Curvilinear finite elements for modeling the sliding surface in rotating electrical machines and its applications

A finite element method using curvilinear elements is presented for modeling the sliding surface in rotating electric machines. The advantage of the proposed method is that the mesh has the same curved shape as the geometry and thus numerical accuracy is improved when connecting the stator mesh and the rotor mesh across a sliding surface. The procedure is applied to the computation of cogging torque for a permanent magnet motor. Different methods to reduce the cogging torque are then evaluated and compared.