Operation of Six-Phase Drives with Synchronized PWM in the Overmodulation Region

Analysis of operation of the six-phase (dual three-phase) drives with basic schemes of synchronized pulsewidth modulation (PWM) in the zone of overmodulation has been performed. Control of six-phase drives is based on the 30deg-phase-shifting between signals of two standard inverters, supplied from a single DC voltage source. Algorithms of synchronized PWM provide continuous synchronization of the output voltage waveforms of each inverter. The four-level phase voltage of six-phase drives has quarter-wave symmetry during control in this zone. Continuous and discontinuous versions of synchronized PWM, based on space-vector approach for determination of the pulse patterns, have been analyzed and compared by simulations of drive systems with low switching frequencies.