Abstract
This paper describes a rotor speed estimation technique of an induction motor, which utilizes slot harmonics on the d-axis caused by permeance variation across the air gap. The frequency of the slot harmonics is a multiple of the actual rotor speed, and is proportional to the number of rotor slots. In order to extract the slot harmonics, a novel adaptive band-pass filter incorporating coordinate transformation is proposed, which is effective to estimate the rotor speed from 400 to 2000r/min. This rotor speed estimation is applied to a field-oriented controller as well as a speed controller. In addition, performance improvement is carried out by compensating a motor parameter mismatch. Feasibility of the proposed technique is confirmed through several tests, using a prototype experimental setup.
