An identification method of suspension force and magnetic unbalance pull force parameters in buried-type IPM bearingless motors

A new on-line identification method of suspension force and magnetic unbalance pull force parameters in buried-type IPM bearingless motors has been presented in this paper. The suspension force parameters depend on the current condition, because armature reaction and magnetic saturation in the stator teeth often occur in this type of machines. Moreover, the magnetic unbalance pull force also generates due to the small airgap, which are also dependent on the current. Thus, it is necessary that these parameters are accurately identified so that the rotor shaft is stably supported. An on-line parameter identification method has been proposed. It is possible that the parameters are accurately identified by a simple experiment. It is confirmed that the suspension force decoupling tests accurately identifies the parameters. The obtained parameters by the proposed method are compared with the FEM results and discussed. The proposed on-line identification method is good enough to realize stable magnetic suspension