Experimental verification of quasi-nonlinear modeling of magnetic steel for time-harmonic eddy current loss calculation

Eddy current losses are evaluated on FEM (finite element method) models of magnetic steel rings. DC magnetization curve has been obtained from measurements on steel samples and is used in FEM models for defining relative magnetic permeability of magnetic steel. Calculation is made with time “step-by-step” (transient) and quasi-static (time-harmonic) nonlinear solvers. Results of nonlinear calculations are compared to measurements made on two magnetic steel rings. Difference in losses when applying forced sinusoidal current or voltage source is analyzed. Using transient calculation, waveforms of total flux and magnetic field on the surface of magnetic steel are shown. Waveforms show clear presence of higher harmonics. Further on, nonlinear time-harmonicmethod is used for calculation of losses on a 3D special stray flux experimental model. Model consists of winding, core and magnetic steel plate. Loss measurement and FEM computation are compared for different values of excitation currents and clearances between plate and core.