Battery module detection system and detection method

Abstract

The application discloses a battery module detection system and a detection method, and relates to the field of ion capacitor type thin film sensors. The battery module detection system comprises a tool clamp, an ion capacitor type thin film sensor and a signal processing module. The ion capacitor type thin film sensor is used for outputting a first capacitor, a second capacitor and a third capacitor. The first capacitor and the second capacitor contain a pressure signal and a noise signal, and the third capacitor only contains the noise signal. The signal processing module is used for converting the first capacitor, the second capacitor and the third capacitor into a first voltage, a second voltage and a third voltage, and then processing the first voltage, the second voltage and the third voltage into a real voltage containing only the pressure signal. The first pressure value of the battery module is calculated based on the real voltage. The application eliminates the noise through physical hardware and differential operation, retains the pure pressure signal and accurately separates the pressure signal from the environmental noise.

Description

Technical Field

[0001] This invention belongs to the field of pressure sensor technology, specifically relating to a battery module detection system and detection method. Background Technology

[0002] In the manufacturing and service life of battery modules, real-time monitoring of cell expansion force is one of the core methods for assessing battery state of health (SOH) and predicting the risk of thermal runaway. By measuring the changes in surface pressure during battery charging and discharging, faults such as internal short circuits and electrolyte drying can be indirectly identified. Therefore, high-precision, long-term stable pressure sensing technology is crucial for improving battery safety.

[0003] There is still room for improvement in the pressure sensors currently used in battery modules: 1. The dielectric layer material of the current pressure sensor is prone to material creep and ion escape during long-term use, which seriously affects the mechanical strength and durability of the dielectric layer, leading to baseline drift or even functional failure of the sensor; 2. Noise signals during battery charging and discharging can be coupled into the pressure signal, and traditional single-channel sensing cannot distinguish between real pressure and environmental noise.

[0004] It should be noted that this part of the present invention only provides background technology related to the present invention, and does not necessarily constitute prior art or known technology. Summary of the Invention

[0005] This invention provides a battery module testing system and method, which at least solves the problem of data failure caused by environmental interference in the long-term battery testing of existing pressure sensors.

[0006] To achieve the above objectives, in one aspect, the present invention provides a battery module testing system, including a tooling fixture, an ion-capacitive thin-film sensor, and a signal processing module; the battery module is disposed within the tooling fixture, and the ion-capacitive thin-film sensor is disposed on the battery module; the ion-capacitive thin-film sensor includes a dielectric layer, a first electrode, a second electrode, and a third electrode; the top surface of the dielectric layer is planar, and both the first and second electrodes are disposed on the top surface of the dielectric layer and are completely attached to the top surface; the bottom surface of the dielectric layer has a concave-convex microstructure for sensing pressure, and the third electrode is disposed on the bottom surface of the dielectric layer and abuts against the concave-convex microstructure; the first electrode and the third electrode are shaped as follows: A first sensing path is formed to output the first capacitor, a second electrode and a third electrode form a second sensing path to output the second capacitor, and a third sensing path to output the third capacitor is formed by the first electrode and the second electrode. The first and second capacitors contain pressure signals and noise signals, while the third capacitor contains only noise signals. A signal processing module is electrically connected to an ion-capacitive thin-film sensor to convert the first, second, and third capacitors into a first voltage, a second voltage, and a third voltage, respectively. The first, second, and third voltages are then processed into real voltages containing only pressure signals, and the first pressure value of the battery module is calculated based on the real voltages.

[0007] Preferably, the first electrode and the second electrode are independent interdigitated electrodes or separate electrodes.

[0008] Preferably, the first electrode and the second electrode are coaxially nested spiral interdigitated structures, both extending outward in a clockwise direction from different origins; the spiral fingers of the first electrode and the spiral fingers of the second electrode are arranged alternately to form a continuous and uniformly wide gap.

[0009] Preferably, the gaps are filled with the same material as the dielectric layer so that both the first electrode and the second electrode are fully attached to the top surface of the dielectric layer and the top surface is flat.

[0010] Preferably, the dielectric layer is formed by cross-linking a uniformly dispersed ionic liquid in polyvinylidene fluoride.

[0011] Preferably, the signal processing module includes a capacitive-to-voltage conversion unit, a differential operation unit, and a pressure conversion unit; the capacitive-to-voltage conversion unit is used to convert the first capacitor, the second capacitor, and the third capacitor into a first voltage, a second voltage, and a third voltage; the differential operation unit is used to process the first voltage, the second voltage, and the third voltage into a real voltage containing only pressure signals through differential operation; the pressure conversion unit calculates the first pressure value of the battery module based on the real voltage.

[0012] Preferably, the detection system further includes a data acquisition board for acquiring the first pressure value output by the signal processing module and uploading it to the data terminal.

[0013] Preferably, the detection system further includes an auxiliary weighing sensor, which is installed in the tooling fixture and is used to collect the second pressure value of the battery module. After the acquisition board uploads the first pressure value and the second pressure value to the data terminal, the data terminal compares the first pressure value and the second pressure value to determine the validity of the acquisition by the ion capacitive thin film sensor.

[0014] On the other hand, the present invention provides a battery module testing method, which is applied to the above-mentioned battery module testing system, and the testing method includes:

[0015] The first capacitance, the second capacitance, and the third capacitance are obtained using an ion-capacitive thin-film sensor.

[0016] Convert the first capacitor, the second capacitor, and the third capacitor into a first voltage, a second voltage, and a third voltage;

[0017] Differential operations are used to process the first voltage, the second voltage, and the third voltage into real voltages containing only pressure signals.

[0018] The first pressure value of the battery module is calculated based on the actual voltage.

[0019] Preferably, the detection method further includes:

[0020] Simultaneously acquire the second pressure value from the auxiliary weighing sensor;

[0021] When the absolute value of the difference between the first pressure value and the second pressure value is greater than a preset threshold, the ion capacitive thin-film sensor is determined to be faulty.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. This invention innovatively designs a sandwich interdigital electrode structure (top spiral interdigital electrode + middle dielectric layer + bottom electrode), and uses three capacitive sensing paths to achieve differential noise reduction. The first / second sensing paths output a mixed signal containing pressure and noise; the third sensing path outputs only the ambient noise signal. Noise is eliminated through physical hardware and differential operation, retaining the pure pressure signal and accurately separating the pressure signal from the ambient noise.

[0024] 2. This invention uses polyvinylidene fluoride (PVDF)-based composite material as the core material of the dielectric layer, and performs functional modification on it by uniformly dispersing a highly stable ionic liquid to form a stable three-dimensional network structure. This design effectively suppresses material creep and ion escape, enhances mechanical strength and durability, solves the problem of long-cycle data failure caused by material degradation in traditional pressure sensors, and significantly improves the long-cycle stability of the sensor.

[0025] 3. This invention integrates an auxiliary weighing sensor and an ion-capacitive thin-film sensor to simultaneously monitor the battery module pressure. The data terminal compares the two pressure values ​​in real time, and determines that the main sensor has failed when the deviation exceeds a preset threshold, thus realizing a self-verification function in long-term monitoring. Cross-verification by the two sensors ensures data reliability. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the battery module testing system provided in an embodiment of the present invention;

[0028] Figure 2 This is a top view of the ion-capacitive thin-film sensor provided in an embodiment of the present invention.

[0029] Figure 3 A bottom view of the ion-capacitive thin-film sensor provided in an embodiment of the present invention;

[0030] Figure 4 This is a schematic cross-sectional view of the unfilled gap of the ion-capacitive thin-film sensor provided in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the cross-sectional structure of the ion-capacitive thin-film sensor after filling the gap, as provided in an embodiment of the present invention.

[0032] Figure 6 A digital optical mirror image of the unfilled gap structure of the ion-capacitive thin-film sensor provided in an embodiment of the present invention;

[0033] Figure 7 A digital optical mirror image of the top view of the ion-capacitive thin-film sensor after the gaps have been filled, as provided in an embodiment of the present invention.

[0034] Figure 8 for Figure 7 A magnified view of the central area.

[0035] Explanation of reference numerals in the attached figures:

[0036] 100. Tooling fixture; 110. First pressure plate; 120. Second pressure plate; 130. Third pressure plate; 140. Screw;

[0037] 200. Ion capacitive thin-film sensor; 210. Dielectric layer; 220. First electrode; 230. Second electrode; 240. Third electrode;

[0038] 300. Data acquisition board;

[0039] 400, Data Terminal;

[0040] 500. Auxiliary weighing sensor;

[0041] 600. Battery module. Detailed Implementation

[0042] In this invention, unless otherwise stated, directional terms such as "up," "down," "left," and "right" are generally understood in conjunction with the accompanying drawings and the directions shown in actual applications.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0045] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. The terms "optional" and "discretionary" mean that they may or may not be included (or may or may not be present).

[0046] This invention provides a battery module 600 testing system, such as... Figure 1 , Figure 2 , Figure 3 , Figure 5As shown, the system includes a fixture 100, an ion-capacitive thin-film sensor 200, and a signal processing module. A battery module 600 is disposed within the fixture 100, and the ion-capacitive thin-film sensor 200 is disposed on the battery module 600. The ion-capacitive thin-film sensor 200 includes a dielectric layer 210, a first electrode 220, a second electrode 230, and a third electrode 240. The top surface of the dielectric layer 210 is planar, and both the first electrode 220 and the second electrode 230 are disposed on the top surface of the dielectric layer 210 and are completely attached to the top surface. The bottom surface of the dielectric layer 210 has a concave-convex microstructure for sensing pressure, and the third electrode 240 is disposed on the bottom surface of the dielectric layer 210 and abuts against the concave-convex microstructure. The first electrode 220 and... The third electrode 240 forms a first sensing path for outputting the first capacitor, the second electrode 230 and the third electrode 240 form a second sensing path for outputting the second capacitor, and the first electrode 220 and the second electrode 230 form a third sensing path for outputting the third capacitor. The first and second capacitors contain pressure signals and noise signals, while the third capacitor contains only noise signals. The signal processing module is electrically connected to the ion-capacitive thin-film sensor 200 and is used to convert the first, second, and third capacitors into a first voltage, a second voltage, and a third voltage, respectively. Then, the first, second, and third voltages are processed into real voltages containing only pressure signals, and the first pressure value of the battery module 600 is calculated based on the real voltages.

[0047] This invention innovatively designs a sandwich interdigital electrode structure (top spiral interdigital electrode + middle dielectric layer 210 + bottom electrode), and uses three capacitive sensing paths to achieve differential noise reduction. The first / second sensing paths output a mixed signal containing pressure and noise; the third sensing path outputs only the ambient noise signal. Noise is eliminated through physical hardware and differential operation, retaining the pure pressure signal and accurately separating the pressure signal from the ambient noise.

[0048] Preferably, such as Figure 1 As shown, the tooling fixture 100 includes a first pressure plate 110, a second pressure plate 120, and a third pressure plate 130 arranged sequentially at intervals. Each of the three pressure plates is secured by screws 140 passing through its perimeter. The battery module 600 and the ion-capacitive thin-film sensor 200 are positioned between the first pressure plate 110 and the second pressure plate 120, while the auxiliary weighing sensor 500 is positioned between the second pressure plate 120 and the third pressure plate 130.

[0049] Preferably, the first electrode 220, the second electrode 230, and the third electrode 240 are made of conductive materials such as metal foil or conductive polymers, such as silver paste, carbon paste, nickel paste screen-printed electrodes, copper foil, etc.

[0050] It should be noted that environmental noise signals include: 1. Temperature fluctuation noise (caused by changes in ambient temperature leading to alterations in the dielectric constant, viscosity, and ion mobility of the ionic liquid, resulting in capacitance drift); 2. Humidity change noise (caused by changes in ambient humidity leading to hygroscopic changes in capacitance due to hygroscopic impurities or hygroscopic absorption or loss of moisture by the ionic liquid); 3. Solvation effect noise (caused by residual high-boiling-point solvents, treatment agents, or moisture affecting the properties of the ionic liquid, resulting in nonlinear capacitance drift). These noise signals, by altering the capacitance characteristics of the electrode-ion conductive film interface double layer, are coupled into the capacitance values ​​of all sensing pathways in a common-mode manner.

[0051] Preferably, such as Figure 5 As shown, the side of the third electrode 240 facing the dielectric layer 210 can be relatively flat with the dielectric layer 210. The relatively flat third electrode 240 and the side of the dielectric layer 210 with microstructures form a pressure-modulated double-layer capacitor structure. The surfaces of the first electrode 220 and the second electrode 230 can be uneven, but because the first electrode 220 and the second electrode 230 are closely attached to the dielectric layer 210, a relatively large and fixed double-layer capacitor structure can be formed.

[0052] Preferably, the mechanism of the first sensing path is that current (or signal) flows in from the first electrode, passes through the double-layer capacitance at the interface between the first electrode and the ion gel, is then conducted within the ion gel body, passes through the double-layer capacitance at the interface between the third electrode and the ion gel, and finally reaches the third electrode. The entire path can be equivalent to a series circuit of two double-layer capacitors and one ion gel body resistor. The signal measured is the signal of this composite impedance, where the pressure modulates the double-layer capacitor structure formed by the microstructure on the side of the dielectric layer 210 with the third electrode 240.

[0053] Preferably, the mechanism of the second sensing pathway is similar to that of the first sensing pathway, and will not be elaborated further here.

[0054] Preferably, the mechanism of the third sensing path is as follows: current (or signal) flows in from the first electrode, passes through the double-layer capacitor with a fixed contact area formed at the interface between the first electrode and the ionogel, then conducts in the plane containing the top surface of the dielectric layer, and finally reaches the second electrode via the double-layer capacitor at the interface between the second electrode and the ionogel. This path is equivalent to a series circuit of two double-layer capacitors and one ionogel resistor. Since both the first and second electrodes are completely, tightly, and fixedly attached to the flat top surface of the dielectric layer, the effective contact area between them does not change with external pressure. Therefore, the equivalent capacitance of the third sensing path is not sensitive to pressure, and its change is mainly or entirely modulated by environmental noise signals that can simultaneously affect the properties of the dielectric layer material, thus becoming a pure noise reference channel.

[0055] Preferably, both the first and second sensing paths span the thickness direction of the dielectric layer 210, wherein the bottom surface of the dielectric layer 210 has a pressure-sensing microstructure, and the third electrode 240 is relatively flatly covered on it. When pressure is applied to the sensor, the deformation of the microstructure causes a significant change in the effective contact area between the third electrode 240 and the bottom surface of the dielectric layer 210, thereby directly modulating the first and second capacitors. Since ambient noise signals effectively affect the dielectric properties between all electrodes, the first and second capacitors simultaneously contain the actual pressure signal (caused by the change in contact area) and the coupled ambient noise signal. Conversely, the third sensing path is located on the flat top surface of the dielectric layer 210, and the first electrode 220 and the second electrode 230 are completely, tightly, and fixedly attached to the top surface, forming a stable in-plane third capacitor. Pressure has negligible effect on the horizontal distance between these two tightly attached electrodes on the top surface, so the third capacitor is almost unaffected by pressure modulation, and its changes are mainly or entirely caused by ambient noise signals. Through this physical structure design, the third capacitor can serve as a pure noise reference channel.

[0056] Preferably, the first electrode 220 and the second electrode 230 are independent interdigitated electrodes or separate electrodes. More preferably, the first electrode 220 and the second electrode 230 are independent interdigitated electrodes. The purpose is to achieve high consistency acquisition of dual-path pressure signals and maximize coupling of common-mode noise through spatial symmetry and electrical isolation. Specifically, the interdigitated electrodes form a highly symmetrical and uniformly spaced interactive distribution of the first electrode 220 and the second electrode 230 on the top surface of the dielectric layer 210. This design ensures that the first sensing path and the second sensing path have exactly the same electrode spacing, coverage area, and electric field distribution characteristics, thereby generating capacitance change signals with equal amplitude and synchronized phase when pressure is applied, providing a matching raw input for subsequent differential operations. At the same time, due to the symmetry and proximity of the two paths in physical structure, environmental noise will be coupled into the first capacitor and the second capacitor with almost the same amplitude and phase, making the noise behave as a strict common-mode signal.

[0057] Preferably, such as Figure 2 As shown, the first electrode 220 and the second electrode 230 are coaxially nested spiral interdigitated structures. They both extend outward in a clockwise direction from different origins. The spiral fingers of the first electrode 220 and the spiral fingers of the second electrode 230 are arranged alternately to form a continuous and uniformly wide gap.

[0058] Preferably, a coaxial nested helical interdigitated electrode design is adopted. The electric field generated by the helical path is highly continuous and uniformly gradient-distributed within the sensing region, fundamentally eliminating the electric field concentration or distortion phenomena present at the fingertips and corners of traditional linear interdigitated electrodes. This uniform electric field ensures that the capacitance change rate caused by deformation of the dielectric layer microstructure under any pressure point remains highly consistent, significantly reducing the nonlinear error of the sensor and laying the physical foundation for measurement across the entire range. Because the two electrodes adopt a coaxial and unidirectional helical design, the electrical path length from the excitation source to the end of the sensing unit is statistically completely symmetrical and equal for the first and second sensing paths. This structure ensures that when high-frequency noise or rapidly changing pressure signals propagate in the ionogel, the transmission delay and phase drift experienced in the two paths are nearly identical, ensuring high synchronization of the signal in the time domain and providing a key guarantee for noise cancellation in subsequent differential operations. The continuity and global symmetry of the helical structure allow environmental noise from any source to be synchronously coupled into the first and second sensing paths in common-mode form. The forced noise synchronization of this physical structure makes the noise components in the output signals of the two paths highly correlated in terms of amplitude and phase, so that they can be canceled by the reference signal of the third path in the subsequent differential operation, thereby improving the actual common-mode rejection ratio of the signal processing circuit.

[0059] It is understandable that, such as Figure 4 and Figure 6 As shown, Figure 4 and Figure 6 The diagram illustrates a scenario where the gap between the first electrode 220 and the second electrode 230 is not filled with dielectric layer 210 material. It can be seen that the top layer of dielectric layer 210 is not flat; its top surface has continuous gaps and depressions. Without filling material, the bottoms of the first electrode 220 and the second electrode 230 cannot achieve physical contact with the top surface of dielectric layer 210. In this case, when pressure is applied to the ion-capacitive thin-film sensor 200, because the top surface of dielectric layer 210 is not flat, pressure signals will still be generated when the first electrode 220 and the second electrode 230 contact the top surface of dielectric layer 210, making it unsuitable as a reference for a pure noise signal. Simultaneously, the third capacitor relies on the horizontal electric field between the first electrode 220 and the second electrode 230, and the air in the gap and the dielectric layer 210 material also create a significant difference in dielectric constant, resulting in the third capacitor containing non-uniform noise signals.

[0060] Preferably, such as Figure 5 , Figure 7 and Figure 8As shown, the present invention fills the gap between the first electrode 220 and the second electrode 230 with the same material as the dielectric layer 210 so that both the first electrode 220 and the second electrode 230 are completely in contact with the top surface of the dielectric layer 210 and the top surface is flat. Filling the gap with the dielectric layer 210 material not only maintains the flatness of the top surface of the dielectric layer 210 to ensure the pure noise reference function of the third sensing path, but also eliminates other dielectrics so that the third capacitance between the first electrode 220 and the second electrode 230 is completely dominated by the stable solid dielectric material, avoiding interference from other factors to the noise channel.

[0061] Preferably, the third sensing path, because the first electrode 220 and the second electrode 230 are located on the same plane of the dielectric layer 210 and are closely attached, has almost no response to vertical pressure, becoming a pure noise reference channel, thus greatly improving anti-interference capability. The top-layer dual electrodes adopt a coaxial nested spiral structure to achieve uniform electric field distribution across the entire domain, eliminate edge effects, and achieve pressure response consistency far superior to discrete array layouts. Simultaneously, by physically isolating the noise reference path from the pressure path—the noise path being located in the horizontal plane (unaffected by pressure modulation) and the pressure path being located in the vertical direction (subject to pressure modulation)—signal coupling problems are effectively avoided.

[0062] Preferably, the dielectric layer 210 is formed by crosslinking a uniformly dispersed ionic liquid in polyvinylidene fluoride. Specifically, in one embodiment, the dielectric layer 210 can be formed by curing an ionic gel solution. The ionic gel solution can be obtained by uniformly mixing a PVDF-based polymer, an ionic liquid, a wetting agent, a solvent, and a filler. The PVDF-based polymer can include a first PVDF-based polymer and a second PVDF-based polymer; for example, the first PVDF-based polymer includes PVDF, and the second PVDF-based polymer includes PVDF-HFP. The anions of the ionic liquid include at least one selected from hexafluorophosphate anion, tetrafluoroborate anion, bis(trifluoromethanesulfonyl)imide anion, trifluoromethanesulfonate anion, acetate anion, dicyandiamide anion, bromide anion, ethyl sulfate anion, and hydrothioate anion. The cations of the ionic liquid include at least one selected from 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, and 1-octyl-3-methylimidazolium cation. The wetting agent includes dimethyl carbonate; the solvent includes at least one of acetone, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran. The filler includes at least one of nano-iron oxide, nano-ferric oxide, nano-alumina, nano-calcium carbonate, nano-zinc oxide, nano-tin oxide, nano-cerium oxide, and fumed silica.

[0063] In this embodiment, the first PVDF-based polymer has high crystallinity and high content, enabling it to spontaneously form microstructures (spherical or near-spherical structures). The second PVDF-based polymer has low crystallinity and low content, and during film formation, it participates less in the formation of the polymer skeleton of spherical or near-spherical structures, thus acting to bond the spherical or near-spherical structures formed by the first PVDF-based polymer together, forming a stable polymer ionogel particle layer. Adding fillers to the ionogel solution promotes the spontaneous formation of the polymer ionogel particle layer, improves the consistency of the uneven structure on one side of the dielectric layer 210, and avoids inconsistencies in strength, resilience, and sensitivity at different points of the gel film. As an example, the specific preparation method of the ionogel solution can be found in previous patents CN119060387A and CN119060476A. However, it should be noted that the ionogel solution in this application can also be prepared using other components, and this application does not impose any restrictions on this.

[0064] Furthermore, the bottom surface of the dielectric layer has uneven microstructures for sensing pressure. These microstructures can be in the form of nanopores, microchannels, microprotrusions, etc. These microstructures can increase the surface area of ​​the ion exchange membrane, improve ion conduction efficiency, and help improve the capacitance effect. The shape of the microstructures can be referred to in the descriptions in patents CN119060476B and CN119060387B, and will not be repeated here.

[0065] Preferably, the signal processing module includes a capacitance-voltage conversion unit, a differential operation unit, and a pressure conversion unit; the capacitance-voltage conversion unit is used to convert the first capacitor, the second capacitor, and the third capacitor into a first voltage, a second voltage, and a third voltage; the differential operation unit is used to process the first voltage, the second voltage, and the third voltage into a real voltage containing only pressure signals through differential operation; the pressure conversion unit calculates the first pressure value of the battery module 600 based on the real voltage.

[0066] Preferably, the specific implementation of the capacitive-voltage conversion circuit can be referred to the description of existing technologies such as CN118961004B and CN118961003B, the contents of which are incorporated into this application and will not be repeated here.

[0067] Preferably, the differential operation unit is composed of multi-cascaded circuits used to eliminate environmental noise and extract a pure pressure signal. Specifically, it includes an input buffer stage, a signal synthesis stage, a programmable noise gain stage, and a noise cancellation output stage. The input buffer stage uses three independent instrumentation amplifiers to perform impedance isolation and signal conditioning on the first voltage (V1), second voltage (V2), and third voltage (V3), ensuring that the original capacitor-converted voltage is transmitted to subsequent circuits without distortion. The signal synthesis stage uses a precision operational amplifier and a matching resistor network to form an adder, outputting the average value V of the mixed signal. avg= (V1 + V2) / 2. The programmable noise gain stage uses a digital potentiometer to apply a pre-calibrated correction coefficient k, converting V3 to k·V3; this k value is determined through factory calibration. The capacitive pressure sensor is placed in a zero-pressure state in a programmable temperature and humidity chamber, and the following cycle is performed: under standard atmospheric pressure, the ambient temperature is cyclically varied between -40℃ and 85℃, and the relative humidity is varied between 10%RH and 90%RH. During this process, the voltage V of the first sensing path is simultaneously acquired. 1噪声 The voltage V of the second sensing path 2噪声 and the voltage V of the third sensing path 3噪声 According to the formula k=(V 1噪声 +V 2噪声 ) / 2V 3噪声 The correction factor k is calculated. The noise cancellation output stage uses a differential amplifier to perform V. true =V avg The -k·V3 operation outputs the true voltage containing only the pressure signal. This circuit structure compensates for the noise coupling amplitude deviation between the first / second and third sensing paths caused by electrode geometric differences through a correction coefficient k, achieving accurate cancellation of ambient noise across the entire range.

[0068] Preferably, the present invention cancels common-mode noise in real time through hardware circuits, and the noise can be removed by the correction coefficient k obtained by the previous single-point calibration. It does not require a complex, multi-parameter online calibration model or nonlinear compensation algorithm, which simplifies the signal processing flow and reduces the dependence on external computing resources.

[0069] It should be noted that the specific circuit implementation of the aforementioned differential operation unit (including the input buffer stage, signal synthesis stage, programmable noise gain stage, and noise cancellation output stage) is merely an exemplary implementation scheme, essentially an engineering optimization variant of the differential amplifier circuit. Within the technical framework of this invention, the core of differential processing of the first voltage, the second voltage, and the third voltage lies in performing differential operations, i.e., V... true =f1(V1,V2)-f2(V3) (where f1(V1,V2) is the synthesis function of the dual-channel pressure signals and f2(V3) is the noise channel correction function), and the hardware architecture for implementing this operation can be extended to any differential processing system based on analog or digital circuits.

[0070] Preferably, the specific implementation of the pressure conversion unit can be referred to the descriptions of existing technologies such as CN119564386B and CN119595150A, which will not be repeated here.

[0071] Preferably, such as Figure 1 As shown, the detection system also includes a data acquisition board 300, which is used to acquire the first pressure value output by the signal processing module and upload it to the data terminal 400.

[0072] Preferably, such as Figure 1 As shown, the detection system also includes an auxiliary weighing sensor 500, which is installed in the tooling fixture 100. The auxiliary weighing sensor 500 is used to collect the second pressure value of the battery module 600. After the acquisition board 300 uploads the first pressure value and the second pressure value to the data terminal 400, the data terminal 400 compares the first pressure value and the second pressure value to determine the validity of the acquisition by the ion capacitive thin film sensor 200.

[0073] In some implementations, the acquisition board 300 can upload the first pressure value and the second pressure value to the data terminal 400 via a wireless communication module (such as Bluetooth, Wi-Fi, Zigbee, etc.), a wired transmission method (such as a serial port, USB port, Ethernet, etc.), or a storage method (such as a TF card, SD card, FLASH storage chip, etc.).

[0074] In one embodiment, the data terminal 400 may be a smartphone, tablet, laptop, embedded computer, wearable device, or cloud server, etc.

[0075] This invention provides a method for testing a battery module 600. The method is applied to the aforementioned battery module 600 testing system, and the testing method includes:

[0076] The first capacitance, the second capacitance, and the third capacitance are obtained by the ion capacitive thin-film sensor 200.

[0077] Specifically, when the battery module 600 is tested, the battery module applies pressure to the ion-capacitive thin-film sensor 200, and the ion-capacitive thin-film sensor 200 acquires in real time the first capacitor (C1) output by the first sensing path, the second capacitor (C2) output by the second sensing path, and the third capacitor (C3) output by the third sensing path. Among them, C1 and C2 are mixed capacitance signals containing pressure signals and environmental noise, and C3 is a reference capacitance signal containing only environmental noise.

[0078] Convert the first capacitor, the second capacitor, and the third capacitor into a first voltage, a second voltage, and a third voltage;

[0079] Specifically, the capacitor-to-voltage conversion unit in the signal processing module converts C1, C2, and C3 into the corresponding first voltage (V1), second voltage (V2), and third voltage (V3), respectively. The conversion process uses a low-noise instrumentation amplifier for impedance isolation and signal conditioning to ensure that the voltage signal is transmitted to the differential operation unit without distortion.

[0080] Differential operations are used to process the first voltage, the second voltage, and the third voltage into real voltages containing only pressure signals.

[0081] Specifically, noise cancellation is performed by a differential operation unit to generate a true voltage (V) containing only the pressure signal. true ): Calculate the average value V of the dual-channel pressure signals. avg = (V1 + V2) / 2; Based on the pre-calibrated correction coefficient k, convert the noise reference signal to k·V3. Execute V true =V avg -k·V3 operation, stripping away environmental noise.

[0082] The correction factor k is determined through factory calibration: Temperature and humidity changes are applied under zero pressure, and the average noise voltage of three channels is collected, according to k = (V... 1噪声 +V 2噪声 ) / 2V 3噪声 Calculated;

[0083] The first pressure value of battery module 600 was calculated based on the actual voltage.

[0084] Through the pressure conversion unit, V true The value is mapped to the real-time pressure value (P1) of battery module 600. The mapping relationship is based on a preset pressure-voltage calibration curve, which is established by fitting the curve under a known pressure load through calibration experiments.

[0085] Preferably, the detection method further includes:

[0086] Simultaneously acquire the second pressure value of the auxiliary weighing sensor 500;

[0087] When the absolute value of the difference between the first pressure value and the second pressure value is greater than the preset threshold, the ion capacitive thin film sensor 200 is determined to be faulty.

[0088] The second pressure value (P2) output by the auxiliary weighing sensor 500 is acquired synchronously, and P1 and P2 are uploaded to the data terminal 400. The data terminal 400 calculates the absolute value of the difference between the two, ΔP = |P1-P2|. If ΔP exceeds the preset threshold (set according to the allowable deviation range of the expansion force of the battery module 600), the main ion capacitive thin film sensor 200 is determined to be faulty, triggering the calibration alarm mechanism.

[0089] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A battery module testing system, characterized in that, include: The battery module is housed within the tooling fixture. An ion-capacitive thin-film sensor is disposed on the battery module; The ion-capacitive thin-film sensor includes a dielectric layer, a first electrode, a second electrode, and a third electrode. The top surface of the dielectric layer is planar, and both the first and second electrodes are disposed on the top surface of the dielectric layer and are completely attached to it. The bottom surface of the dielectric layer has a concave-convex microstructure for sensing pressure, and the third electrode is disposed on the bottom surface of the dielectric layer and abuts against the concave-convex microstructure. The first electrode and the third electrode form a first sensing path for outputting a first capacitance, the second electrode and the third electrode form a second sensing path for outputting a second capacitance, and the first electrode and the second electrode form a third sensing path for outputting a third capacitance. The first and second capacitances contain pressure signals and noise signals, while the third capacitance contains only noise signals. The signal processing module is electrically connected to the ion capacitive thin-film sensor and is used to convert the first capacitor, the second capacitor, and the third capacitor into a first voltage, a second voltage, and a third voltage, respectively. Then, it processes the first voltage, the second voltage, and the third voltage into a real voltage containing only pressure signals through differential operation, and calculates the first pressure value of the battery module based on the real voltage.

2. The battery module testing system according to claim 1, characterized in that, The first electrode and the second electrode are independent interdigitated electrodes.

3. The battery module testing system according to claim 2, characterized in that, The first electrode and the second electrode are coaxially nested spiral interdigitated structures, both extending outward in a clockwise direction from different origins; the spiral fingers of the first electrode and the spiral fingers of the second electrode are arranged alternately to form a continuous and uniformly wide gap.

4. The battery module testing system according to claim 3, characterized in that, The gaps are filled with the same material as the dielectric layer so that both the first electrode and the second electrode are completely in contact with the top surface of the dielectric layer and the top surface is flat.

5. The battery module testing system according to claim 1, characterized in that, The dielectric layer is formed by cross-linking of a uniformly dispersed ionic liquid in polyvinylidene fluoride.

6. The battery module testing system according to claim 1, characterized in that, The signal processing module includes: A capacitive-to-voltage conversion unit is used to convert the first capacitor, the second capacitor, and the third capacitor into a first voltage, a second voltage, and a third voltage, respectively. The differential operation unit is used to process the first voltage, the second voltage, and the third voltage into a real voltage containing only pressure signals through differential operation; A pressure conversion unit calculates the first pressure value of the battery module based on the actual voltage.

7. The battery module testing system according to claim 1, characterized in that, The detection system also includes a data acquisition board and a data terminal, used to acquire the first pressure value output by the signal processing module and upload it to the data terminal.

8. The battery module testing system according to claim 7, characterized in that, The detection system also includes an auxiliary weighing sensor, which is disposed in the tooling fixture and is used to collect the second pressure value of the battery module. After the acquisition board uploads the first pressure value and the second pressure value to the data terminal, the data terminal compares the first pressure value and the second pressure value to determine the validity of the acquisition by the ion capacitive thin film sensor.

9. A method for testing a battery module, characterized in that, The battery module testing method is applied to the battery module testing system as described in any one of claims 1 to 8, and the testing method includes: The first capacitance, the second capacitance, and the third capacitance are obtained using an ion-capacitive thin-film sensor. The first capacitor, the second capacitor, and the third capacitor are converted into a first voltage, a second voltage, and a third voltage; Differential operations are used to process the first voltage, the second voltage, and the third voltage into real voltages containing only pressure signals. The first pressure value of the battery module is calculated based on the actual voltage.

10. The battery module testing method according to claim 9, characterized in that, The detection system further includes an auxiliary weighing sensor, which is disposed within the tooling fixture and is used to collect a second pressure value of the battery module; the detection method further includes: Simultaneously acquire the second pressure value from the auxiliary weighing sensor; When the absolute value of the difference between the first pressure value and the second pressure value is greater than a preset threshold, the ion capacitive thin-film sensor is determined to be faulty.

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