Droop Compensation in Battery EIS for Spectral Leakage Reduction
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Solution Overview
Problem
Spectral leakage due to voltage droop interference in electrochemical impedance spectroscopy (EIS) measurements of battery cells reduces the accuracy of impedance spectrum determination, particularly for non-periodic voltage signals during discharge.
Innovation Solution
A method and system for determining and correcting the droop component in the frequency domain representation of the measured parameter by estimating the droop component using phase values at different times and applying it to the frequency domain representation of the parameter corresponding to the excitation signal frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage droop is present during spectroscopy measurement, then the measurement process can proceed, but spectral leakage occurs which reduces measurement precision
Solution Approach 1:
The patent extracts and removes the droop component from the measured signal. The droop estimation circuit separates the harmful voltage droop portion from the impedance response signal, allowing the useful impedance information to be measured without the contaminating droop effect that causes spectral leakage.
Solution Approach 2:
The patent introduces a droop estimation circuit as an intermediary component between the measurement system and the impedance spectra analysis. This intermediary circuit estimates and compensates for the droop component, acting as a mediator that eliminates the harmful effect of voltage droop before the signal is processed for impedance calculation.
2Measurement precision
If droop compensation is applied, then measurement precision is improved, but device complexity increases due to additional circuits
Solution Approach 1:
The droop estimation circuit is designed to perform multiple functions: it estimates the droop component, generates compensation signals, and integrates with the existing impedance measurement system. This multi-functional design reduces the need for separate dedicated circuits for each function, thereby limiting the increase in overall device complexity while achieving droop compensation.
Solution Approach 2:
The measurement system performs self-compensation by using its own resources. The droop estimation circuit utilizes the measured signal itself to estimate and compensate for the droop component, rather than requiring external calibration equipment or additional complex reference measurements. The system serves its own compensation needs through internal processing.
Data Source
AI summary
A method includes transforming a signal from a first domain representation to a second domain representation, the signal representing a parameter of a device and having multiple cycles. The method further comprises determining the second domain representation of a droop component of the parameter based on the signal, in which the droop component represents a rate of change of the parameter across one or more cycles of the multiple cycles. The method further comprises generating an adjusted parameter of the device based on combining the respective second domain representations of the parameter and the droop component.