Design of an energy storage unit for fuel-cell and hybrid-electric vehicles

This dissertation describes an ESU design methodology capable of minimizing the volume, weight and cost of the MES and ESU (i.e., battery pack, ultracapacitor pack and PE interfaces) while allowing for the implementation of power management in a cost-effective manner. The proposed ESU design methodology is based on a holistic approach that includes the vehicle performance requirements and allows for the optimization of the ESU with respect to predetermined goals of minimum volume, weight and cost.; Substantial weight and volume reductions are accomplish when combining batteries and ultracapacitors even when considering the efficiencies of the PE interfaces. The optimized BU-ESU achieved a volume reduction of over 37% (from 135 liters to 84 liters) and a weight reduction of over 66% (from 333 kg to 148 kg) when compared to a 'classic' BO-ESU design.; The benefits of the optimized BU-ESU are not limited to weight and volume reductions since sweeping the battery cost in {dollar}/kW predicts that the BU-ESU provides the lowest cost path to meet the vehicles energy and power requirements. Additional benefits, such as improve ESU efficiency, vehicle acceleration, regenerative braking capabilities, and battery life are also identified in this research work.; The proposed ESU design and optimization procedure also includes the associated PE interfaces by selecting and designing the most suitable converter topology. The design is carried out by encompassing the wide output-to-input voltage ratio variation and output power typical on this automotive application. The comparison process identifies the half-bridge converter topology as the most cost-effective converter topology for this application. A novel design approach that incorporated a ratio defined as transitioning power ratio is proposed to overcome shortcoming of the 'classical' approach. This novel design approach allows the minimization of inductor size requirements and current stresses present in active components when designing converters with wide output-to-input voltage ratio.