Sliding mode variable-structure MRAS speed identification for induction motor direct torque control system

This paper proposes a novel sliding mode reference adaptive system(SM MRAS) observer for speed identification in a sensorless direct torque control induction motor system. The SM MRAS method uses the voltage model (VM) as reference and the current model (CM) as adjustable model to estimate the motor speed by combining MRAS with sliding mode variable-structure control to formulate a slide mode surface according to two model output errors. Theoretical analysis shows that the proposed strategy has stronger robustness and satisfactory performance. Simulations show that they yield accurate estimates; good dynamic behavior and resist disturb design.