A partial power processing of battery/ultra-Capacitor hybrid energy storage system for electric vehicles

A new hybrid energy storage system is proposed in this paper based on partial power processing concept. Unlike the conventional designs, the proposed HESS processes only a portion of the vehicle power through the interfacing DC/DC converter. The new concept reduces the converter losses, enables the full usage of stored energy in the storage units and provides stable DC bus voltage irrespective of the operating conditions. The interfacing converter is only active when there is a need to supply power from the ultra-capacitors (UC). The regenerative braking energy is captured by both the UC, and the battery via the bidirectional converter. The proposed topology is analyzed, simulation and experimental results are presented in the paper to confirm the validity and the effectiveness of the proposed system.