Influence of the Slot and Pole Number Combination on the Eddy Current Loss of Permanent Magnet Machines

Abstract

In this study, the influence of the combination of slot number and pole number of permanent magnet machines on the iron loss is mathematically investigated in order to obtain guidelines that can help reduce iron loss; such reduction can facilitate miniaturization and improve the efficiency. By simplifying the machine electromagnetic model, the iron loss can be evaluated for any combination of slot number and pole number. The distribution of the magnetomotive force on the stator teeth and its complex Fourier series expansion are obtained so that coordinate transform can be easily done and the rotor iron loss can thereby be calculated. A core factor is defined on the basis of the calculated iron losses, and a core factor map of slot and pole number combinations is prepared.