Published online by Cambridge University Press: 17 July 2003
In this paper a new method of stator-core lamination characterization, aimed at studying magnetic field in the vicinity of a machine, is proposed. This characterization, made with small signals over a wide frequency range, is useful to study high frequency magnetic behavior of motors fed by PWM static converters. Small minor hysteresis loops of magnetic steel are assimilated to ellipses and, neglecting anisotropy, any point of a stator-core lamination is characterized by two local parameters: the relative permeability and the resistivity. The proposed method consists in measuring the impedance of a test coil over a wide frequency range by an impedance analyzer and in comparing experimental results to theoretical predictions based on magnetic field diffusion equation. An algorithm yields values of local relative permeability and resistivity from inductance measurements and experimental values of resistances are used to control the result quality.