The Multidisciplinary Design of Rotor Geometry in a Permanent Magnet Traction Motor

Abstract

The paper addresses the embedding parameters of permanent magnets and their effects on the performance of an interior permanent magnet radial-flux machine. Special attention is paid to the embedding depth of the permanent magnets and the design of the magnet pockets in the rotor laminations to ensure the optimal mechanical and electromagnetic performances of the machine. There are hollow spaces on the sides of the magnets to prevent permanent magnet leakage flux and to minimize mechanical stresses in the lamination steel. Smart interaction between the mechanical and electrical engineering designs is needed to streamline the design process. By considering these design approaches, a rough estimation can be obtained for an appropriate rotor design. To this end, the study seeks solutions to the height of the rotor steel bridge and the shape of the hollow space that are viable both from the mechanical and electrical aspects. The mechanical stresses and the electromagnetic forces are calculated by Finite Element Analyses (FEA). The effects of the embedding depth of the magnets on torque, efficiency, and mechanical stresses are reported. The results are used to provide guidelines on the permanent magnet traction motor (PMTM) design.