Sliding mode and disturbance observer: Two viable schemes for sensorless control of induction machines

In this paper two algorithms for sensorless control of induction machines, linear reduced-order and sliding mode observer will be discussed and compared. The linear reduced-order method is a third order disturbance observer which is very simple to design and execute, while the sliding mode observer is complicated. It will be shown by the simulation results that the estimated speed by the two methods are very well, but proposed reduced order observer is sensitive to the stator and rotor resistance parameters while the sliding mode observer is robust against parameter variation.