It is important to clarify the rotor eddy current losses in bearingless permanent magnet synchronous (BPMSM) for temperature rising to induce irreversible demagnetization. In this paper, the torque and radial suspension force producing mechanisms of BPMSM are introduced. The relative motion relationships among radial suspension force, rotor magnetic field and suspension winding magnetic field are analyzed. The necessary conditions of producing stable controllable radial suspension force in single direction are concluded. The rotor eddy current losses in BPMSM with PB=PM+1 and PB=PM-1 are calculated and compared using 2D time-steeping finite element method. The research results have shown that the BPMSM with PB=PM+1 is the most suitable for high speed operation with the minimum eddy current losses in rotor.