Performance Investigation and Comparison of Two Different Electrical Hybrid System Structures

Two different topologies of an electrical hybrid system composed of a fuel cell as main source and an ultracapacitor as auxiliary source are investigated in this paper. To control these hybrid systems, a flatness-based control method which eliminates algorithm commutation in different operating modes is employed and its operation is studied in each structure. After simulating model of the structures, system efficiency in steady states is calculated while all ohmic, switching and conduction losses are considered. The simulation results show well performance of the proposed control method in both topologies and allow comparing operation of the systems in different situations.