Design of a D Q Axis Controlled Micro Inverter with Flyback Converter for Grid Connected PV Systems

Inverters are one of the most important components of photovoltaic (PV) systems. Inverters are utilized as an operational interface between PV panels and the power grid or residential applications. In order to provide high system efficiency and reliable power transfer from PV panels, intensive studies have been conducted on the power circuit topologies and control structures of these inverters. In this paper, a two-stage grid-connected microinverter is designed. There is a flyback converter on the DC-DC side and a full-bridge inverter structure on the DC-AC side. The designed microinverter has the ability to amplify the input voltage. The DC voltage amplified at the inverter output is converted at the output of the microinverter to be suitable for the grid. The flyback converter is controlled by a maximum power point tracking (MPPT) algorithm and a PI controller. On the other side, the full-bridge inverter section is controlled by a D-Q axis controller. The system response is analyzed under different irradiance values. The control structures created in the designed microinverter accurately tracked the maximum power point, and maximum power transfer to the grid is observed according to different irradiance values.