Calculation and analysis of 3D electromagnetic field for high speed permanent magnet generator end region with back around winding

Taking a 117 kW, 60000 r/min high-speed permanent magnet generator (HSPMG) with back around winding as an example, the mathematical model for 3-D electromagnetic field analysis was established, and the basic assumptions and boundaries were given. The end region flux distributions in the generator operating at non-load and rated load were calculated by using the finite element method, some of which were compared with the test data. Taking the air gap flux density as the main study object, the variation of the flux density in the end region was obtained after the quantitative analysis, and then the radial component and the axial component of the flux density in sleeve, air-gap, tooth-top and stator yoke were analyzed. Based on the above analysis, the variation of the radial component density and the axial component density along the axial direction were obtained. Lastly the end region flux leakage of the generator running at different speeds was calculated and the relationship between the flux leakage and speed was studied. The obtained conclusions may provide useful reference for the design and research of HSPMG.