Cogging torque optimization of a novel transverse flux permanent magnet generator with double C-hoop stator for wind power application

Transverse flux permanent magnet generator (TFPMG) is especially suitable for wind power application for the merits of large pole numbers, decoupled magnetic circuit, and high power density. The distinguishing feature of TFPMG is the magnetic flux existed in three-dimensional space and three-dimensional finite element method (3-D FEM) is employed to analyze its characteristics. Such as flux-switching TFPM generator [1], many TFPMGs with new topologies have been proposed. However, they commonly have a drawback that only half of PMs do work at the same time and the cogging torque vibrations are unacceptable and desiderated to be optimized. The proposed 12 pole-pairs TFPMG overcomes these shortcomings, which schematic structure is shown in Fig. 1 (a). The generator is constructed by the double C-hoop stator cores inserted into machined cavities in the stator holder, the doubled PMs screwed onto two rotor disks with opposite polarities to enable the flux-concentrated effect, and the armature winding bundling all stator hoops.