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.