Soft-Switching Three-Port Converter with a Three-Winding Coupled Inductor

In this article, a nonisolated soft-switching three-port converter (TPC) is proposed for renewable energy systems (RES). Only one coupled inductor is used for regulating five different power flows among the three ports to improve the voltage gain. By cascoding photovoltaic (PV) and battery modules, the input current is reduced, enabling the proposed converter to operate at a reasonable duty cycle and achieve higher efficiency. In addition, utilizing only one active clamp circuit in all power flows, the leakage inductor energy can be recycled, and the main switches can achieve zero voltage switching (ZVS), resulting in low-voltage spike and high efficiency in all power flow stages. Operating principles and steady-state analyses of the proposed TPC are presented, and the design of key parameters is then discussed in detail. Finally, a 300 W-400 V converter prototype is implemented in the laboratory to verify the theoretical analyses.