A Dual-input Bidirectional DC-DC Converter for Hybrid Energy Storage System in Electric Vehicles

In Electric Vehicles (EVs), hybrid energy storage systems (HESS) are becoming popular to increase the cycle life of the battery. Ultracapacitor (UC) is one of the energy storages, which is preferred along with battery because it has higher cycle life and power density compared to the battery. Thus, frequent charging and discharging of UC are preferred. A new UC/battery HESS-based dual input bidirectional dc-dc converter is proposed and is operated in four modes: low power, medium power, high power and regenerative braking mode. Particularly, medium power mode has four states during its operation and in all states, sources are directly connected to the dc link, which leads to the higher efficiency of the system. Moreover, zero voltage switching (ZVS) is achieved in the modes, which further enhances the efficiency of the system. The control scheme and operating principle of the proposed converter have been explained in detail. All four modes of the proposed converter are validated by MATLAB-based simulation.