Study On Radial Displacement Sensorless Operation Of Bearingless Induction Motor

Bearingless motor with integration of driving and self- suspension, is a new type motor which can implement electromagnet torque control and levitation force control in the motor at the same time. Thus, Bearingless motor is one of the focuses in the research field of motors at present.Bearingless induction motor offer the advantages in structure, manufacture, high reliability and high speed. It has been applied in many domains successfully, for instance, Vacuum pump driven by the bearingless induction motor applied to the areas such as semiconductors and life science presently. Radial displacement sensorless technology of bearingless induction motor with the advantages of non-contactness, high reliability, low cost, short shaft length and small system size. So it is suitable for high speed and high power operations, which can improve the system dynamic performance as well.In the dissertation, the principle of bearingless induction motor is described. Considering the rotor radial displacement, an analytical expression of the magnetic force is analyzed and has been verified by Ansoft. The flux linkage between the suspension winding and torque winding is analyzed based on the magnetic motive force distributions. The mutual inductances which vary as a function of the rotor displacement is proposed and has been verified by Ansoft. Based on the above analysis, the principle of radial displacement sensorless operation of bearingless induction motor is analyzed, and the estimation circuit of the rotor radial displacement is designed and simulated by PSpice. In order to simplify the system, improve the system performance, and meet the demands of bearingless technology towards practicality, the suspension winding independent control method is considered base on U-I flux linkage observer by comparing the current domestic bearingless induction...