Common-mode voltage cancellation in dual three-phase systems with synchronized PWM

Asymmetrical and symmetrical dual three-phase (six-phase) adjustable speed drives with control algorithms, providing elimination of undesirable common-mode voltages, have been analyzed in the paper. In particular, asymmetrical six-phase motor drive with common-mode voltage cancellation is based on dual neutral-point-clamped inverters with specialized algorithms of synchronized pulsewidth modulation (PWM). Symmetrical dual three-phase system with common-mode voltage elimination is based on two standard three-phase inverters, with the 60⁰-phase-shift of signals of the two inverters. Basic schemes of synchronized PWM, applied for control of both two-level and three-level inverters, have been analyzed and compared. Simulations give a behavior of dual three-phase systems with algorithms of synchronized PWM, providing elimination of undesirable common-mode voltages.