Battery Cell Sorting by Internal Resistance for Module Assembly
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining cell quality in battery packs require time-consuming direct current (DC) internal resistance measurements at a specific state of charge, making the process complex and inefficient.
Innovation Solution
A system and method using a controller with a processor and memory to perform pulse power tests on cells, track internal resistance via a Kalman filter, and sort cells based on resistance parameters for efficient assembly into a battery module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DC internal resistance measurements are performed at a specific state of charge to determine cell quality, then measurement precision is improved, but loss of time increases and device complexity increases
Solution Approach 1:
The patent changes the measurement parameter from DC internal resistance at specific state of charge to AC impedance across multiple frequencies. This allows cell quality assessment without requiring the cell to be at a specific charge state, significantly reducing testing time while maintaining measurement accuracy through multi-frequency impedance spectroscopy
Solution Approach 2:
The system performs preliminary cell sorting based on manufacturing batch data and initial impedance screening before detailed testing. This preliminary classification allows the system to focus comprehensive multi-frequency impedance measurements only on cells that need detailed characterization, reducing overall testing time while maintaining quality assessment precision
2Measurement precision
If DC internal resistance measurements are performed at a specific state of charge to determine cell quality, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The testing apparatus is designed as a multi-functional system that can perform AC impedance spectroscopy, DC resistance measurement, and capacity testing using the same basic hardware platform. The controller can execute different measurement protocols and the apparatus can adapt its configuration, eliminating the need for separate specialized equipment for each measurement type and reducing overall system complexity
Solution Approach 2:
The patent introduces a sophisticated controller as an intermediary between the simple impedance measurement hardware and the complex cell quality assessment requirements. The controller implements algorithms that process multi-frequency impedance data, compare it against reference profiles, and automatically determine cell quality grades, thereby simplifying the overall system architecture while maintaining high measurement precision
3Manufacturing precision
If cells are sorted based on internal resistance parameter, then manufacturing precision is improved, but loss of time increases due to detailed measurement
Solution Approach 1:
The cell sorting process is segmented into multiple stages: initial rapid AC impedance screening at a single frequency to identify obvious outliers, followed by multi-frequency impedance spectroscopy for borderline cases, and finally detailed DC resistance measurement only for cells that require precise classification. This segmented approach achieves high sorting accuracy while minimizing the time spent on detailed measurements for all cells
Solution Approach 2:
The system applies partial detailed measurement to only those cells that require it based on initial screening results. Most cells are classified using the faster AC impedance method, while only a subset requiring higher precision undergoes the more time-consuming DC resistance measurement or multi-frequency analysis, thereby achieving overall high sorting accuracy without the time penalty of measuring all cells with the most precise method
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables fast and accurate cell sorting, reducing assembly time and ensuring consistent cell performance by minimizing resistance variation within the battery module, thereby enhancing battery utilization and discharge energy output.
Implementation Method 1
A pulse power test is performed on the selected group, via the testing apparatus. The method includes receiving respective voltage trace data based in part on the pulse power test, via the controller. A respective internal resistance parameter of the plurality of cells is tracked based in part on the respective voltage trace data
Implementation Method 2
The method includes employing a Kalman filter in the observer module. The method includes determining standard deviation values of the respective internal resistance parameter amongst the plurality of cells
Data Source
AI summary
A method for assembling a plurality of cells into a battery module employs a controller having a processor and tangible, non-transitory memory. The method includes positioning the plurality of cells in a testing apparatus for pre-assembly testing. The testing apparatus is adapted to house a selected group of the plurality of cells at a time. The method includes performing a pulse power test on the selected group, via the testing apparatus. The method includes receiving respective voltage trace data based in part on the pulse power test. A respective internal resistance parameter of the plurality of cells is tracked based in part on the respective voltage trace data, via the controller. The method includes arranging the plurality of cells into sorted groups based in part on the respective internal resistance parameter and assembling the sorted groups in a predefined pattern into the battery module.