Performances comparison of PM machines with different rotor topologies and similar slot and pole numbers

This paper presents performances comparison of several permanent-magnet (PM) machines with different rotor topologies and similar slot and pole numbers. These rotor topologies include one surface-mounted PM (SPM) topology and three interior PM (IPM) topologies. The four structures are compared for the same stator geometry and winding excitations, and the rotor topologies are considered with the same volume of PM materials. The performances comparison includes the air-gap flux density, the back-electromotive force (EMF), the cogging and ripple torque, the losses (i.e., in the iron and in the PMs) and the efficiency. The 2D finite-element method (FEM) is used to achieve this comparison.