The impacts of fuel cell system power response capability on optimal hybrid and neat fuel cell vehicle configurations have been explored. Vehicle system optimization was performed with the goal of maximizing fuel economy over a drive cycle. Optimal hybrid vehicle design scenarios were derived for fuel cell systems with 10 to 90% power transient response times of 0, 2, 5, 10, 20, and 40 seconds. Optimal neat fuel cell vehicles where generated for responses times of 0, 2, 5, and 7 seconds. DIRECT, a derivative-free optimization algorithm, was used in conjunction with ADVISOR, a vehicle systems analysis tool, to systematically change both powertrain component sizes and the vehicle energy management strategy parameters to provide optimal vehicle system configurations for the range of response capabilities.
Results indicate that the power response capability of the fuel cell system significantly influences the preferred powertrain component characteristics and the resulting fuel economy in a neat fuel cell vehicle. Slower transient capability leads to larger component sizes and lower fuel economy. For a hybrid fuel cell vehicle, optimal combinations of component sizes and energy management strategy parameters can be found that lead to only a minor variation in vehicle fuel economy with respect to fuel cell system power response capability.