Dimensioning of the peripheral components for a fuel cell based auxiliary power unit in vehicle electrical system

The increasing demand of electrical energy in automobiles has led to the problem that the vehicle electrical system does not get enough energy from the generator. Therefore, an additional energy converter is needed to supply the system with the higher demand. A fuel cell system can be used as an additional converter. However, this fuel cell system needs a lot of peripheral components in order to operate. This paper presents the investigation of the peripheral components of such a fuel cell system as an auxiliary power unit (APU) in the vehicle electrical system. A model of a fuel cell system was designed to determine the peripheral power requirement of PEM fuel cell systems between 300 W and 5 kW. For this purpose, appropriate electric factors of different performance classes were selected on the basis of measurements and data sheets. The result produced is the net power that can be made available for the connected vehicle electrical distribution system. On average, one should budget for 20% of the maximum output to be used by the peripheral power supply and power adjustment.