Sensorless variable structure speed control of an induction motor

Abstract

A field oriented, variable structure speed control scheme of an induction motor is presented. No mechanical transducers are employed. A sliding surface is defined in terms of the rotor flux producing component of the stator current. Once the sliding surface is reached, the rotor flux tends asymptotically to a constant value.where is the rotor flux, i,, , is, , uSd and uX4 are the d , qThe ferns induced in the rotor estimated and used to orient the components Of the Stator current and "Itage respectively, is controller. A derivative free estimator for the fems is derived. Simulation results are presented, showing very good transient and steady state behavior.the rotor mechanical speed, U, is angular velocity of the rotor flux spatial vector, L, , L, and A4 are the stator, rotor and magnetizing inductance respectively, 0 is the total leakage factor, R, is the