Observability of Speed in an Induction Motor from Stator Currents and Voltages

This paper describes a new approach to estimating the speed of an induction motor from the measured terminal voltages and currents without the use of a speed/position sensor. The new observer uses a purely algebraic speed estimator to stabilize a dynamic speed estimator and it is shown that it has the potential to provide low speed (including zero speed) control of an induction motor under full rated load.