A Proposal and the Effect of Novel Two-Phase PWM Scheme for the Three-Phase Multi-Level Voltage-Fed Converter－Time-Frequency Analyses for the AC-Side Line-to-Line Voltage using Wavelet Transform－

Abstract

– Three-phase multi-level voltage-fed converters operated by a two-phase PWM scheme offers relatively high ac voltage, low switching times, and low switching losses in comparison to that operated by a three-phase PWM scheme.However, the harmonics involved in the ac-side voltages and currents produced in the two-phase PWM scheme are distributed over a wide frequency range, which can be a significant drawback depending on its applications. To overcome this problem,the authors propose novel two-phase PWM scheme in which the harmonics appear in a frequency range as narrow as that in a the conventional three-phase PWM scheme. In this paper, the authors present the validity of the proposed PWM scheme from simulation and wavelet transform results.