Synchronous control of six-phase traction drive with two DC links

Novel method of synchronized pulsewidth modulation (PWM) has been applied for a dual source fed multiphase drive using an asymmetrical six-phase induction machine. Detail description of modulation processes in hybrid six-phase system controlled by two inverters with continuous and discontinuous schemes of synchronized PWM and supplied by two separate DC sources with different voltages, has been presented. Special attention has been given to analysis of performance of the six-phase drive with synchronized PWM in the zone of overmodulation. Simulations give a behavior of six-phase drives controlled by two inverters with synchronized PWM, based on space-vector approach. It provides minimum number of switchings and minimal switching losses in the systems. The spectra of the phase voltage of the six-phase 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 high power/current applications.