Estimation of rotor eddy-current losses for high speed SPMSM

Surface-mounted permanent magnet synchronous machine (SPMSM) is widely used in various fields due to its high power density and reliability (compressors, turbine generators...) [1], in our case it is used in aeronautics. However, in high-speed operations eddy-current losses can be important and lead to a damage because of an overheating (PM detachment, demagnetization...). Therefore, it is important to estimate these losses during the design phase. This paper describes a technique to estimate rotor eddy-current losses (magnets and sleeve) for the design of 25 kW, 10.5 krpm 3-phase motor by means of both analytical and finite-element approach. Firstly, we study the spatial variation of the magnetic flux density in the magnets and the sleeve. Consequently, it results a segmentation of magnet and sleeve according to the half of slot pitch. Secondly, we estimate the maximum variation of magnetic flux density (36 mT in the summit of magnets, 125 mT in the sleeve) by finite-element analysis (COMSOL Multiphysics). Finally, this paper presents the result of computation of rotor eddy-current losses (97 Watt).