Analytical Prediction of No-Load Stator Iron Losses in Spoke-Type Permanent-Magnet Synchronous Machines

This paper presents an analytical approach for the prediction of no-load stator iron losses in spoke-type permanent-magnet synchronous machines. The influence of bridge saturation is considered. According to the permeability distribution, the bridge is equivalent to fan-shaped saturation region with constant permeability. The magnetic equivalent circuit and iterative method are used to calculate the permeability. The motor is divided into six regions, i.e., shaft, inner saturation region, magnet, outer saturation region, air-gap, and slot. The air-gap magnetic field distribution is first calculated on the basis of Poisson's and Laplace's equations. Then, according to the flux paths, the stator core is divided into tooth and yoke. The magnetic densities of the tooth and yoke are obtained on the basis of the continuity of magnetic flux. Finally, the Bertotti model is employed to calculate the stator iron losses. The validity of the proposed method is verified by the finite element method.