Novel soft-switching snubberless naturally clamped current-fed full-bridge front-end converter based bidirectional inverter for renewables, microgrid and UPS applications

This paper presents a soft-switching snubberless current-fed full-bridge converter based bidirectional inverter for photovoltaic (PV) grid-connected system for residential application. The proposed converter is an isolated boost converter with high voltage conversion ratio that is essential for the PV parallel-connected configuration. Device voltage is clamped naturally by secondary modulation eliminating the need of active-clamp circuit or passive snubbers. Zero-current switching (ZCS) or natural commutation of primary devices and zero-voltage switching (ZVS) of secondary devices are achieved. Soft-switching is inherent owing to proposed secondary modulation and is maintained over wide variation in source voltage and output power. Steady state analysis and design have been explained. Simulation results using PSIM 9.0.4 are presented to verify the accuracy of the proposed analysis and design. A 200 W converter prototype is developed and tested to demonstrate the performance over wide variations in input voltage and output power.