Fuel Cell Impedance Measurement DC Fluctuation Compensation
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Solution Overview
Problem
Existing methods for measuring impedance of a fuel cell stack fail to account for fluctuations in direct current (DC) due to load changes, leading to inaccurate measurements.
Innovation Solution
An apparatus and method that compensates for AC voltage measurements by adjusting them based on the measured DC current, using an AC current applier, AC voltage measurer, DC current measurer, AC voltage compensator, and impedance measurer to ensure accurate impedance measurement even under fluctuating load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AC voltage measurement is performed without compensation, then measurement process is simple, but measurement precision deteriorates when DC current fluctuates
Solution Approach 1:
The patent implements a feedback mechanism where the measured DC current value is fed back to the AC voltage compensator, which then adjusts the AC voltage measurement accordingly. This closed-loop feedback system ensures that impedance measurements remain accurate despite fluctuations in DC current, resolving the contradiction between measurement precision and device complexity by using a systematic approach to compensation.
Solution Approach 2:
The patent changes the measurement parameter from raw AC voltage to compensated AC voltage, where the compensation is based on the measured DC current. By transforming the measurement parameter and applying a compensation factor derived from DC current measurements, the system maintains high measurement precision without requiring completely new measurement equipment.
2Reliability
If AC voltage amplitude is kept constant, then impedance measurement reliability is improved, but ability to handle load fluctuations is worsened
Solution Approach 1:
The patent applies dynamics by making the AC voltage compensation adaptive rather than fixed. The AC voltage compensator dynamically adjusts the compensation based on real-time DC current measurements, allowing the system to maintain reliable impedance measurements while adapting to varying load conditions. This dynamic approach resolves the contradiction by enabling the system to respond to load fluctuations while maintaining measurement reliability.
Solution Approach 2:
Through the feedback mechanism where DC current measurements inform AC voltage compensation adjustments, the system achieves both reliability and adaptability. The feedback loop enables the measurement system to automatically adapt to load changes while maintaining consistent measurement reliability through continuous compensation based on actual operating conditions.
Data Source
AI summary
An apparatus and method for measuring impedance of a fuel cell stack capable of accurately measuring the impedance even when a DC current of the fuel cell stack is changed depending on fluctuation of a load, by compensating for an AC voltage (or AC current) used to measure the impedance of the fuel cell stack based on a DC current of the fuel cell stack.