The objective of this article is to study how the stator step skewing method can lead to the reduction of the cogging torque of a transverse‐flux permanent‐magnet (TFPM) machine with flux concentrators. Three structures are analysed and compared in terms of their influence of the skewed displacement on the cogging torque using the three‐dimensional finite element method (3D‐FEM). Thereafter, to validate the FEM results, cogging torque is calculated by applying a Schwarz–Christoffel (SC) conformal mapping. To apply this transformation, the 3D TFPM generator structure with axially magnetised permanent magnets (PMs) is converted into a 2D structure with radially magnetised PMs and the cogging torque of the machine is predicted using both the analytical method and 3D‐FEM. The accuracy of the approach is demonstrated by the adequate agreement between the results obtained through this SC mapping and those of the 3D‐FEM. In addition, two 100 W prototyped TFPM machines are designed, simulated, manufactured and tested to validate the effects of the step‐skewed stator yoke on the predicted cogging torque and back‐EMF.

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.

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