Battery Impedance Measurement Using Step-Current Transients

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Solution Overview

Problem

Existing methods for measuring the p constant and T constant of lithium-ion batteries in a time domain are time-consuming, making it difficult to detect abnormal batteries due to degradation modes affecting safety, and the cost of dedicated measurement devices is prohibitive for widespread implementation.

Innovation Solution

A method and device that measure impedance parameters by making a step change in current, measuring voltage at multiple timings during the transient response, and deriving the p and T constants based on these measurements, reducing calculation time and eliminating the need for costly dedicated equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If time domain calculation method is used to measure p constant and T constant, then measurement capability is achieved, but calculation time becomes excessively long

Engineering Contradiction:

Improvep constant and T constant measurementVSAvoidcalculation time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent transforms the time domain calculation problem into a frequency domain problem by changing the mathematical parameter domain. This allows the use of Fourier transform methods to calculate the p constant and T constant, significantly reducing computation time while maintaining measurement accuracy.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the computationally intensive time domain calculation mechanism with a frequency domain analysis mechanism. By substituting direct time domain integration with spectral analysis methods, the system achieves faster computation without sacrificing measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If dedicated measurement devices are used to measure impedance parameters, then measurement accuracy is improved, but device cost becomes prohibitive

Engineering Contradiction:

Improveimpedance parameter measurement accuracyVSAvoiddevice cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent enables general-purpose battery testing equipment to perform specialized impedance parameter measurements by incorporating frequency domain analysis algorithms. This multi-functional approach eliminates the need for dedicated expensive measurement devices while maintaining measurement accuracy through mathematical transformation methods.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent creates a virtual measurement system using software-based frequency domain analysis that replicates the functionality of dedicated hardware measurement devices. By copying the measurement capability through algorithmic processing rather than specialized hardware, the system achieves comparable accuracy at lower cost.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS20250277865A1Method of measuring impedance parameter and impedance parameter measurement device

Publication Date: 2025.09.04 MURATA MFG CO LTD

AI summary

A method of measuring an impedance parameter is provided and includes:(A) making a step change in current of the electrochemical device;(B) performing measurement of a voltage of the electrochemical device at multiple different timings during a transient response of the voltage of the electrochemical device caused by making the step change in the current of the electrochemical device; and(C) deriving a p constant of the CPE, based on multiple voltage values determined through the measurement, and deriving a T constant of the CPE, based on the derived p constant and the multiple voltage values determined through the measurement.