Two-stage flyback micro inverter for solar power conversion

Abstract

The solar energy has become an easily accessible source for electricity generation due to its characteristics preventing pollution, decreasing the carbon emission, and lower manner of maintenance requirements. The most significant components of a photovoltaic (PV) power conversion system is the inverter that can be configured in central, string or micro topologies. Nowadays, the micro inverters which brings advantages and drawbacks are one of the most extensively researched devices. In this study, the micro inverter which is comprised by flyback converter and H-bridge sections is designed and analyzed in terms of reliability and efficiency. The switching control of flyback converter is performed by using Incremental Conductance based Maximum Power Point Tracking (IC MPPT) algorithm while switching pulses of H-bridge are generated with Sinusoidal Pulse Width Modulation (SPWM). Both simulation and implementation of the designed micro inverter have been realized in this study. The input voltage of flyback micro inverter is obtained from a single PV module at 50 V dc whereas output voltage is generated at 220 V ac 50 Hz for single-phase lines. The proposed flyback micro inverter which has LC filter is firstly simulated with MATLAB Simulink software. The efficiency and THD ratio of simulated micro inverter are respectively obtained as 0.35 and 94%. The performance of implemented flyback micro inverter is investigated with LC and LCL filters in terms of output voltage quality. The THD ratios of output voltage are acquired 4.41% and 2.57% with LC and LCL filters while the efficiency of designed flyback micro inverter is measured around 82.3%.