On-board diagnosis tool for fuel cells
The overall performance during the lifetime of a proton exchange membrane (PEM) system plays significant role in the total cost of the FC system. Limiting or preventing degradation and highly damaging failures through diagnosis tools that can be used on board when diagnosing systems failures is crucial for commercialising PEM FC systems. The EU-funded project D-CODE (DC/DC converter-based diagnostics for PEM systems) developed an innovative diagnostic procedure to detect FC stack faults and support stack degradation-level analysis. The project took a promising technique – electrochemical impedance spectroscopy (EIS) – from the lab to the real world. EIS is a way of characterising the dynamics of an electrochemical process. Researchers integrated EIS software and hardware into both low- and high-temperature PEM FCs. Compared to conventional techniques, the impedance spectrum provides much information with only one measurement. Two stationary applications, namely backup power generation and combined heat and power generation, were considered. Thanks to both new DC/DC converter hardware and diagnosis algorithms, many faults and potential failures can be detected online while the system runs. These relate to electrochemical processes, component faults (blower, power electronics and actuators) or external parameters (erroneous control and critical load). When the FC system is switched off, an additional device with a dedicated diagnostic function monitors the status of the stack. The D-CODE concept can be easily applied to other FC technologies, such as solid oxide FCs, thanks to the hardware and generic theoretical and experimental methodologies implemented. Except for enhancing fault and failure detection in PEM FCs, on-board EIS-based diagnostics should result in improved maintenance, decreased costs, and increased operating time and reliability. Increasing the competitive edge of such technologies should promote more widespread market uptake with important benefits for related industries, consumers and the environment.
Keywords
Fuel cells, online diagnostics, proton exchange membrane, stack degradation, electrochemical impedance spectroscopy
