Control strategies design for a fuel cell hybrid electric vehicle

Under the pressure of air pollution and oil shortage of transportations, hydrogen as a renewable and clean energy gets more and more attentions from all over the world. Nowadays, for the cost and not matured technology of fuel cell stack, hybrid system becomes the best solution. For a 5-ton fuel cell hybrid electric bus discussed in this paper, high-pressure PEMFC and high-power NiMH battery pack forms the hybrid system. In order to get the higher fuel efficiency and avoid the frequent charge & discharge of battery pack, a fuel cell output power-oriented control system is built. Also three kinds of control strategies for the control system are put forward as conventional Fuel cell output power oriented control, Fuel cell output power oriented control based on FCE loading and unloading equations and FCE output power oriented control based on instantaneous power optimization. Their corresponding effects are compared based on simulation results. Finally, the fuel cell output power-oriented control system was applied on the fuel cell hybrid electric bus and the experiments are carried out.