A novel direct torque control (DTC) for six-phase induction motors with common neutrals

This paper introduces direct torque control (DTC) for six-phase induction motors (SPIM) with common neutrals. The machine has six phase windings spatially shifted by 60 electrical degrees and connected to a single neutral. SPIM drive has 64 inverter switching stages which provide higher possibility in selecting space voltage vectors than three phase induction machines. We will show that, it is not possible to use conventional biggest voltage vectors for DTC of SPIM with common neutral, because of producing high harmonic currents. This paper introduces a novel DTC for SPIM with 12 voltage vectors in six groups of two collinear vectors whose amplitude is high enough on alpha-beta plane where their components on z1-z2 and z3-z4 planes give opposite vectors. We will show this new method suppresses harmonic currents. The simulation results illustrate the validity and efficiency of proposed method.