State observer with parameter estimation for sensorless induction motor

Variable-speed drives are being continually innovated. Recently, sensorless induction motor drives have been much studied due to several advantages, and various sensorless algorithms for an induction motor drive have been proposed. Most sensorless control algorithms are based on the flux and speed estimations which are obtained from the voltage equations. Therefore, the sensorless control performance is largely influenced by the parameter errors of a motor. This paper investigates an improved state observer with the rotor resistance estimation which the speed error due to parameter error is excluded in the sensorless induction motor drive. The proposed parameter estimation is obtained from the slip angular speed which is calculated from the measured and estimated currents. The proposed sensorless control scheme is verified through simulation and experimentation.