Battery pack insulation detection method and device and storage medium

Abstract

The invention discloses a battery pack insulation detection method and device and a storage medium, and the method comprises the steps: obtaining a first insulation parameter and a second insulation parameter of each battery cell in a battery pack, the first insulation parameter being an insulation parameter between a battery cell tab and an aluminum plastic film of the battery cell, and the second insulation parameter being an insulation parameter between a battery cell tab and an aluminum plastic film of the battery cell; the second insulation parameter is an insulation parameter between the battery cell tab and a battery pack shell; calculating associated parameters according to the first insulation parameter and the second insulation parameter of each battery cell; and on the basis of the associated parameters, positioning a battery cell with abnormal insulation performance in the battery pack. According to the invention, through correlation analysis of the internal and external insulation states of the cell, accurate positioning and type distinguishing of the insulation fault cell are realized, the depth and precision of insulation detection of the battery pack are effectively improved, rapid maintenance is facilitated, and economic loss is reduced.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method, apparatus, and storage medium for testing the insulation of a battery pack. Background Technology

[0002] In the field of battery technology, the insulation performance of a battery pack is crucial to ensuring its safe use. Currently, insulation testing methods in the industry are mainly divided into two levels: one is system-level testing of the entire battery pack, which measures the insulation resistance between the positive and negative terminals of the battery pack and the outer casing (ground). This method can only determine whether there is an insulation abnormality in the entire battery pack, but it cannot pinpoint which specific cell or component the fault occurs in; the other is testing of the cell itself, such as testing the insulation between the cell tab and the aluminum-plastic film, but this is usually a separate quality inspection step that is disconnected from the overall structure of the battery pack.

[0003] The two levels of detection described above are isolated from each other. When system-level detection detects an anomaly, it cannot quickly and accurately determine which cell's aluminum-plastic film is damaged, whether the mounting medium (such as structural adhesive) between the cell and the casing is defective, or whether there are other electrical wiring problems. This leads to low troubleshooting efficiency, often requiring the entire battery pack to be disassembled and inspected piece by piece, which is time-consuming and labor-intensive. It may even result in the scrapping of slightly degraded but still usable cells or modules due to the inability to accurately locate the problem, causing unnecessary economic losses. Summary of the Invention

[0004] To address the problem that existing battery pack insulation testing methods cannot accurately locate faulty cells and differentiate insulation defect types, this invention proposes a method, apparatus, and storage medium for battery pack insulation testing.

[0005] The specific technical solution is as follows: A method for detecting the insulation of a battery pack, comprising the following steps:

[0006] Obtain the first insulation parameter and the second insulation parameter for each cell in the battery pack. The first insulation parameter is the insulation parameter between the cell tab and the aluminum-plastic film of the cell, and the second insulation parameter is the insulation parameter between the cell tab and the battery pack shell.

[0007] Calculate the associated parameters based on the first insulation parameter and the second insulation parameter of each cell;

[0008] Based on the aforementioned correlation parameters, the method locates the battery cells with abnormal insulation performance within the battery pack. This method can deeply identify the specific location of the battery cells with insulation abnormalities within the battery pack, achieving a breakthrough from overall detection to precise cell-level localization, significantly improving fault diagnosis efficiency.

[0009] Furthermore, the calculation of the correlation parameters includes:

[0010] The first insulation resistance R1 is determined based on the first insulation parameter;

[0011] The second insulation resistance R2 is determined based on the second insulation parameter;

[0012] Calculate the correlation parameter ΔR = R2 - R1. By quantifying the difference between the internal and external insulation states of the battery cell, an intuitive and reliable insulation assessment index is provided, facilitating accurate subsequent determination of defect types.

[0013] Furthermore, the method of locating cells with abnormal insulation performance based on correlation parameters includes:

[0014] When the ΔR value is lower than the first preset threshold, it is determined that the aluminum-plastic film of the corresponding battery cell has an insulation defect;

[0015] When the ΔR value is higher than the second preset threshold, it is determined that there is a defect in the insulation medium between the corresponding cell and the battery pack casing;

[0016] The first and second preset thresholds are determined based on the design and selection of the insulation medium between the battery cell and the casing. This effectively distinguishes between defects in the aluminum-plastic film and defects in the insulation medium between the battery cell and the casing, enabling accurate classification of fault types and providing a clear basis for repair or downgrading.

[0017] Furthermore, it also includes battery pack-level insulation verification steps:

[0018] Obtain a third insulation parameter, which is the insulation parameter between the total positive and total negative terminals of the battery pack and the outer casing of the battery pack;

[0019] Based on the third insulation parameter and the parameter selected from the second insulation parameter, the logical consistency of the overall insulation state of the battery pack is verified. Linking cell-level testing with battery pack-level testing ensures consistency between overall insulation safety and cell state, avoids missed or false detections, and improves the comprehensiveness of testing.

[0020] Furthermore, the verification logic consistency includes:

[0021] The overall insulation resistance R3 of the battery pack is determined based on the third insulation parameter.

[0022] The maximum second insulation resistance R2 is determined based on the second insulation parameters of all cells. max ;

[0023] For a series circuit, verify whether the following condition is met: R3 > R2 max *N, where N is the number of cells connected in series;

[0024] If the conditions are not met, it is determined that there is an insulation abnormality in other electrical components outside the battery cell itself within the battery pack. Optimizing the insulation verification logic of the series-connected battery pack can efficiently identify insulation abnormalities in other electrical components outside the battery cell itself, reducing overall safety risks.

[0025] Furthermore, the verification logic consistency includes:

[0026] The overall insulation resistance R3 of the battery pack is determined based on the third insulation parameter.

[0027] For parallel circuits, verify whether the following condition is met: R3 > R standard / N, where N is the number of cells connected in parallel, R standard This refers to the standard value of unit insulation resistance determined based on the design and selection of the insulating medium;

[0028] If the conditions are not met, it is determined that there is an insulation abnormality in other electrical components outside the battery cell itself within the battery pack. The insulation verification logic for parallel battery packs is optimized to ensure that the overall insulation resistance meets design standards, thereby improving the detection accuracy of parallel battery pack structures.

[0029] Furthermore, the first insulation parameter is obtained by applying a first constant voltage of 10V to 100V between the cell tab and the aluminum-plastic film and measuring the first leakage current; the second insulation parameter is obtained by applying a second constant voltage of 25V to 1000V between the cell tab and the battery pack casing and measuring the second leakage current. By optimizing the test voltage, both test safety and signal sensitivity are considered, ensuring reliability and accuracy under different test scenarios.

[0030] Furthermore, the first and second insulation parameters were obtained under the same environmental conditions, and all tests for the same battery pack were completed within 5 minutes. This reduces the interference of environmental fluctuations on the test results, ensures data comparability and repeatability, and improves the stability and reliability of the testing process.

[0031] A battery pack insulation testing device, comprising:

[0032] A test circuit is used to apply a test voltage to the object under test and measure the response signal.

[0033] The processing module is configured to execute the aforementioned method for battery pack insulation detection.

[0034] The positioning output module is used to output the location information of cells with abnormal insulation performance.

[0035] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for detecting insulation in a battery pack.

[0036] The above technical solution has the following advantages or technical effects:

[0037] 1. This invention achieves precise location of insulation-faulted cells by correlating internal and external insulation parameters, solving the problem that existing technologies cannot deeply identify fault points; through ΔR calculation and threshold comparison, it can distinguish different types of insulation defects, providing decision support for maintenance and downgrading, and reducing economic losses.

[0038] 2. This invention ensures the consistency between overall insulation safety and cell-level testing through battery pack-level verification logic, improving the comprehensiveness and reliability of testing; and provides a complete device and storage medium solution to automate and standardize the method, facilitating large-scale application and promotion. Attached Figure Description

[0039] Figure 1 This is a flowchart of the method of the present invention;

[0040] Figure 2 This is a schematic diagram of the battery cell structure within the module of the present invention;

[0041] Figure 3 This is a diagram showing the leakage current relationship between the soft-pack battery cell of the present invention and its own aluminum-plastic film. Detailed Implementation

[0042] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] like Figure 1 As shown, a method for testing the insulation of a battery pack includes the following steps:

[0045] Obtain the first insulation parameter and the second insulation parameter for each cell in the battery pack. The first insulation parameter is the insulation parameter between the cell tab and the aluminum-plastic film of the cell, and the second insulation parameter is the insulation parameter between the cell tab and the battery pack shell.

[0046] Calculate the associated parameters based on the first and second insulation parameters of each cell;

[0047] Based on the associated parameters, the cells with abnormal insulation performance within the battery pack can be located.

[0048] Taking a battery pack composed of 14 pouch cells connected in series as an example, the implementation method of this application is described in detail. The test environment temperature is controlled at 25±2℃, and the humidity is controlled at 50±10%RH. All tests are completed within 5 minutes. The specific steps are as follows:

[0049] Obtain the first insulation parameter. The first insulation parameter is the insulation parameter between the cell tab and the aluminum-plastic film of the cell. Specifically, a first constant voltage U1 is applied between the cell tab and the aluminum-plastic film. In this embodiment, U1 is a 50V DC voltage, with a stabilization time of 3 seconds, and the first leakage current I1 is measured. The range of the first constant voltage is typically 10V to 100V, selected according to the cell specifications to ensure safe and sensitive testing. Figure 2 As shown, the battery cell tabs and the aluminum-plastic film are isolated by an insulating medium. During the test, voltage is applied between the tabs and the aluminum-plastic film to measure the leakage current.

[0050] Obtain the second insulation parameter. The second insulation parameter is the insulation parameter between the cell tab and the battery pack casing. Specifically, a second constant voltage U2 is applied between the cell tab and the battery pack casing. In this embodiment, U2 is a 200V DC voltage with a stabilization time of 3 seconds, and the second leakage current I2 is measured. The range of the second constant voltage is typically 25V to 1000V to simulate actual high-voltage operating conditions. Figure 2 As shown, the battery cell is fixed to the casing by structural adhesive and other media, and voltage is applied between the tab and the casing during testing.

[0051] By testing the insulation parameters of the cell's internal (tab-aluminum-plastic film) and external (tab-shell) components separately, isolated defects are avoided, and a specific voltage range ensures testing safety and sensitivity. Correlation parameters are calculated based on the acquired insulation parameters and used to locate abnormal cells and differentiate defect types.

[0052] The first insulation resistance R1 is determined based on the first insulation parameter. R1 is calculated using the formula R1=U1 / I1; similarly, the second insulation resistance R2 is determined based on the second insulation parameter, R2=U2 / I2. The associated parameter ΔR=R2-R1 is calculated, which characterizes the relative relationship between the insulation state of the aluminum-plastic film of the battery cell and the insulation state of the battery cell to the casing. Changes in the value of ΔR can reflect the type of insulation defect: if ΔR is low, it indicates that the aluminum-plastic film insulation has deteriorated; if ΔR is high, it indicates that there is a problem with the insulation medium between the battery cell and the casing.

[0053] Cells with abnormal insulation performance are located based on the ΔR value, specifically including:

[0054] When the ΔR value is lower than the first preset threshold, it is determined that the aluminum-plastic film of the corresponding battery cell has an insulation defect. The aluminum-plastic film defect may lead to insulation degradation between the electrode tab and the aluminum-plastic film.

[0055] When the ΔR value is higher than the second preset threshold, it is determined that there is a defect in the insulation medium between the corresponding cell and the battery pack casing. Insulation medium defects (such as structural adhesive bubbles or metallic foreign objects) may cause abnormal insulation between the tab and the casing.

[0056] In this embodiment, the preset thresholds are determined based on the design selection of the insulating medium between the battery cell and the casing. For example, for a medium using structural adhesive, the design standard level R value is 500 MΩ, the first preset threshold is set to 300 MΩ (for identifying defects in the aluminum-plastic film), and the second preset threshold is set to 700 MΩ (for identifying dielectric defects). These thresholds are determined through simulation verification during the design and development phase, and with reference to, for example... Figure 3 Leakage current relationship data.

[0057] By calculating ΔR and comparing thresholds, insulation defect types can be accurately distinguished, enabling cell-level fault location and providing a clear basis for repair or downgrading, thus reducing economic losses. Furthermore, the thresholds are based on design selection, improving the accuracy and adaptability of detection.

[0058] Battery pack-level insulation verification verifies the logical consistency of the overall insulation state of the battery pack, ensuring the correlation between cell-level testing and system-level testing. The steps include:

[0059] Obtain the third insulation parameter. The third insulation parameter refers to the insulation parameter between the total positive and total negative terminals of the battery pack and the battery pack casing. Specifically, a third constant voltage U3 is applied between the total positive and total negative terminals and the casing. In this embodiment, U3 is a 500V DC voltage with a stabilization time of 3 seconds, and the third leakage current I3 is measured. The range of the third constant voltage is typically 500V to 3000V to meet high-voltage safety test standards.

[0060] The logic consistency is verified based on the third insulation parameter and the second insulation parameter, specifically including:

[0061] For a series circuit (such as the 14 series cells in this embodiment), the overall insulation resistance R3 of the battery pack is determined according to the third insulation parameter (R3=U3 / I3), and the maximum second insulation resistance R2 is determined according to the second insulation parameters of all cells. max (That is, the maximum value among all R² values). Verify whether the inequality: R³ > R² is satisfied. max *N, where N is the number of cells connected in series (N=14 in this embodiment). If this condition is not met, it is determined that there is an insulation abnormality in other electrical components outside the cell body within the battery pack, such as wiring harness or connector problems.

[0062] For parallel circuits (not shown in this embodiment, but the method is applicable), determine R3 based on the third insulation parameter and verify whether the inequality is satisfied: R3 > R standard / N, where N is the number of cells connected in parallel, R standard This refers to the standard value of unit insulation resistance (e.g., 500MΩ) determined based on the design and selection of the insulation medium. If this value is not met, it is determined that there are other electrical insulation abnormalities.

[0063] Battery pack-level verification ensures overall insulation safety is consistent with cell condition, preventing missed detections due to faults in other components and improving the comprehensiveness and reliability of testing. Furthermore, the verification logic has been optimized for specific inequalities in series and parallel circuits.

[0064] Comprehensive judgment: Only when both cell-level testing (ΔR meets the standard) and battery pack-level verification (logic consistency is satisfied) pass can the battery pack be considered to have qualified insulation. Otherwise, the cells will be replaced or reworked based on the positioning results.

[0065] Taking the test data of this embodiment as an example, as shown in Table 1:

[0066] Table 1: Insulation Test Results

[0067]

[0068] In module 1, the ΔR values ​​of cell 1 and cell 2 are 245.3MΩ and 451.2MΩ respectively, which are lower than the qualified standard (500MΩ). They are judged to be defects in aluminum-plastic film and the cells need to be replaced.

[0069] In module 2, all ΔR values ​​meet the standard, and the battery pack-level verification satisfies the inequality (R3 > R2_max ×14), thus it is deemed qualified.

[0070] In module 3, the ΔR values ​​all meet the standards, but the battery pack level verification does not meet the inequality, and it is judged to be other electrical insulation abnormalities, requiring rework and inspection of components such as wiring harnesses.

[0071] Through multi-level correlation detection, a holistic insulation assessment from the cell to the battery pack is achieved, significantly improving the efficiency and accuracy of fault diagnosis.

[0072] Example 2

[0073] A battery pack insulation detection device for implementing the method of Embodiment 1, the device comprising:

[0074] Test Circuit: Used to apply a test voltage to the object under test and measure the response signal. The test circuit includes an adjustable voltage source, a high-precision current measurement module, and a multi-channel switch, which can automatically connect to test points such as cell tabs, aluminum-plastic film, battery pack casing, main positive terminal, and main negative terminal. The test circuit supports applying a first constant voltage (10V to 100V), a second constant voltage (25V to 1000V), and a third constant voltage (500V to 3000V), and measures the corresponding leakage currents I1, I2, and I3.

[0075] Processing module: Configured to execute the method steps of Embodiment 1. The processing module is an embedded microprocessor, pre-installed with detection algorithms, including calculating insulation resistances R1, R2, and R3, calculating the associated parameter ΔR, performing threshold comparisons, and verifying logical consistency inequalities. The processing module is also responsible for controlling the switching and timing of the test circuit.

[0076] Location Output Module: Used to output the location information of cells with abnormal insulation performance. This module includes a display screen and a communication interface. The display screen can show the faulty cell number and defect type, and the communication interface (such as CAN bus or Ethernet) can send the results to a host computer or production management system.

[0077] This device, by integrating a test circuit, a processing module, and a positioning output module, achieves automated operation of the method in Example 1, thereby improving detection efficiency and consistency.

[0078] Example 3

[0079] A computer-readable storage medium for implementing the method of Embodiment 1 stores a computer program that, when executed by a processor, performs the battery pack insulation detection method of Embodiment 1.

[0080] Storage media can be non-transitory computer-readable media such as ROM, RAM, flash memory, hard disk, optical disk, or cloud storage. A computer program includes instructions for controlling the processor to perform the following steps.

[0081] The control and testing equipment is used to obtain the first and second insulation parameters of each battery cell.

[0082] The associated parameter ΔR is calculated based on the first insulation parameter and the second insulation parameter.

[0083] Cells with abnormal insulation performance are located based on ΔR positioning.

[0084] Obtain the third insulation parameter and verify the logical consistency of the overall insulation state of the battery pack.

[0085] Output the detection results, including the location of abnormal cells and the type of defect.

[0086] The storage medium of this embodiment can be embedded in the device of embodiment 2, or deployed independently in a general-purpose computer system to realize the software-based promotion of the method.

[0087] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method of battery pack insulation detection, the method comprising the steps of The method comprises: obtaining a first insulation parameter and a second insulation parameter of each cell in the battery pack, the first insulation parameter being an insulation parameter between the cell tab and the aluminum plastic film of the cell, and the second insulation parameter being an insulation parameter between the cell tab and the battery pack shell; calculating a correlation parameter according to the first insulation parameter and the second insulation parameter of each cell; locating the cell with abnormal insulation performance in the battery pack based on the correlation parameter.

2. The method of claim 1, wherein, The calculation of the correlation parameter comprises: determining a first insulation resistance R1 according to the first insulation parameter; determining a second insulation resistance R2 according to the second insulation parameter; calculating the correlation parameter ΔR = R2 - R1.

3. The method of battery pack insulation detection of claim 2, wherein, The locating of the cell with abnormal insulation performance based on the correlation parameter comprises: when the ΔR value is lower than a first preset threshold, determining that the aluminum plastic film of the corresponding cell has an insulation defect; when the ΔR value is higher than a second preset threshold, determining that the insulation medium between the corresponding cell and the battery pack shell has a defect; wherein the first preset threshold and the second preset threshold are determined based on the design selection of the insulation medium between the cell and the shell.

4. The method of claim 1, wherein, Further comprising a battery pack level insulation verification step: obtaining a third insulation parameter, the third insulation parameter being an insulation parameter between the total positive electrode and the total negative electrode of the battery pack and the battery pack shell; verifying the logical consistency of the overall insulation state of the battery pack based on the third insulation parameter and a parameter selected from the second insulation parameter.

5. The method of battery pack insulation detection of claim 4, wherein, The verification of the logical consistency comprises: determining the overall insulation resistance R3 of the battery pack according to the third insulation parameter; determining a maximum second insulation resistance R2 from the second insulation parameter of all cells max ; For series loop, verify if R3 > R2 max *N, where N is the number of series cells if not satisfied, determining that there is an insulation abnormality of other electrical components in the battery pack other than the cell body.

6. The method of battery pack insulation detection of claim 4, wherein, The verification of the logical consistency comprises: determining the overall insulation resistance R3 of the battery pack according to the third insulation parameter; For parallel circuit, verify whether the following condition is met: R3 > R / N, where N is the number of parallel cells, R is the unit insulation resistance standard value determined based on insulation medium design selection; standard standard is the unit insulation resistance standard value determined based on insulation medium design selection;​ if not satisfied, determining that there is an insulation abnormality of other electrical components in the battery pack other than the cell body.

7. The method of battery pack insulation detection of claim 1, wherein, The first insulation parameter is obtained by applying a first constant voltage of 10V to 100V between the cell tab and the aluminum plastic film and measuring a first leakage current; and the second insulation parameter is obtained by applying a second constant voltage of 25V to 1000V between the cell tab and the battery pack shell and measuring a second leakage current.

8. The method of battery pack insulation detection of claim 1, wherein, The acquisition of the first insulation parameter and the second insulation parameter is carried out under the same environmental conditions, and all tests for the same battery pack are completed within 5 minutes. 9.A battery pack insulation detection device, characterized by, The method comprises: a test circuit for applying a test voltage to a test object and measuring a response signal; a processing module configured to perform a battery pack insulation detection method according to any one of claims 1 to 8; a positioning output module for outputting the location information of the cell with abnormal insulation performance.

10. A computer-readable storage medium, characterized in that, A computer program is stored, and the computer program is executed by a processor to implement a battery pack insulation detection method according to any one of claims 1 to 8.

Images