Dual-stage microinverter design with a GaN-based interleaved flyback converter stage

Photovoltaic (PV) systems must maximize the energy harvested from the PV panel. One method is the use of microinverters that are less susceptible to shade effects when compared to string or central inverters. Efficiency is always an important specification, particularly, when compared to that of a central inverter. The main losses of a microinverter are transformer and semiconductor losses. Power switching devices based on silicon (Si) material are traditionally used, and silicon carbide (SiC) Schottky diodes are replacing Si diodes due to their low reverse recovery energy. Recently, Gallium Nitride (GaN) power switching devices, capable of switching at higher frequencies with fewer losses when compared to Si or SiC devices, have been introduced. Higher frequencies enable designs with smaller capacitive and inductive elements. This in turn reduces system size and cost. This work analyzes a dual-stage microinverter with an interleaved flyback converter in the dc-dc stage and GaN devices for the low-voltage side. Experimental results from a 40W prototype confirm the benefits of the proposed system.