Hydrogen Stack EIS Stimulus Circuit for Cell Degradation Monitoring
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Solution Overview
Problem
Hydrogen producing cells in electrolyser systems are prone to failures, and existing methods lack effective means to predict and monitor their degradation accurately.
Innovation Solution
An EIS-based system is employed to apply both DC and AC stimuli to electrochemical cells, measuring impedance at multiple frequencies to assess cell health and predict degradation, using a controller to synchronize stimulus application and impedance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EIS measurement is applied to monitor hydrogen producing cells, then cell health assessment capability is improved, but system complexity increases
Solution Approach 1:
The EIS measurement system is designed to monitor multiple hydrogen producing cells simultaneously using a single measurement device, making the device universal for health assessment across the entire cell stack. This multi-functionality approach reduces the need for separate monitoring systems for each cell, thereby improving reliability without proportionally increasing system complexity.
Solution Approach 2:
The patent introduces an intermediary measurement system that indirectly assesses cell health through electrical impedance characteristics rather than requiring direct physical inspection or complex diagnostic equipment. This intermediary EIS measurement approach simplifies the monitoring system while maintaining effective health assessment capability.
2Measurement precision
If multiple frequency AC stimulus is applied for accurate EIS measurement, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The EIS measurement system applies AC stimulus at multiple discrete frequencies in a periodic sequence rather than continuous sweeping. This periodic multi-frequency approach allows the system to capture essential impedance characteristics across the frequency spectrum while maintaining relatively quick measurement times suitable for routine monitoring of hydrogen producing cells.
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
The system provides precise health assessments and predicts cell degradation, enabling timely replacement of faulty cells and optimizing system performance.
Implementation Method 1
Electrical impedance spectroscopy (EIS) is a measurement of electrochemical impedance. Electrochemical impedance is usually measured by applying an AC (alternating current) signal, such as a sinusoidal test voltage or current, to an electrochemical cell under test and then measuring the current or voltage through the electrochemical cell over a suitable frequency range.
Implementation Method 2
An electrolyser system can include multiple hydrogen producing cells connected together as a cell stack. Hydrogen producing cells may be prone to failures.
Data Source
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AI summary
A measurement device for an electrochemical system includes a stimulus circuit configured to simultaneously apply a direct current (DC) stimulus and an alternating current (AC) stimulus to one or more electrochemical cells of the electrochemical system, wherein the AC stimulus is applied at multiple frequencies; an impedance measurement circuit configured to measure impedance of the one or more electrochemical cells; and a controller configured to synchronize application of the DC stimulus and AC stimulus with measuring of impedance at the multiple frequencies and record the measured impedance of the one or more electrochemical cells.