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 a 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 stator voltage vector in a deadbeat fashion. The look-up table in the DTC is replaced, by a minimum-distance vector selection scheme to minimize the flux and torque ripples over a fixed sampling period. Simulation and experimental results show that the proposed algorithm effectively reduces the flux and torque ripples.