Eddy Current Reduction in High-Speed Machines and Eddy Current Loss Analysis With Multislice Time-Stepping Finite-Element Method

The significance of eddy-current in high-speed permanent magnet machines cannot be underestimated in that it has serious implications on the machine's efficiency or even demagnetizes the PMs because of an overheating problem. It is necessary to accurately estimate the eddy-current losses and find an optimal design to minimize the losses and improve the machine's performance. In this paper, the axial segmentation of the PMs is first employed to cut off the eddy-current axial paths. Then, a conductive shield is introduced to smooth the time varying magnetic field in the conductive sleeve and the PMs in order to reduce the eddy-current losses. A nodal method based network-field coupled multislice time-stepping finite element method (TS-FEM) is proposed to analyze the steady-state and dynamic characteristics of the high-speed PM machine; its merit is that sub-block matrixes of the circuit equations are more convenient to be established compared with that of mesh method. Analysis of eddy-current losses in the rotor is reported.