Fuel Cell-Based Auxiliary Power Unit: EMS, Sizing, and Current Estimator-Based Controller

Fuel cells have increasingly become an attractive option for providing clean electricity at relatively high efficiency. This paper discusses the key features of a proton exchange membrane fuel cell for a fuel cell-based auxiliary power unit (FC-APU) to supply a portion of electric loads in a vehicle. The FC-APU includes two converters: a unidirectional converter to control the fuel cell current and a bidirectional converter to control the dc-link voltage and battery current. This paper proposes 1) an energy management system (EMS) to manage the power transfer between the load and energy sources with emphasis on low stress on the fuel cell, 2) an iterative method to size the fuel cell and battery for a given load profile, based on the proposed EMS, and 3) a current estimator to reduce the effects of system transients on the dc-link voltage and increase system modularity. Simulation and experimental results validate the proposed EMS, sizing, and controller design.