Design and analysis of a single phase flyback micro inverter

Abstract

The reserve of fossil sources such as coal, natural gas, and crude oil are rapidly decreasing with increasing demand of electricity in the world. On the other hand, fossil fuels cause air pollution, global warming and similar environmental problems. Therefore, recent studies have become widespread about renewable energy sources (RESs) such as biomass, hydropower, geothermal, wind and solar which are the most popular in the worldwide. Among other RESs, solar energy is assumed as the best alternative to fossil sources. The photovoltaic (PV) systems generate electricity by using solar energy. In this study, a micro inverter is designed by using flyback converter on dc-dc side and neutral point clamped (NPC) inverter for dc-ac conversion. The power capacity of designed micro inverter is rated at 345 W where the input voltage is 62 V while output voltage is converted to 220 Vrms at 50 Hz frequency. Two different controllers are used against changing irradiation conditions in this work. The flyback converter is controlled by a maximum power point tracking (MPPT) while a proportional integral (PI) controller controls the NPC inverter. The designed micro inverter presents 0.57% total harmonic distortion (THD) ratio of voltage and current in FFT spectrum.