Observer of induction motor speed based on exact disturbance model

A simplified speed observer was proposed previously by the author to estimate the rotor speed needed in control system of a drive with induction motor. Small error of estimated rotor speed was observed but errors of the stator current and rotor flux vector components appear in dependence of rotor speed. A new structure of the speed observer is proposed now with exact disturbance model and gain coefficients depending on stator frequency. The new structure was derived from the previous one by analysis of dependencies appearing in differential equations. Explanation of observer stability is presented. Properties of the proposed observer are presented using simulations of full control system.