Modulated Multi-Level Fundamental Frequency Inverter for Three-Phase Photovoltaic Application

Abstract

A fundamental frequency modulated multi level inverter scheme is introduced (best suited for a three phase stand alone photovoltaic (PV) system). The system consists of four series connected PV arrays, a five level diode clamped multi level inverter (DCMLI) generating fundamental modulation staircase three phase voltages, with three phase induction motor as a load. A five-level diode clamped multilevel inverter (DCMLI) fundamental frequency switching strategy is proposed by selecting the switching angles such that the lower order harmonics are eliminated. In this study a harmonic elimination technique is presented that allows one to control a multilevel inverter in such that it is an efficient low total harmonic distortion (THD) inverter that can be used to interface distributed dc energy sources with a main ac grid or as an interface to a motor drive powered by fuel cells, batteries, or ultra-capacitors.