Design and analysis of a micro inverter for PV plants

Abstract

Renewable energy sources are obviously accepted as clean energy sources of future. The solar energy is the most popular among other renewable energy sources in all over the world. Many studies are performed on photovoltaics (PVs) and solar energy systems. Inverter is the most important power converter section of photovoltaic systems in terms of efficiency in changing weather conditions. This study presents the design and analysis of a micro inverter for PV systems. The proposed micro inverter is designed by using MATLAB Simulink software, and the control algorithms are implemented according to Incremental Conductance method. It consists of isolated boost converter with Maximum Power Point Tracking (MPPT) and H-bridge inverter with PI controller. The reaction of system has been observed under changing irradiation conditions. The implemented micro inverter has compensated the irradiation changes at boost converter stage, and dc-ac conversion process is performed regarding to the designed PI controller. The dc bus voltage is increased to around 300V, and the HF transformer is used to increase inverter input voltage to 420V. The output of inverter is generated with the support of PI controller to track 220Vrms line voltage. The THD rates for both voltage and current are measured at 0.51% in FFT spectrum, and the overall power of the micro inverter is supplied around 315W.