The Impact of Magnetomechanical Effects on Ferrite B–H Loop Shapes

Under high dc bias conditions, experimental observations show B-H loops can exhibit a figure-eight shape, as energy is returned from the magnetic core back to the magnetic excitation supply during a portion of the excitation cycle. However, an explanation for this phenomenon is yet to be reported. In this paper, experimental evidence is presented showing a correlation between the asymmetrical nature of vibration due to magnetostriction and figure-eight B-H loops. Based on this evidence, it is proposed that mechanical energy generated during part of a magnetization cycle can be converted to magnetic energy during another part, aiding the magnetization process to such an extent that energy is returned to the excitation supply. The proposed theory is supported by a modified Jiles-Atherton (J-A) model, showing that a stress related H-field component caused by magnetomechanical iteractions is responsible for generating figure-eight shaped B-H loops.