Influence of sleeve thickness and various structures on eddy current losses of rotor parts and temperature field in surface mounted permanent-magnet synchronous motor

For surface mounted permanent magnet synchronous motor (PMSM), due to the large rotor rotational centrifugal forces, a sleeve is often used to prevent damage to rotor permanent magnets. However, eddy current losses appearing in the sleeve can increase the temperature of surface mounted PMSM. If the rotor heat dissipation condition is poor, high temperature can influence the surface mounted PMSM performance and even result in thermal demagnetisation of the permanent magnets. Thus, a sleeve scheme designed with low eddy current loss is very necessary. In this study, taking a 12.5 kW, 2000 rpm PMSM with 0.2 mm thickness stainless steel sleeve as an example, first, the influences of sleeve thickness on the eddy current loss and temperature field are analysed. Then, sleeve various composition structures of carbon fibre and stainless steel are presented, and the influences of different composition percentages on the eddy current losses and temperature field are analysed in detail, which shows the effectiveness in reducing the eddy current losses and temperature in the rotor. The obtained conclusions can provide useful reference for the design and research of surface mounted PMSM.