Speed Estimation Method utilizing Rotor Slot Harmonics Detected from Line Current for Speed Sensorless Drive of Ultra High Speed Induction Machine

Recently, development of power electronics technology has made it possible to realize ultra high speed machine and it has been expected in various applications. This research aims at sensorless control drive of induction machine in the ultra high speed region by utilizing rotor slot harmonics caused by structure of induction machine. In this paper, we proposed a novel speed estimation method utilizing rotor slot harmonics detected form line current for speed sensorless drive of ultra high speed induction machine. It is possible to detect the rotor slot harmonics with high signal-noise ratio by utilizing a harmonics model of IM and fast Fourier transform (FFT) with limitation of a detection band. Moreover, the effectiveness of the proposed method is confirmed by experimental result.