A robust sensorless AC motor drive based on simple flux observer with voltage error compensation

This paper describes a new flux observer with voltage error compensation for sensorless AC motor drives. Incorporated with conventional open loop sensorless drive, the proposed observer gives good performance on the speed control like closed loop sensorless drive. Furthermore, the proposed drive system shows robust feature concerned with parameter variation from set-values without direct parameter tuning. The observer estimates flux, current, and error vectors simultaneously in the rotor reference frame from an EMF command and measured currents. The estimated flux vector is utilized in both optimal flux control and speed compensation, and the estimated error vector deriving from voltage command error is utilized to compensate the voltage command. The system has very simple scheme in practical point of view. The modeling and design of the observer are described, and some test results are shown to verify the performance of the proposed system.