Equivalent 2-D FEA Modeling Method for AC Loss Analysis of High-Speed Electrical Machines With Litz Winding Considering Incomplete Transposition

Abstract

In high-speed electrical machines, litz wire shows great performance on reducing the AC loss under complete transposition, which is well-known. However, due to technological limitation, its pitch cannot be made to match the stack length in small aspect ratio machines, bringing significant AC loss. And 3D FEA modeling method is too complicated for its twisted structure and time-consuming. This paper proposed an equivalent 2D FEA modeling method for high-speed electrical machines with litz winding. The machine is divided into several parts along the axial equally, and each part is established by a 2D FEA model approximatively in which litz winding transposition is considered. All 2D models are connected in series in field-circuit coupling model. The influences of structural parameters on AC loss are also analyzed, providing guidance for the optimal design of litz winding in high-speed electrical machines.