Abstract: Firstly，the radial force mathematical model of central winding bearingless slice permanent magnet

motors was built. Subsequently，parameters tuning theory of displacement loop PID controller for bearingless motor suspension system was studied，and its inherent drawbacks of PID controller when used for bearingless motor suspension control system were analyzed. To improve the suspension control system performances，suspension control algorithm for the displacement stiffness potential energy was proposed，the theoretical derivation show that the dynamic and stable performance are taken into consideration in the proposed algorithm. Because the proposed algorithm cannot consider the influence of radial load force on the rotor，a radial load force observer was introduced to overcome this problem. Finally，the effectiveness of the proposed control algorithm was verified by simulation and experiment.

      Key words: bearingless slice motors；parameter tuning；displacement stiffness potential energy control；radial

load observation