A novel bearingless motor with hybrid rotor structure and levitation force control

Bearingless motors are very attractive because of mechanical wear free and noise free operation. Based on a comparative study of torque and magnetic levitation force of a bearingless motor with different rotor structures, this paper presents a new hybrid rotor structure, which has the advantages of both permanent magnet rotor and induction rotor. The proposed bearingless motor with the hybrid rotor cannot only produce large electromagnetic torque and levitation force, but also provide a base to realize decoupled control of levitation force through current vector orientation. The control strategy for the proposed bearingless motor with hybrid rotor is realized using a TMS320C32 DSP and Xilinx CPLD. The tested results show that the proposed motor design and control strategy of the novel bearingless motor are feasible.