Eccentricity harmonics detection-based speed estimation approach in a sensorless induction motors

This paper presents an eccentricity harmonics detection-based speed estimation method in a sensorless efficient induction motors. Because of the influence of spectrum leakage, the motor current signature signals analysis method, which is based the stator current, could not extract eccentricity directly. We first utilize Teager-Kaiser Energy Operator (TKEO) to demodulate the sampled stator currents, and then extract the speed related harmonics with weakening the fundamental frequency component. At the same time, the digital signal-processing techniques are exploited to extract the eccentricity harmonics signals, and the windowed and interpolated FFT are also be used to improve the accuracy of rotor speed estimation. Finally, by comparing the different speed estimation methods, this paper finishes the rotor speed estimation of induction motors. Experimental results show that the proposed speed estimation method can effectively extract the rotor speed harmonics under different load conditions.