Multi-Objective Optimal Design of μ–Controller for Active Magnetic Bearing in High-Speed Motor

Abstract

In this paper, a control strategy based on the inverse system decoupling method and μ-synthesis is proposed to control vibration in a rigid rotor system with active magnetic bearings that are built into high-speed motors. First, the decoupling method is used to decouple the four-degrees-of-freedom state equation of the electromagnetic bearing rigid rotor system; the strongly coupled and nonlinear rotor system is thus decoupled into four independent subsystems, and the eigenvalues of the subsystems are then configured. The uncertain parametric perturbation method is used to model the subsystem, and the multi-objective ant colony algorithm is then used to optimize the sensitivity function and the pole positions to obtain the optimal μ-controller. The closed-loop system thus has the fastest possible response, the strongest internal stability, and the best disturbance rejection capability. Then, the unbalanced force compensation algorithm is used to compensate for the high-frequency eccentric vibration; this algorithm can attenuate the unbalanced eccentric vibration of the rotor to the greatest extent and improve the robust stability of the rotor system. Finally, simulations and experiments show that the proposed control strategy can allow the rotor to be suspended stably and suppress its low-frequency and high-frequency vibrations effectively, providing excellent internal and external stability.

Comparing the Performance of Robust Controllers for Vibration Suppression in Long Rotor Systems

“…This builds Equation (1a), from which a transfer function matrix can be estimated. Therefore, the dynamic model is embedded in the elements' transfer function matrix (5).…”

“…Apart from experimental attempts, a theoretical investigation of optimal controllers and robust-type vibration suppressors via AMBs has been performed for short rotors that are assumed rigid [5,6]. For short and flexible rotors, optimal controllers have also been studied [7].…”