Static characteristic of a novel stator surface-mounted permanent magnet machine for brushless DC drives

In this paper, a novel brushless machine with 12-stator-slot/8-rotor-pole having magnets surface-mounted in the stator instead of rotor is proposed, which can be regarded as an improved flux-reversal permanent magnet (FRPM) machine and is especially suitable for brushless DC operation. The topology, operation principle and static characteristics of the proposed three-phase 12/8 stator surface-mounted permanent magnet (SSPM) prototyped machine are analyzed based on 2-D finite element analysis. A comparison between the FRPM and SSPM machines having the same dimensions is presented including the field distributions, back-EMF, cogging torque and electromagnetic torque. In addition, an optimization on the key dimensions of the SSPM machine is explored to improve the characteristics of PM flux-linkage, back-EMF as well as to reduce cogging torque. The predicted results confirm that the SSPM machines with special stator slots and rotor poles combinations are attractive candidates in brushless DC drives.