A New Active Zero State PWM for Six-Phase Inverter

This paper presents a new active zero state pulse width modulation (AZSPWM) that improves the performance of both switching and common-mode voltage (CMV) of six-phase drives. The new AZSPWM applies two opposite large voltage vectors instead of zero voltage vectors for synthesizing the reference voltage vector. Compared with conventional space vector PWM (CSVPWM), the switching patterns of the new AZSPWM present a symmetrical waveform, halving the switching frequency and reducing the total switching dramatically. The simultaneous switchings are also eliminated and the CMV is reduced by 1/3 in full modulation index. Simulation results show that the new AZSPWM slightly increases α-β, and x-y current distortions, but these distortions rapidly decrease as modulation index increases.