Battery cell explosion prevention valve deformation monitoring device and method

Abstract

The application provides a kind of electric core explosion-proof valve deformation monitoring device and method, it is related to battery safety technical field, including integrated acquisition board, for fixed on the top cover of electric core module above, integrated acquisition board is integrated with multiple groups of sensor units, each group of sensor units corresponds to a electric core, and includes first displacement sensor and second displacement sensor;Signal processing unit is set on integrated acquisition board, and is electrically connected with first displacement sensor and second displacement sensor, for determining the local expansion displacement amount of the explosion-proof valve area of electric core relative to non-explosion-proof valve rigid area based on the displacement signal output by first displacement sensor and second displacement sensor respectively.The application greatly reduces the false positive rate while improving assembly efficiency and reducing cost, realizes the accurate monitoring of electric core thermal runaway early.

Description

Technical Field

[0001] This application relates to the field of battery safety technology, and in particular to a device and method for monitoring the deformation of a battery cell explosion-proof valve. Background Technology

[0002] During charge-discharge cycles and under abnormal operating conditions, the internal gas generation of lithium-ion batteries causes the casing to expand. The explosion-proof valve area in the top cover, due to its weak structure, is the first part to deform. Real-time monitoring of its expansion displacement is crucial for early identification of cell anomalies and prevention of thermal runaway accidents. Current technologies typically employ the method of independently installing displacement sensors on each cell outside the cell module and wiring them separately to collect overall expansion displacement data on the cell surface. This approach suffers from low deployment efficiency, high material costs, and fails to distinguish between localized deformation in the explosion-proof valve area and normal overall cell expansion. Furthermore, the monitoring signal contains a large number of common-mode displacement components unrelated to the explosion-proof valve deformation, resulting in insufficient sensitivity and accuracy in anomaly identification. Therefore, how to achieve efficient deployment at the module level while accurately identifying localized abnormal expansion in the explosion-proof valve area is a technical problem that needs to be solved in this field. Summary of the Invention

[0003] The purpose of this application is to provide a device and method for monitoring the deformation of a battery cell explosion-proof valve, so as to alleviate the above-mentioned technical problems existing in the prior art.

[0004] In a first aspect, the present invention provides a battery cell explosion-proof valve deformation monitoring device, comprising: An integrated acquisition board is used to fix it on the top cover of the battery cell module. The integrated acquisition board integrates multiple sets of sensor units, each set of sensor units corresponds to one battery cell, and includes a first displacement sensor and a second displacement sensor. A signal processing unit, disposed on the integrated acquisition board, is electrically connected to the first displacement sensor and the second displacement sensor, and is used to determine the local expansion displacement of the explosion-proof valve region of the battery cell relative to the non-explosion-proof valve rigid region based on the displacement signals output by the first displacement sensor and the second displacement sensor respectively.

[0005] In an optional embodiment, the sensing direction of the first displacement sensor is aligned with the center of the explosion-proof valve of the corresponding battery cell; the sensing direction of the second displacement sensor is aligned with a rigid area on the top cover of the same battery cell that is away from the center of the explosion-proof valve.

[0006] In an optional implementation, the integrated acquisition board has a rectangular plate structure, and the layout of the integrated acquisition board matches the arrangement of the battery cells in the battery cell module, so that the first displacement sensor and the second displacement sensor in each group of sensor units are respectively aligned vertically with the explosion-proof valve area and the non-explosion-proof valve rigid area of ​​the corresponding battery cell top cover.

[0007] In an optional implementation, the integrated acquisition board is fixed to the busbar bracket of the battery cell module by bolts or clips.

[0008] In an optional embodiment, the first displacement sensor and the second displacement sensor are selected from any one of inductive displacement sensors, laser displacement sensors, eddy current displacement sensors, magnetostrictive displacement sensors, and pole pitch variation capacitive displacement sensors.

[0009] In an optional implementation, the signal processing unit is specifically used for: Receive displacement signals output by the first displacement sensor and the second displacement sensor respectively; The first displacement increment of the explosion-proof valve region is determined based on the displacement signal output by the first displacement sensor, and the second displacement increment of the non-explosion-proof valve rigid region is determined based on the displacement signal output by the second displacement sensor. The difference between the first displacement increment and the second displacement increment is calculated to obtain the local expansion displacement.

[0010] In an optional implementation, the signal processing unit is further configured to: The displacement signal output by the second displacement sensor is obtained after the battery cell has completed a preset number of charge-discharge cycles or has been running for a preset time, and is in a static state. The initial reference value corresponding to the second displacement increment is updated based on the displacement signal.

[0011] In an optional embodiment, the apparatus further includes: The early warning unit, electrically connected to the signal processing unit, is used to receive the local expansion displacement, compare the local expansion displacement with a preset graded early warning threshold, and output the corresponding safety early warning level.

[0012] In an optional implementation, the early warning unit is specifically used for: The local expansion displacement is compared with the first-level warning threshold. If the local expansion displacement is greater than or equal to the first-level warning threshold, the first-level safety warning is output and the location information of the cell that triggered the first-level safety warning in the cell module is reported to the operation management platform. The local expansion displacement is compared with the secondary warning threshold. If the local expansion displacement is greater than or equal to the secondary warning threshold, a second-level safety warning is output, and the current of the module containing the cell that triggered the second-level safety warning is cut off, and a cooling strategy for the module is initiated.

[0013] Secondly, the present invention provides a method for monitoring the deformation of a battery cell explosion-proof valve, applied to the battery cell explosion-proof valve deformation monitoring device described in the foregoing embodiments, the method comprising: The first displacement increment of the explosion-proof valve region is obtained by the first displacement sensor, and the second displacement increment of the rigid region of the non-explosion-proof valve is obtained by the second displacement sensor. Based on the difference calculation between the first displacement increment and the second displacement increment, the local expansion displacement of the explosion-proof valve region relative to the rigid region of the non-explosion-proof valve is obtained; The local expansion displacement is compared with a preset graded warning threshold, and the safety warning level of the battery cell is output.

[0014] The battery cell explosion-proof valve deformation monitoring device and method provided in this application integrates multiple sensor units onto a single integrated acquisition board, which is then fixed to the top cover of the battery cell module. This allows for the simultaneous installation of sensors for all cells within the module, solving the problems of low assembly efficiency and high cost associated with installing sensors individually in existing technologies. Each sensor unit includes a first displacement sensor and a second displacement sensor. The first displacement sensor detects the displacement of the explosion-proof valve area, while the second displacement sensor detects the displacement of the non-explosion-proof valve rigid area. These sensors respectively acquire displacement signals from the explosion-proof valve area and the non-explosion-proof valve rigid area, providing a data basis for subsequent differential calculations to separate different displacement components. The signal processing unit determines the local expansion displacement of the explosion-proof valve area relative to the non-explosion-proof valve rigid area based on the two displacement signals, separating normal aging expansion of the battery cell from abnormal local expansion of the explosion-proof valve. This allows the early warning judgment to exclude interference from normal expansion, thus solving the problem of high false alarm rates in existing solutions due to the inability to distinguish between the two types of expansion. Overall, this application significantly reduces the false alarm rate while improving assembly efficiency and reducing costs, achieving accurate monitoring of early-stage thermal runaway of the battery cell. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 A structural diagram of a battery cell explosion-proof valve deformation monitoring device provided in this application embodiment; Figure 2 A structural diagram of a specific battery cell explosion-proof valve deformation monitoring device provided in this application embodiment; Figure 3A schematic diagram of the overall structure of a battery cell explosion-proof valve deformation monitoring device based on integrated PCB sampling and background displacement compensation provided in this application embodiment; Figure 4 This is a schematic diagram of an integrated PCB sampling board provided in an embodiment of this application; Figure 5 A flowchart of a method for monitoring the deformation of a battery cell explosion-proof valve provided in this application embodiment; Figure 6 A flowchart illustrating a specific method for monitoring the deformation of a battery cell explosion-proof valve, as provided in this application embodiment. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0019] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0020] This application provides a cell explosion-proof valve deformation monitoring device, which is used for early deformation monitoring of the cell explosion-proof valve in power batteries or energy storage systems. In the early stages of cell thermal runaway, internal chemical reactions generate gas, and the internal pressure of the cell gradually increases. Under this pressure, the explosion-proof valve area undergoes localized expansion and deformation. This localized expansion occurs before the explosion-proof valve opens. By monitoring this deformation, abnormal cells can be identified in advance, providing a time window for emergency response. The technical solution of this application is described in detail below with reference to the accompanying drawings.

[0021] like Figure 1 As shown, this application provides a deformation monitoring device for a battery cell explosion-proof valve, which mainly includes an integrated acquisition board and a signal processing unit.

[0022] The integrated data acquisition board is fixed to the top cover of the battery cell module, and its surface integrates multiple sensor units. "Integrated" means that all sensors and signal processing circuits corresponding to all battery cells within the module are integrated onto a single data acquisition board, rather than having sensors installed separately for each cell and connected via wiring harnesses. Each sensor unit corresponds to one battery cell and includes a first displacement sensor and a second displacement sensor. The number of sensor units is the same as the number of battery cells in the module—the integrated data acquisition board integrates as many sensor units as the module contains. The layout of the sensor units corresponds one-to-one with the arrangement of the battery cells; when the integrated data acquisition board is installed, each sensor unit is precisely positioned above the top cover of its corresponding battery cell.

[0023] The first displacement sensor detects displacement changes in the explosion-proof valve area, with its sensing direction aligned with the center of the explosion-proof valve corresponding to the battery cell. The second displacement sensor detects displacement changes in the rigid area outside the explosion-proof valve, with its sensing direction aligned with the rigid area on the top cover of the same battery cell away from the center of the explosion-proof valve. The two sensors operate independently, each outputting an electrical signal reflecting the displacement of its corresponding area. By comparing the two sets of signals, interference from the overall expansion of the battery cell (background displacement) can be eliminated, retaining only the localized expansion displacement of the explosion-proof valve caused by increased internal pressure.

[0024] The integrated data acquisition board is fixed to the busbar bracket of the battery cell module by bolts or clips, and after installation, the board is located above the top cover of the battery cell. The sensor is positioned facing the top cover of the battery cell in a non-contact manner, with a certain gap maintained between the sensing surface and the top cover, and does not contact the surface of the battery cell. This non-contact design will not affect the expansion and deformation of the explosion-proof valve, nor will it hinder the normal opening action of the explosion-proof valve after reaching the pressure threshold, and it will not cause additional stress to the top cover of the battery cell.

[0025] The signal processing unit is mounted on the integrated acquisition board and electrically connected to the first and second displacement sensors. Based on the displacement signals output by the first and second displacement sensors, the signal processing unit determines the local expansion displacement of the explosion-proof valve region relative to the non-explosion-proof valve rigid region of the battery cell. Specifically, the signal processing unit receives the displacement signal of the explosion-proof valve region output by the first displacement sensor and the displacement signal of the non-explosion-proof valve rigid region output by the second displacement sensor. By performing a difference calculation on the two sets of signals, it obtains the local expansion displacement of the explosion-proof valve region relative to the non-explosion-proof valve rigid region. This difference represents the amount of local expansion deformation of the explosion-proof valve caused by abnormal gas generation inside the battery cell, after excluding normal expansion interference.

[0026] In one specific implementation, the signal processing unit may include a signal conditioning circuit, an analog-to-digital converter (ADC), and a microprocessor. The signal conditioning circuit amplifies and filters the analog signal output from the sensor, the ADC converts the analog signal into a digital signal, and the microprocessor performs interpolation and subsequent processing. All of these circuits are integrated into a vacant area of ​​the integrated acquisition board, eliminating the need for a separate signal acquisition box, thus simplifying the wiring layout within the module and improving integration and reliability.

[0027] Through the coordinated operation of the integrated acquisition board and signal processing unit, this device enables real-time monitoring of the early deformation of the cell explosion-proof valve. It can accurately identify the local expansion deformation of the explosion-proof valve caused by abnormal internal gas generation without contacting the cell surface, and provide early monitoring data before the cell thermal runaway occurs.

[0028] Figure 2 A specific battery cell explosion-proof valve deformation monitoring device is shown, which mainly includes an integrated acquisition board, a signal processing unit, and an early warning unit.

[0029] The integrated data acquisition board is used to fix the battery cell module above its top cover. This integrated data acquisition board is a plate-shaped structure that matches the arrangement of the battery cells in the module. Multiple sets of sensor units are integrated on the board surface, each set corresponding to one battery cell, and includes a first displacement sensor and a second displacement sensor. The number of sensor units is the same as the number of battery cells in the module; that is, each battery cell corresponds to one set of sensor units. The layout of the integrated data acquisition board matches the arrangement of the battery cells in the module—when the battery cells in the module are arranged linearly, the integrated data acquisition board is a long rectangular plate; when the battery cells in the module are arranged in a matrix, the integrated data acquisition board is a large rectangular plate. The integrated data acquisition board is fixed to the busbar bracket of the module by bolts or clips, and after installation, it is located at a certain distance above the top cover of the battery cell module.

[0030] The signal processing unit is mounted on the integrated acquisition board and is electrically connected to the first and second displacement sensors. Based on the displacement signals output by the first and second displacement sensors, the signal processing unit determines the local expansion displacement of the explosion-proof valve region of the battery cell relative to the non-explosion-proof valve rigid region. The signal processing unit may include a signal conditioning circuit, an analog-to-digital conversion circuit, and a microprocessor, all integrated into a spare area of ​​the integrated acquisition board, eliminating the need for a separate signal acquisition box.

[0031] The early warning unit is electrically connected to the signal processing unit. It receives the local expansion displacement and compares it with a preset graded early warning threshold, outputting the corresponding safety early warning level. The early warning unit can be integrated into an integrated acquisition board or set up independently in the battery management system (BMS).

[0032] Preferably, each battery cell is assigned a unique identification code in the signal processing unit of the integrated acquisition board (this can be achieved via hardware jumpers or memory writing). During the initial calibration phase after the module's initial assembly, the signal processing unit independently performs multiple load-unload cycles for each battery cell (e.g., recording displacement-pressure curves during module charging and discharging) to obtain personalized deformation response characteristic parameters for each cell (including the initial stiffness of the explosion-proof valve area and the expansion coefficient of the rigid area of ​​the non-explosion-proof valve). These parameters are stored in the non-volatile memory of the signal processing unit, indexed by the battery cell's identification code, serving as a personalized baseline for subsequent monitoring of that cell. During operation, the signal processing unit compares the currently acquired displacement signal with the personalized baseline of the corresponding battery cell, rather than with a uniform reference value. When a battery cell is replaced, the system automatically identifies the new battery cell's identification code and re-performs the initial calibration, updating the baseline parameters of that cell. Through personalized baseline calibration, the impact of battery cell manufacturing tolerances on the accuracy of early warnings is eliminated, allowing each battery cell to be judged for anomalies based on its own characteristics, significantly reducing false alarms and missed alarms caused by individual differences.

[0033] Regarding the thickness of the integrated acquisition board, the board thickness can be set according to the actual application scenario and strength requirements. In one specific implementation, the board thickness can be set to 1.5mm to 2.5mm, for example, 2mm. This thickness range ensures that the board has sufficient mechanical strength to support the sensor and signal processing circuitry, without occupying too much module height space due to excessive thickness. It should be noted that the above numerical range is only an example, and the specific thickness can be adjusted according to the module's structural design and space constraints.

[0034] Figure 3 This is a schematic diagram of the overall structure of the battery cell explosion-proof valve deformation monitoring device based on integrated PCB sampling and background displacement compensation provided in this application. The diagram shows the assembly relationship between the device and the battery cell module, as well as the relative positions of the components.

[0035] like Figure 3 As shown, the module housing 100 contains multiple battery cells 200 arranged linearly to form a standard power battery module. Each battery cell 200 has an explosion-proof valve 210 on its top cover. The explosion-proof valve 210 is an integrated grooved structure on the top cover of the battery cell, used to rupture and release pressure when the internal pressure of the battery cell reaches the opening threshold.

[0036] A busbar assembly 300 is provided on the top of the module housing 100. The busbar assembly 300 is used to connect the terminals of each battery cell to realize series or parallel connection between the battery cells. An integrated PCB sampling board 400 is fixedly installed on top of the busbar assembly 300 and is fixedly connected to the busbar assembly 300 by bolt fixing points 430 (i.e., bolts or clips). After installation, the PCB sampling board 400 is located above the top cover of the battery cell.

[0037] The PCB sampling board 400 integrates multiple sets of sensor units, each corresponding to a battery cell 200. Each set of sensor units includes a detection displacement sensor 410 (i.e., the aforementioned first displacement sensor) and a reference displacement sensor 420 (i.e., the aforementioned second displacement sensor). The detection displacement sensor 410 is positioned on the PCB sampling board 400 above the explosion-proof valve 210 corresponding to the battery cell 200, with its sensing direction vertically downwards and aligned with the center of the explosion-proof valve 210. The reference displacement sensor 420 is positioned on the PCB sampling board 400 above the non-explosion-proof valve rigid area corresponding to the same battery cell 200, at a certain distance from the detection displacement sensor 410, with its sensing direction vertically downwards and aligned with the rigid area on the top cover of the battery cell 200 away from the center of the explosion-proof valve.

[0038] The PCB sampling board 400 also integrates a signal processing unit, which is not separately labeled in the figure but is located in an empty area of ​​the PCB sampling board 400. The PCB sampling board 400 is connected to the warning unit, which can be integrated on the PCB sampling board or set in the battery management system.

[0039] Among the aforementioned components, the integrated PCB sampling board 400 is fixed to the bus assembly 300 via bolt fixing points 430. The detection displacement sensor 410 and the reference displacement sensor 420 are soldered onto corresponding pads on the PCB sampling board 400. Each sensor adopts a non-contact design, with the sensing surface facing the top cover of the battery cell, maintaining a predetermined gap (e.g., 3mm to 10mm) between it and the top cover. Through this integrated layout, the entire device is tightly integrated with the battery cell module without changing the original outline dimensions of the module, adapting to the existing battery pack assembly space.

[0040] Considering that the reference displacement sensor is located in the plane area next to the negative terminal of the same cell top cover (single reference point), when this reference point happens to be in a local stress concentration area (e.g., a local bulge caused by the release of residual stress from the terminal welding), the displacement signal of a single reference point may not accurately represent the overall expansion of the cell, leading to compensation errors. This embodiment sets multiple reference displacement sensors for each cell, distributed in multiple rigid areas of the cell top cover (e.g., next to the positive terminal, next to the negative terminal, at the edge of the top cover, etc.). The signal processing unit collects the displacement signals from multiple reference displacement sensors, calculates their average value as the background displacement of the cell, and then performs a difference calculation between this average value and the displacement value of the detected displacement sensor. When the signal of a certain reference displacement sensor is abnormal (e.g., sensor failure or local stress interference), the system can automatically discard the abnormal signal and use the average value of the remaining reference sensors for compensation. Through multi-point averaging compensation, the impact of random errors from a single reference point on the compensation accuracy can be effectively reduced, further improving the accuracy and robustness of the local expansion displacement.

[0041] In practice, the signal processing of multi-point reference sensors can adopt median filtering or weighted averaging methods—the weights can be dynamically adjusted according to the historical stability of each reference sensor signal, and the weights of reference sensors with larger signal fluctuations are reduced accordingly.

[0042] Building upon this, to further eliminate the impact of module-level structural deformation on measurement results, a module-level reference displacement sensor can be added to the edge of the integrated acquisition board or at a fixed position on the module housing. Its sensing direction is aligned with a fixed rigid reference point on the module housing (e.g., a reference surface on the module end plate). This module-level reference displacement sensor acquires the structural deformation displacement of the entire module. The signal processing unit first subtracts the corresponding cell-level reference displacement sensor signal from the detection displacement sensor signal of each cell (i.e., basic difference calculation), and then further subtracts the module-level reference displacement sensor signal from this difference (i.e., second-order compensation). The local expansion displacement after second-order compensation eliminates the common-mode error introduced by module-level structural deformation. Through two levels of background displacement compensation—cell-level and module-level—the separation accuracy of normal expansion and abnormal local expansion is improved from the cell-level to the module-level, which is particularly suitable for scenarios where large modules or battery packs experience significant structural deformation during long-term cyclic use.

[0043] like Figure 4 As shown, the integrated acquisition board has a rectangular plate structure, and its layout matches the arrangement of the battery cells in the battery cell module. On the board, a set of sensor units is set for each battery cell within the module, and each set of sensor units includes a first displacement sensor and a second displacement sensor. In practice, the sensor pads on the board are arranged according to the spacing of the battery cells to ensure that each sensor, after installation, can be aligned with the target detection position of its corresponding battery cell.

[0044] The sensing direction of the first displacement sensor is aligned with the center of the explosion-proof valve of the corresponding battery cell. The first displacement sensor is used to detect displacement changes in the explosion-proof valve area. The displacement changes in the explosion-proof valve area include two components: one is the background displacement caused by the overall expansion of the battery cell (the normal volume change of the battery cell due to lithium insertion and extraction during charge and discharge cycles); the other is the local expansion displacement of the explosion-proof valve caused by the increase in internal pressure.

[0045] The second displacement sensor is positioned to detect a rigid area on the top cover of the same battery cell, away from the center of the explosion-proof valve. This second displacement sensor detects background displacement caused by the overall expansion of the battery cell. The non-explosion-proof valve rigid area is selected from a rigid region on the top cover of the battery cell, away from the explosion-proof valve. This region will not experience localized expansion due to increased internal pressure, and its displacement changes accurately reflect the overall expansion of the battery cell. In one specific embodiment, the non-explosion-proof valve rigid area can be a pre-reserved flat area next to the negative electrode post on the top cover of the same battery cell, with a distance of at least 15mm from the center of the explosion-proof valve. This distance ensures that the reference displacement sensor does not interfere with the electrode post welding while remaining within the rigid, fixed area of ​​the top cover, allowing displacement changes to accurately reflect the normal expansion of the battery cell. It should be noted that this distance is only an example; the actual selection can be adjusted according to the layout of the top cover of the battery cell.

[0046] The sensing surfaces of both the first and second displacement sensors face the top cover of the battery cell. The sensing distance can be set according to the sensor type and measurement accuracy requirements. In one specific embodiment, the sensing distance can be set to 3mm to 10mm, for example, 5mm. Within this distance range, the sensor can obtain a good signal strength without contacting the surface of the top cover of the battery cell, thus neither affecting the expansion and deformation of the explosion-proof valve nor hindering its normal opening after reaching the pressure threshold.

[0047] The first and second displacement sensors can be various types of non-contact displacement sensors. In one specific embodiment, the sensor can be selected from any one of inductive displacement sensors, laser displacement sensors, eddy current displacement sensors, magnetostrictive displacement sensors, and pole-gap changing capacitive displacement sensors.

[0048] In a preferred embodiment, the sensor can be a miniature inductive displacement sensor. Inductive displacement sensors utilize the principle that the inductance of a coil changes with the air gap in the magnetic circuit. They are characterized by simple structure, low cost, and strong environmental adaptability (high temperature resistance, vibration resistance), making them suitable for installation environments inside power battery modules. In specific implementations, the sensor can be packaged in a 6mm diameter cylindrical package and directly soldered to the corresponding pads on the integrated acquisition board. The sensor size can be selected according to actual needs; the 6mm diameter is only an example, and the actual selection can be adjusted according to the installation space and measurement accuracy requirements.

[0049] Eddy current displacement sensors measure the displacement of a conductor surface using the eddy current effect. They are insensitive to changes in the state of the measured surface and are suitable for detecting displacement changes in the top cover of metal battery cells. Laser displacement sensors offer high accuracy but are also relatively expensive, making them suitable for applications requiring higher precision. Electrode spacing variable capacitive displacement sensors utilize the principle that changes in electrode spacing lead to changes in capacitance, offering advantages in both high accuracy and high resolution. When selecting a specific sensor, factors such as cost, accuracy, and installation space should be considered comprehensively.

[0050] The signal processing unit is integrated on the integrated acquisition board and is electrically connected to the first displacement sensor and the second displacement sensor. The signal processing unit is used to receive the displacement signals output by the first displacement sensor and the second displacement sensor respectively, and determine the local expansion displacement of the explosion-proof valve region of the battery cell relative to the non-explosion-proof valve rigid region based on the displacement signals.

[0051] Specifically, the signal processing unit receives displacement signals output by the first displacement sensor and the second displacement sensor, respectively. Based on the displacement signal output by the first displacement sensor, it determines the first displacement increment of the explosion-proof valve region and, based on the displacement signal output by the second displacement sensor, determines the second displacement increment of the rigid region of the non-explosion-proof valve. Then, it performs a difference calculation on the first and second displacement increments to obtain the local expansion displacement.

[0052] In one specific implementation, the signal processing unit may include a signal conditioning circuit, an analog-to-digital converter (ADC), and a microprocessor. For an inductive displacement sensor, the signal conditioning circuit includes an oscillation circuit, a demodulation circuit, and an amplification circuit to convert the sensor's inductance change into a voltage signal. For an eddy current sensor, the signal conditioning circuit includes a high-frequency oscillator and a detection circuit. For a laser sensor, the signal conditioning circuit includes a photoelectric conversion circuit and a signal amplification circuit. The conditioned analog signal is converted into a digital signal by the ADC for the microprocessor to perform difference calculations and subsequent processing.

[0053] In the difference calculation, both the first and second displacement increments are calculated relative to the initial calibration values. After the module assembly is completed, the system first performs initial calibration, recording the initial detected displacement value S00 of the first displacement sensor and the initial reference displacement value Sr0 of the second displacement sensor. During system operation, the signal processing unit collects the current detected displacement value St of the first displacement sensor and the current reference displacement value Sr of the second displacement sensor in real time. The first displacement increment is ΔS = St - S00, the second displacement increment is ΔS0 = Sr - Sr0, and the local expansion displacement is ΔS' = ΔS - ΔS0. When the battery cell is in a normal state, the displacement increments of the explosion-proof valve area and the non-explosion-proof valve area are basically the same, and the difference is close to zero. When abnormal gas generation inside the battery cell causes local expansion in the explosion-proof valve area, the displacement increment of the explosion-proof valve area is greater than the displacement increment of the non-explosion-proof valve area, and the difference is the positive local expansion displacement.

[0054] The early warning unit is electrically connected to the signal processing unit. It is used to receive the local expansion displacement, compare the local expansion displacement with the preset graded early warning threshold, and output the corresponding safety early warning level.

[0055] In one specific implementation, the graded early warning system employs a two-level threshold design. The first-level early warning threshold corresponds to the local expansion displacement, which is the deformation of the explosion-proof valve when the internal pressure of the battery cell reaches a certain percentage of the rated opening pressure. This percentage can be set according to the type of battery cell and the characteristics of the explosion-proof valve. In one specific implementation, this percentage can be set to 30% to 70% of the rated opening pressure of the explosion-proof valve, for example, 30%. When the local expansion displacement is greater than or equal to the first-level early warning threshold, the early warning unit outputs a first-level safety warning and reports the location information of the battery cell that triggered the warning within the battery cell module to the operation management platform.

[0056] The local expansion displacement corresponding to the secondary warning threshold corresponds to the deformation of the explosion-proof valve when the internal pressure of the battery cell reaches a higher percentage of the rated opening pressure of the explosion-proof valve. In one specific embodiment, this percentage can be set to 70% to 90% of the rated opening pressure of the explosion-proof valve, for example, 75%. When the local expansion displacement is greater than or equal to the secondary warning threshold, the warning unit outputs a second-level safety warning and cuts off the current to the module containing the battery cell that triggered the warning, initiating a cooling strategy for that module (e.g., starting a liquid cooling system or fan). The secondary warning threshold is higher than the primary warning threshold, but still occurs before the explosion-proof valve opens, allowing sufficient time to trigger the warning before the valve opens, without prematurely triggering unnecessary emergency measures. It should be noted that the above percentage is only an example, and the specific threshold can be calibrated according to the battery cell type, explosion-proof valve characteristics, and actual safety requirements.

[0057] During long-term service, the battery cell will slowly age and expand, and the metal grooves in the explosion-proof valve area may also experience stress relaxation, causing the zero point of the displacement sensor to drift slowly. To address this, this application establishes a periodic baseline calibration mechanism.

[0058] After the battery cell completes a preset number of charge-discharge cycles or runs for a preset duration, the signal processing unit acquires the displacement signal output by the second displacement sensor in a static state, and updates the initial reference value corresponding to the second displacement increment based on the displacement signal.

[0059] In one specific implementation, the preset number of cycles can be set to every 200 charge-discharge cycles, the preset duration can be set to every 3 months, and the resting state can be set to resting the battery cell in a fully charged state for at least 12 hours. The fully charged resting state is chosen for calibration because the battery cell's state of charge is consistent in this state, making the expansion states of different cells more comparable. Regular baseline calibration can offset the zero-point drift caused by long-term stress relaxation of the explosion-proof valve and slow aging of the battery cells, ensuring long-term testing accuracy. The above parameters are only examples; actual settings can be adjusted according to the battery cell type, operating conditions, and accuracy requirements.

[0060] Based on the above-described device embodiments, this application also provides a method for monitoring the deformation of a battery cell explosion-proof valve. This method is applied to the aforementioned battery cell explosion-proof valve deformation monitoring device and is executed collaboratively by the signal processing unit and the early warning unit on the integrated acquisition board. See also... Figure 5 As shown, the method mainly includes the following steps.

[0061] S510, the first displacement increment of the explosion-proof valve region is obtained through the first displacement sensor, and the second displacement increment of the non-explosion-proof valve rigid region is obtained through the second displacement sensor.

[0062] The first displacement sensor is mounted on the integrated acquisition board, with its sensing direction aligned with the center of the explosion-proof valve of the corresponding battery cell. It is used to detect displacement changes in the explosion-proof valve area. The first displacement increment refers to the difference between the current displacement value of the explosion-proof valve area and the initial calibration value. The second displacement sensor is mounted in the non-explosion-proof valve rigid area of ​​the same battery cell. It is used to detect background displacement caused by the overall expansion of the battery cell. The second displacement increment refers to the difference between the current displacement value of the non-explosion-proof valve rigid area and the initial calibration value.

[0063] In practical implementation, after the module assembly is completed, initial calibration is performed first. The module is left to stand for a preset time under set environmental conditions until the internal pressure of the battery cell stabilizes. Then, the first and second displacement sensors of each battery cell are zero-point calibrated, and the initial detected displacement value S00 of the first displacement sensor and the initial reference displacement value Sr0 of the second displacement sensor are recorded. During system operation, the signal processing unit acquires the current detected displacement value St of the first displacement sensor and the current reference displacement value Sr of the second displacement sensor in real time. The first displacement increment is ΔS = St - S00, and the second displacement increment is ΔS0 = Sr - Sr0.

[0064] The first displacement sensor detects the displacement of the explosion-proof valve area, where the displacement change includes both overall cell expansion (background displacement) and local expansion of the explosion-proof valve. The second displacement sensor detects the displacement of the rigid area outside the explosion-proof valve, where the displacement change only includes overall cell expansion (background displacement). By acquiring the displacement increments of the two areas separately, a data basis is provided for subsequent difference calculations to separate the background displacement and the local expansion displacement.

[0065] S520, perform difference calculation based on the first displacement increment and the second displacement increment to obtain the local expansion displacement of the explosion-proof valve area relative to the rigid area of ​​the non-explosion-proof valve; compare the local expansion displacement with the preset graded warning threshold and output the safety warning level of the battery cell.

[0066] The local expansion displacement refers to the local expansion displacement value of the explosion-proof valve area caused by abnormal gas generation inside the battery cell, after excluding the normal expansion background displacement of the battery cell. This value is obtained by subtracting the second displacement increment from the first displacement increment. Since the first displacement increment includes the overall displacement of the explosion-proof valve area (background displacement plus local expansion displacement), and the second displacement increment only includes the overall displacement of the non-explosion-proof valve area (background displacement), the difference between the two, ΔS' = ΔS - ΔS0, is the local expansion displacement of the explosion-proof valve area relative to the non-explosion-proof valve rigid area.

[0067] In practical implementation, the signal processing unit performs a difference calculation on the first displacement increment ΔS and the second displacement increment ΔS0, and outputs the difference ΔS' as the local expansion displacement of the explosion-proof valve of the battery cell. This difference calculation is implemented in the signal processing unit through a differential amplifier or a digital signal processor. When the battery cell is in a normal state, the displacement increments of the explosion-proof valve area and the non-explosion-proof valve area are basically the same, and the difference is close to zero. When abnormal gas generation inside the battery cell causes local expansion in the explosion-proof valve area, the displacement increment of the explosion-proof valve area is greater than the displacement increment of the non-explosion-proof valve area, and the difference is the positive local expansion displacement.

[0068] The early warning unit receives the local expansion displacement ΔS' output by the signal processing unit and compares it with preset first-level and second-level early warning thresholds. The first-level early warning threshold corresponds to the deformation of the explosion-proof valve when the internal pressure of the battery cell reaches a certain percentage (e.g., 30% to 70%) of the rated opening pressure of the explosion-proof valve. The second-level early warning threshold corresponds to the deformation of the explosion-proof valve when the internal pressure of the battery cell reaches a higher percentage (e.g., 70% to 90%) of the rated opening pressure of the explosion-proof valve. If ΔS' is greater than or equal to the first-level early warning threshold but less than the second-level early warning threshold, the early warning unit outputs a first-level safety warning and reports the location information of the battery cell that triggered the warning in the module to the operation management platform. If ΔS' is greater than or equal to the second-level early warning threshold, the early warning unit outputs a second-level safety warning, cuts off the current to the module containing the battery cell that triggered the warning, and initiates a cooling strategy for that module. Through the above-mentioned graded early warning, a sufficient time can be allocated before the explosion-proof valve opens, reserving a time window for emergency response.

[0069] In one specific implementation, the signal processing unit also performs periodic baseline calibration. After each preset number of charge-discharge cycles (e.g., 200 cycles) or each preset operating period (e.g., 3 months), with the battery cell fully charged and left to rest for at least a preset time (e.g., 12 hours), the displacement signal from the second displacement sensor is re-acquired, and the initial reference value Sr0 corresponding to the second displacement increment is updated based on this displacement signal. Periodic baseline calibration can offset the zero-point drift caused by long-term stress relaxation of the explosion-proof valve and slow aging of the battery cell, ensuring long-term detection accuracy. The above values ​​are for illustrative purposes only; actual parameters can be calibrated according to the battery cell type and operating conditions.

[0070] The cell explosion-proof valve deformation monitoring method provided in this application uses a first displacement sensor and a second displacement sensor to collect the displacement increments of the explosion-proof valve area and the rigid area of ​​the non-explosion-proof valve, respectively, and performs difference calculations to effectively separate the normal aging expansion of the cell from the local expansion of the explosion-proof valve caused by abnormal gas generation. Based on this, by comparing graded early warning thresholds, an early warning is triggered before the explosion-proof valve opens, reserving a time window for emergency response while avoiding premature triggering of unnecessary emergency responses.

[0071] Furthermore, this application also provides a specific method for monitoring the deformation of a battery cell explosion-proof valve. See [link to application]. Figure 6 As shown, the method mainly includes steps such as initial calibration, real-time acquisition, displacement compensation calculation, graded early warning judgment, and periodic baseline calibration.

[0072] Initial calibration steps: After the module assembly is completed, it is left to stand for a preset time under set environmental conditions until the internal pressure of the battery cell stabilizes. Then, the first and second displacement sensors of each battery cell are zero-point calibrated. In one specific embodiment, the ambient temperature can be set to 25℃, and the standing time can be set to 12 hours. The initial value of the detected displacement S00 and the initial value of the reference displacement Sr0 are recorded, and the initial relative expansion displacement ΔS'0 is zeroed. The above parameters are only examples; actual calibration can be adjusted according to environmental conditions and battery cell characteristics.

[0073] Real-time data acquisition steps: During the operation of the power battery or energy storage system, the signal processing unit acquires the detected displacement St and reference displacement Sr of each cell in real time. The sampling frequency can be set according to actual needs, for example, at a frequency of 10Hz to 100Hz during vehicle operation or energy storage system charging and discharging, and at a lower frequency when stationary.

[0074] Displacement compensation calculation steps: The signal processing unit calculates the detected displacement increment ΔS = St - S00, the background displacement increment ΔS0 = Sr - Sr0, and then calculates the local expansion displacement ΔS' = ΔS - ΔS0. This local expansion displacement is the local expansion displacement of the explosion-proof valve caused by abnormal gas generation inside the battery cell after eliminating the interference of normal battery cell expansion.

[0075] The tiered early warning determination process involves comparing ΔS' with preset first-level and second-level early warning thresholds. If ΔS' is greater than or equal to the first-level early warning threshold but less than the second-level early warning threshold, a first-level safety early warning is triggered, and the location of the faulty cell is reported to the operation platform. If ΔS' is greater than or equal to the second-level early warning threshold, a second-level safety early warning is triggered, cutting off the current to the corresponding module or battery cluster and initiating a cooling strategy.

[0076] Periodic baseline calibration steps: After each preset number of charge-discharge cycles or after each preset running time, with the battery cell fully charged and left to stand for at least a preset time, recalibrate the reference displacement zero point Sr0 and update the background displacement baseline.

[0077] The technical solution of this application will be fully explained below with reference to a specific engineering application case.

[0078] A certain power battery module consists of 12 square lithium iron phosphate cells with a capacity of 150Ah connected in series. The rated opening pressure of the explosion-proof valve of each cell is 0.6MPa. For this module, an integrated PCB sampling board is configured, with dimensions of 580mm in length, 120mm in width, and 2mm in thickness, corresponding to the arrangement of the 12 cells. Each cell corresponds to a set of detection displacement sensors and a reference displacement sensor, for a total of 12 sets of sensors. The sensors are 6mm diameter miniature inductive displacement sensors, directly soldered to the corresponding pads on the PCB board. The center of the detection displacement sensor corresponds to the center of the cell's explosion-proof valve, with a sensing distance set to 5mm; the reference displacement sensor is located in the plane area next to the negative terminal of the same cell's top cover, 20mm away from the center of the detection displacement sensor. The signal processing circuit is integrated in the unused area of ​​the PCB board. The above dimensions and values ​​are for illustrative purposes only; actual applications can be adjusted according to the specific structure of the module and the cell size.

[0079] After module assembly, the cells were left to stand at 25℃ for 12 hours to allow the internal pressure of the cells to stabilize. Then, the sensors for each cell were zero-point calibrated. The initial displacement value S00 = 1.82 mm was recorded, and the initial reference displacement value Sr0 = 1.78 mm was recorded. Based on the explosion-proof valve opening pressure of 0.6 MPa, and after experimental calibration, the first-level warning threshold was set to 0.12 mm (corresponding to an internal pressure of 0.18 MPa), and the second-level warning threshold was set to 0.32 mm (corresponding to an internal pressure of 0.45 MPa). The above values ​​are for illustrative purposes only; the actual thresholds need to be calibrated according to the specific cell type and explosion-proof valve characteristics.

[0080] After the module completes 1000 charge-discharge cycles under normal operating conditions, the battery cell expands overall. Data collected under a fully charged, stationary state shows: detected displacement St = 2.25 mm, reference displacement Sr = 2.21 mm. The calculated detected displacement increment ΔS = 2.25 - 1.82 = 0.43 mm, background displacement increment ΔS0 = 2.21 - 1.78 = 0.43 mm, and local expansion displacement ΔS' = 0.43 - 0.43 = 0 mm, all far below the first-level warning threshold, and will not trigger an alarm.

[0081] In a simulated abnormal gas generation scenario, the internal pressure of one of the battery cells was increased to 0.2 MPa through gas injection. Data collected at this time showed: detected displacement St = 2.38 mm, reference displacement Sr = 2.21 mm, ΔS = 0.56 mm, ΔS0 = 0.43 mm, and ΔS' = 0.13 mm. This exceeded the first-level warning threshold of 0.12 mm, triggering a first-level safety warning and reporting the location of the faulty battery cell. When the internal pressure increased to 0.48 MPa through gas injection, ΔS' increased to 0.34 mm, exceeding the second-level warning threshold and triggering a second-level safety warning. The system then cut off the current to this module and initiated a cooling strategy. At this point, the explosion-proof valve (rated opening pressure 0.6 MPa) remained closed, allowing sufficient time for emergency response.

[0082] This application integrates multiple sensor units onto a single acquisition board, enabling the deployment of sensors for all battery cells in a single installation. This significantly improves assembly efficiency compared to individual installation methods and reduces manufacturing costs. By using a first displacement sensor and a second displacement sensor to collect displacement signals from the explosion-proof valve area and the rigid area outside the explosion-proof valve, and performing differential calculations, the application effectively separates normal aging expansion of the battery cells from localized expansion of the explosion-proof valve caused by abnormal gas generation, greatly reducing the false alarm rate. Regular baseline calibration compensates for zero-point drift caused by long-term stress relaxation of the explosion-proof valve and slow aging of the battery cells, ensuring long-term detection accuracy. Through tiered warning threshold comparison, a sufficient time is provided before the explosion-proof valve opens to trigger an early warning, reserving a time window for emergency response while avoiding premature triggering of unnecessary emergency responses.

[0083] The method provided in this application embodiment has the same implementation principle and technical effect as the aforementioned device embodiment. For the sake of brevity, any part of the method not mentioned in the embodiment section can be referred to the corresponding content in the aforementioned device embodiment.

[0084] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0085] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A device for monitoring the deformation of a battery cell explosion-proof valve, characterized in that, include: An integrated acquisition board is used to fix it on the top cover of the battery cell module. The integrated acquisition board integrates multiple sets of sensor units, each set of sensor units corresponds to one battery cell, and includes a first displacement sensor and a second displacement sensor. A signal processing unit, disposed on the integrated acquisition board, is electrically connected to the first displacement sensor and the second displacement sensor, and is used to determine the local expansion displacement of the explosion-proof valve region of the battery cell relative to the non-explosion-proof valve rigid region based on the displacement signals output by the first displacement sensor and the second displacement sensor respectively.

2. The apparatus according to claim 1, characterized in that, The sensing direction of the first displacement sensor is aligned with the center of the explosion-proof valve of the corresponding battery cell; the sensing direction of the second displacement sensor is aligned with the rigid area on the top cover of the same battery cell that is far from the center of the explosion-proof valve.

3. The apparatus according to claim 1, characterized in that, The integrated acquisition board has a rectangular plate structure. The layout of the integrated acquisition board matches the arrangement of the battery cells in the battery cell module, so that the first displacement sensor and the second displacement sensor in each group of sensor units are respectively aligned vertically with the explosion-proof valve area and the non-explosion-proof valve rigid area of ​​the corresponding battery cell top cover.

4. The apparatus according to claim 3, characterized in that, The integrated acquisition board is fixed to the busbar bracket of the battery cell module by bolts or clips.

5. The apparatus according to claim 1, characterized in that, The first displacement sensor and the second displacement sensor are selected from any one of inductive displacement sensors, laser displacement sensors, eddy current displacement sensors, magnetostrictive displacement sensors, and pole pitch changing capacitive displacement sensors.

6. The apparatus according to claim 1, characterized in that, The signal processing unit is specifically used for: Receive displacement signals output by the first displacement sensor and the second displacement sensor respectively; The first displacement increment of the explosion-proof valve region is determined based on the displacement signal output by the first displacement sensor, and the second displacement increment of the non-explosion-proof valve rigid region is determined based on the displacement signal output by the second displacement sensor. The difference between the first displacement increment and the second displacement increment is calculated to obtain the local expansion displacement.

7. The apparatus according to claim 6, characterized in that, The signal processing unit is also used for: The displacement signal output by the second displacement sensor is obtained after the battery cell has completed a preset number of charge-discharge cycles or has been running for a preset time, and is in a static state. The initial reference value corresponding to the second displacement increment is updated based on the displacement signal.

8. The apparatus according to claim 1, characterized in that, The device further includes: The early warning unit, electrically connected to the signal processing unit, is used to receive the local expansion displacement, compare the local expansion displacement with a preset graded early warning threshold, and output the corresponding safety early warning level.

9. The apparatus according to claim 8, characterized in that, The early warning unit is specifically used for: The local expansion displacement is compared with the first-level warning threshold. If the local expansion displacement is greater than or equal to the first-level warning threshold, the first-level safety warning is output and the location information of the cell that triggered the first-level safety warning in the cell module is reported to the operation management platform. The local expansion displacement is compared with the secondary warning threshold. If the local expansion displacement is greater than or equal to the secondary warning threshold, a second-level safety warning is output, and the current of the module containing the cell that triggered the second-level safety warning is cut off, and a cooling strategy for the module is initiated.

10. A method for monitoring the deformation of a battery cell explosion-proof valve, characterized in that, The method applied to the cell explosion-proof valve deformation monitoring device according to claim 1 includes: The first displacement increment of the explosion-proof valve region is obtained by the first displacement sensor, and the second displacement increment of the rigid region of the non-explosion-proof valve is obtained by the second displacement sensor. Based on the difference calculation between the first displacement increment and the second displacement increment, the local expansion displacement of the explosion-proof valve region relative to the rigid region of the non-explosion-proof valve is obtained; The local expansion displacement is compared with a preset graded warning threshold, and the safety warning level of the battery cell is output.

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