Optimal design of magnetically suspended high-speed rotor in turbo-molecular pump

A large scale magnetically suspended turbo-molecular pump is optimized and designed in this paper. A multi-objective integral optimal design method is proposed to design the rotor applied in a magnetically suspended turbo-molecular pump with high pumping speed, considering the interactive influence on electromagnetic and mechanical performances. The analytical models of the rotor strength, the rotor modal and the electromagnetic field of the magnetic bearing and the permanent magnet motor are established. A multi-objective optimization is conducted and the optimized parameters include dimensions of magnetic bearing and motor. The optimal objectives include electromagnetic, dynamic and static performances. A series of optimal Pareto results is obtained and the correlations between input and output variables are analyzed. The analytical results are compared with the results using finite element method and show good agreement. A prototype is fabricated and the optimal results are validated.