Modified Modulation Method for Single Phase Multilevel Inverter with DC link Switches

Abstract

This paper presents Modified Modulation Method for Single Phase Multilevel Inverter with DC link Switches. Based on a Phase Opposition Disposition (POD) modulation method, a new PWM method using one reference signal and two carrier signal is suggested. Most of Distributed Generator (DG) systems, such as photovoltaic (PV), wind turbine and fuel cells, normally require the switching sequence to balance the capacitor voltage. Moreover, lower Total Harmonic Distortion (THD) is also considered as important factor. Because of minimum number of component, conventional H6 topology suits a new PWM method compared with other topologies. It also applicable to a power conditioning system for renewable energy sources and can be used as a module of a cascaded multilevel inverter for high voltage applications. The operating principle of a new PWM method and H6 topology configuration are analyzed, and the inverter control schemes are proposed and simulated. Also, the conventional PWM control method and the proposed PWM method are compared. Results of the new PWM method are verified by software and experimental with a 36W small power system