Influence of Eddy Current Loss on Electromagnetic Field and Temperature Field of High-Speed Permanent Magnet Generator With the Toroidal Windings

The toroidal windings can shorten the axial length of the machine, so it is widely used in high-speed permanent magnet machine. However, under high-frequency operation, the magnetic flux leakage generated by the toroidal windings can cause a lot of eddy current loss on the shell, which will negatively influence the heat dissipation of the machine, resulting to overheating and the machine being unable to function. In this paper, the 40kW,20000rpm high-speed permanent magnet generator (HSPMG) with the toroidal windings is taken as an example to analysis the shell eddy current loss. Based on Laplace and Poisson equations, a quickly analytical calculation model of the shell eddy current loss is established, the influencing factors of the shell eddy current loss are elucidated. By using the finite element method (FEM), the influence of the shell structure and the shell material on the shell eddy current loss is studied, the mechanism of nonlinear variation of eddy current loss is revealed. In addition, the influence of load on the eddy current loss is studied. Furthermore, the 3-D temperature field calculation model of the generator is established, the influence of the shell eddy current loss on the generator temperature is studied, and the temperature distribution is obtained. Finally, the electromagnetic test and temperature rise experiment of the generator are carried out, while the experimental and finite element results are compared to verify the correctness of the model.