Soft-switched non-isolated high step-up DC–DC converter with reduced voltage stress

In this study, a novel soft-switched high step-up DC/DC converter is presented. This converter is suitable to be employed in photovoltaic and fuel cell systems. The proposed topology is based on coupled inductors and switched-capacitor techniques to provide high step-up gain. Also, due to high conversion ratio, and symmetrical structure of the proposed topology, the voltage stress of semiconductor elements is low; therefore, high performance metal–oxide–semiconductor field-effect transistors with low ON-resistance, and also low-voltage rating diodes can be utilised to reduce the circuit cost, conduction, and reverse-recovery losses which improve the converter efficiency and power density. Furthermore, by adopting an active clamp circuit, the stored energy in the leakage inductance of coupled inductors is recycled and zero-voltage-switching turn-on condition for both main and clamp switches are provided. Operating principle and steady-state analysis of the converter are discussed in detail. Finally, an experimental prototype of the proposed converter with 200 W output power is implemented which verifies the theoretical analysis.