Output current ripple analysis for asymmetrical six-phase drives using double zero-sequence injection PWM

Modulation techniques for asymmetrical six-phase drives have been extensively studied during the last decade. This has included analysis of the switching behavior, in terms of harmonic flux distortion factor and current ripple RMS value, for a number of available PWM methods. One particular PWM technique, which is frequently applied in practice, is the so-called double zero-sequence injection. Switching characteristics of this method have not been examined so far, and this paper attempts to fill in this gap. A theoretical study is reported at first. Theoretical findings are verified by experimental investigation, which includes comparison with a number of other PWM techniques for asymmetrical six-phase inverter-fed drives.