Induction Motor Sensorless Speed Estimation by Space Vector Angular Fluctuation

A novel method of obtaining sensorless speed information of induction motors, derived from space vector angular fluctuation, is presented in this paper. It obtains data from stator current by exploring the position of the current space vector in the space vector plane. The space vector signal and variations of the phase angle of the vector are subjected to Short Time Fourier Transformation (STFT) and analyzed in the time-frequency domain. High-resolution spectrum technique is adopted to modify spectrum of FFT. The method has been tested on laboratory induction motors, as well as by computer simulation. In the case of motor starting, when motor speed can change rapidly, this allows speed estimation within a few cycles.