Energy management of vehicle electrical system with auxiliary power unit

The electrical energy demand in automobiles has increased in recent years. As a result, the generator cannot deliver enough energy for the vehicle electrical system. Therefore an additional energy converter is needed to assure the higher demand. In this paper the integration of a fuel cell system as auxiliary power unit (APU) and a capacitor in an existing vehicle electrical system are modelled and taking into account of typical scenarios some simulation results are presented and discussed. As a result of these investigations a guideline for the dimensioning of such APU is given.