Sensorless rotor velocity tracking control for induction motors

In this paper, we present a sensorless control algorithm that achieves semiglobal exponential rotor velocity tracking for the full-order nonlinear dynamic model of an induction motor actuating a mechanical subsystem, The proposed controller utilizes stator current measurements but is termed sensorless due to the fact that no mechanical sensors are required and that stator current measurements can be obtained in an inexpensive/simplistic manner (e,g,, relatively inexpensive Hall effect current sensors can be used to obtain current measurements). The control strategy utilizes a novel rotor velocity observer which facilitates the potential for improved rotor velocity tracking transient performance. In addition, the observed integrator backstepping technique is utilized to ensure that the observer-based controller remains bounded. Experimental results are included to verify the effectiveness of the controller,