A continuous parameter-based approach to model the effect of mechanical stress on the electromagnetic hysteresis characteristic

Abstract

Increasing rotating frequencies of electrical machines to maximize the power density lead to higher tensile and compressive mechanical stresses that are distributed inhomogeneously along the rotors’ cross section and add up to the already present residual stresses induced by the preceding manufacturing and processing steps. These effects are either neglected or considered only in the post-processing of the machine layout and design.Neglecting the mechanical impact on the magnetic properties during numerical machine simulations leads to uncertainties and deviations from the actual material behavior. This deviations are transmitted to the subsequent loss calculation and further post-processing resulting in inaccurate loss maps. In this paper the influence of mechanical stress on the hysteresis properties and occurring losses of a non-oriented soft magnetic material are examined and replicated by an adjusted energy-based hysteresis model. The chosen models ability to recreate the observed behavior for both, anhysteretic and hysteretic components, will then be evaluated. The evaluation of the model will be performed with focus on a variety of characteristic magnetic properties. Namely the required maximum magnetic field, measured and simulated losses and the ability of the model, to recreate the actual measured magnetic flux paths including the remanence polarisation and coercive magnetic field.