Model-based Loss Minimization Control of a Squirrel cage Induction Motor Drive with shorted Rotor under Indirect Field Orientation

This paper presents the development of an energy saving scheme via indirect field oriented control (IFOC) at the optimum operating region. A model-based steady state power loss analysis is carried out to determine the optimal speed and the optimal rotor flux that will serve as reference for the speed and torque tracking control. IFOC ensures the decoupled control of the torque and flux components of the stator current in a similar version as in DC drives through rotor flux orientation. The need for multiple sensors is eliminated by the analytical loss model approach, leading to an appreciable cost reduction. PI controller is used for the independent control of the flux and the torque producing components of the stator current. This is done at steady state, using the optimal rotor flux and speed computed in a loss minimization algorithm. The gains for optimum performance of the PI controller is selected via genetic algorithm (GA) optimization technique. The developed scheme is validated via a realistic numerical simulation and, the shorted rotor induction machine shows a very efficient speed and torque tracking performance at various load conditions and speed settings.