Model of laminated ferromagnetic cores for loss prediction in electrical machines

An iron-loss model for laminated ferromagnetic cores of electrical machines is presented and applied to estimate the core losses of an induction machine with finite-element analysis. Skin effect in the cross section of the core lamination is modelled using a set of sinusoidal basis functions while locally considering both the hysteretic material properties and the excess field caused by domain wall motion. After spatial and time discretisation, a single non-linear equation system is obtained. An accurate vector Preisach model, the differential reluctivity tensor and the Newton-Raphson method guarantee excellent convergence of the iteration procedure. Results from the model correspond well to iron-loss data obtained by measurements.