Iron losses in permanent magnet synchronous motors

Iron losses in permanent magnet synchronous machines form a larger portion of the total losses than in the induction machines and, hence, more importance should be given to the minimization of iron loss. Previously, models have been presented for the calculations of these losses but these models still rely on finite element simulations to obtain correction factors, which are substantial, to apply to the theoretically derived formulas in order to obtain good agreement with the experimental data. In this paper we point out the source of this correction factor: the neglect of excess eddy current loss component. In many cases this loss component dominates the total iron losses and need to be incorporated in the theoretical considerations. We also provide a more complete model of iron loss, which greatly reduces the need for calculating the correction factors using FEM. The use of this more complete model will result in reduced design time especially when a number of candidate designs need to be analyzed because otherwise the calculation of these correction factors using FEM would be cumbersome as these correction factors tend to be non-linear.