Development of a Hybrid Fuel Cell-Based Energy System for Small Mobile Applications

This paper describes the general architecture of a hybrid energy system developed under the FEMAG (Flexible Multipurpose Advanced Generator) project, funded within the VI EU Framework Programme, and presents the most important results obtained with the experimental tests carried out on the first FEMAG prototype. The FEMAG project intended to explore the optimal integration of a fuel cell with a battery pack and ultracapacitors, delivering an energy generator for the flexible supply at variable power of small mobile non-automotive devices. In particular, the project’s main goal was to develop two prototype power systems, namely an electric wheelchair for disabled people and an industrial AGV for the transportation of finished goods inside an industrial area. The FEMAG system relies on metal hydride canisters, due to their distinctive safety features, to store the required amount of hydrogen. The fuel cell, the ultracapacitors and the metal hydride canisters were externally acquired, while the ECU, the electronic converters and the software were developed in-house. In this paper the first experimental results carried out on a FEMAG prototype are described, showing that the extra components, required in order to manage the hybrid system, do not remarkably affect the overall system efficiency, which is always higher than 36% in all the test configurations examined. As a matter of fact, the fuel cell is most often able to work at quasi-optimal conditions, near its maximum efficiency (i.e. at low and medium loads), because high external loads are met by the combined effort of the fuel cell and the ultracapacitors