An Optimization of Perturbative Current Algorithm for Vehicular PEMFC Stack Online EIS Measurements

This paper presents an implementation method of perturbative current for vehicular proton exchange membrane fuel cells (PEMFCs) online electrochemical impedance spectroscopy (EIS) measurements. In this approach, DCdc and DCac modules in the DC/DC converter independently implement the DC current and the sinusoidal AC current with DC current bias of the PEMFC stack, respectively. Simulation results show that such a perturbation can be efficiently implemented. However, the current of DCdc is coupled to the perturbative current of DCac, lading to a decrease in the amplitude of the synthesized current after the superposition of the two currents. The mechanism of synthesized current excitation amplitude decreasing is analyzed and a feed-forward based optimization method for EIS perturbation current control is proposed. Simulation and experimental results show that the proposed method significantly improves the amplitude and total harmonic distortion (THD) of the perturbation current in the full frequency range.