System and method for evaluating a battery module

Abstract

Systems and methods for evaluating a battery module are provided. A method includes performing a battery module function test on arrays of battery cells within a battery module to obtain battery test data for each array of battery cells. The battery test data is used to determine whether a measurement parameter of one of the battery cell arrays deviates from a predetermined threshold of the measurement parameter. A centralized secondary battery test is performed on each battery cell array having a measurement parameter deviating from a predetermined threshold. The battery module is then identified based on at least one of the battery test data and the centralized secondary battery test.

Description

[0001] introduction Technical Field

[0002] The present disclosure relates to systems and methods for detecting defects in battery modules. Background Art

[0003] A battery or battery module (e.g., a rechargeable battery for an electric vehicle and / or a hybrid electric vehicle) may include individual battery cells. Types of rechargeable batteries include, but are not limited to, lithium ion, lithium sulfur (Li-S), lithium metal, and / or other types of rechargeable batteries. Battery cells may be assembled into battery modules. Individual battery cells in a battery module are typically arranged into a battery cell array, wherein the battery cells are connected in parallel via bus bars. The individual battery cell arrays are then connected in series to each other. The bus bars may be connected to the battery cells by a welding process such as laser welding. Summary of the invention

[0004] A method for evaluating a battery module is disclosed herein. The method includes performing a battery module functional test on a battery cell array within the battery module to obtain battery test data for each battery cell array. The battery test data is used to determine whether a measured parameter of one of the battery cell arrays deviates from a predetermined threshold of the measured parameter. A centralized secondary battery test is performed on each battery cell array having a measured parameter that deviates from the predetermined threshold. Then, the battery module is identified based on at least one of the battery test data and the centralized secondary battery test.

[0005] Another aspect of the present disclosure may include forming each battery cell array by welding battery cells to at least one corresponding bus bar.

[0006] Another aspect of the present disclosure may be where the battery cell arrays each include battery cells welded in parallel to at least one corresponding bus bar.

[0007] Another aspect of the present disclosure may be where the battery module functional test includes performing a hybrid pulse power characteristic test on each battery cell array in the battery module.

[0008] Another aspect of the present disclosure may be where the hybrid pulse power characteristic test includes applying a discharge pulse and a charge pulse on each battery cell array in the battery module.

[0009] Another aspect of the present disclosure may be wherein determining whether a measured parameter of one of the battery cell arrays deviates from a predetermined threshold comprises performing a statistical analysis to determine whether the measured parameter of one of the battery cell arrays is an outlier compared to measured parameters of the remaining battery cell arrays.

[0010] Another aspect of the present disclosure may be where the outliers are determined based on performing static analysis on battery test data of each battery cell array.

[0011] Another aspect of the present disclosure may be where the statistical analysis includes performing a principal component analysis based on measured parameters from the battery test data.

[0012] Another aspect of the present disclosure may include tracking measured parameters from battery module functional testing with a Kalman filter.

[0013] Another aspect of the present disclosure may include identifying tracking trajectories of the measurement parameters and performing a principal component analysis on the tracking trajectories of the measurement parameters.

[0014] Another aspect of the present disclosure may be where the predetermined threshold comprises a predetermined range of values ​​for the measured parameter.

[0015] Another aspect of the present disclosure may be where obtaining battery test data includes performing a direct current internal resistance test on each battery cell array.

[0016] Another aspect of the present disclosure may be where obtaining the battery test data includes measuring a voltage across each battery cell array.

[0017] Another aspect of the present disclosure may be wherein the focused secondary testing includes performing flash thermography by applying a flash to a target area, the target area including one of the battery cell arrays where the measured parameter deviates from a predetermined threshold, and capturing at least one image of the target area using an imaging camera to evaluate welds in the target area.

[0018] Another aspect of the present disclosure may be where the secondary testing includes directing at least one of an optical sensor or ultrasound toward the target area.

[0019] Disclosed herein is a non-transitory computer-readable storage medium embodying programming instructions, which when executed by a processor are operable to perform a method. The method includes performing a battery module functional test on a battery cell array within a battery module to obtain battery test data for each battery cell array. The battery test data is used to determine whether a measured parameter of one of the battery cell arrays deviates from a predetermined threshold of the measured parameter. A centralized secondary battery test is performed on each battery cell array having a measured parameter that deviates from the predetermined threshold. Then, the battery module is identified based on at least one of the battery test data and the centralized secondary battery test.

[0020] A system for evaluating a battery module is disclosed herein. The system includes a battery module having a battery cell array and a secondary battery test device configured to point to the battery module. A controller communicates with the battery module and the secondary battery test device. The controller is configured to perform a battery module functional test on the battery cell array within the battery module to obtain battery test data for each battery cell array, and to determine from the battery test data whether a measured parameter of one of the battery cell arrays deviates from a predetermined threshold of the measured parameter. The controller is also configured to perform a centralized secondary battery test on each battery cell array including a measured parameter that deviates from a predetermined threshold, and to identify the battery module based on at least one of the battery test data and the centralized secondary battery test.

[0021] The present disclosure also includes the following solutions:

[0022] Solution 1. A method for evaluating a battery module, the method comprising:

[0023] performing a battery module functional test on a plurality of battery cell arrays within the battery module to obtain battery test data for each of the plurality of battery cell arrays;

[0024] determining from the battery test data whether a measured parameter of one of the plurality of battery cell arrays deviates from a predetermined threshold value of the measured parameter;

[0025] performing a centralized secondary battery test on each of the plurality of battery cell arrays including a measurement parameter that deviates from the predetermined threshold; and

[0026] The battery module is qualified based on at least one of the battery test data and the centralized secondary battery test.

[0027] Option 2. The method according to Option 1 includes forming each of the plurality of battery cell arrays by welding a group of a plurality of battery cells to at least one corresponding bus bar.

[0028] Option 3. The method according to Option 2, wherein each of the plurality of battery cell arrays comprises a plurality of battery cells welded in parallel to the at least one corresponding bus bar.

[0029] Option 4. The method according to Option 1, wherein the battery module functional test includes performing a hybrid pulse power characteristic test on each of the plurality of battery cell arrays in the battery module.

[0030] Option 5. The method according to Option 4, wherein the hybrid pulse power characteristic test includes applying a discharge pulse and a charge pulse to each of the plurality of battery cell arrays in the battery module.

[0031] Option 6. A method according to Option 1, wherein determining whether the measurement parameters of one of the multiple battery cell arrays deviate from the predetermined threshold includes performing statistical analysis to determine whether the measurement parameters of one of the multiple battery cell arrays are abnormal values ​​compared to the measurement parameters of the remaining battery cell arrays in the multiple battery cell arrays.

[0032] Embodiment 7. The method according to embodiment 6, wherein the outlier is determined based on performing static analysis on battery test data of each of the plurality of battery cell arrays.

[0033] Option 8. A method according to Option 7, wherein the statistical analysis includes performing a principal component analysis based on measured parameters from the battery test data.

[0034] Option 9. The method according to Option 8 includes tracking measured parameters from the battery module functional test using a Kalman filter.

[0035] Option 10. The method according to Option 9 includes identifying a tracking trajectory of the measurement parameters and performing a principal component analysis on the tracking trajectory of the measurement parameters.

[0036] Embodiment 11. The method according to embodiment 1, wherein the predetermined threshold value comprises a predetermined range of values ​​of the measured parameter.

[0037] Embodiment 12. The method according to embodiment 1, wherein obtaining the battery test data comprises performing a direct current internal resistance test on each of the plurality of battery cell arrays.

[0038] Embodiment 13. The method of embodiment 1, wherein obtaining the battery test data comprises measuring a voltage across each of the plurality of battery cell arrays.

[0039] Option 14. A method according to Option 1, wherein the concentrated secondary battery testing includes performing flash thermal imaging by applying a flash to a target area, the target area including one of the multiple battery cell arrays having a measurement parameter that deviates from the predetermined threshold, and capturing at least one image of the target area using an imaging camera to evaluate multiple welds in the target area.

[0040] Option 15. A method according to Option 14, wherein the centralized secondary battery testing includes directing at least one of an optical sensor or ultrasound toward a target area.

[0041] Embodiment 16. A non-transitory computer-readable storage medium embodying programming instructions, the programming instructions, when executed by a processor, being operable to perform a method, the method comprising:

[0042] performing a battery module functional test on a plurality of battery cell arrays within the battery module to obtain battery test data for each of the plurality of battery cell arrays;

[0043] determining from the battery test data whether a measured parameter of one of the plurality of battery cell arrays deviates from a predetermined threshold value of the measured parameter;

[0044] performing a centralized secondary battery test on each of the plurality of battery cell arrays including a measurement parameter that deviates from the predetermined threshold; and

[0045] The battery module is qualified based on at least one of the battery test data and the centralized secondary battery test.

[0046] Option 17. A method according to Option 16, wherein determining whether the measurement parameters of one of the multiple battery cell arrays deviate from the predetermined threshold includes performing statistical analysis to determine whether the measurement parameters of one of the multiple battery cell arrays are outliers compared to the measurement parameters of the remaining battery cell arrays in the multiple battery cell arrays.

[0047] Embodiment 18. The method according to embodiment 17, wherein the outlier is determined based on performing static analysis on battery test data of each of the plurality of battery cell arrays.

[0048] Solution 19. A system for evaluating a battery module, the system comprising:

[0049] A plurality of battery cell arrays in the battery module;

[0050] a secondary battery testing device configured to be directed toward the battery module;

[0051] a controller in communication with the battery module and the secondary battery testing device, the controller being configured to:

[0052] performing a battery module functional test on the plurality of battery cell arrays within the battery module to obtain battery test data for each of the plurality of battery cell arrays;

[0053] determining from the battery test data whether a measured parameter of one of the plurality of battery cell arrays deviates from a predetermined threshold value of the measured parameter,

[0054] performing a centralized secondary battery test on each of the plurality of battery cell arrays including a measurement parameter that deviates from the predetermined threshold; and

[0055] The battery module is qualified based on at least one of the battery test data and the centralized secondary battery test.

[0056] Option 20. A system according to Option 19, wherein the controller determines whether the measurement parameters of one of the multiple battery cell arrays deviate from the predetermined threshold by performing statistical analysis to determine whether the measurement parameters of one of the multiple battery cell arrays are abnormal values ​​compared to the measurement parameters of the remaining battery cell arrays in the multiple battery cell arrays. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 Components used to manufacture a battery module are illustrated.

[0058] Figure 2 A method for evaluating a battery module is illustrated.

[0059] Figure 3A A first example measured parameter for each of a plurality of battery cell arrays in a battery module is graphically illustrated.

[0060] Figure 3B A second example measured parameter for each of a plurality of battery cell arrays in a battery module is graphically illustrated.

[0061] Figure 3C A third example measured parameter for each of a plurality of battery cell arrays in a battery module is graphically illustrated.

[0062] Figure 3D A fourth example measured parameter for each of a plurality of battery cell arrays in a battery module is graphically illustrated.

[0063] Figure 4 A set of modal coefficients are graphically illustrated. DETAILED DESCRIPTION

[0064] The components of the disclosed embodiments as described and shown herein can be arranged and designed in various configurations. Therefore, the following specific embodiments are not intended to limit the scope of the disclosure claimed for protection, but merely represent possible embodiments thereof. In addition, although many specific details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed herein, some embodiments can be practiced without some of these details. In addition, for the purpose of clarity, some technical materials understood in the relevant art are not described in detail in order to avoid unnecessarily obscuring the disclosure. In addition, as shown and described herein, the disclosure can be practiced in the absence of elements not specifically disclosed herein.

[0065] Referring to the drawings, wherein like reference numerals correspond to like or similar components throughout the several views, embodiments consistent with the present disclosure are described herein. Figure 1An example system 10 for evaluating a battery module 20 is illustrated, such as evaluating welds formed during assembly of individual battery cells 22 to form the battery module 20. The battery module 20 may be used to power a machine such as a vehicle, an electric cart, or a stationary electrical device. The individual battery cells 22 in the battery module 20 are arranged into a battery cell array 24. The battery cell array 24 includes a group of battery cells 22 connected in parallel to each other by bus bars 26. The bus bars 26 are connected to one of the anodes or cathodes of the battery cells 22.

[0066] like Figure 1 As shown in , a welding machine 40 (such as a laser welding machine) is used to weld the tabs 26T on the bus bar 26 to the corresponding anodes or cathodes on the battery cells 22 in each battery cell array 24. Although the illustrated example shows two pairs of bus bars 26, adjacent battery cell arrays 24 in the first group 22A and the second group 22B in the battery module 20 are connected in series. In addition, the electrical connection 23 connects the first group and the second group 22A in series with each other. In addition to the number of battery cell arrays 24 connected in series with each other, the number of battery cells 22 in each battery cell array 24 can vary. In the illustrated example, the battery module 20 includes twelve battery cell arrays 24, each battery cell array having four battery cells 22, for a total of 48 battery cells 22.

[0067] The electronic controller 30 is in electrical communication with the battery module 20, a secondary battery testing device 32 (such as a flash thermography device) for performing concentrated secondary battery testing, and a welding machine 40. The flash thermography device includes a light source 34 for generating and directing a flash of light to a target area on the battery module 20 and an imaging camera 36 for receiving light reflected off the target area on the battery module 20 to evaluate the welding quality of the battery module 20. The controller 30 is configured to perform the method 100 for evaluating the battery module 20 disclosed below, such as performing functional tests on the battery module 20, obtaining and analyzing battery module test data, and operating the flash thermography device to determine the welding quality between the bus bar 26 and the battery cell 22. However, the secondary battery testing device 32 may also include at least one of an ultrasonic testing device or an optical sensor.

[0068] The electronic controller 30 may be embodied as one or more digital computers or mainframes, each having one or more processors, read-only memory (ROM), random access memory (RAM), electrically programmable read-only memory (EPROM), optical drives, magnetic drives, etc., high-speed clocks, analog-to-digital (A / D) circuits, digital-to-analog (D / A) circuits, and input / output (I / O) circuits, I / O devices, and communication interfaces, as well as signal conditioning and buffering electronics. Computer-readable memory may include non-temporary / tangible media that participate in providing data or computer-readable instructions. The memory may be non-volatile or volatile. Non-volatile media may include, for example, optical or magnetic disks and other permanent memory. Example volatile media may include dynamic random access memory (DRAM), which may constitute main memory. Other examples of embodiments of memory include floppy disks, hard disks, tapes or other magnetic media, CD-ROMs, DVDs, and / or other optical media, as well as other possible memory devices (such as flash memory).

[0069] The electronic controller 30 includes a tangible, non-transitory memory having recorded thereon computer executable instructions (including one or more algorithms) for evaluating the battery module 20 as disclosed herein. The subject algorithm(s) may specifically include an algorithm configured to evaluate the quality of welds in the battery module 20.

[0070] FIG3 illustrates a method 100 for evaluating the quality of a battery module 20. In particular, the method 100 evaluates the quality of welds in the battery module 20, such as welds between the bus bar 26 and each battery cell 22. At block 102, the battery cell 22 is identified based on battery cell performance or charge level and is selected for assembly into one of the battery cell arrays 24. The battery cell 22 is identified based on at least one of performance or battery cell voltage so as to closely match the battery cell characteristics of the battery cell 22 in each battery cell array 24. The battery cell arrays 24 are assembled by welding the bus bars 26 corresponding to the battery cells 22 with a welding machine 40 to manufacture the battery cell arrays 24, which form the battery module 20 as described above (block 104).

[0071] Once the battery module 20 is assembled to include a predetermined number of battery cell arrays 24 connected in series, a battery module functional test is performed (block 106). In one example, the battery module functional test includes performing at least one of a DC internal resistance test or a hybrid pulse power characteristic test on each of the plurality of battery cell arrays 24. The hybrid pulse power characteristic test includes performing a discharge pulse and a charge pulse on each of the plurality of battery cell arrays.

[0072] In one example, the controller 30 performs a battery module functional test and obtains battery test data for each battery cell array 24 forming the battery module 20. The battery module functional test may be performed for a given load current ( Figure 3A ) measures the battery cell current across each battery cell array 24 ( Figure 3B ) or battery cell voltage ( Figure 3C ) to obtain at least one of the measurement parameters.

[0073] Figure 3A Plotted is load current in amperes (A) (vertical axis) versus time (t) (horizontal axis). Figure 3B The graph shows the response of the Figure 3A The load current is the battery cell current in amperes (A) (vertical axis). Figure 3B In the illustrated example of , lines 50 , 52 , 54 , and 56 correspond to battery test data for the battery cell array 24 in the battery module 20 . Figure 3C Example battery cell voltage (V) over time (t) is illustrated. Figure 3D 2 represents the tracking parameter of the internal resistance of each battery cell array 24 over time (t) (horizontal axis). The multiplication factor of the internal resistance may be the tracking parameter of the internal resistance.

[0074] For simplicity, Figure 3A-3D Results for four battery cell arrays 24 are shown. In some examples, if all four battery cells are equal, then Figure 3B-Figure 3D The lines 50-56 in FIG. 5 may be folded over each other and appear as a single line for a particular period of time.

[0075] At box 108, the method 100 analyzes the battery test data from the battery module functional test to determine whether one of the measured parameters deviates from a predetermined threshold, such as a relative maximum value, minimum value, or range of values. In one example, the analysis includes obtaining a voltage trajectory, a temperature trajectory, or another tracking trajectory for each battery cell array 24 from the battery module functional test. A tracking parameter of the internal resistance of each battery cell is obtained from the voltage trajectory of the battery cell using a Kalman filter. The trajectory of the tracking parameter of the internal resistance of the battery cell array 24 is then analyzed by performing a statistical analysis, such as a principal component analysis (PCA). Loose weld bonds within the battery module can result in different trajectory patterns of the internal resistance tracking parameter.

[0076] PCA is a statistical procedure that transforms a set of traces into a weighted sum of a set of linearly uncorrelated (orthogonal) traces, called principal modes. For a given set of possibly correlated signals or traces, significant common modes and their contributions to individual signals can be obtained by PCA.

[0077] In one example, PCA subtracts the average of the individual trajectories of the internal resistance tracking parameter from each individual trajectory of the internal resistance tracking parameter to obtain the difference between each individual trajectory of the internal resistance tracking parameter and the average. The difference between each individual trajectory of the internal resistance tracking parameter and the average can then be described by a series of main modes (such as a first main mode, a second main mode, a third main mode, etc.). The coefficients (i.e., weights) of the first main mode can be plotted as a graph to illustrate the health of each battery cell array 24.

[0078] like Figure 4 As shown in , the coefficients of the first main mode each surround zero on the x-axis. However, if there is a problematic battery cell array 24, the coefficients of the first main mode of the battery cell array 24 graphically push the healthy battery cell arrays 50-A, 52-A, 54-A to one side of the zero value and push the coefficients of the unhealthy battery cell array 56-A to the other side of the zero value. This identifies the unhealthy battery cell array 24 as an outlier compared to the healthy battery cell array 24. This occurs because the sum of the coefficients corresponding to each battery cell array 24 being tested will equal zero.

[0079] If an unhealthy battery cell array 24 is detected at box 108, the method 100 performs a focused secondary battery test (such as a focused flash thermography test) on the battery cell array 24 to evaluate the quality of the welds on the battery cell array 24 (box 110). If the battery cell array 24 passes the flash thermography test of weld quality, the battery module 20 becomes a certified battery module (box 112). If the battery cell array 24 fails the flash thermography test, the battery module 20 can be repaired and re-certified by the method 100, or the battery module 20 becomes scrapped.

[0080] The terms "a" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referred items. The term "or" means "and / or" unless the context clearly indicates otherwise. References throughout the specification to "an aspect" mean that a particular element (e.g., feature, structure, step, or characteristic) described in conjunction with that aspect is included in at least one aspect described herein and may or may not be present in other aspects. In addition, it should be understood that the described elements may be combined in appropriate manners in the various aspects.

[0081] When an element (such as a layer, film, region, or substrate) is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

[0082] Unless otherwise specified herein, the test standard is the most recent standard in effect as of the filing date of this application (or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears).

[0083] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0084] Although the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and elements thereof may be replaced with equivalents without departing from the scope thereof. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present disclosure without departing from the scope of the present disclosure. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed, but will include embodiments falling within its scope.

Claims

1. A method for evaluating a battery module, the method comprising: performing a battery module functional test on a plurality of battery cell arrays within the battery module to obtain battery test data for each of the plurality of battery cell arrays; determining from the battery test data whether a measured parameter of one of the plurality of battery cell arrays deviates from a predetermined threshold value of the measured parameter; performing a centralized secondary battery test on each of the plurality of battery cell arrays including a measured parameter that deviates from the predetermined threshold; as well as The battery module is qualified based on at least one of the battery test data and the centralized secondary battery test. 2 . The method of claim 1 , comprising forming each of the plurality of battery cell arrays by welding a group of a plurality of battery cells to at least one corresponding bus bar. 3 . The method of claim 2 , wherein the plurality of battery cell arrays each include a plurality of battery cells welded in parallel to the at least one corresponding bus bar. 4 . The method of claim 1 , wherein the battery module functional test comprises performing a hybrid pulse power characteristic test on each of the plurality of battery cell arrays in the battery module. 5 . The method of claim 4 , wherein the hybrid pulse power characteristic test comprises applying a discharge pulse and a charge pulse to each of the plurality of battery cell arrays in the battery module.

6. The method of claim 1 , wherein determining whether a measurement parameter of one of the plurality of battery cell arrays deviates from the predetermined threshold comprises performing a statistical analysis to determine whether the measurement parameter of one of the plurality of battery cell arrays is an outlier compared to measurement parameters of remaining battery cell arrays in the plurality of battery cell arrays. 7 . The method of claim 6 , wherein the outlier is determined based on performing a static analysis on battery test data of each of the plurality of battery cell arrays.

8. The method of claim 7, wherein the statistical analysis comprises performing a principal component analysis based on measured parameters from the battery test data.

9. The method of claim 8, comprising tracking measured parameters from the battery module functional test with a Kalman filter.

10. The method of claim 9, comprising identifying the tracking traces of the measurement parameters and performing a principal component analysis on the tracking traces of the measurement parameters.

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