A critical evaluation and design of bi-directional DC/DC converters for super-capacitors interfacing in fuel cell applications

Among innovative conversion systems for alternative energy, fuel cells (FCs) are ideal in applications as distributed power generation or automotive. The connection of FCs to domestic or industrial loads requires a DC/AC converter also acting as an energy buffer to match the different dynamics of FCs and loads. In the last years, a new type of electrolytic capacitors called super-capacitors (SCs), has been designed using double layers technology. Such components are able to store more energy than electrolytic capacitors maintaining the capability to swap it at high power levels. Firstly, different solution used to connect SCs to a FC based conversion system are considered. Then, a comparison of bi-directional DC/DC converters designed to manage SCs energy is performed. Finally, the converter design and a laboratory prototype of the adopted solution are reported.