Comparision of multi-carrier techniques in seven-level asymmetric cascade multilevel inverter

Abstract

The multilevel inverters (MLIs) are classified into three topologies such as Diode Clamped, Flying Capacitor and Cascade Multilevel Inverter (CMLI). CMLI topologies include two kind of structure that is named symmetric and asymmetric topologies. Asymmetric Cascade MLI (ACMLI) topologies consist of unequal DC sources. Many modulation techniques have been used in ACMLI topology such as Multi-Carrier PWM (MC-PWM), Space Vector PWM and Selective Harmonic PWM. The MC-PWM technique is achieved by four different types. In this study, MC-PWM techniques which are named Phase Disposition PWM, Phase Opposition Disposition PWM, Alternate Phase Opposition Disposition PWM and Phase Shifted PWM have been compared. It is uncovered that Phase Opposition Disposition PWM technique is more convenient in terms of Total Harmonic Distortion of output voltage and current signals and in terms of the quality of power factor in ACMLI which is performed in this study.