the fault type, timestamp, environmental parameters, and associated cell numbers in the FRAM memory in real time, and interacts with the vehicle control system through the communication interface unit 3d to support remote fault diagnosis and parameter configuration, ensuring the reliable operation and rapid maintenance of the system under complex working conditions.

[0073] The embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method part.

[0074] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-voltage lithium battery protection system for vehicles, characterized in that, Comprising: a battery cell module (1), a PCB adapter board (2), a battery management module (3), a first connector (4), a flexible flat cable FFC (5), and a second connector (6); The battery cell module (1) includes a plurality of series - connected or parallel - connected single battery cells, which are welded to the PCB adapter board (2) through battery cell tabs (7) extending from the single battery cells; The PCB adapter board (2) is connected to the battery management module (3) through the first connector (4), the flexible flat cable FFC (5), and the second connector (6).

2. The vehicle low-voltage lithium battery protection system according to claim 1, wherein, Four - corner regions of the PCB adapter board (2) are symmetrically provided with a first thermistor (11), a second thermistor (12), a third thermistor (13), and a fourth thermistor (14) for collecting temperature signals of the battery cell module (1).

3. The vehicle low-voltage lithium battery protection system according to claim 1, wherein, The PCB adapter board (2) is provided with a voltage - dividing circuit (21) for collecting voltage signals of the battery cell module (1); the voltage - dividing circuit includes voltage - dividing resistors, and the voltage - dividing resistors adopt low - temperature - drift metal - film resistors.

4. A vehicle low-voltage lithium battery protection system according to claim 1, characterized in that, The PCB adapter board (2) is provided with a Hall current sensor (31) for collecting current signals of the battery cell module (1); the Hall current sensor (31) adopts a closed - loop Hall sensor, supports a multi - threshold trigger mechanism, including a warning threshold and an emergency shutdown threshold.

5. A low-voltage lithium battery protection system for vehicles according to claim 1, characterized in that, The flexible flat cable FFC (5) is composed of copper - foil conductors and upper and lower layers of polyester insulating materials; the copper - foil conductors are arranged in parallel and at regular intervals, and both ends are stamped into flat plugs with guiding protrusions.

6. The vehicle low-voltage lithium battery protection system according to claim 1, characterized in that, The first connector (4) and the second connector (6) adopt an anti - misplugging structure, are provided with an elastic terminal array, and form full - area contact with the flat plugs at both ends of the flexible flat cable FFC (5) through a vertical crimping method.

7. A low-voltage lithium battery protection system for vehicles according to claim 1, characterized in that, The battery management module (3) includes: A data acquisition and processing unit (3a): for receiving voltage, current, and temperature signals from the voltage - dividing circuit (21), the Hall current sensor (31), and the thermistors, and performing signal denoising and calibration through a digital filtering algorithm; A dynamic equalization control unit (3b): for analyzing the state of charge of single battery cells in real time through a dynamic priority allocation algorithm, generating equalization instructions, and performing current equalization operations; A multi - level protection decision - making unit (3c): for determining warning, current - limiting, or hardware shutdown actions according to preset voltage, current, and temperature thresholds, combining time - sharing trigger logic, and outputting control signals to the battery cell module (1) and external loads; A communication interface unit (3d): for supporting two - way data interaction with a vehicle control system, and transmitting battery status, fault codes, and system configuration parameters; A fault diagnosis and storage unit (3e): for real - time monitoring of the operating states of each functional unit, recording historical fault information in a non - volatile memory, and generating readable alarm signals.

8. A low-voltage lithium battery protection system for vehicles according to claim 1, characterized in that, In the dynamic equalization control unit (3b), performing the current equalization operation includes: Dynamically allocating equalization priorities according to the voltage deviation and temperature difference of single battery cells, and using pulse - width modulation PWM to control the equalization current, and activating the equalization operation in stages at the end of charging and the beginning of discharging.

9. The vehicle low-voltage lithium battery protection system according to claim 1, characterized in that, In the multi - level protection decision - making unit (3c), the time - sharing trigger logic includes: Primary protection: When the current exceeds the warning threshold, trigger a current limiting instruction and send a warning signal to the communication interface unit (3d); Secondary protection: When the current continuously exceeds the emergency shutdown threshold or the temperature is abnormal, directly cut off the main circuit MOSFET; Tertiary protection: When a serious voltage imbalance or a single cell failure is detected, start the system-level isolation protection.

10. A low-voltage lithium battery protection system for vehicles according to claim 1, characterized in that, The fault diagnosis and storage unit (3e) supports classified storage of fault codes, including: Sensor failure, communication interruption, equalization timeout, overvoltage / undervoltage, over-temperature / under-temperature fault types; Timestamp, environmental parameters and associated cell numbers at the time of fault occurrence.

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