A Grid-Connected PV System Based on a Multilevel Cascaded Inverter with a Single and Three-Phase Two-Level Inverters

Abstract

In this work a new multilevel cascaded inverter (MCI) based grid connected photovoltaic system is presented. The proposed MCI is based on a classic three-phase bridge inverter, where is connected the PV generator and three single-phase inverters. The asymmetry between the amplitude of the three phase bridge inverter DC source and the single phase inverter capacitor allows maximize the output levels voltage. In order to control this three-phase MCI a SPWM is used. The algorithm of this modulator will also be used to ensure the DC voltage balancing of the capacitors connected to the inverter. For this control strategy a sliding mode and PI linear controllers were also designed to obtain the modulator parameters. Simulation results are presented in order to confirm the proposed topology and the control adopted.