Synchronous modulation of cascaded inverters of asymmetrical open-end winding motor drive

Algorithms of space-vector-based synchronized pulsewidth modulation (PWM) have been applied for control of dual-inverter fed open-end winding induction motor drive supplied by two isolated dc-sources with non-equal voltages. It has been shown, that algorithms of synchronized PWM provide continuous phase voltage symmetry for any ratios (integral or fractional) between the switching and fundamental frequencies of dual-inverter systems on the base of either standard or neutral-point-clamped inverters, and also for any ratios between voltages of two dc-sources of systems. Spectra of the phase voltage of the open-end winding drives with algorithms of synchronized PWM do not contain even harmonics and sub-harmonics during the whole control range, which is especially important for the medium-power and high-power applications.