Two-Winding Procedure for the Measurement of the Anhysteretic Curve Points and Small-Signal Magnetic Permeability of Ferromagnetic Materials

At a first approximation and sufficiently low frequencies, two macroscopic phenomena influence the hysteresis cycle shape in ferromagnetic materials: magnetic hysteresis and magnetic saturation. Different magnetic models use the anhysteretic curve as a fundamental locus in the magnetic material representation. In the literature, many authors proposed easier measurement methods to obtain the anhysteretic curve, or methods, which envisage the use of standard equipment already available on the market. In the present work, a measurement procedure is outlined, involving only two windings, being partly or fully compliant with the sample preparation described in the 60404 standards. Additionally, the proposed method is suitable to measure the small-signal permeability in each point of the anhysteretic curve right after the determination of the point itself. Also, the local magnetic permeability is obtained directly from the measurement. The method is executed on three toroidal samples made of different materials: a laminated sheet, a Soft Magnetic Composite and an amorphous ferrite core. The results are then compared with those of a very low frequency, large cycle conventional measurement, showing a good matching with the expected anhysteretic behavior of the three materials.