Design and Comparison of Power Systems for a Fuel Cell Hybrid Electric Vehicle

In a fuel cell hybrid electric vehicle (FCHEV) the fuel cell stack is assisted by one or more energy storage devices. Thereby the system cost, mass, and volume can be decreased, and a significant better performance can be obtained. Two often used energy storage devices are the battery and ultracapacitor. In this paper a design method to design the power system of a FCHEV is presented. 10 cases of combining the fuel stack with either the battery, ultracapacitor, or both are investigated. The system volume, mass, efficiency, and battery lifetime are also compared. It is concluded that when ultracapacitors are the only energy storage device the system becomes too big and heavy. A fuel cell/battery/ultracapacitor hybrid provides the longest life time of the batteries. If the fuel cell stack power is too small, the system will be big, heavy, and have a poor efficiency.