Magnetic field analysis of a resolver with a skewed and eccentric rotor

Factory automation applications such as machine tools, etc., with high prec ision motion control require a feedback sensor with low speed-ripple for pr ecise velocity control. The resolver is one of feedback sensors widely used in automation applications. Distorted signal-output related to speed fluct uations of the resolver result from permeance ripples, etc., produced by ec centricity of the rotor and stator slots in which coils are installed, and of the rotor itself. Although the permeance method has been used to analyze and determine the optimal magnetic design of a resolver, it remains an imp erfect solution. This paper proposes a new magnetic field analysis method w hich offers the means to produce better analysis. The most significant feat ure of our method is that the skewed resolver rotor is divided into segment s and the induced voltages of each segments are calculated and combined. Th erefore, the analysis of the skew affect and the eccentricity of the rotor becomes possible by using the 2-D FEM (two-dimensional finite element metho d) with magnetic vector potential. The analyzed results of the spectrum in the induced dual phase voltage waveforms indicate the possibilities of clos e agreement with the measured values. These results confirm the validity of this method. (C) 2000 Elsevier Science S.A. All rights reserved.