A unified flux and torque control method for DTC-based induction-motor drives

In the direct torque control(DTC) of induction motor, flux linkage and electromagnetic torque are controlled directly by the selection of switching vector from a look-up table. However, the selected vector is not always the best one since only the sector is considered where the flux linkage space vector lies without considering its accurate location. This paper presents a unified flux and torque control method for DTC-based induction-motor drives, where the flux and torque errors are geometrically put together to make a reference stator voltage vector in a deadbeat fashion. The look-up table in the DTC is replaced by a minimum-distance vector selection scheme for a better choice of the stator voltage to reduce the flux and torque ripples. Simulation results show that the proposed algorithm effectively reduces the flux and torque ripple.