18 Optimal Design of Permanent Magnet Segmentation and Condu.pdf

ANSYS 2011 中国用户大会优秀论文 Optimal Design of Permanent Magnet Segmentation and Conductive Shields in High-speed Machines Using Network-field Coupled Multislice Time-stepping Finite-element Method S. L. Ho, Shuangxia Niu, and W. N. Fu The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Eddy-current loss in high-speed permanent magnet (PM) machines is a critical factor that could affect the machine’s efficiency or even demagnetizes the PMs because of overheating problems. Hence it is necessary and important to accurately estimate the eddy- current loss and search for the optimal design to minimize the eddy-current loss and improve the machine’s performance. In this paper, firstly, an axial segmentation method of PMs is proposed to cut off the eddy-current axial paths. Secondly, a conductive shield is adopted to smoothen the time varying magnetic fields, in both the conductive sleeve and the PMs, in order to reduce the eddy-current loss. A nodal method based network-field coupled multi-slice time-stepping finite element method (TS-FEM) is presented to analyze the steady-state and dynamic characteristics of the high-speed PM machine; its merit is that the sub-block matrixes of the circuit equations can be established more conveniently when compared with that of mesh method. The analysis of eddy-current loss in the rotor is described in details. Index Terms—Eddy-current loss, high speed motor, network-field coupled, multislice, permanent magnet segmentation, time- stepping finite-element method. proposed to analyze the eddy-current loss in high-speed PM I. INTRODUCTION