Comparison of methods for the determination of dc-magnetic properties of laminated SiFe alloys

A comparative study was performed of the different techniques for determination of dc-magnetic properties of laminated SiFe alloys. Three characterization methods are considered: (1) the point-by-point method (PbPM) for the construction of magnetization loops; (2) the slow time-varying excitation in which a low-frequent periodic magnetic field excitation is used; and (3) fitting of the dc properties based on the statistical power loss model of Bertotti. All experiments are performed on the Epstein frame using the same excitation source and the same electronic flux integrator. Both grain-oriented, in both the rolling direction (RD) and transverse direction (TD), and non-oriented (NO-RD) materials are considered. In the low induction range, fitting by the Steinmetz formula is used to compare the methods. Under slow time-varying excitation, the loss in energy observed when samples are magnetized at constant dB/dt is always lower than at constant dH/dt excitation for the same frequency. It is also observed that the PbPM for the low induction range gives a lower value of hysteresis loss than the other methods (approximately 30% for GO-RD, 10% for GO-TD and 5% for NO-RD).