Influence of the Lamination Material and Rotor Pole Geometry on the Performance of Wound Field Synchronous Machines

This paper examines the influence of the lamination material and rotor pole geometry on the steady-state performance of a wound field synchronous machine operated in the generating mode. The investigations are carried out through 2D finite element analyses using a commercial software package. Non-Oriented silicon-iron alloys of various grades are selected to recognize the impact of their magnetic properties on the machine performance. Different methods for the extrapolation of BH curves from low medium field levels to saturation are reviewed and compared. The effect of using different materials on both the rotor and the stator core is assessed in terms of variation of the air gap power, the torque ripple and the core losses. The performance of a new machine featuring a higher-grade lamination material and a refined rotor pole geometry are compared at constant air gap power with those of the reference machine. The results show that, depending on the adopted strategy, it is possible to almost halve the torque ripple and slightly decrease the mass of the rotor core.