DC-DC Converter Topologies for Fuel Cell-Ultracapacitor Hybrid System

DC microgrids have recently attracted research interest. A DC microgrid is composed of different dispatchable and non-dispatchable power generators and energy buffers, such as fuel cells and ultracapacitors, which are employed to provide the steady-state and transient power demanded by the load. To interface these generation resources to a common DC bus-bar, different configurations of power converters have been proposed in the literature. For the fuel cell, a unidirectional DC-DC converter is utilised, for the ultracapacitor, however, a bidirectional DC-DC converter is needed to maintain the state-of-the-charge of the ultracapacitor. The overall efficiency of the microgrid will depend on the efficiency of these converters. High efficiency and low cost converters are very important to obtain a cost-effective solution. In addition, the converters must be chosen in respect to the characteristics of these generation resources. In this regard, this book introduces an overview on different of DC-DC converter topologies and investigates their applicability for fuel cell and ultracapacitor based on the electrical output characteristics of these resources.