Direct torque control has several advantages such as simplicity, fast transient response, and less parameter dependence. However, the high torque and flux ripples are considered the main drawback of the classical direct torque control especially at low speeds. The torque and flux hysteresis controllers are considered the main source of these ripples. This problem is solved in this paper using sliding mode torque and flux controllers instead of the hysteresis controllers and lookup table. Moreover, space vector modulation is combined with the sliding controllers to achieve high performance. New control voltage equations are derived to realize actual dynamic decoupling between stator flux and electromagnetic torque in the induction motor drive. The effectiveness and validity of the proposed control approach are verified through computer simulation results.

induction motor, direct torque control, sliding mode control, space vector modulation, variable speed drives.