Effects of Eddy Current in Electrical Connection Surface of Laminated Cores on High-Speed PM Motor Supported by Active Magnetic Bearings

For the high-speed permanent magnet (PM) motor supported by active magnetic bearings (AMBs), the iron cores of radial AMBs and the motor are made of laminations in order to reduce eddy-current loss. However, the surfaces of laminations are usually not smooth enough, so further surface manufacturing is required, by which the surfaces of each lamination are connected and a conductive layer is formed on the laminations surface. In the varying magnetic field, these conductive surface layers will generate additional eddy currents, which will increase the machine loss and affect the distribution of original magnetic field. In this paper, these effects on magnetic bearing and PM motor are investigated by the finite-element method.