Direct Stator Flux and Torque Control for asymmetrical six-phase induction motor drives

A Direct Stator Flux and Torque Control (DSFTC) scheme for asymmetrical six-phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees with isolated neutral points. The proposed control strategy is very simple and it is based on Proportional Integral (PI) regulators implemented in the stator flux synchronous reference frame. The advantages of the discussed control strategy are: constant inverter switching frequency, inherent current limitation, good transient and steady-state performance, maximum torque capability at field weakening even with large variations of the inverter DC link voltage and less distorted machine currents in contrast to DTC schemes with variable switching frequency. Simulation results are presented for a low voltage/high current 10 kW asymmetrical six-phase induction motor drive prototype designed for light traction.