A Nonisolated High Step-Up Three-Port Soft-Switched Converter With Minimum Switches

In this article, a nonisolated high step-up three-port converter is proposed based on the single-ended primary-inductor converter. The proposed converter includes two switches, which are turned on under zero voltage switching or low-voltage condition intrinsically. The overall number of elements used in the converter is small. Furthermore, the conduction losses are reduced by reducing the number of the semiconductor elements in both battery and photovoltaic (PV) current flow paths. The input inductor is not coupled to any inductors to reduce the PV current ripple and enhance the realization of maximum power point tracking (MPPT). Since low-voltage switches with low on -resistance are selectable, conduction losses are reduced. All modes of operation in the steady-state condition are discussed and design considerations in each mode are presented. Finally, the experimental prototype of the proposed converter with a 24 V PV source, 36 V battery pack, and a 380 V-200 W load is presented.