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.