Difficulty in identification of Preisach hysteresis model weighting function using first order reversal curves method in soft magnetic materials

The Preisach model can be used for detailed analysis of devices based on ferromagnetic materials, if its parameter, its weighting function, is well-known. Usually the weighting function is approximated by analytical formula. The second approach is to determine it directly from experimental data. Most widely used method to obtain the weighting function is the first order reversal curve method that is based on two partial derivatives of measured magnetization using a special excitation pattern beginning from deep material saturation. Since the derivative enhances the experimental error, a precision experiment is necessary. Furthermore, it is not easy to achieve the deep saturation with the required signal pattern. Therefore sophisticated data processing followed, in order to reduce experimental errors before performing the numerical derivative. The paper concerns measurements errors caused by insufficient saturation and also problems of negative values of the weighting function, partially due to the noise. Irrespective of measurement errors, the agreement between model and experiment is good and fully acceptable in technical praxis.