Mitigation of cogging torque in TFPM machines with flux concentrators and evaluation of the structures by using the SC method

Abstract

In this study, the effect of adding of new stator and rotor slots on cogging torque of a transverse-flux permanentmagnet (TFPM) machine with flux concentrators is studied. To reduce the cogging torque, the widths and the positions of the slots of concern are improved through three-dimensional finite element method (3D-FEM). After that, to validate the 3D-FEM results, cogging torque is determined by applying a Schwarz-Christoffel (SC) conformal mapping. To apply this transformation, the 3D TFPM structure with axially magnetised PM is converted into a 2D structure with radially magnetised PMs and cogging torque of the machine is predicted using both the analytical method and 3D-FEM. The agreement in the obtained results through this SC mapping and the 3D-FEM method is the indicative of the accuracy of the efforts. © 2019 The Institution of Engineering and Technology.