Modelling and design of PM retention sleeves for High-Speed PM Synchronous Machines

An analytical procedure for designing mechanical sleeves in surface-mounted High-Speed Permanent Magnet Synchronous Machines (HS-PMSMs) is presented in this paper. It is based on the theory of elastic mechanics and enables the computation of contact pressures between rotor layers (shaft, back-iron, permanent magnets and sleeve) and the Von Mises equivalent stress. The proposed procedure can be combined with the electromagnetic machine analysis, leading to fast and effective HS-PMSM design. This can be accomplished in accordance with different Permanent Magnets (PMs) and/or sleeve materials. Particularly, NdFeB and Ferrite-based PMs are alternatively considered, as well as the employment of Titanium and Carbon-Fiber as sleeve materials. The proposed approach is validated through Finite Element Analysis (FEA), which regards four different HS-PMSM configurations characterized by the same rated power and speed.