Single Inductor Bidirectional Multi-Input Converter With Continuous Battery Current Based On Integration of Buck and Three Port Boost Topologies

Abstract

In this paper, a novel non-isolated bidirectional multi-input DC-DC converter with continuous battery current is proposed specifically for photovoltaic (PV)-battery hybrid power system application. The converter combines two boost topologies to deliver power from the energy generator source (EGS) and energy storage source (ESS) to the output while two buck topologies are integrated to transfer energy from EGS and the output to ESS. Furthermore, only a single inductor is utilized for all operating modes which leads to smaller volume and higher power density. Hence, power conversion in all operating modes is performed in a single stage and consequently the conduction loss is reduced. The battery current unlike many converters based on three port boost topology is continuous since the power is delivered between EGS and ESS by an integrated buck structure which extends battery life time. Moreover, the power is directly transferred between different ports red without power reprocessing which contributes to the improved converter efficiency. The proposed converter is analyzed for both step-up and step-down operating modes in details and a 300 W converter is simulated to verify the main converter features and the theoretical analysis.