Impact of the airgap magnetic field harmonics on the performances of a disc type flux switching machine for wind application

This paper presents a detailed study of the impact of the airgap magnetic field harmonics on some performances of a disc-type switching flux permanent magnet generator. More precisely, the presented study concerns the cogging torque, the total torque as well as the torque ripple, the eddy currents in the permanent magnets and finally the vibro-acoustic emissions due to electromagnetic origins. First, maximizing average output electromagnetic torque and minimizing cogging torque are done varying the rotor tooth dimensions. This study is achieved using a multislice 2D finite element (FE) magnetic model in order to reduce computation time. Then, eddy current loss in permanent magnet is estimated using 3D FE method for the machine having optimal dimensions. Finally, the previously computed airgap flux density is used to evaluate the local magnetic forces acting on the airgap side stator faces. Estimated local forces serve as an input for a 3D mechanical structural FE model quantifying the vibro-acoustic performances of the studied machine. The various results are presented and discussed in each section of this paper.