Investigation of the Power Factor and the Specific Torque Trade-off in a Double-sided Flux-concentrated Transverse-flux Machine

A double-sided flux-concentrated transverse-flux machine (TFM) is investigated by using analytical models and three-dimensional finite-element methods (3D-FEM) for application as a 500 kW wind generator and as a 5 kW servomotor. The validity of the analytical models is first assessed with both electrical steel and iron powder (soft magnetic composite) for the iron parts. Analytical parametrical studies are subsequently made in order to study the relationship between the specific torque and power factor. It is found that the discussed TFM is quite superior to a surface-mounted TFM. Finally, the results are also compared with other TFM topologies and other types of electrical machines, like the axial and radial flux permanent-magnet machines and induction machines.