Analysis And Design Of An Isolated Converter With Embedded Eis Function For Fuel Cell Stack Considering Low-Frequency Oscillations

This paper presents the analysis and design of an isolated dc-dc power conditioning converter (PCC) for use with a fuel cell stack (FCS) incorporating the function of online electrochemical impedance spectroscopy (EIS). The converter is designed considering the output characteristics of the FCS. The challenge of producing full-frequency-range perturbations with PCC based EIS is highlighted, where a focus of this work is related to the low-frequency perturbation generation and resolving the oscillations introduced by it. The oscillations propagated to the dc bus and load can cause severe disturbances in a vehicle powertrain. The problem is effectively tackled by guiding the oscillations from the load side to the primary side energy storage (PSES) with the designed PCC and its control. A detailed design case and its simulation results are presented to demonstrate the validity of the proposed approach.