Comparative study of synchronous machines having permanent magnets in stator

• SPMSMs having doubly salient stator and rotor structure and non-overlapping armature winding are investigated.
• The choice of rotor pole number is flexible and can be any integers except the phase number and its multiples.
• For SPMSMs with 6-pole stator, 7-pole rotor has the largest average torque under the rated copper loss.
• Among the SPMSMs with three typical PM locations, the SM-SPMSM has the highest PM utilization efficiency while the SYM-SPMSM exhibits the largest average torque.

Stator permanent magnet synchronous machines (SPMSMs) with doubly salient stator and rotor structure and non-overlapping winding are investigated in this paper. The PMs can be located on the surface or in the stator pole and even in the stator yoke with alternative polarities. The selection of rotor pole number is flexible, which can be any integers except the phase number and its multiples. When the numbers of stator and rotor poles (Ns/Nr) are differed by one, 6-stator pole SPMSMs have bipolar phase flux-linkages and symmetric phase back-EMFs as well as high torques. Further, three typical PM locations are chosen to compare and analyze the influence of PM locations on electromagnetic performances under 6/7 Ns/Nr combination. The results show that SPMSM with PMs mounted on the surface of stator pole has the highest PM utilization efficiency and the most sinusoidal phase back-EMF but the largest cogging torque. The SPMSM with PMs mounted on the stator yoke exhibits the largest average torque as well as the lowest torque ripple and cogging torque but the lowest PM utilization efficiency. The analyses are experimentally validated on several prototype machines.