Performance Comparison between Sequential Command SPWM and MLI-NPC in Multi-MW drives for WECSs

Abstract

The paper presents a comparison between two energy conversion methods for a multi-modular axial flux machine used for wind energy conversion systems, namely: Sequential Command for series connected two-level converters and a Multilevel NPC converter. The Sequential Command is the shift of the carrier signals for the neighbouring two-level converters connected in series in order to minimize harmonic distortion. A phase disposition PWM is used for Multilevel NPC since it offers much lower harmonic content. The comparison takes into account both harmonic content of current and torque waveforms and losses in the converter.