Iron-Loss Modeling for Rotating Machines: Comparison Between Bertotti's Three-Term Expression and 3-D Eddy-Current Analysis

Two calculation methods for iron-loss estimation of rotating machines are investigated. One is based on the conventional three-term expression. In this case, the losses are calculated from the time variation in the flux density obtained by the finite element analysis, which approximates the stator and rotor cores as solid magnetic materials without conductivity. The other is based on the 3-D eddy current analysis in the electrical steel sheet. In this case, the excess loss is calculated with a simple approximation. It is clarified that both methods can estimate the no-load iron loss in the similar accuracy and that the method based on the eddy-current analysis is suitable for the estimation of high-order harmonic iron losses.