The single closed-loop direct control of levitation force for bearingless permanent magnet synchronous motor

In this paper the polar-coordinate mathematical model of levitation force on bearingless permanent-magnet synchronous motor was deduced. The single closed-loop direct control of levitation force was proposed based on the mathematical model deduction and combined with space vector pulse with modulation algorithm. The traditional closed-loop control of levitation current was ignored using the single closed-loop direct control algorithm. The whole levitation control system was simplified. The simulation results show the proposed control strategy can enhance system dynamic performance and achieve stable levitation under rated speed condition.