Research on rotor eccentricity compensation control for bearingless surface-mounted permanent-magnet motors based on an exact analytical method

With the advantages of axial high utilization, small size and low power consumption, the bearing-less permanent-magnet synchronous motor (BPMSM) demonstrates the potential applications in space technology, machine tools, ultra-speed drives and so on. Generally, the magnetic circuit method (MCM) is applied to analyze the mathematical model of levitation force with rotor eccen-tricity[1-3]. However, the coefficients calculated by MCM are not suitable for the situation of speed and load variation. Hence, the finite element method is presented to identify the parameters. The Complex of pre-processing is the big disadvantage of the finite element method, though the accuracy results can be achieved. In this paper, an exact analytical model of a surface-mounted BPMSM with rotor eccentricity by a perturbation method is proposed and a corresponding compensation control strategy for rotor eccentricity is presented. The experiment results suggest the successful suspension in steady state based upon the model and prove the feasibility and effectiveness of the exact analytical method (EAM).