Real-time PEMFC diagnosis using electrochemical impedance spectroscopy under limited data conditions

In proton-exchange membrane fuel cells (PEMFCs), output voltage fluctuates based on the internal state. Therefore, evaluating fuel cell conditions is crucial for controlling operating parameters and maintaining an appropriate internal state. While electrochemical impedance spectroscopy (EIS) is used to determine the internal state during operations, conventional techniques require long measurement times. This delay is problematic during load fluctuations because the internal state may shift before measurement, leading to inaccurate diagnoses. Thus, reducing measurement time is essential for diagnosing the internal conditions of fuel cells using EIS. In this study, we limit the measured frequency range and decrease the number of measured frequencies to reduce measurement time. Comparing results obtained using the conventional and proposed methods suggests that combinations of frequencies can minimize the error rate of the calculated equivalent circuit parameters compared with those obtained without frequency restrictions; thus, the proposed EIS method is applicable to PEMFC control.