Battery pack and protection level determination method thereof

Abstract

The application provides a battery pack and a protection level determination method thereof. The protection level determination method of the battery pack comprises: obtaining a gas tightness test leakage rate value of a battery pack to be tested; determining whether the battery pack to be tested meets a target protection level requirement according to the gas tightness test leakage rate value of the battery pack to be tested and a mapping relationship library; and establishing a mapping relationship between the gas tightness test leakage rate value and a protection level test result, so as to realize rapid prediction and determination of the protection level of the battery pack. The protection level verification mode in the related art depending on destructive testing is changed into a nondestructive testing mode, the test cost and time of the protection level of the battery pack are reduced, the product damage risk is avoided, and the product delivery reliability is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery pack and a method for determining its protection level. Background Technology

[0002] With the widespread application of energy storage technology, the safety and environmental adaptability of battery packs have received increasing attention. The IP protection rating standard formulated by the International Electrotechnical Commission (IEC) has become an important basis for measuring their dustproof and waterproof capabilities.

[0003] In energy storage devices, to ensure the safe operation of battery packs, their protective performance is typically subject to specific requirements based on IP rating standards. For example, according to standards such as IEC 60529 published by the International Electrotechnical Commission, finished battery packs undergo practical tests for dust resistance (IP6X), water spray / spray resistance (IPX5 / IPX6), and immersion (IPX7 / IPX8). However, current IP rating testing methods for battery packs are often destructive and carry high risks. After testing, residual moisture may remain inside the product, rendering the sample unusable and potentially causing corrosion problems, thus affecting the long-term reliability and service life of the product. Summary of the Invention

[0004] This application provides a battery pack and a method for determining its protection level, in order to solve or at least partially solve the deficiencies of the above-mentioned background technology.

[0005] In a first aspect, embodiments of this application provide a method for determining the protection level of a battery pack, including: Obtain the leak rate value of the airtightness test of the battery pack under test; Based on the leak rate value of the airtightness test of the battery pack under test and the mapping relationship library, it is determined whether the battery pack under test meets the target protection level requirements; wherein, the mapping relationship library stores multiple mapping relationship information, and each mapping relationship information includes the leak rate value of the airtightness test of a battery pack sample and the corresponding standard protection level test result.

[0006] In one embodiment, the step of determining whether the battery pack under test meets the target protection level requirements based on the leak rate value of the airtightness test and the mapping relationship library includes: The critical leak rate threshold for the protection level is determined based on the mapping relationship library. The critical leak rate threshold for the protection level is used to characterize the maximum allowable airtightness test leak rate value that meets the target protection level requirements. The airtightness test leakage rate value of the battery pack under test is compared with the critical leakage rate threshold of the protection level, and the battery pack under test is determined to meet the target protection level requirements based on the comparison result.

[0007] In one embodiment, the step of comparing the airtightness test leakage rate value of the battery pack under test with the critical leakage rate threshold of the protection level, and determining whether the battery pack under test meets the target protection level requirements based on the comparison result, includes: If the leak rate value of the airtightness test of the battery pack under test is less than or equal to the critical leak rate threshold of the protection level, the battery pack under test is determined to meet the target protection level requirements; or if the leak rate value of the airtightness test of the battery pack under test is greater than or equal to the critical leak rate threshold of the protection level, the battery pack under test is determined to not meet the target protection level requirements, and an alarm message is generated.

[0008] In one embodiment, the method for determining the critical leakage rate threshold of the protection level includes the following steps: Based on the mapping relationship library, statistical analysis is performed on the air tightness test leakage rate values ​​and their corresponding protection level test results of multiple battery pack samples to establish the correlation between the air tightness test leakage rate value and the protection level pass rate. Based on the aforementioned correlation, the critical leakage rate threshold of the protection level corresponding to the target protection level is determined.

[0009] In one embodiment, the method for constructing the mapping relationship library includes the following steps: Provide multiple battery pack samples, including samples that are properly sealed and samples that have at least one preset failure characteristic; Under preset test conditions, the airtightness test leakage rate value of each battery pack sample was obtained. Each of the battery pack samples was subjected to a standard protection level test to obtain the measured protection level results and corresponding failure characterization data for each battery pack sample. The airtightness test leakage rate value, the corresponding protection level test result, and the failure characterization data of each battery pack sample are associated and recorded as a mapping relationship information. Multiple mapping relationship information are stored to construct a mapping relationship library.

[0010] In one embodiment, the preset failure characterization includes setting simulated defects of different diameters or shapes at at least one of the screw connections, welds, sealing surfaces, or housing assembly interfaces of the battery pack sample to simulate leakage channels of different severity.

[0011] In one embodiment, the step of obtaining the airtightness test leakage rate value of each battery pack sample under preset test conditions includes: Under a preset test pressure, an airtightness test is performed on each of the battery pack samples, and the test temperature and relative humidity are monitored simultaneously to obtain the gas leakage rate value of each battery pack sample, as well as the test pressure, temperature data and relative humidity data during the test process.

[0012] In one embodiment, the standard protection level test includes at least one of dustproof test, spray test, or immersion test; the failure characterization data includes at least one of dust ingress, water ingress, and insulation resistance change.

[0013] In one embodiment, the method for determining the protection level of the battery pack further includes the following steps: Randomly sample the battery packs to be tested that have been determined to meet the target protection level requirements to obtain sampled battery packs; The sampled battery packs were subjected to standard protection level tests to verify whether they met the standard protection level requirements. When the standard protection level test result of the sampled battery pack does not meet the target protection level requirements, the actual protection level test result, the corresponding failure characterization data, and the corresponding airtightness test leakage rate value of the sampled battery pack are obtained. For each sampled battery pack that does not meet the target protection level requirements, the actual protection level test results, the corresponding failure characterization data, and the corresponding airtightness test leakage rate value are associated to construct a mapping relationship information, and the mapping relationship information is stored in the mapping relationship library.

[0014] Secondly, embodiments of this application provide a battery pack, wherein the battery pack is tested using the protection level determination method for the battery pack described in the first aspect.

[0015] The beneficial effects of the embodiments of this application are as follows: The embodiments of this application provide a battery pack and a method for determining its protection level. The method for determining the protection level of the battery pack includes obtaining the airtightness test leakage rate value of the battery pack under test; determining whether the battery pack under test meets the target protection level requirements based on the airtightness test leakage rate value and the mapping relationship library; by establishing a mapping relationship between the airtightness test leakage rate value and the actual test results of the protection level, the protection level of the battery pack can be quickly predicted and determined, transforming the protection level verification method that relies on destructive testing in related technologies into a non-destructive testing method, reducing the testing cost and time of the protection level of the battery pack, avoiding the risk of product damage, and improving the reliability of product delivery. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this embodiment, the accompanying drawings used in the description of the embodiment will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating the method for determining the protection level of a battery pack provided in an embodiment of this application; Figure 2 A flowchart illustrating the method for constructing the mapping relationship library provided in this application embodiment; Figure 3 A flowchart illustrating the method for determining the critical leakage rate threshold of the protection level provided in the embodiments of this application; Figure 4 A flowchart illustrating the calculation of the critical leakage rate threshold for the protection level provided in this application embodiment; Figure 5 This is a schematic diagram of the battery structure provided in an embodiment of this application.

[0018] Explanation of reference numerals in the attached figures: 1-Battery pack; 10-Battery box. Detailed Implementation

[0019] 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 a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0020] Please see Figure 1 This is a flowchart of a method for determining the protection level of a battery pack according to an embodiment of this application; this embodiment provides a method for determining the protection level of a battery pack, including the following steps: Step S1: Obtain the airtightness test leakage rate value L_test of the battery pack under test.

[0021] The battery pack under test can be a lithium-ion battery pack, a sodium-ion battery pack, or other types of power battery packs, and its packaging form includes, but is not limited to, a square aluminum shell, a pouch, or a cylindrical structure. This embodiment does not limit the specific type, packaging form, or application scenario of the battery pack under test; any battery pack that needs to have its shell sealing performance evaluated through an airtightness test is applicable.

[0022] Further, step S10 includes performing an airtightness test on the battery pack under test to obtain its airtightness test leakage rate value L_test. An airtightness test refers to a detection method that quantitatively evaluates the sealing integrity by filling the battery pack under test with a gas (such as compressed air, nitrogen, or helium) at a certain pressure and monitoring the pressure decay rate or gas flow rate. In this embodiment, the airtightness test method can be selected from any one of the pressure decay method, differential pressure method, or helium mass spectrometry detection method, but is not limited to these; other methods capable of quantitatively detecting sealing performance can also be used.

[0023] Step S2: Based on the airtightness test leakage rate value L_test of the battery pack under test and the mapping relationship library, determine whether the battery pack under test meets the target protection level requirements; wherein, the mapping relationship library stores multiple mapping relationship information, and each mapping relationship information includes the airtightness test leakage rate value L_gas of a battery pack sample and its corresponding standard protection level test results.

[0024] It should be noted that the above-mentioned target protection level requirements refer to the target IP (Ingress Protection) level requirements. IP level refers to the rating standard defined in IEC 60529, published by the International Electrotechnical Commission (IEC), which evaluates the ability of electrical equipment enclosures to protect against the intrusion of solid foreign objects (such as dust) and liquids (such as water). The IP level requirements for battery packs include, but are not limited to, IP67, IP68, and IP65. IP67 represents complete dust protection (level 6) and waterproof capability (level 7) that allows the product to continue operating normally after immersion in 1 meter of water for 30 minutes.

[0025] Furthermore, the target protection rating requirement refers to the protection performance standards that the battery pack under test must meet before leaving the factory. The specific rating can be set according to the application scenario, customer requirements, or industry standards. For example, battery packs used in outdoor energy storage systems typically need to achieve an IP67 or higher rating to ensure long-term reliable operation under complex environmental conditions.

[0026] It is understandable that this embodiment establishes a mapping relationship between the leak rate value of the airtightness test and the measured results of the protection (IP) level, thereby enabling rapid prediction and determination of the protection level of the battery pack. It also transforms the original macroscopic performance indicators represented by the protection (IP) level into quantifiable gas leak rate parameters, thereby realizing digital and quantitative control of the protection performance of the battery pack. This overcomes the problems in related technologies where the airtightness test standards are set rather blindly and lack a clear correspondence with the protection (IP) level requirements, providing a scientific and traceable basis for production line quality judgment.

[0027] Meanwhile, compared to the protection (IP) level tests in related technologies (such as IPX7 immersion tests which usually take more than 30 minutes and IP6X dustproof tests which usually take 2 to 8 hours), air tightness tests can usually be completed in just tens of seconds to a few minutes, improving testing efficiency and making it feasible to conduct full inspection of battery packs at the production line off-line stage.

[0028] In addition, the airtightness test uses gas as the testing medium. During the test, it does not cause any damage to the internal structure and electrical performance of the battery pack. After the test, the product can directly enter the next process or be shipped. This avoids the potential corrosion risk and product scrapping issues caused by moisture or dust residue in the protection (IP) level test of related technologies, and further improves the reliability of product delivery.

[0029] Further, please refer to Figure 2 Here is a flowchart of the method for constructing the mapping relationship library provided in this application embodiment. The method for constructing the mapping relationship library includes the following steps: Step S10: Provide multiple battery pack samples, including samples that are properly sealed and samples that have at least one preset failure characteristic.

[0030] It should be noted that a qualified sealing sample refers to a battery pack manufactured using normal production processes, whose sealing structure is confirmed to be intact and free of visible defects through preliminary testing. It is used to represent the product benchmark under normal production conditions. The preset failure mode refers to the active introduction of simulated defects at the weak points of the battery pack sample to reproduce various sealing failure scenarios that may occur during actual production or use.

[0031] Specifically, the preset failure modes include, but are not limited to, setting simulated defects of different diameters or shapes at at least one of the screw connections, welds, sealing surfaces, or housing assembly interfaces of the battery pack sample to simulate leakage channels of different severity, thereby obtaining complete data covering "complete sealing" to "significant leakage"; the parameter settings of the preset failure modes and the corresponding markings of the battery pack samples are shown in Table 1 below:

[0032] It is understood that this embodiment constructs a battery pack sample set covering a wide range of sealing conditions by providing multiple battery pack samples, including those with qualified sealing and various preset failure modes. Among them, the qualified sealing sample (S-001) provides a data benchmark under normal production conditions to determine the leakage rate distribution range of the airtightness test under defect-free conditions. The various preset failure mode samples (S-002~S-006) cover various typical sealing failure scenarios that may occur in the battery pack during actual production and life cycle, including different leakage forms such as point leakage, interface leakage, and spiral leakage, as well as different severities from micro-leakage to obvious leakage.

[0033] Therefore, the mapping relationship between the leak rate value of the airtightness test and the measured results of the protection (IP) level established based on the battery pack sample set can not only accurately reflect the sealing performance of normal products, but also effectively identify the critical leakage characteristics corresponding to various potential failure modes. This makes the final mapping relationship library have a wide coverage and good generalization performance, providing reliable data support for the subsequent determination of the protection (IP) level of the battery pack under test.

[0034] Step S20: Under preset test conditions, obtain the airtightness test leakage rate value L_gas for each battery pack sample.

[0035] In step S20, the preset test conditions include, but are not limited to, environmental parameters such as test temperature, test pressure, and relative humidity; wherein, in order to ensure the consistency and comparability of the airtightness test data of each battery pack sample, multiple battery pack samples should be tested under uniform and recordable benchmark conditions.

[0036] Specifically, step S20 includes: conducting an airtightness test on each battery pack sample under a preset test pressure, and simultaneously monitoring the test temperature and relative humidity to obtain the airtightness test leakage rate value L_gas for each battery pack sample, as well as the test pressure, temperature data and relative humidity data during the test process.

[0037] The test temperature is set to a constant room temperature greater than or equal to 15 degrees Celsius and less than or equal to 35 degrees Celsius to avoid interference from gas volume changes caused by temperature fluctuations on the leak rate measurement; the test pressure is set to a standard atmospheric pressure range greater than or equal to 86 kPa and less than or equal to 106 kPa to ensure that the test environment pressure is close to the actual operating conditions of the battery pack; the relative humidity is controlled to be greater than or equal to 45% and less than or equal to 75% to prevent excessive humidity from adversely affecting the airtightness testing equipment and the battery pack sample under test.

[0038] The airtightness testing method can be any of the pressure decay method, differential pressure method, or helium mass spectrometry leak detection method, or other means that can achieve quantitative measurement of airtightness. Among them, the pressure decay method is fast and the equipment is relatively simple, making it suitable for online or batch screening. It calculates the leak rate by monitoring the pressure change in the closed cavity over time. The differential pressure method is suitable for steady-state or transient detection with moderate sensitivity requirements. Helium mass spectrometry leak detection has high sensitivity and is suitable for accurate measurement of small leaks. It is often used for calibration or verification.

[0039] It is understood that, through step S20, this embodiment obtains the airtightness test leakage rate value L_gas of each battery pack sample under uniform preset test conditions, thereby eliminating the interference of environmental factors on the measurement results, ensuring the comparability of data between different battery pack samples, and laying a reliable data foundation for establishing accurate mapping relationships in the future; at the same time, the airtightness test itself has the characteristics of being fast and quantitative, and can complete the test of a large number of battery pack samples in a short time.

[0040] Furthermore, by selecting a suitable airtightness testing method, testing efficiency can be considered while ensuring measurement accuracy, making the battery pack sample data acquisition process industrially feasible. Thus, step S20 provides high-quality, standardized airtightness test data input for the mapping relation library, ensuring the accuracy and reliability of subsequent correlation analysis and model building.

[0041] Step S30: Perform standard protection level tests on each battery pack sample to obtain the measured protection level results and corresponding failure characterization data for each battery pack sample.

[0042] Specifically, step S30 should be performed as soon as possible after step S20, for example, within 6 hours, to ensure that the sealing state of the battery pack sample has not changed significantly, and to avoid the impact of factors such as long-term storage of the battery pack sample, environmental changes, or long-distance transportation on the test results. Therefore, the leak rate value L_gas of the airtightness test of the battery pack sample obtained in step S20 and the measured protection level obtained in step S30 can accurately reflect the performance characteristics of the battery pack sample under the same sealing state, ensuring that the correlation between the two is true and reliable.

[0043] In step S30, tests are conducted according to the target IP protection level specified in the product specification and the corresponding protection level test standards. Test standards include, but are not limited to, the IEC 60529 standard published by the International Electrotechnical Commission or the Chinese national standard GB / T 4208-2017 "Degrees of Protection Provided by Enclosures (IP Codes)"; standard protection level tests include, but are not limited to, at least one of the following: dustproof testing (e.g., IP6X), spray testing (e.g., IPX5 / IPX6), and immersion testing (e.g., IPX7 / IPX8).

[0044] Specifically, in the standard protection level test, the measured protection (IP) level of each battery pack sample must be recorded in detail, i.e., judged as "qualified" or "unqualified". For battery pack samples judged as "unqualified", their corresponding failure characterization data must also be recorded. Failure characterization data includes, but is not limited to, at least one of the following: dust ingress, water ingress location, water ingress condition, water ingress amount, or insulation resistance change.

[0045] Failure characterization data includes, but is not limited to, at least one of the following: dust ingress (e.g., dust ingress location and amount), water ingress (e.g., water ingress location, amount, and rate), and changes in key electrical parameters before and after testing (e.g., decrease in insulation resistance, short circuit conditions, etc.). This failure characterization data provides important basis for subsequent analysis of the correspondence between different leakage modes and IP protection level test failures.

[0046] It is understood that this embodiment obtains the standard protection (IP) level test results and failure characterization data of each battery pack sample through step S30; wherein, the standard IP test is an authoritative means of verifying protection performance, and its results have legal effect and industry recognition, providing a reliable "benchmark truth value" for the subsequent establishment of the correlation between airtightness leakage rate value and IP level.

[0047] Meanwhile, by scheduling step S30 to be executed shortly after step S20, it is ensured that the airtightness test and the IP test are performed on battery pack samples under the same sealed condition. This eliminates the interference of state changes caused by time intervals on data correlation, and enables the final mapping relationship library to truly reflect the intrinsic relationship between "airtightness test leak rate value" and "protection level".

[0048] Furthermore, the detailed recording of failure characterization data not only provides a specific basis for determining "non-conformity", but also lays the foundation for subsequent analysis of the correspondence between different failure modes (such as point leakage and interface leakage) and failure performance of specific protection (IP) level tests, which helps to guide design optimization and process improvement.

[0049] Step S40: Associate the airtightness test leakage rate value L_gas, the corresponding protection level test results, and the failure characterization data of each battery pack sample, and record them as a mapping relationship information. Store multiple mapping relationship information to build a mapping relationship library.

[0050] Specifically, in step S40, for each battery pack sample prepared and tested in steps S10 to S30, the corresponding three types of data are correlated and integrated: ① the airtightness test leakage rate value L_gas obtained in step S20; ② the protection level test results (pass / fail judgment) obtained in step S30; ③ the failure characterization data obtained in step S30 (such as water ingress location, water ingress volume, insulation resistance change, etc.).

[0051] The three types of data mentioned above are associated using the sample ID as an index to form a structured mapping relationship. This process is repeated for all samples to obtain multiple mapping relationships. These multiple mapping relationships are then aggregated and stored in a database, thus constructing a mapping relationship library. This mapping relationship library can be stored in tabular form on a local server, cloud storage, or production management system for easy access and updates later.

[0052] It is understandable that this embodiment achieves a direct connection between "sealing performance index" and "protection capability" by directly linking the leak rate value of the airtightness test with the measured result of the protection level, providing the most basic data unit for establishing a quantitative mapping model between the two in the future.

[0053] Meanwhile, by introducing failure characterization data, each mapping relationship not only contains the binary result of "whether it is qualified" but also the deeper reason information of "why it is unqualified", which greatly enriches the data dimensions and lays the foundation for subsequent analysis of the correspondence between different failure modes and specific leakage rate characteristics.

[0054] Furthermore, by aggregating multiple mapping relationship information into a database, scattered individual sample data are transformed into systematic structured data. This not only supports statistical association analysis but also provides training datasets for advanced modeling methods such as machine learning. As a result, the predictive model built on the mapping relationship library has the ability to continuously evolve and adapt to new demands brought about by product iteration and process changes.

[0055] Further, step S2 includes the following steps: Step S21: Determine the critical leak rate threshold of the protection level according to the mapping relationship library. The critical leak rate threshold of the protection level is used to characterize the maximum allowable airtightness test leak rate value L_max that meets the target protection level requirements.

[0056] Specifically, step S21 establishes a quantitative correlation between the leak rate value of the airtightness test and the measured results of the protection (IP) level through statistical analysis based on the mapping relationship library, and determines a critical leak rate threshold of the protection level that can effectively distinguish between "qualified" and "unqualified" samples.

[0057] It should be noted that the critical leakage rate threshold of the protection level is a value with a clear physical meaning. The leakage rate value L_test of the airtightness test of the battery pack under test is compared with the critical leakage rate threshold of the protection level to determine whether the battery pack under test can pass the corresponding target protection (IP) level test.

[0058] Further, please refer to Figure 3 This is a flowchart of a method for determining the critical leakage rate threshold of the protection level provided in this application embodiment; the method for determining the critical leakage rate threshold of the protection level includes the following steps: Step S100: Based on the mapping relationship library, perform statistical analysis on the airtightness test leakage rate value L_gas and the corresponding protection level test results of multiple battery pack samples to establish the correlation between the airtightness test leakage rate value and the protection level pass rate.

[0059] Specifically, step S100 includes the following steps: Step S101: Extract the air tightness test leakage rate value L_gas and the corresponding protection (IP) level test results of all battery pack samples from the mapping relationship library; wherein, the air tightness test leakage rate value of the battery pack sample is recorded as L_gas; the protection (IP) level test results are binary classification variables, namely "qualified" (recorded as 1) or "unqualified" (recorded as 0).

[0060] Step S102: Sort the battery pack samples according to the airtightness test leakage rate value L_gas from smallest to largest, and observe the distribution pattern of the failure samples of protection (IP) level test in the leakage rate sequence; among them, as the airtightness test leakage rate value L_gas of the battery pack samples increases, the proportion of failure samples of protection (IP) level test gradually increases, that is, in the low leakage rate area, qualified samples are the main ones, and in the high leakage rate area, unqualified samples are the main ones. There is a transition area between the two, which is the distribution range of critical leakage characteristics.

[0061] Step S103: Determine the correlation between the leakage rate value L_gas of the airtightness test of the battery pack sample and the pass rate of the protection level through statistical analysis methods; wherein, the statistical analysis methods include, but are not limited to, at least one of logistic regression analysis or distribution analysis.

[0062] Specifically, when using logistic regression analysis to establish the correlation, the airtightness test leakage rate value L_gas of each battery pack sample is used as the input feature, and the corresponding protection (IP) level test result (pass = 1, fail = 0) is used as the output label. The logistic regression classification model is obtained through training.

[0063] The formula for the logistic regression model is: P = 1 / (1 + e^(-1 / 2)) -(w × L_gas + b)); where P represents the probability that a battery pack sample can pass the target protection (IP) level test when the airtightness test leak rate value is L_gas, and the value ranges from 0 to 1; L_gas is the input feature, that is, the airtightness test leak rate value of the battery pack sample; w is the model weight, which represents the degree of influence of the leak rate value L_gas on the pass probability P; b is the bias term, which is used to adjust the baseline probability level of the model.

[0064] During model training, the weights w and bias b are calculated by using the leak rate values ​​L_gas from the airtightness test of all battery pack samples in the mapping relation library and their corresponding IP rating test results as inputs, and training the logistic regression model using the maximum likelihood estimation method to optimize the fit between the model's predicted pass probability and the actual sample results.

[0065] In one specific embodiment, a model is trained based on a mapping database containing multiple battery pack samples, resulting in the following parameters: weight w = -20, bias b = 3. Substituting the specific airtightness test leakage rate value into the logistic regression model, the corresponding pass probability P can be calculated. For example, when the leakage rate value L_gas = 0.1 sccm for a certain battery pack sample, we calculate w×L_gas+b = -20×0.1 + 3 = 1, then P = 1 / (1+e^-1) ≈ 0.731, meaning that this sample has approximately a 73.1% probability of passing the target IP rating test.

[0066] Therefore, a quantitative mapping relationship from "air tightness test leak rate value" to "protection (IP) level pass probability" was established through a logistic regression model, so that the air tightness test results can be transformed into probability prediction values ​​with clear physical meaning.

[0067] Step S200: Based on the correlation, determine the critical leakage rate threshold of the protection level corresponding to the target protection level.

[0068] Specifically, based on the correlation established in step S100 (such as a logistic regression model), the critical leakage rate threshold for the protection level used for online judgment can be further determined. Please refer to [link to relevant documentation]. Figure 4 Here is a flowchart illustrating the calculation of the critical leakage rate threshold for the protection level provided in this application embodiment; the calculation process for the critical leakage rate threshold for the protection level includes the following steps: Step S1000: Set the pass probability threshold P_th. For example, set P_th = 0.95, which means that the battery pack that is judged to be qualified must have at least a 95% probability of passing the target protection (IP) level test.

[0069] It should be noted that the pass probability threshold can be flexibly adjusted according to product reliability requirements and quality costs. For products with high reliability requirements, a higher pass probability threshold P_th (such as 0.99) can be set, while for cost-sensitive products, the pass probability threshold P_th can be appropriately reduced. This embodiment does not impose specific restrictions on this.

[0070] Step S2000: Substitute the set pass probability threshold P_th into the logistic regression model to obtain the corresponding protection level critical leakage rate threshold.

[0071] Specifically, according to the logistic regression model formula: P = 1 / (1 + e) -(w × L_gas + b) From this, we can obtain the formula for calculating the critical leak rate threshold / maximum airtightness test leak rate value L_max: L_max = (ln(P_th / (1-P_th)) - b) / w.

[0072] In one specific embodiment, substituting P_th = 0.95, w = -20, and b = 3 into the above formula for calculating the critical leak rate threshold of the protection level, the critical leak rate threshold of the protection level / the maximum airtightness test leak rate value L_max = (2.944 - 3) / (-20) = (-0.056) / (-20) = 0.0028 sccm. That is, in this embodiment, when the pass probability threshold P_th = 0.95 is set, the corresponding critical leak rate threshold of the protection level L_max ≈ 0.0028 sccm.

[0073] Understandably, logistic regression, as a mature probabilistic prediction model, can output continuous probability values ​​rather than simple binary judgments, providing richer decision-making information for quality control. By setting different pass / fail probability thresholds P_th, the stringency of quality control can be flexibly adjusted to meet the needs of different application scenarios. At the same time, the model parameters w and b are trained based on a large amount of real sample data, ensuring that the established association has statistical reliability and generalization ability.

[0074] Step S22: Compare the airtightness test leakage rate value L_test of the battery pack under test with the critical leakage rate threshold of the protection level, and determine whether the battery pack under test meets the target protection level requirements based on the comparison result.

[0075] Specifically, in step S22, after obtaining the airtightness test leak rate value L_test of the battery pack under test in step S10 and determining the critical leak rate threshold for the protection level in step S21, the two are compared. The comparison result is used to finally determine the IP level compliance of the battery pack under test. If the leak rate value L_test of the airtightness test of the battery pack under test is less than or equal to the critical leak rate threshold of the protection level, the battery pack under test is determined to meet the target protection level requirements. The physical meaning of this determination is that the leakage degree of the battery pack under test is within an acceptable range, and its probability of passing the standard protection (IP) level test is not less than the preset confidence level (e.g., 95%). Therefore, it can be used as a qualified product to enter the next process or be shipped.

[0076] Alternatively, if the leak rate value L_test of the airtightness test of the battery pack under test is greater than or equal to the critical leak rate threshold of the protection level, the battery pack under test is determined to be non-compliant with the target protection level requirements, and an alarm message is generated. The physical meaning of this determination is that the leakage level of the battery pack under test has exceeded the safety boundary, and its probability of passing the standard protection (IP) level test is lower than the preset confidence level, indicating a high risk of failure. In this case, the system generates an alarm message, prompting operators to isolate, rework, or scrap the non-conforming product to prevent it from entering the market.

[0077] It should be noted that the technical effect of this embodiment is not merely to determine a specific critical leakage rate threshold for the protection level, but rather to transform the destructive, time-consuming, and sampling-only protection level testing process in related technologies into a non-destructive, rapid, and fully inspectable airtightness testing process. This transformation reduces testing costs (e.g., reducing the time of a single test from several hours to several minutes), avoids the risk of product damage (by changing from destructive testing to non-destructive testing), and enables quality confirmation for each product.

[0078] It is understood that the above-mentioned effects are brought about by the overall technical solution of this embodiment, and do not depend on a specific critical leakage rate threshold value for a particular protection level. Even if the critical leakage rate threshold for the protection level varies depending on the battery pack model or the target protection level, as long as the core logic of "establishing a mapping relationship library → calibrating the critical leakage rate threshold → online judgment" is adopted, the above-mentioned technical effects can be achieved.

[0079] In one embodiment, the method for determining the protection level of a battery pack further includes the following steps: Step S3: Randomly sample the battery packs to be tested that have been determined to meet the target protection level requirements to obtain sampled battery packs.

[0080] Specifically, step S3 includes the quality control stage of the production line, where, for battery packs that have been deemed qualified in step S22, random sampling is conducted according to a preset sampling frequency (e.g., sampling a certain number of units per batch, or sampling one unit after a certain quantity is produced), to serve as samples for subsequent verification. The sampling strategy can be dynamically adjusted according to the product's reliability requirements, the stability of the production process, and the quality control objectives. For example, the sampling frequency can be appropriately increased in the early stages of new product introduction, and appropriately decreased after the process has matured and stabilized.

[0081] Step S4: Perform standard protection level tests on the sampled battery packs to verify whether they meet the standard protection level requirements.

[0082] Specifically, in step S4, the sampled battery packs extracted in step S3 are subjected to a standard protection rating (IP) test according to the same standard as in step S30 (such as IEC 60529 or GB / T 4208-2017). The purpose of this test is to verify whether the actual protection rating (IP) of the products deemed qualified by this method truly meets the target requirements. During the test, the test results (pass / fail) and corresponding failure characterization data for each sampled battery pack must be recorded in detail.

[0083] Step S5: When the standard protection level test result of the sampled battery pack does not meet the target protection level requirements, obtain the actual protection level test result, the corresponding failure characterization data, and the corresponding airtightness test leakage rate value L_test for the sampled battery pack.

[0084] Specifically, in step S5, for the sampled battery packs that were found to have failed the actual test in step S4, the system can automatically trace back the airtightness test leakage rate value L_test obtained in step S1, and combine it with the protection (IP) level test results (failed) recorded in step S4 and detailed failure characterization data (such as water ingress location, water ingress volume, insulation resistance change, etc.).

[0085] Step S6: Associate the measured protection level results, the corresponding failure characterization data, and the corresponding airtightness test leakage rate value L_test for each sampled battery pack that does not meet the target protection level requirements, construct a mapping relationship information, and store the mapping relationship information in the mapping relationship library.

[0086] Specifically, in step S6, each set of "air tightness test leak rate value - protection level test result - failure characterization data" obtained in step S5 is associated and integrated according to the same data structure as in step S40 to form a new mapping relationship information; the mapping relationship information is added to the original mapping relationship library to realize the dynamic update of the database.

[0087] Please see Figure 5 This embodiment also provides a battery pack 1, which is tested using the battery pack protection level determination method described in any of the above embodiments and is determined to be a battery pack that meets the target protection level requirements.

[0088] It is understood that the method for determining the protection level of the battery pack has been described in detail in the above embodiments, and will not be repeated here.

[0089] Specifically, the battery pack 1 includes battery cells and a battery case 10. The battery case 10 has an internal cavity, and the battery cells are disposed within the cavity. It is understood that after the battery pack passes the protection level determination method test, the battery pack can be used as a power supply for various electrical devices, thereby helping to improve the reliability and safety of the electrical devices in complex environments. The electrical devices may be automobiles, aircraft, ships, mechanical production equipment, energy storage power stations, or portable electronic devices, etc.

[0090] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for determining the protection level of a battery pack, characterized in that, include: Obtain the leak rate value of the airtightness test of the battery pack under test; Based on the leak rate value of the airtightness test of the battery pack under test and the mapping relationship library, it is determined whether the battery pack under test meets the target protection level requirements; wherein, the mapping relationship library stores multiple mapping relationship information, and each mapping relationship information includes the leak rate value of the airtightness test of a battery pack sample and the corresponding standard protection level test result.

2. The method for determining the protection level of a battery pack according to claim 1, characterized in that, The step of determining whether the battery pack under test meets the target protection level requirements based on the leak rate value of the airtightness test and the mapping relationship library includes: The critical leak rate threshold for the protection level is determined based on the mapping relationship library. The critical leak rate threshold for the protection level is used to characterize the maximum allowable airtightness test leak rate value that meets the target protection level requirements. The airtightness test leakage rate value of the battery pack under test is compared with the critical leakage rate threshold of the protection level, and the battery pack under test is determined to meet the target protection level requirements based on the comparison result.

3. The method for determining the protection level of a battery pack according to claim 2, characterized in that, The step of comparing the airtightness test leakage rate value of the battery pack under test with the critical leakage rate threshold of the protection level, and determining whether the battery pack under test meets the target protection level requirements based on the comparison result, includes: If the leak rate value of the airtightness test of the battery pack under test is less than or equal to the critical leak rate threshold of the protection level, the battery pack under test is determined to meet the target protection level requirements; or if the leak rate value of the airtightness test of the battery pack under test is greater than or equal to the critical leak rate threshold of the protection level, the battery pack under test is determined to not meet the target protection level requirements, and an alarm message is generated.

4. The method for determining the protection level of a battery pack according to claim 2, characterized in that, The method for determining the critical leakage rate threshold of the protection level includes the following steps: Based on the mapping relationship library, statistical analysis is performed on the air tightness test leakage rate values ​​and their corresponding protection level test results of multiple battery pack samples to establish the correlation between the air tightness test leakage rate value and the protection level pass rate. Based on the aforementioned correlation, the critical leakage rate threshold of the protection level corresponding to the target protection level is determined.

5. The method for determining the protection level of a battery pack according to any one of claims 1 to 4, characterized in that, The method for constructing the mapping relationship database includes the following steps: Provide multiple battery pack samples, including samples that are properly sealed and samples that have at least one preset failure characteristic; Under preset test conditions, the airtightness test leakage rate value of each battery pack sample was obtained. Each of the battery pack samples was subjected to a standard protection level test to obtain the measured protection level results and corresponding failure characterization data for each battery pack sample. The airtightness test leakage rate value, the corresponding protection level test result, and the failure characterization data of each battery pack sample are associated and recorded as a mapping relationship information. Multiple mapping relationship information are stored to construct a mapping relationship library.

6. The method for determining the protection level of a battery pack according to claim 5, characterized in that, The preset failure characterization includes setting simulated defects of different diameters or shapes at at least one of the screw connections, welds, sealing surfaces, or housing assembly interfaces of the battery pack sample to simulate leakage channels of different severity.

7. The method for determining the protection level of a battery pack according to claim 5, characterized in that, The step of obtaining the airtightness test leakage rate value of each battery pack sample under preset test conditions includes: Under a preset test pressure, an airtightness test is performed on each of the battery pack samples, and the test temperature and relative humidity are monitored simultaneously to obtain the gas leakage rate value of each battery pack sample, as well as the test pressure, temperature data and relative humidity data during the test process.

8. The method for determining the protection level of a battery pack according to claim 5, characterized in that, The standard protection level test includes at least one of dustproof test, spray test or immersion test; the failure characterization data includes at least one of dust ingress, water ingress and insulation resistance change.

9. The method for determining the protection level of a battery pack according to any one of claims 1 to 4, characterized in that, The method for determining the protection level of the battery pack further includes the following steps: Randomly sample the battery packs to be tested that have been determined to meet the target protection level requirements to obtain sampled battery packs; The sampled battery packs were subjected to standard protection level tests to verify whether they met the standard protection level requirements. When the standard protection level test result of the sampled battery pack does not meet the target protection level requirements, the actual protection level test result, the corresponding failure characterization data, and the corresponding airtightness test leakage rate value of the sampled battery pack are obtained. For each sampled battery pack that does not meet the target protection level requirements, the actual protection level test results, the corresponding failure characterization data, and the corresponding airtightness test leakage rate value are associated to construct a mapping relationship information, and the mapping relationship information is stored in the mapping relationship library.

10. A battery pack (1), characterized in that, The battery pack (1) is tested using the method for determining the protection level of a battery pack as described in any one of claims 1 to 9.

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