Development of energy efficient scheme for speed sensorless induction motor drive

The present paper validates the working of a new model reference adaptive system (MRAS) based sensorless speed control strategy for induction motor (IM) drive in general, using a Golden section (GS) based energy optimization method for low and medium speed range operation. The MRAS is formed using instantaneous and steady-state values of a fictitious resistive quantity (R) that does not carry any physical significance. The said formulation is free from flux computation and independent on stator/rotor resistance variation. Moreover, the sensorless formulation does not involve any integration/differentiation operator. This makes the scheme immune to the drift, saturation and noise related problems enabling accurate estimation of speed even at zero and low-speeds. This sensorless scheme is further unified with an elementary energy optimization strategy. The overall scheme is observed to work even more efficiently at low load torque without hindering the speed response. Moreover, the performance of the proposed scheme is compared with Q-MRAS estimator. All the relevant studies, in this context, are done in Matlab/Simulink. The overall scheme has also been verified experimentally using a 3 HP IM drive setup.