A test method for detecting performance of a power battery

Abstract

A kind of test method for detecting the performance of power battery, it is related to battery pack field, solve the problem that the safety performance failure risk exists due to the poor electric performance of module in existing battery pack, cannot guarantee the safe use of battery pack, the implementation process of the method is as follows: the method is by distinguishing the regularity of pressure difference, pressure drop change of module in different storage time periods, the standard deviation of corresponding pressure difference, pressure difference difference, pressure drop is calculated, the standard line is drawn using 3σ analysis method, respectively, the scatter points outside the standard line of the calculated values of three test methods are removed, through the joint action of three test methods, the abnormal module / cell is identified in advance, the electric performance and safety performance failure risk of soft package module are reduced, and the stability and reliability of soft package power battery pack are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery packs, and specifically relates to a test method for detecting the performance of power batteries. Background Art

[0002] A battery pack is an important part of new energy technologies, which supplies energy and power for the storage of new energy vehicles; battery packs impose extremely high requirements on the consistency of modules, and the consistency of modules directly affects key service performances such as the capacity and cruising range of the power battery pack, so the consistency of modules is an important indicator in the battery pack; secondly, thermal runaway in soft-pack battery packs is a factor that vehicle manufacturers need to consider particularly, as it is related to the personal safety of everyone and has become an important factor restricting the development of the new energy industry; especially in the case of large electric capacity and a large number of electric cores in use, how to identify the poor electrical performance of modules is an important factor to ensure the service performance and safety of the battery pack. Therefore, how to ensure the consistency of the modules / electric cores in the battery pack has become a key indicator for the performance and safety of the battery pack.

[0003] In the prior art, after a conventional module is off the production line, only the data from the module production process is used as the judgment criterion, and the module can be shipped after being judged as qualified. In the present invention, 3 additional judgments are added for the module, and the module can be shipped only when all 3 judgments are qualified. Contents of the Invention

[0004] The present invention aims to solve the problem that the poor electrical performance of modules in existing battery packs leads to the risk of safety performance failure and cannot guarantee the safe use of the battery pack, and provides a test method for detecting the performance of power batteries.

[0005] A test method for detecting the performance of power batteries, which is implemented by the following steps:

[0006] Step 1: Static pressure difference test;

[0007] The produced modules are subjected to a static voltage sampling test by means of two interval samplings to obtain the static pressure difference standard deviation σ3, and the standard line value Δσ1 is calculated;

[0008] Step 2: Judge the standard line value Δσ1 described in Step 1. If σ3 > Δσ1, the module is judged to be unqualified; otherwise, proceed to Step 3;

[0009] Step 3: Static pressure difference difference test;

[0010] According to the pressure differences ΔV1 and ΔV2 of the static voltages obtained from the two interval samplings, the standard deviation ΔσV of the pressure difference difference is calculated, and the standard line value Δσ2 is calculated;

[0011] Step 4: Judge the standard line value Δσ2 mentioned in Step 3. If ΔσV > Δσ2, the module is determined to be unqualified; otherwise, proceed to Step 5.

[0012] Step 5: Perform a static voltage drop test;

[0013] Calculate the difference between the second static voltage test data and the first static voltage test data, and calculate the standard deviation Δσx and the standard line value Δσ3 of the difference;

[0014] Step 6: Determine the standard line value Δσ3 from Step 5. If Δσx > Δσ3, the module is deemed unqualified; otherwise, it is deemed qualified.

[0015] The beneficial effects of this invention are:

[0016] The method described in this invention distinguishes the regularity of the changes in differential pressure and voltage drop of modules within different storage time periods, and calculates the corresponding 3σ test of the difference in standard deviation of the modules, the 3σ test of the differential pressure of the modules, and the 3σ test of the voltage drop of the modules. This invention uses the 3σ analysis method to define the standard line, and removes scattered points whose calculated values ​​of the three test methods exceed the standard line. Through the combined effect of the three test methods, abnormal modules / cells can be identified in advance, reducing the risk of failure of the electrical performance and safety performance of soft-pack modules, and improving the stability and reliability of soft-pack power battery packs. Attached Figure Description

[0017] Figure 1 This is a flowchart of a test method for detecting the performance of a power battery according to the present invention;

[0018] Figure 2 This is a scatter plot of the standard deviation of the pressure difference.

[0019] Figure 3 A scatter plot of the standard deviation of the pressure difference;

[0020] Figure 4 This is a scatter plot of the standard deviation of the pressure drop. Detailed Implementation

[0021] Combination Figures 1 to 4 This embodiment describes a testing method for detecting the performance of a power battery. This method distinguishes the regularity of the changes in differential pressure and voltage drop of the module within different storage periods, calculates the corresponding differential pressure, the difference between differential pressures, and the standard deviation of voltage drop, uses the 3σ analysis method to define a standard line, and eliminates scattered points whose calculated values ​​for the three testing methods exceed the standard line. Through the combined effect of the three testing methods, abnormal modules / cells can be identified in advance, reducing the risk of electrical and safety performance failures of pouch modules and improving the stability and reliability of pouch power battery packs.

[0022] The method described in this embodiment performs tests using the standard deviation of pressure difference, the standard deviation of pressure difference, and the standard deviation of pressure drop, respectively. The specific process is as follows:

[0023] Step 1: Static differential pressure test;

[0024] First, perform the first static voltage test on the module, using the number of series connections within the module as the data reference (e.g., the first series is denoted as V). 1-V …V X-V Using the standard deviation calculation formula STDEV(V) 1-V :V X-V Calculate the standard deviation σ1 of the first static voltage test; the module resting time is N (N≥3 days, calculated in days), and the module is subjected to a second static voltage test, using the number of series connections within the module as the data reference (e.g., the first series is denoted as V). 2-V …V X-V Using the standard deviation calculation formula STDEV(V) 2-V :V X-V ), calculate the standard deviation σ2 of the second static voltage test;

[0025] Secondly, calculate the difference between the two standard deviations σ = (σ2 - σ1) × 1000; calculate the standard deviation of the difference σ again to obtain the pressure difference standard deviation σ3;

[0026] Then, calculate the average value AVERAGE1 of the standard deviation σ3; and use the formula 3*σ3+AVERAGE1 to find the standard line value Δσ1;

[0027] Finally, the standard line value Δσ1 is used for judgment. If σ3 > Δσ1, the module is judged to be unqualified; if σ3 < Δσ1, step two is executed. The main point is that the absolute value is not used as the judgment basis here, and negative values ​​are assumed to be less than Δσ1.

[0028] Step 2: Static pressure difference test;

[0029] First, using the data from the first static voltage test as a benchmark, calculate the voltage difference between the highest and lowest series voltage values ​​within a module; that is, calculate the maximum value V. max-1 and minimum value V min-1 Calculate the pressure difference ΔV1, ΔV1 = V max-1 -V min-1 ;

[0030] Based on the data from the second static voltage test, the voltage difference ΔV2 from the second static voltage test is calculated, i.e., ΔV2 = V max-2 -V min-2 ;

[0031] Secondly, calculate the difference between the two pressure differences ΔV, i.e., ΔV = ΔV2 - ΔV1; and calculate the standard deviation ΔσV of the pressure difference ΔV, and the average value AVERAGE2 of the standard deviation ΔσV of the pressure difference.

[0032] Then, the standard line value Δσ2 is calculated using the formula 3*ΔσV+AVERAGE2;

[0033] Finally, the standard line value Δσ2 is used for judgment. If ΔσV > Δσ2, the module is judged to be unqualified; otherwise, proceed to step three. Note that the absolute value is not used as the judgment criterion here, and negative values ​​are assumed to be less than Δσ2.

[0034] Step 3: Perform a pressure drop test;

[0035] First, subtract the first static voltage test data of the module from the second static voltage test data. That is, the voltage is the difference between the static voltage data of the corresponding single string before and after the module. For example, the voltage of the first string in the first test is recorded as V. 1-1 The voltage of the first series in the second iteration is denoted as V. 1-2 The voltage difference between the two subtractions is denoted as ΔV. 1x ΔV 2x And so on, with the number of modules denoted as ΔV. xx ;

[0036] Secondly, calculate ΔV 1x ΔV 2x …ΔV xx The standard deviation Δσx; and the mean AVERAGE3 of Δσx;

[0037] Then, the standard line value Δσ3 is calculated using the formula 3*Δσx+AVERAGE3;

[0038] Finally, Δσ3 is used for judgment. If Δσx > Δσ3, the module is judged as unqualified. Otherwise, if Δσx < Δσ3, the module is judged as qualified. Note that the absolute value is not used as the judgment criterion here, and negative values ​​are assumed to be less than Δσ3.

[0039] In this embodiment, if the static pressure difference is <10mV, and the calculated values ​​of σ3, ΔσV, and Δσx are all within the corresponding standard values ​​Δσ1, Δσ2, and Δσ3, the module is deemed qualified. If the static pressure difference is ≥10mV, or any one of the calculated values ​​of σ, ΔV1, and ΔV2 exceeds the standard value, the module is deemed unqualified.

[0040] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. 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 all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A test method for detecting the performance of a power battery, characterized in that: The method is implemented by the following steps: Step 1: Static differential pressure test; The produced modules were subjected to static voltage sampling tests using a two-interval sampling method to obtain the static voltage difference standard deviation σ3, and the standard line value was calculated. σ1; Step 2: Apply the standard line value described in Step 1. σ1 is used for judgment, when σ3 > If σ1 is found, the module is deemed unqualified; otherwise, proceed to step three. Step 3: Static pressure difference test; Based on the voltage difference of the static voltage sampled at the two intervals. V1, V2, calculate the standard deviation of the pressure difference. σV, and calculate the standard line value. σ2; Step 4: Apply the standard line value mentioned in Step 3. σ2 is used for judgment, when σV> σ2 indicates the module is defective; otherwise, proceed to step five. Step 5: Perform a static voltage drop test; Calculate the difference between the second static voltage test data and the first static voltage test data, and calculate the standard deviation of the difference. σx and standard line value σ3; Step Six: Adjust the standard line values ​​from Step Five. σ3 is used for judgment, when σx> If σ3 is found, the module is deemed unqualified; otherwise, it is deemed qualified. The specific process of step one is as follows: Step 1: Perform the first static voltage test on the module and calculate the standard deviation σ1 of the first static voltage test; the static time of the module is N, and the second static voltage test is performed, and the standard deviation σ2 of the second static voltage test is calculated. Step 12: Calculate the difference between the two standard deviations σ = (σ2 - σ1) × 1000; calculate the standard deviation of the difference σ to obtain the pressure difference standard deviation σ3; Step 13: Calculate the average value of the standard deviation σ3 (AVERAGE1); and use Formula 3. σ3+AVERAGE1 obtains the standard line value σ1; The specific process of step three is as follows: Step 3: Using the first static voltage test data as a benchmark, calculate the voltage difference between the highest and lowest series voltage values ​​within a module. V1; Step 3.2: Based on the second static voltage test data, calculate the voltage difference between the highest and lowest series voltage values ​​within a module. V2; Step 3: Calculate the difference between the two pressure differentials. V, that is V= V2- V1; and calculate the pressure difference. Standard deviation of V σV, and the standard deviation of the calculated pressure difference. The average value of σV, AVERAGE2; Steps 3 and 4: Using Formula 3 σV+AVERAGE2 calculates the standard line value σ2; The specific process of step five is as follows: Step 51: Calculate the voltage difference between the second static voltage test data and the first static voltage test data of the module, and calculate the standard deviation of the voltage difference. σx and calculation The average value of σx is AVERAGE 3; Step 52: Using Formula 3 σx+AVERAGE3 calculates the standard line value σ3.

2. The test method for detecting the performance of a power battery according to claim 1, characterized in that: This also includes situations where the static pressure difference is <10mV, and simultaneously satisfies σ3, σV、 The calculated values ​​of σx are all within the corresponding standard line values. σ1、 σ2、 Within σ3, it is determined to be a valid module combination.

3. The test method for detecting the performance of a power battery according to claim 1, characterized in that: In step one, the two interval samplings are: the time interval between two samplings of the stationary module is N.

4. The test method for detecting the performance of a power battery according to claim 1, characterized in that: In step 33, the difference between the two pressure differentials V is the difference between the pressure difference of the module in the first test and the pressure difference of the module in the second test.

5. The test method for detecting the performance of a power battery according to claim 1, characterized in that: In step 51, the difference between the two static voltage values ​​specifically refers to the difference between the static voltage data of a single string during the first test and the corresponding static voltage data of a single string during the second test.

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