A Novel 9-Level Multilevel Inverter Based on 3-Level NPC/H-Bridge Topology for Photovoltaic Applications

A Cascaded NPC/H-Bridge inverter is introduced as an interface in photovoltaic (PV) - Grid application. The Multilevel inverter has many advantages such as better utilization of switching devices, lower switching frequency at semiconductor, reduced harmonic content. In this paper a novel nine-level inverter is constructed from two cascaded three-l vel NPC/H-Bridge inverter. Compared to the classic strait forward nine level inverter, this proposed inverter requires less DC sources. This paper proposes a modified Phase Shifted PWM technique based on decomposition of the whole system into a series of four positive and negative 3-level legs. A harmonic analysis of the proposed control is carried out using double Fourier principle. Computer simulation is performed to verify the accuracy of the model and performance of the proposed model. Copyright (C) 2009 Praise Worthy Prize S.r.l. - All rights reserved.