Speed sensorless vector control of induction motors utilizing slot harmonics caused by variation of inductance

This paper considers the method to estimate the rotor speed by making a pulse and counting a slot harmonics in the negative-sequence carrier signal current method and the removal method of the saturation-induced harmonics with a high-pass filter in the standard induction motors using skewed rotor. The feature of the proposed method is to be able to extract of a slot harmonics and to remove the saturation- induced harmonics with an easy circuit. Experimental results show that the slot harmonics can be accurately detected of sensorless drive at low speed in a no load, and the speed estimation value is well equal to the measurement value.