The thesis deals with the development of a fast and easy to use online monitoring system for the detection of different harmful operating conditions in fuel cell stacks as used for example in fuel cell cars. The monitoring technique is based on the Total Harmonic Distortion (THD) method, derived from impedance spectroscopy.
Measurements are performed by means of electrochemical impedance spectroscopy (EIS). Using these spectra and their operating points, so-called dynamic large-signal equivalent circuits (dLSEC) are parameterized under normal and harmful operating conditions or after accelerated load tests. These dLSECs can then be used to simulate THD measurements with different excitation signals in order to obtain the best THD responses under different harmful operating conditions. In a final step, the results of these simulations are tested on fuel cells during operation.
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