Symmetrical six-phase drives with common-mode voltage elimination based on synchronized PWM

Abstract

Novel methodology of synchronized pulsewidth modulation (PWM) has been disseminated for control of symmetrical six-phase (dual three-phase) induction motor drives fed by two three-phase inverters with single DC voltage source. Control algorithms are based in this case on the 60deg-phase- shifting of control signals of two standard voltage source inverters. Four basic schemes of synchronized continuous and discontinuous PWM, applied for control of symmetrical dual three-phase systems, have been analyzed and compared. All these schemes allow providing cancellation of undesirable common- mode voltages in systems during the whole control range. Simulations give the behavior of symmetrical dual three-phase system with synchronized PWM. The spectra of the phase voltage of six-phase drives with algorithms of synchronized PWM do not contain even harmonics and sub-harmonics, which is especially important for the high power/high current applications.