Battery Impedance Measurement Using Multi-Step Staircase Waves
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Solution Overview
Problem
Conventional AC impedance methods using sine waves can only obtain impedance values at a single frequency per measurement, while methods using square waves can obtain values at odd multiples of frequencies, but lack detailed frequency-by-frequency plots needed for accurate battery condition diagnosis.
Innovation Solution
The use of a staircase wave with 3 or more steps as an input signal in impedance measurements allows for the acquisition of impedance values at more frequencies in a single measurement, improving analysis accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a square wave is used as input signal, then impedance values at odd multiple frequencies can be obtained, but the number of obtainable frequency points is limited and insufficient for detailed analysis
Solution Approach 1:
The input signal is segmented into a staircase wave with multiple discrete steps (3 or more), where each step corresponds to a different frequency component. This segmentation allows the system to obtain impedance values at multiple frequency points simultaneously, resolving the limitation of having only odd multiple frequencies from square waves.
Solution Approach 2:
The input signal waveform is dynamically changed from a conventional square wave to a staircase wave with 3 or more steps. This dynamic modification of the signal shape enables the generation of additional frequency components beyond odd multiples, providing more comprehensive frequency coverage for impedance analysis.
2Ease of manufacture
If conventional AC impedance method with sine wave is used, then equipment cost is reduced, but only single frequency impedance value can be obtained per measurement
Solution Approach 1:
The staircase wave input signal serves multiple functions simultaneously: it provides excitation at multiple frequency points (3 or more steps) while maintaining compatibility with simple power controller equipment. This multi-functionality allows a single measurement to yield impedance values across multiple frequencies, eliminating the need for expensive specialized AC impedance measurement equipment.
3Measurement precision
If more impedance values at multiple frequencies are obtained, then analysis accuracy is improved, but measurement complexity increases
Solution Approach 1:
The staircase wave input signal self-generates multiple frequency components through its inherent multi-step structure. The system automatically obtains impedance values at all frequency points corresponding to each step without requiring external excitation signals or complex multi-frequency testing procedures, thereby improving analysis accuracy without proportionally increasing measurement complexity.
Data Source
AI summary
An impedance measurement device includes: an applicator that applies a voltage or a current consisting of a staircase wave with 3 or more steps to any electrochemical system as an input signal; a measurer that measures a voltage input value or a current input value of the input signal and a current response value or a voltage response value corresponding to the input signal as a response signal; and a calculator that calculates impedance values at plural frequencies from the current response value or the voltage response value of the response signal.