Analytical Rotor Thermal Modelling Accounting for Retaining Sleeve in High-speed PM Machines

For high-speed permanent magnet machines (HSPMMs), the rotor retaining sleeve has a critical effect on thermal performances. This paper presents an analytical multi-element modelling method for predicting sleeve and magnet thermal fields for HSPMMs accounting for both metallic and non-metallic rotor sleeves. The proposed analytical multi-element thermal model consists of rotor sleeve and magnet, which are obtained based on the respective conduction heat equations in the axial centre domain. The proposed thermal model can be combined with a lumped-parameter thermal model considering the thermal states of the entire machine. Finally, based on a 3-slot/2-pole prototype HSPMM, the proposed analytical multi-element thermal model is validated by the finite element analysis.