Soft-Switched High Voltage Gain Boost-Integrated Flyback Converter Interfaced Single-Phase Grid-Tied Inverter for SPV Integration

Abstract

A two-stage grid-tied efficient solar photovoltaic (SPV) system with zero voltage switching (ZVS) and zero current switching (ZCS) at the dc-dc converter stage and adaptive synchronization at the inverter stage is proposed. In the first stage, an improved high step-up boost-integrated flyback converter with quasi resonant voltage multiplier cell is proposed. ZVS turn-on of all mosfets and ZCS turn-off of all diodes of resonant voltage multiplier cell results in high efficient power conversion compared with the conventional boost-integrated flyback converters. Small-sized coupled inductor enhances magnetic utilization in this converter. Second stage consists of a single-phase H-bridge grid interfaced inverter with variable band hysteresis current control technique. Amplitude adaptive notch filter is used to extract fundamental unit voltage vector of grid voltage required for estimation of synchronized reference current for hysteresis controller. A 250 W laboratory prototype is developed and experimentally evaluated. Experimental results demonstrate efficient renewable energy conversion at dc-dc converter stage and quality power injection at dc-ac inverter stage of the proposed grid-tied SPV system under changing solar insulation levels.