GENERALIZED PREISACH MODEL FOR THE DESCRIPTION OF HYSTERESIS AND EDDY-CURRENT EFFECTS IN METALLIC FERROMAGNETIC MATERIALS

We discuss a generalization of the Preisach model, based on the assumption that each point (alpha, beta) of the Preisach plane corresponds to a small correlation region of the system cross section, inside which magnetic flux reverses at a rate phi proportional-to H(a) - alpha (or H(a) - beta) when the applied field H(a) exceeds the threshold-alpha (or beta). When the magnetizing frequency f is low, the model reduces to the conventional Preisach model. When f is increased, the model predicts that the area of the hysteresis loop should increase with f according to the law C0 + C1f + C2 square-root f, where C1 is related to the so-called classical loss and C2 is expressed directly in terms of the Preisach function, p(alpha, beta). The prediction of the existence of the excess loss term C2 square-root f is in agreement with experiments. The fact that the coefficient C2 is calculated from p (alpha, beta) implies that one can predict dynamic losses directly from quasistatic hysteresis losses, a remarkable conclusion which is also confirmed by recent investigations with electrical steels.