A New Hybrid Energy Storage System Topology for Electric and Hybrid Electric Vehicular Applications

This paper proposes a new semi-active hybrid energy storage system (HESS) topology involving batteries and ultracapacitors (UC) in electric/hybrid electric vehicular applications. The main motivation of the new topology is to overcome the drawbacks of the conventional UC-DC topology. The proposed structure provides peak power to and absorbs regenerative braking energy from the DC bus without using the DC-DC converter. Hence, the power rating of the DC-DC converter is much lower than the one used in the UC-DC topology. Further, the DC-DC converter of the proposed topology is unidirectional and thus has fewer components and less control complexity than the bidirectional DC-DC converter of the UC-DC topology. Both these factors reduce the cost of the overall system. Since, the DC-DC converter is used less frequently during typical urban driving, the converter losses are reduced and the system efficiency is enhanced. To evaluate the performance of the proposed topology, simulations are carried out in the MATLAB/Simulink environment. The simulation results confirm the validity of the proposed topology.