Observer-based indirect speed control for induction machines

In this paper, we present a strategy for the design of an observer-based indirect speed control for induction motors. We first derive a reduced (3rd) order complex differential model for induction motors using the α - β model. For the sake of simplicity, we use this new formulation of the induction motor model as basis for the design of observer-based control methodology. Next, we design an indirect torque controller giving rise to an indirect way of controlling the speed of the machine. Then, as the controller requires the measurements of the rotor fluxes, we synthesise a rotor flux observer which facilitates the implementation of the torque (and speed) controller. Consequently, an observer-based indirect speed controller is essentially designed. The validity of the proposed methodology is assessed via simulation using Matlab/Simulink software package.