A Review on 7 Level Symmetrical Inverter for Photovoltaic System

The input source for the multilevel inverter is a series combination of three PV arrays. In this paper we compare the outputs of three phase bridge inverter and seven level multilevel inverter for input of a PV system. Here two cases are considered. In first case, PV module output is applied to three phase full bridge inverter. In second case, PV module output is applied to symmetrical seven level inverter. The more the number of PV modules the more the number of voltage levels, the more faithful is the output sinusoidal waveform. Multi level inverters (MLI) are being preferred over conventional two level inverters as the former topologies have minimum harmonic distortion, electromagnetic interference and higher DC link voltages. On the other hand, these devices have some inherent drawbacks like increased number of switches, complicated control techniques and requirement of many voltage sources. A conventional topology uses 12 switches for a 7-level MLI design.