Battery Diagnosis Device Using Multi-Frequency Impedance Analysis
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Solution Overview
Problem
Determining the precise deterioration state and present value of batteries used in electric vehicles is challenging due to varying deterioration patterns and the inability of existing methods to accurately predict future performance based on internal resistance alone.
Innovation Solution
An apparatus and method that measure solution resistance (Rsol) and charge transfer resistance (Rct) of batteries, comparing these values to historical deterioration data to estimate remaining charge cycles and determine the battery's present value, considering future use purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If only DC resistance components are used to determine battery deterioration, then the measurement method is simple, but the prediction accuracy of future deterioration tendency is insufficient
Solution Approach 1:
The internal resistance is segmented into multiple frequency-dependent components (DC resistance at 0 Hz, intermediate frequency resistance at 10-1000 Hz, and high frequency resistance at 10 kHz-1 MHz). Each component is measured separately using impedance spectroscopy at different frequencies, allowing comprehensive characterization of battery deterioration mechanisms at different timescales.
Solution Approach 2:
The measurement approach transitions from a single DC resistance value to a multi-dimensional frequency spectrum analysis. By measuring impedance across a range of frequencies (0 Hz to 1 MHz), the system captures deterioration information that cannot be obtained from DC measurements alone, adding the frequency dimension to the assessment.
2Ease of operation
If battery value is determined only from degree of deterioration based on battery capacity, then the assessment is straightforward, but the present value is unreliable when deterioration patterns differ
Solution Approach 1:
The assessment methodology expands from a single parameter (battery capacity) to multiple parameters including impedance at multiple frequencies (0 Hz, 10-1000 Hz, 10 kHz-1 MHz), charge-discharge characteristics at different C rates, and temperature-dependent behavior. These changing parameters provide a more reliable fingerprint for identifying deterioration patterns.
Solution Approach 2:
The system incorporates feedback by comparing measured impedance spectra and charge-discharge characteristics against reference data from batteries with known deterioration patterns. This feedback mechanism allows the system to identify and adapt to different deterioration patterns, improving the reliability of present value determination.
3Adaptability or versatility
If batteries are evaluated only for vehicle-mounted use, then the evaluation criteria are clear, but valuable batteries may be discarded that could serve other purposes
Solution Approach 1:
The evaluation system uses multiple measurable parameters (impedance at different frequencies, charge-discharge rates, capacity retention) to create a comprehensive profile of battery health. This multi-parameter approach preserves information about the battery's actual condition, enabling flexible re-evaluation for different application scenarios rather than binary pass/fail judgments.
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 accurate determination of battery deterioration and value assessment, accounting for different usage purposes by combining Rsol and Rct measurements with historical data, providing a precise indicator of remaining charge cycles and discharge capacity/time limits.
Implementation Method 1
the resistance component determining unit determines an impedance of the battery at each frequency as a complex representation from the measured voltage change and the measured current change at each of the frequencies
Implementation Method 2
a battery's internal resistance components that affect the battery capacity and power are not only the DC resistance that is the resistance components of an electrolytic solution
Implementation Method 3
determines the solution resistance Rsol and the charge transfer resistance Rct of the battery
Data Source
AI summary
An apparatus is disclosed that includes a resistance measuring unit operable to determine a solution resistance Rsol and a charge transfer resistance Rct of a battery; and at least one computer-readable non-transitory storage medium comprising code, that, when executed by at least one processor, is operable to provide an estimate of the present value of the battery by: comparing Rsol and Rct to historical deterioration transition information; estimating the number of remaining charge cycles before a discharge capacity lower limit is reached by the battery using the comparison; and estimating the number of remaining charge cycles before a discharge time lower limit is reached by the battery using the comparison. The estimate of the present value of the battery includes the smaller of the number of remaining charge cycles before a discharge capacity lower limit is reached or the number of remaining charge cycles before a discharge time lower limit is reached.