Optimal design for quasi-zero power performance of a permanent magnetic suspension system

A proposed permanent magnetic suspension using flux path control has quasi-zero power characteristic since its unique structure realizes transmitting the suspended object's gravity the system frame, and the motor just drives the permanent magnet to rotate and suffers a small regular torque caused of the system magnetic potential. The small regular torque will deteriorate the system's response characteristics and suspension stability. This paper optimizes the system structure for improving the quasi-zero power characteristic. Firstly, the structure and the suspension principle of the former system is introduced, and the rotational torque on the motor's shaft was measured using an experimental prototype. Secondly, a symmetric offset optimal structure was proposed through analyzing the experimental results of rotational torque, and the torque on the motor's shaft was calculated by using a FEM model. The simulation results indicate that the rotational torque was reduced to about 15% of the former structure using the optimized structure with a magnetic separation iron plate. Finally, the experimental prototype with the optimized structure was manufactured, and the measurement experiment for the torque was carried out. The experiment results verified the validity of the simulation results and the optimizations.