Speed sensorless field-oriented control based on phase difference

Speed sensorless field-oriented control strategies that estimate rotor speed are being researched and many methods have been presented. However, in general, complex calculations are necessary to estimate the rotor speed. In this paper, an original sensorless field-oriented control method for an induction motor using easy and simple speed estimation is presented. In the proposed method, the motor speed is estimated by measuring the command frequency and the phase difference between the stator current vector and the stator voltage vector. By comparing the measured values with a table of data measured beforehand, the rotor speed can be estimated satisfactorily through simple calculations. In this paper, the principle and method of speed estimation and control set-up are described, as well as the results of an experiment that verified the effectiveness of the proposed method.