Design of a High-Speed Permanent-Magnet Machine for Electrically-Assisted Turbocharger Applications with Reduced Noise Emissions

This paper addresses the issue of mitigating the noise emission of high-speed permanent-magnet (HSPM) machines. HSPM machines are increasingly used in a large field of applications for their power density and compactness. However, increasing the speed tends to intensify the noise emissions where more and more applications require a quiet operation. The focus of this paper is to propose a HSPM structure to cope with this problem that is also well-suited to competitive markets where cost is an important factor. First, high-speed machine topologies are briefly presented in the general case and a comparison between a reference PM slotted structure with tooth-coil windings and a slotless structure toroidally wound is made. Then, general considerations are given regarding the design parameters that impact the vibrational behavior with an analytical description and a three-dimensional (3-D) mechanical finite element analysis (FEA). Finally, the noise emission and losses for both machines are compared showing that the slotless toroidal machine can be a good candidate in this field of applications.