Design of a fuel cell-based battery extender auxiliary power unit for a vehicular microgrid

Fuel cell-based power units have increasingly become an attractive option to provide clean and efficient electricity in certain niche applications. This paper discusses the characteristics of a proton exchange membrane (PEM) fuel cell for a battery extender auxiliary power unit and explains the steps of the design process. A two-leg converter topology is proposed to control the fuel cell output, battery charge and discharge process, and the voltage of the DC link. Different operating modes of the system are analyzed and the functions of energy management system are studied. Sizing for the fuel cell, battery, power electronic converter, and passive components are presented, and the controllers of the power electronic converter are designed. Simulation case studies in both steady state and transient conditions are presented to validate the effectiveness of the presented fuel cell-based battery extender power unit and the proposed design process.