Differences between Preisach model and experiment for soft ferromagnetic materials, effect of instrument accuracy

The practical use of Preisach hysteresis model is based on proper identification of weighting function that characterizes the material. Obtaining of the weighting function needs two partial derivations of two-dimensional flux density function, called Everett surface, measured by specific procedure. Since the derivatives require exact measurements, the possible source of errors are studied. Main method is to compare experimental results and simulation. The comparison showed that the excitation current source accuracy influences the quality of Everett surface. Also the numeric integration drift plays an important role. The random or systematic failure in excitation current results in the minor secondary loops on the main hysteresis loop. Simulations of these effects confirmed the predicitons. As practical output it was found that the errors in excitation can be reduced by repeated measurements. The drift can be eliminated, if a more suitable wavefrom is used.