Comparative assessment of voltage modulation methods for asymmetric six-phase machines

In the most common industrial adaptation of electric drives for asymmetric six-phase machines, two independent three-phase converter units are configured to supply two three-phase winding sets. In principle, the converter units may use their own internal clock, acting independently on the two sets of windings with both the voltage pulse-width modulation and the sampling of phase currents. In the case, the machine is controlled with a vector space decomposition approach, this may cause some synchronization issues with voltage references and current sampling. In this paper, an asymmetric six-phase permanent-magnet machine is controlled with a vector space decomposition architecture has been controlled with individual current controllers in each harmonic plane. The output voltage references from the current controllers is fed to pulse-width modulators. The modulators are selected among the most promising methods for two-level converter-fed six-phase machines from the literature. A comparative analysis is performed through simulation studies, with the objective of comparing the performance of various modulators considering synchronization of voltage reference signals and phase current sampling.