Variable-structure MRAS Speed Identification for Direct Torque Control of Induction Motor

A novel strategy of variable structure model reference adaptive system (MRAS-VS) observers was proposed for the speed identification of a sensor-less direct torque controlled induction motor drive. This strategy combines MRAS with variable structure control,and selects the voltage model of rotor fluxes as the reference model and the current model of rotor fluxes as the adjustable model,and formulates a slide mode surface according the output errors of two models. Theoretical analysis and simulation results show that the proposed strategy possesses the veracity of fluxes observers and improves the dynamic and static performance of the speed estimation.