Comparison of flux-switching machines with and without permanent magnets

In this paper, three advanced flux-switching (FS) machines, namely the radial-field flux-switching permanent-magnet (RF-FSPM) machine, the radial-field flux-switching DC-field (RF-FSDC) machine, and the axial-field FSDC (AF-FSDC) machine are quantitatively compared. Upon the installation of the high-energy-density PM materials, the RF-FSPM machine can definitely provide the superior torque performances as compared to its magnetless counterparts. However, the PM machines suffer from two major fundamental problems, namely the high material costs, and the uncontrollable flux density. By utilizing the concept of axial-field structure, the AF-FSDC machine can offer comparable torque performance as the RF-FSPM machine. Hence, with the consideration of the cost-effectiveness and the control flexibility, the magnetless AF-FSDC machine has exhibited promising potential in various applications.