Adaptive observers for sensorless control of an induction motor

In this paper, novel adaptive speed and flux observers are designed as a part of the speed sensorless control scheme of an induction motor (IM). The design is based on a special form of IM equations with filtered current and voltage command signals as inputs. The speed tuning algorithm incorporates the stator current observer with gradient or sign speed adjustment schemes. The proposed flux observer is based on an algebraic relation involving measured and filtered signals and it shows better performance than the conventional flux observers in the low speed region and during transients. Various simulation and experimental results are presented to demonstrate the potential and practicality of the approach.