Decoupling control of AC-DC-3DOF-HMB based on inverse system method

The AC-DC 3 degrees of freedom hybrid magnetic bearing (AC-DC-3DOF-HMB) is a multivariable, nonlinear and strong coupled system. In the paper, a decoupling control approach based on inverse system method is proposed, which is used to decouple this system. Firstly, the configuration of the AC-DC-3DOF-HMB is introduced briefly, the mathematical equations of radial and axial suspension forces are set up. Secondly, the state equations of the AC-DC-3DOF-HMB are set up, the analytical inverse system of the AC-DC-3DOF-HMB is obtained by analyzing the reversibility of the mathematical model, and then inverse system and original system are in series to constitute pseudo linear systems. Finally, controllers of the pseudo linear systems are designed by using linear system theory, and the whole control system is simulated by using Matlab software. The simulation results show that this control strategy can realize decoupling control among 3 degrees of freedom displacements for the AC-DC-3DOF-HMB, and the whole control system has good dynamic and static performance.