Current space vector amplitude fluctuation based sensorless speed measurement of induction machines using Short Time Fourier Transformation

A novel method of obtaining sensorless speed information of induction motors, derived from current space vector amplitude fluctuation (SVAF), is presented in this paper. The space vector amplitude fluctuation associated with the eccentricity harmonics is first demodulated using Park transformation in space vector plane. Short Time Fourier Transformation (STFT) is then carried out to estimate the speed of an induction machine running under transient conditions phase such as motor starting. The method has been tested and verified on an ABB 2-pole induction machine in laboratory; excellent agreement has been achieved between the estimated speed using the proposed scheme and the measured speed using an actual speed sensor. The advantage of the proposed method is that it is more effective to estimate the motor speed running with high acceleration rate during motor starting.