Résumé
This paper presents a comparative study of rotor eddy-current losses, due to stator slotting, in two types of sleeves (composite: carbon-fibre and metallic: Inconel718) mounted on the rotor of high-speed permanent magnet synchronous machine (60 kW, 10000 RPM), dedicated to an aeronautical application. Roughly speaking, there are two groups of sleeves used to increase the mechanical strength of magnets: composite sleeves (carbon-fibre, fibre-glass) and metallic sleeves (Inconel718, titanium). The major advantage of composite sleeves is the low electrical conductivity, which limits the eddy-currents, but at the same time they behave like a good thermal insulator that prevents the heat dissipation and may cause the overheating of magnets. For the two types of sleeves, losses are estimated by two means: 2D finite-element model (AnsysMaxwell) and experimental tests. According to the test bench results, the use of a composite sleeve reduces the losses by 330 W (370 W found with finite-element model), so the reduction is equal to 0.6% of rated power of the machine. The eddy-current losses in the magnets are equal to 60 W.