Investigation of various operating modes of fuelcell/ultracapacitor/multiple converter based hybrid system

Fuel cells (FC) suffer with low energy density and hence required to be hybridized with Energy Storage Systems(ESS) like ultra capacitors (UC) or batteries to cater to load profiles that have periodic demands for higher power. Generally converters are connected to each ESS and hence they idle most of the time as they are operated only during peak demands. This paper proposes various operating modes in which the converters can be used in interleaved or isolated configurations upon predetermined load demand patterns. This paper analyses various operating modes and proposes control strategy to utilize the converters effectively. A multi objective energy and power management algorithm is derived based on predicted/predefined load pattern to meet tight load regulation, operate fuel cells at MPPT, regeneration and protect fuel cell from starvation. The merits of the proposed configuration are illustrated through theoretical and experimental investigation.