An Analytical Optimization Method for Improved Fuel Cell–Battery–Ultracapacitor Powertrain

Fuel-cell vehicles have the potential to revolutionize transportation. In particular, a fuel-cell vehicle using a combined battery–ultracapacitor energy storage system can provide excellent fuel economy and performance while extending the battery life due to more frequent use of the ultracapacitor. This paper first presents a new fuel cell–battery–ultracapacitor (FC–B–UC) vehicle topology. Then, a vehicle simulator is used to show that the new topology is superior to a promising FC–B–UC topology from the literature. Finally, an analytical optimization method is developed to determine the optimal battery and ultracapacitor sizes for two different options of the novel FC–B–UC topology. The optimization method seeks to maximize efficiency and minimize mass and cost of the overall system. Numerical examples are provided to validate the analytical optimization method.