Low Cogging Torque Design of Permanent Magnet Machine Using Modified Multi-Level Set Method With Total Variation Regularization

This paper proposes a topology optimization method, which allows to design a permanent magnet (PM) excited machine with improved high-speed features, incorporating the topological gradient into the multi-level set method with total variation regularization. It involves the design of both the stator and the rotor, the shape of which has a predominant impact on the mechanical and electric features of a PM machine. The concept of the topological gradient is incorporated for the nucleation of new holes in the distribution of level sets. The essential advantage of the proposed method is its ability to handle topology change on a fixed mesh and its flexibility in terms of shape changing that leads to efficient computational schemes. Finally, 2/3-D models are developed and deeply analyzed to indicate that the applied method leads to a significant reduction of both the cogging torque and the amount of higher back EMF harmonics.