Novel soft-switching snubberless current-fed half-bridge front-end converter based PV inverter

摘要

This paper proposes a new novel snubberless currentfed half-bridge front-end isolated dc/dc converter based inverter for photovoltaic applications. It is suitable for grid-tied (utility interface) as well as off-grid (standalone) application based on the mode of control. Proposed converter attains clamping of the device voltage by secondary modulation, thus eliminating the need of snubber or active-clamp. Zero-current switching (ZCS) or natural commutation of primary devices and zero-voltage switching (ZVS) of secondary devices is achieved. Soft-switching is inherent owing to proposed secondary modulation and is maintained during wide variation in voltage and power transfer capacity, and thus is suitable for PV applications. Primary device voltage is clamped at reflected output voltage and secondary device voltage is clamped at output voltage. Steady state operation and analysis, and design procedure are presented. Simulation results using PSIM 9.0 are given to verify the proposed analysis and design. An experimental converter prototype rated at 200W has been designed, built, and tested in the laboratory to verify to demonstrate the converter performance over wide variations in input voltage and output power for PV applications. The proposed converter is a true isolated boost converter and has higher voltage conversion ratio compared to conventional active-clamped converter.