Influence of Sleeve Material on Electromagnetic Field Based on Multi-Physical Field for Permanent Magnet Synchronous Motor

摘要

For permanent magnet synchronous motor (PMSM), in order to prevent permanent magnets from being damaged by the large rotor rotational centrifugal forces, normally, the sleeve is coated on the outer surface of permanent magnets. However, the sleeve material characteristics have much influence on the PMSM, and therewith, most of rotor eddy-current losses are generated in the sleeve, which could increase the temperature of PMSM. If the rotor heat dissipation condition is poor, high temperature can influence the PMSM performance and even result in thermal demagnetization of the permanent magnets. Thus, a sleeve scheme designed with low eddy-current losses is very necessary. In this paper, taking a 12.5 kW, 2000 rpm PMSM with 0.2mm thickness stainless steel sleeve as an example, based on the principle of thermos cup, the sleeve adopted insulation cylinder material is proposed. Then, the 2-D mathematical model of PMSM is established, and the electromagnetic field can be calculated by utilizing the time-stepping finite element method under rated load condition. The calculation results show the effectiveness of the insulation cylinder in reducing the eddy-current losses in the rotor. On this basis, by utilizing the composite material structure of sewer pipe which is noncorrosive, in order to ensure mechanical strength and improve machine efficiency, the sleeve composition structure of insulation cylinder and stainless steel is proposed. The obtained conclusions can provide useful reference for the design and research of PMSM.