Design and Analysis of the Interior Permanent-Magnet Machine Considering Slot-pole Combination and Rotor Topology

This paper presents how to select the proper slot and pole combination (SPC) and reasonable rotor topologies for an interior permanent-magnet (IPM) machine. Firstly, the selection principle of SPC is reported, and some electromagnet performances, including winding factor, stator space magneto-motive force (MMF) harmonics, radial force harmonics, and cogging torque, are analyzed and compared. Secondly, four PM rotor topologies are designed and discussed, including surface permanent-magnet (SPM), spoke type, V-shape, and multi-layer reluctance (MR) type. Their performances, such as back-EMFs, torque, and ripple and flux-weakening capability, are thoroughly analyzed and compared by the finite-element method (FEM). Finally, a 27-slot and 8-pole V-shape IPM machine is selected and designed optimally, which offers high power/torque density, high efficiency, and less torque ripple. In order to ensure the reliability of its rotor mechanical strength, the equivalent stress and deformation are analyzed by ANASY. Besides, its d-q axis mathematical model is built to verify its performance further. Then experiments on the prototypes are carried out for validation.