A battery pack monitoring and early warning method and system based on an optical fiber embedded intelligent busbar

Abstract

The application provides a battery pack monitoring and early warning method and system based on an optical fiber embedded intelligent busbar. The application takes a battery pack busbar as a structural carrier of a sensor, preopens a containing channel in a busbar matrix, realizes fine sensing and early warning of a battery pack state, arranges distributed sensing optical fibers horizontally along the containing channel of the busbar, and extends a vertical optical fiber probe at each electrode lug connection. The probe is close to the electrode surface, and the detection point covers at least the upper part of the electrode and the lower part of the electrode. If the upper part of the electrode is preferentially heated, it is determined that the contact resistance of the busbar connection is abnormal. If the lower part of the electrode is preferentially heated, it is determined that the internal thermal runaway of the battery cell is budding. The application realizes decoupling diagnosis of busbar connection abnormalities and battery internal faults by arranging the vertical dimension optical fiber probe at the battery electrode.

Description

Technical Field

[0001] This invention relates to the fields of fiber optic sensing technology and battery safety monitoring technology, and in particular to a battery pack monitoring and early warning method and system based on fiber optic embedded smart busbars. Background Technology

[0002] With the widespread application of high-nickel ternary and high-capacity lithium iron phosphate batteries, the energy density of power battery systems continues to rise, increasing the pressure to prevent thermal runaway. During charge-discharge cycles, batteries experience not only heat generation and transfer, but also lattice expansion due to lithium insertion / deintercalation of active materials, and internal pressure changes caused by gas production from side reactions. With the rapid development of the new energy vehicle industry, the safety of power battery systems is receiving increasing attention. Batteries generate a large amount of heat during charging and discharging; poor heat dissipation or internal short circuits can lead to thermal runaway, potentially causing fires in severe cases. Therefore, accurately capturing the changes in the internal physical state of the battery is crucial for early safety warnings and is of great significance for real-time monitoring and early warning of battery packs.

[0003] Traditional thermistors or thermocouples, due to size and wiring limitations, can only capture localized temperatures, resulting in significant spatial blind spots and making it difficult to detect minute localized overheating in multi-cell arrays. Furthermore, these electrical signal sensors are highly susceptible to electromagnetic interference in high-voltage, high-current electromagnetic environments, leading to false alarms or missed alarms.

[0004] To overcome the limitations of point-based measurements, distributed fiber optic sensing technology based on OFDR (Optical Frequency Domain Reflectometry) has emerged in recent years. A method for dynamic temperature monitoring of lithium batteries based on OFDR is disclosed, which constructs a two-dimensional temperature field by deploying sensing fibers laterally or longitudinally on the upper and lower surfaces and sides of the lithium battery pack. However, existing technologies still face the following challenges: Current fiber deployments are mostly located on the surface or within the battery pack layers, resulting in significant thermal resistance between the fiber and the core heat-generating area (electrode tabs), limiting the measurement response speed and making it difficult to detect transient temperature rises inside the battery in a timely manner. This approach, to obtain accurate temperature readings, explicitly requires strain shielding of the fiber, i.e., adding a capillary sleeve to the outside of the fiber and ensuring the fiber can slide freely within the sleeve to eliminate stress interference. However, in the field of battery safety, gas generation, expansion, and mechanical deformation (stress changes) caused by battery charging and discharging are often crucial early warning signs of thermal runaway. Existing strain shielding methods lose this critical dimension of early warning information. Laying out a complex fiber optic network (such as an S-shaped orientation) within the limited space of the battery pack not only increases the assembly complexity, but also exposes the fiber optics directly to the surface, making them extremely susceptible to damage under long-term vehicle vibration. Summary of the Invention

[0005] The purpose of this invention is to address the problems in existing technologies by proposing a battery pack monitoring and early warning method and system based on fiber optic embedded smart busbars. This invention achieves decoupled diagnosis of busbar connection anomalies and internal battery faults by deploying vertical fiber optic probes at the battery electrodes.

[0006] This invention is achieved through the following technical solution: A battery pack monitoring and early warning system based on an embedded fiber optic intelligent busbar is proposed. The system uses the battery pack busbar as the structural carrier for sensors, with pre-opened containment channels within the busbar substrate to achieve precise sensing and early warning of the battery pack's status. Distributed sensing optical fibers are horizontally laid along the containment channels of the busbar, with vertical fiber probes extending from each cell tab connection point. These probes are in close contact with the electrode surface, with detection points covering at least the upper and lower parts of the electrode. If the upper part of the electrode heats up first, it is determined that the contact resistance at the busbar connection is abnormal; if the lower part of the electrode heats up first, it is determined that thermal runaway is beginning inside the cell.

[0007] Furthermore, the sensing fiber extends along the busbar axis. When it passes each electrode connection point, the sensing fiber detaches from the horizontal channel of the busbar and is laid vertically downward along the side of the electrode to form a vertical detection loop covering the upper and lower parts of the electrode. Then it returns to the horizontal channel of the busbar to continue to the next cell.

[0008] Furthermore, the bus consists of a bus base, a single sensing optical fiber, and a flexible thermally conductive buffer material. During installation, an inwardly recessed receiving channel with a depth of 1.0 mm and a width of 0.8 mm is machined along the axial direction on the surface of the bus base. After the sensing optical fiber is installed at the bottom of the middle of the channel, it is filled with a flexible thermally conductive buffer material with high thermal conductivity.

[0009] Furthermore, at the electrode mating point, the sensing fiber is vertically fixed to the electrode surface using a precision dispensing process or a micro-structure; the total length of the probe segment is determined by the exposed height of the electrode, ensuring that the sensing fiber can simultaneously sense the temperature of the electrode root and the welding point.

[0010] This invention also proposes a battery pack monitoring and early warning method based on an optical fiber embedded smart busbar. The early warning method is implemented based on the aforementioned early warning system and includes: Step 1: The system uses a distributed fiber optic demodulator to initialize and calibrate the sensing fibers embedded inside the busbar and extending deep into the electrodes. Step 2: When the battery pack enters a charge / discharge cycle or an abnormal operating condition occurs, the sensing fiber inside the busbar will sense environmental disturbances in real time. Step 3: The sweeping laser inside the demodulator emits a continuous laser beam whose frequency changes linearly with time. It is split into test light and reference light by the optical splitter. The test light enters the sensing fiber in the embedded busbar and propagates forward along the line. Step 4: The data processing module inputs the spatiotemporally aligned data into the multidimensional feature evaluation model to obtain the judgment result.

[0011] Furthermore, in the first step, the system uses a linearly swept-frequency laser to generate an interference signal, performing centimeter-level spatial sampling along the sensing fiber; its physical spatial resolution... z is determined by the sweep bandwidth of the laser. F is determined, satisfying the formula:

[0012] Where c is the speed of light in vacuum and n is the refractive index of the optical fiber; by modulating the sweep bandwidth, the system ensures not only centimeter-level mapping along the busbar axis, but also precise depth calibration in the probe section perpendicular to the electrode direction; when the battery pack is in a static or thermal equilibrium state, the distributed demodulator acquires the initial Rayleigh scattering spectral information of each sampling point along the optical fiber as a reference spectrum; at this time, the frequency shift curve output by the system... Both v(x) and the phase signal acquired by the strain monitoring equipment exhibit smooth linear characteristics, without abrupt peaks or troughs, thus constructing a "physical reference field" for the normal operation of the battery pack.

[0013] Furthermore, in the second step, a physically isolated demodulation method is used to ensure signal purity; for the temperature sensing fiber embedded in the containment channel, its spectral frequency shift... v is only affected by thermal shrinkage; the system extracts the frequency shift by performing cross-correlation calculations on the measured spectrum and the reference spectrum, and calculates the real-time temperature change according to the following formula:

[0014] in The system measures the fiber temperature sensitivity coefficient; at each electrode connection point, the system synchronously acquires the temperature of the upper and lower parts of the electrode using vertical probes; for strain-sensitive fibers tightly coupled to the bus substrate, distributed acoustic sensing or dynamic strain gauges are used to capture the phase difference of light waves inside the fiber. .

[0015] Furthermore, in the third step, when the test light propagates to an anomaly point on the bus, the refractive index or physical length of the fiber changes at that point, causing the Rayleigh backscattered light generated at that location to carry frequency or phase shift information and return to the demodulator along the original path; the returning signal light carrying the anomaly information and the reference light undergo beat frequency interference inside the demodulator, and their interference intensity I satisfies:

[0016] The demodulator performs a fast Fourier transform on the interference signal, mapping the signal from the frequency domain to the time domain. Through sliding window cross-correlation analysis, it outputs a distributed temperature distribution map along the entire line, clarifying the physical state at a specific coordinate x. By performing sliding window cross-correlation analysis on the time domain signal, the demodulator finally outputs a fully distributed frequency shift / phase distribution map along the optical fiber. This clearly shows the degree of change that has occurred in the optical fiber at a specific coordinate x of the battery or busbar.

[0017] Furthermore, in the fourth step, the system extracts four key characteristic parameters in real time: absolute temperature T, temperature rise rate, etc. Space temperature gradient and hotspot scale ;Calculate the comprehensive risk index R based on the preset weighting coefficients:

[0018] Once the R value exceeds the safety threshold, the early warning mechanism is activated immediately.

[0019] Furthermore, in the fourth step, a step-by-step tracing and judgment process is performed according to the following logic: First-level judgment, i.e., absolute temperature control: First, the T value is evaluated; if the absolute temperature exceeds the extreme threshold, it is judged as a risk of thermal runaway, and the system directly outputs a power-off command to the BMS; Second-level judgment, i.e., dynamic characteristic coupling diagnosis: If the T value is normal, then the coupling analysis of temperature rise rate and spatial gradient is entered: High + High The system detects an abnormal reaction inside the battery; it invokes a vertical probe depth mapping algorithm: if the lower electrode heats up first, it indicates an internal cell fault; if the upper electrode heats up first, it indicates excessive contact resistance at the busbar connection, locking the cell number and triggering an alarm; +low Combining hot topic scale Determine; if This is a localized feature, identified as an increase in localized thermal resistance of the busbar; if The widespread distribution indicates excessively high ambient temperatures; the third-level assessment, or early hazard identification, is based on the temperature rise rate. Normal, but spatial gradient If the threshold is exceeded, it is determined to be an early local thermal resistance anomaly in the busbar; the system accurately locates the physical location of the fault and issues a maintenance warning.

[0020] The beneficial effects of this invention are: This invention achieves a leap from passive monitoring to structured intelligent diagnosis through "weighted evaluation + hierarchical logic". By determining the temperature rise sequence using vertical probes, it solves the industry pain point of untraceable heat sources, improving the early warning lead time to the minute level. This system not only improves the early warning lead time and positioning accuracy, but also supports a refined maintenance strategy of "precise disassembly and partial replacement", significantly enhancing the safety and economy of the battery pack throughout its entire lifecycle. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a battery pack monitoring and early warning system based on fiber optic embedded smart busbars. Figure 2 This is a schematic diagram showing an abnormal temperature zone in the battery pack. Figure 3 This is a cross-sectional view of the battery pack temperature and the ambient temperature gradient. Figure 4 This is a cross-sectional view of the battery pack's temperature rise rate. Figure 5 This is a structural diagram of an embedded busbar; Figure 6 This is a cross-sectional view of the probes arranged at the electrodes; Figure 7 A flowchart of a battery pack monitoring and early warning method based on fiber optic embedded smart busbar; The markings in the diagram are as follows: 1 is the distributed fiber optic sensing demodulation integrated chassis, 2 is the laid-out sensing fiber optic cable, 3 is the square battery connected via a busbar, 4 is the embedded busbar, 5 is the busbar substrate, 6 is the thermally conductive material, and 7 is the electrode. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The busbar, as a core electrical component connecting the tabs of each battery cell, is the most direct physical external channel for energy exchange and heat / force conduction within the battery. This invention breaks through the traditional approach of separating sensors from the structure. By pre-opening a containment channel within the busbar substrate, it innovatively constructs a composite sensing network of horizontal and vertical detection. This design utilizes the tab's characteristic as the initial point of internal thermal anomalies and stress release, embedding sensing optical fibers not only in the horizontal section of the busbar but also extending them to the upper and lower ends of the electrodes through a vertical probe structure. Traditional technologies can only sense the temperature rise result and cannot determine the fault source. This invention achieves precise decoupling of fault characteristics by detecting the temperature rise sequence at different depths of the tab using vertical probes—if the upper part of the electrode heats up first, it is determined to be an abnormal contact resistance at the busbar connection; if the lower part heats up first, it is determined to be the initiation of thermal runaway within the battery cell. This enhanced diagnostic capability fills the gap in the industry's inability to accurately locate and trace heat sources, and fundamentally transforms the monitoring logic: shifting the warning trigger point from a delayed external temperature rise to a more proactive dimension of determining the combined effect of electrode stress mutation and temperature rise. Compared to traditional technologies, this invention increases the warning lead time to the minute level and, thanks to the protection of the busbar metal substrate, completely solves the durability and electromagnetic compatibility problems of the sensor throughout its entire lifecycle, achieving a leapfrog progress from add-on sensing to structured intelligent hardware. This design not only utilizes the characteristic of the electrode as the initial point of thermal anomaly but also introduces a real-time warning and hierarchical diagnostic mechanism based on multi-dimensional feature weighting. The system acquires real-time data from four key dimensions through distributed optical fibers: Temperature rise rate Space temperature gradient and hotspot scale By setting the weighting coefficients for each factor. Construct a comprehensive evaluation index R.

[0025]

[0026] When the value exceeds a preset threshold, the system immediately initiates a diagnostic procedure that traces the problem layer by layer from the surface to the core: First, the absolute temperature is determined. If the absolute temperature is too high, the system determines it as an uncontrollable risk and directly issues a power-off command. If the temperature is still within a safe range, the system further analyzes the synergistic relationship between the temperature rise rate and the spatial gradient. If the temperature rise rate is too high and the spatial gradient exceeds the limit simultaneously, it is determined that a violent reaction has occurred inside the battery. At this time, the system calls the vertical probe depth mapping algorithm to determine the cause based on the temperature rise sequence: if the lower part of the tab heats up first, it is confirmed as the beginning of thermal runaway inside the cell; if the upper part heats up first, it is located as an abnormal contact resistance at the busbar connection, and an alarm is issued. If the temperature rise rate is too high but the spatial gradient does not reach the threshold, a hot spot scale is introduced for auxiliary determination: if the hot spot scale is distributed in a small area, it is determined as an increase in local thermal resistance of the busbar and is accurately located; if it is distributed in a large area, it is identified as an excessively high external ambient temperature. If the temperature rise rate is normal but the spatial gradient is abnormally high, it is determined as an early local excessive thermal resistance in the busbar, and the system will lock the area and issue a warning. This invention, through this layered logic, achieves a transformation from "sensing temperature rise" to "precise decoupling," increasing the early warning lead time to the minute level and solving the durability problem by leveraging the protection of the busbar metal substrate. This structured intelligent diagnostic can accurately pinpoint the specific location and type of faulty cells, shifting the maintenance strategy from overall scrapping to "precise disassembly and partial replacement," fundamentally solving the economic challenges of operating and maintaining large battery packs.

[0027] Specifically, in combination Figures 1-7 This invention proposes a battery pack monitoring and early warning system based on an embedded fiber optic intelligent busbar. The system uses the battery pack busbar as the structural carrier of the sensor, with a pre-opened receiving channel within the busbar substrate to achieve precise sensing and early warning of the battery pack status. Distributed sensing optical fibers are horizontally arranged along the receiving channel of the busbar, and a vertical fiber optic probe extends from the connection point of each cell tab (electrode). The probe is in close contact with the electrode surface, and the detection point covers at least the upper part of the electrode (near the busbar connection interface) and the lower part of the electrode (near the cell cover / internal end). If the upper part of the electrode heats up first, it is determined that the contact resistance at the busbar connection is abnormal; if the lower part of the electrode heats up first, it is determined that thermal runaway inside the cell is initiating.

[0028] This invention also proposes a battery pack monitoring and early warning method based on an optical fiber embedded smart busbar. The early warning method is implemented based on the aforementioned early warning system and includes: Step 1: The system uses a distributed fiber optic demodulator to initialize and calibrate the sensing fibers embedded inside the busbar and extending deep into the electrodes; the system employs a linear sweep laser to generate interference signals and perform centimeter-level spatial sampling along the fiber optic line. Its physical spatial resolution... z is determined by the sweep bandwidth of the laser. F is determined, satisfying the formula:

[0029] Where c is the speed of light in vacuum and n is the refractive index of the optical fiber. By modulating the sweep bandwidth, the system ensures not only centimeter-level mapping along the busbar axis but also precise depth calibration in the probe section perpendicular to the electrode direction (covering the upper and lower ends of the tabs). With the battery pack in a static or thermal equilibrium state, the distributed demodulator acquires the initial Rayleigh scattering spectral information at each sampling point along the optical fiber as a reference spectrum. At this time, the frequency shift curve output by the system... The phase signals acquired by v(x) and strain monitoring equipment (such as DAS) both exhibit smooth linear characteristics, without abrupt peaks or troughs, thus constructing a "physical reference field" for the normal operation of the battery pack.

[0030] Step Two: When the battery pack enters a charge / discharge cycle or experiences abnormal operating conditions, the sensing fiber inside the busbar will detect environmental disturbances in real time. This invention employs a physically isolated demodulation method to ensure signal purity. For the temperature sensing fiber embedded in the containment channel, its spectral frequency shift... v is only affected by thermal contraction. The system extracts the frequency shift by performing cross-correlation calculations on the measured spectrum and the reference spectrum, and calculates the real-time temperature change according to the following formula:

[0031] in This represents the fiber temperature sensitivity coefficient. At each electrode connection point, the system synchronously acquires the temperature of the upper part of the electrode (near the bus connection interface) and the lower part of the electrode (near the internal end of the cell) using vertical probes. For strain-sensitive fibers tightly coupled to the bus substrate, distributed acoustic sensing (DAS) or dynamic strain gauges are used to capture the phase difference of the light waves inside the fiber. Because this path is physically independent of the temperature sensing section, it can reproduce the mechanical deformation of the busbar caused by the expansion and compression of the battery cells in real time and at high frequency. This method effectively avoids the calculation errors caused by temperature and stress coupling in traditional single-fiber demodulation, and enables the capture of early signs of thermal runaway, such as cell gas generation and expansion.

[0032] Step 3: The sweeping laser inside the demodulator emits a continuous laser beam whose frequency changes linearly with time. This beam is split into a test beam and a reference beam by an optical splitter. The test beam enters the sensing fiber inside the embedded busbar and propagates forward. When the test beam reaches an anomaly point on the busbar (such as a temperature rise point caused by a short circuit in the battery cell or a strain point caused by expansion), the refractive index or physical length of the fiber changes at that point. This causes the Rayleigh backscattered light generated at that location to carry frequency or phase shift information and return to the demodulator along the original path. The returning signal light carrying the anomaly information and the reference beam undergo beat frequency interference inside the demodulator, and their interference intensity I satisfies:

[0033] The demodulator performs a Fast Fourier Transform (FFT) on the interference signal, mapping the signal from the frequency domain to the distance domain (time domain). Due to pre-calibrated depth, the system can accurately distinguish whether the returned signal originates from the upper connection layer or the lower internal end of the electrode. Through sliding window cross-correlation analysis, a full-line distributed temperature distribution map is output, clarifying the physical state at a specific coordinate x (including depth d). By performing sliding window cross-correlation analysis on the distance domain signal, the demodulator finally outputs a full-line distributed frequency shift / phase distribution map along the optical fiber. This clearly shows the degree of change that has occurred in the optical fiber at a specific coordinate x of the battery or busbar.

[0034] Step 4: The data processing module inputs the spatiotemporally aligned data into the multidimensional feature evaluation model to obtain the judgment result. The system extracts four key feature parameters in real time: absolute temperature (T), temperature rise rate, etc. Space temperature gradient and hotspot scale Calculate the comprehensive risk index R based on the preset weighting coefficients:

[0035] Once the R value exceeds the safety threshold, the early warning mechanism is immediately activated, and a step-by-step tracing judgment is performed according to the following logic: Level 1 Judgment (Absolute Temperature Control): First, the T value is evaluated. If the absolute temperature exceeds the extreme threshold, it is judged as an imminent risk of thermal runaway, and the system directly outputs a power cut-off command to the BMS. Level 2 Judgment (Dynamic Feature Coupling Diagnosis): If the T value is normal, the coupling analysis of temperature rise rate and spatial gradient is entered: High + High The system detects an abnormal reaction inside the battery. It invokes a vertical probe depth mapping algorithm: if the lower electrode heats up first, it's determined to be an internal cell fault; if the upper electrode heats up first, it's determined to be excessive contact resistance at the busbar connection, the cell number is locked, and an alarm is triggered. +low Combining hot topic scale Determine. If This is a localized feature, identified as an increase in localized thermal resistance of the busbar; if The widespread distribution indicates excessively high ambient temperature. Level 3 assessment (early hazard identification): If the temperature rise rate... Normal, but spatial gradient If the threshold is exceeded, it is determined to be an early-stage localized thermal resistance anomaly in the busbar. The system accurately pinpoints the physical location of the fault (e.g., a specific cell in a specific module) and issues a maintenance warning.

[0036] Example In this embodiment, the distributed sensing optical fiber is deployed within the battery pack busbar 4 and its extended electrode probe structure, rather than directly contacting the cell casing. The core logic is that the busbar is directly coupled to the cell electrode 7 via laser welding, bolt connection, or crimping. Since the electrode extends directly into the battery core, it is the most direct channel for the heat generated by the electrochemical reaction and the expansion stress from gas generation inside the battery to be transmitted outwards. Simulation using a thermal diffusion model shows that in a standard battery pack unit, the steady-state temperature gradient between the electrode and its connected busbar is extremely small, with a temperature difference not exceeding 2 degrees Celsius. This means that monitoring the physical state of the busbar is equivalent to high-precision sensing of the state of the core area inside the battery. The optical fiber 2 extends axially along the busbar. Upon passing each electrode connection point, the optical fiber detaches from the horizontal channel of the busbar and is deployed vertically downwards along the side of the electrode, forming a vertical detection loop covering the upper end of the electrode (near the busbar connection) and the lower end of the electrode (near the inner end of the cell). It then returns to the horizontal channel of the busbar to continue deployment to the next cell. This "horizontal + vertical" layout achieves deep coverage of the heat conduction path.

[0037] Before the system is put into real-time monitoring, strict initial calibration must be performed to establish a precise "physical-digital" mapping relationship. Due to the introduction of the vertical probe, the spatial positioning x is redefined. The system establishes a "fiber link length - physical spatial coordinates" mapping table. By calibrating the turning points of the fiber entering and leaving the vertical probe, the length range on the fiber is mapped to specific cell numbers and corresponding probe depths d. Using a sweep bandwidth to lock in centimeter-level spatial resolution, at least 2-3 independent temperature sampling points can be distinguished between the upper end (connection point) and the lower end (cell end) within a vertical probe segment of less than 2 cm, providing a data foundation for subsequent heat source tracing. Under controlled ambient temperature (e.g., constant temperature of 25℃), the initial Rayleigh spectrum of the entire sensing fiber is collected using a distributed demodulator 1 as a reference. Temperature shift coefficients of this batch of fibers are determined through variable temperature experiments, ensuring a strict linear correspondence between the spectral drift and temperature change at each centimeter sampling point. After the battery pack is assembled and in a stress-free (or known pre-tightening) state, the fiber is calibrated to zero phase using a DAS or dynamic strain demodulator 1. The phase difference was measured by applying a small standard mechanical displacement to the bus. With mechanical strain The proportionality constant is used to eliminate the interference of initial residual stress generated during fiber optic deployment on subsequent measurements.

[0038] The embedded bus comprises a bus base 5, a single-mode optical fiber 2, and a flexible thermally conductive buffer material 6. During deployment, an inwardly recessed receiving channel with a depth of approximately 1.0 mm and a width of approximately 0.8 mm is machined along the axial direction on the surface of the bus base 5. The single-mode optical fiber 2 is placed at the bottom of the channel and then filled with a flexible medium with high thermal conductivity. This design eliminates the need for any drilling or disassembly of the battery cell itself; simply replacing the traditional metal connector with a custom-produced intelligent bus achieves deep internal sensing capabilities without altering the battery pack's energy density or structural strength. At the electrode mating points, the optical fiber is vertically fixed to the electrode surface using precision dispensing or microstructures. The total length of the probe segment is determined by the exposed electrode height, ensuring the optical fiber can simultaneously sense the temperature at the root (lower end) of the tab and the welding point (upper end). This design achieves non-destructive monitoring of heat source locations without damaging the original battery encapsulation, thanks to the custom-designed intelligent bus.

[0039] During system operation, signal processing follows a closed-loop logic of "transmission-interaction-reflection-processing". The demodulator transmits a swept-frequency laser signal into the optical fiber. When the laser reaches the electrode probe section or bus section, the change in the fiber's refractive index caused by the ambient temperature rise will cause the returned Rayleigh backscattered light to carry frequency shift information. If there is a change in refractive index at that point due to compression stress caused by cell expansion or thermal anomalies, the returned Rayleigh backscattered light will carry disturbed phase / frequency information. The demodulator receives the returned light and performs interference processing, mapping the composite signal from the frequency domain to the distance domain through a fast Fourier transform, achieving centimeter (cm) level spatial positioning. By switching demodulation algorithms or devices, the absolute temperature distribution map and dynamic strain distribution map of the entire fiber can be output separately.

[0040] The data processing module inputs the spatiotemporally aligned data into the multidimensional feature evaluation model. The system extracts four key feature parameters in real time: absolute temperature (T), temperature rise rate, etc. Space temperature gradient and hotspot scale Calculate the comprehensive risk index R based on the preset weighting coefficients:

[0041] Once the R value exceeds the safety threshold, the early warning mechanism is immediately activated, and a step-by-step tracing judgment is performed according to the following logic: Level 1 Judgment (Absolute Temperature Control): First, the T value is evaluated. If the absolute temperature exceeds the extreme threshold, it is judged as an imminent risk of thermal runaway, and the system directly outputs a power cut-off command to the BMS. Level 2 Judgment (Dynamic Feature Coupling Diagnosis): If the T value is normal, the coupling analysis of temperature rise rate and spatial gradient is then initiated: high + High The system detects an abnormal reaction inside the battery. It invokes a vertical probe depth mapping algorithm: if the lower electrode heats up first, it's determined to be an internal cell fault; if the upper electrode heats up first, it's determined to be excessive contact resistance at the busbar connection, the cell number is locked, and an alarm is triggered. +low Combining hot topic scale Determine. If This is a localized feature, identified as an increase in localized thermal resistance of the busbar; if The widespread distribution indicates excessively high ambient temperature. Level 3 assessment (early hazard identification): If the temperature rise rate... Normal, but spatial gradient If the threshold is exceeded, it is determined to be an early-stage localized thermal resistance anomaly in the busbar. The system accurately pinpoints the physical location of the fault (e.g., a specific cell in a specific module) and issues a maintenance warning. The warning system incorporates a deep learning model that dynamically sets warning thresholds based on different manufacturers, chemical systems (e.g., ternary lithium or lithium iron phosphate), and battery cycle life. For example, for battery blocks with high aging levels, the system automatically optimizes its temperature rise rate warning threshold to exclude normal impedance increase heat generation and accurately capture abnormal runaway precursors. When the distributed fiber optic demodulator detects an abnormal temperature gradient or a surge in temperature rise rate, or when the DAS detects a nonlinear change in the strain signal, the system immediately triggers the warning logic. Based on centimeter-level positioning results from distributed sensing, the system can accurately pinpoint the fault information to the specific cell number. In actual maintenance, the management platform generates a precise maintenance route map based on the positioning data, guiding technicians to disassemble and replace only the specific battery cells (or small modules) affected by strain or thermal anomalies. This partial removal and overall protection approach avoids the entire battery pack being scrapped due to the failure of a single cell, greatly improving asset utilization and the economic efficiency of system operation.

[0042] The foregoing has provided a detailed description of a battery pack monitoring and early warning method and system based on an embedded fiber optic intelligent busbar proposed in this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A battery pack monitoring and early warning system based on fiber optic embedded intelligent busbars, characterized in that, The system uses the battery pack busbar as the structural carrier of the sensor. A pre-opened containment channel is made in the busbar substrate to achieve precise perception and early warning of the battery pack status. Distributed sensing optical fibers are laid horizontally along the containment channel of the busbar, and a vertical optical fiber probe extends from each cell tab connection. The probe is close to the electrode surface, and the detection point covers at least the upper and lower parts of the electrode. If the upper part of the electrode heats up first, it is determined that the contact resistance at the busbar connection is abnormal. If the lower part of the electrode heats up first, it is determined that thermal runaway inside the cell has begun.

2. The system according to claim 1, characterized in that, The sensing fiber extends along the busbar axis. When it passes each electrode connection point, the sensing fiber detaches from the horizontal channel of the busbar and is laid vertically downward along the side of the electrode to form a vertical detection loop covering the upper and lower parts of the electrode. Then it returns to the horizontal channel of the busbar to continue to the next cell.

3. The system according to claim 1, characterized in that, The bus consists of a bus base, a single sensing optical fiber, and a flexible thermally conductive buffer material. During installation, an inwardly recessed receiving channel with a depth of 1.0 mm and a width of 0.8 mm is machined along the axial direction on the surface of the bus base. After the sensing fiber is laid at the bottom of the middle of the channel, it is filled with a flexible thermally conductive buffer material with high thermal conductivity.

4. The system according to claim 1, characterized in that, At the electrode mating point, the sensing fiber is vertically fixed to the electrode surface using a precision dispensing process or a micro-structure; the total length of the probe section is determined by the exposed height of the electrode, ensuring that the sensing fiber can simultaneously sense the temperature of the root of the electrode tab and the welding point.

5. A battery pack monitoring and early warning method based on fiber optic embedded smart busbar, characterized in that, The early warning method is implemented based on the early warning system according to any one of claims 1-4, and the early warning method includes: Step 1: The system uses a distributed fiber optic demodulator to initialize and calibrate the sensing fibers embedded inside the busbar and extending deep into the electrodes. Step 2: When the battery pack enters a charge / discharge cycle or an abnormal operating condition occurs, the sensing fiber inside the busbar will sense environmental disturbances in real time. Step 3: The sweeping laser inside the demodulator emits a continuous laser beam whose frequency changes linearly with time. It is split into test light and reference light by the optical splitter. The test light enters the sensing fiber in the embedded busbar and propagates forward along the line. Step 4: The data processing module inputs the spatiotemporally aligned data into the multidimensional feature evaluation model to obtain the judgment result.

6. The method according to claim 5, characterized in that, In the first step, the system uses a linearly swept-frequency laser to generate an interference signal and perform centimeter-level spatial sampling along the sensing fiber; its physical spatial resolution... z is determined by the sweep bandwidth of the laser. F is determined, satisfying the formula: Where c is the speed of light in vacuum and n is the refractive index of the optical fiber; by modulating the sweep bandwidth, the system ensures not only centimeter-level mapping along the busbar axis, but also precise depth calibration in the probe section perpendicular to the electrode direction; when the battery pack is in a static or thermal equilibrium state, the distributed demodulator acquires the initial Rayleigh scattering spectral information of each sampling point along the optical fiber as a reference spectrum; at this time, the frequency shift curve output by the system... Both v(x) and the phase signal acquired by the strain monitoring equipment exhibit smooth linear characteristics, without abrupt peaks or troughs, thus constructing a "physical reference field" for the normal operation of the battery pack.

7. The method according to claim 5, characterized in that, In the second step, a physically isolated demodulation method is used to ensure signal purity; for the temperature sensing fiber embedded in the containment channel, its spectral frequency shift... v is only affected by thermal shrinkage; the system extracts the frequency shift by performing cross-correlation calculations on the measured spectrum and the reference spectrum, and calculates the real-time temperature change according to the following formula: in The system measures the fiber temperature sensitivity coefficient; at each electrode connection point, the system synchronously acquires the temperature of the upper and lower parts of the electrode using vertical probes; for strain-sensitive fibers tightly coupled to the bus substrate, distributed acoustic sensing or dynamic strain gauges are used to capture the phase difference of light waves inside the fiber. .

8. The method according to claim 5, characterized in that, In the third step, when the test light propagates to an anomaly point on the bus, the refractive index or physical length of the fiber changes at that point, causing the Rayleigh backscattered light generated at that location to carry frequency or phase shift information and return to the demodulator along the original path. The returning signal light carrying the anomaly information and the reference light undergo beat frequency interference inside the demodulator, and their interference intensity I satisfies: The demodulator performs a fast Fourier transform on the interference signal, mapping the signal from the frequency domain to the time domain. Through sliding window cross-correlation analysis, it outputs a distributed temperature distribution map along the entire line, clarifying the physical state at a specific coordinate x. By performing sliding window cross-correlation analysis on the time domain signal, the demodulator finally outputs a fully distributed frequency shift / phase distribution map along the optical fiber. This clearly shows the degree of change that has occurred in the optical fiber at a specific coordinate x of the battery or busbar.

9. The method according to claim 5, characterized in that, In the fourth step, the system extracts four key feature parameters in real time: absolute temperature T, temperature rise rate, and so on. Space temperature gradient and hotspot scale ;Calculate the comprehensive risk index R based on the preset weighting coefficients: Once the R value exceeds the safety threshold, the early warning mechanism is activated immediately.

10. The method according to claim 9, characterized in that, In the fourth step, the following logic is used for step-by-step source tracing and judgment: First-level judgment is absolute temperature control: Firstly, the T value is evaluated; if the absolute temperature exceeds the extreme threshold, it is judged as a risk of thermal runaway, and the system directly outputs a power-off command to the BMS; Second-level judgment is dynamic characteristic coupling diagnosis: If the T value is normal, then the coupling analysis of temperature rise rate and spatial gradient is entered: High + High The system detects an abnormal reaction inside the battery; it invokes a vertical probe depth mapping algorithm: if the lower electrode heats up first, it indicates an internal cell fault; if the upper electrode heats up first, it indicates excessive contact resistance at the busbar connection, locking the cell number and triggering an alarm; +low Combining hot topic scale Determine; if This is a localized feature, identified as an increase in localized thermal resistance of the busbar; if The widespread distribution indicates excessively high ambient temperatures; the third-level assessment, or early hazard identification, is based on the temperature rise rate. Normal, but spatial gradient If the threshold is exceeded, it is determined to be an early local thermal resistance anomaly in the busbar; the system accurately locates the physical location of the fault and issues a maintenance warning.

Images