Principle and realization of a 5-phase PM bearingless motor drive

Due to the increasing requirement of high speed motor, bearingless motor has become more and more fascinated to scientists and technicians. Conventionally, two sets of windings are involved for torque and suspension force respectively. Whereas, in this paper, using the concept of multiple control freedom in multiphase motor, an innovative 5-phase bearingless machine with a single set of windings is developed. The principle of the proposed motor is indicated, in which two groups of currents are fed into a single set of winding to generate two interacting magnetic fields, whose pole pair difference is 1. Further more, the analytical model is given. The hardware system and the control strategy applied in the system are demonstrated. In the end, it is certified that the motor could successfully suspended with a radial displacement variation less than 100 mum.