Research On The Control System Of The Disc Rotor Supported By Active Magnetic Bearings

The mathematical model of the disc rotor is built and the coupling situation of magnetic forces is analyzed based on the structure characteristics of the disc rotor and the active magnetic bearings system. There’s only the coupling of two rotational degrees of freedom remained in axial direction after the mechanical structure optimization. The spatial state model is built. It’s proved that the existence of gyroscopic moment is consequent and the gyroscopic moment would increase with the increasing of rotation speed if the coupling situation and the causes of gyroscopic moment are under consideration. The structure and basic principle of 2DOF-PID controller and cross-feedback PID controller are introduced. The simulation structures are built for each controller with the Simulink Toolbox and the result of simulation shows that the good set-point response and the good disturbance response could be improved as a whole under control of the 2DOF-PID controller. It also shows that the coupling situation of gyroscopic can be completely eliminated using the control system based on cross-feedback theory while over-compensating and less-compensating are not that effective compared with total-compensating. The experiments with 2DOF-PID controller and cross-feedback PID decoupling controller are done. The result of experiments shows that the decoupling controller is still more suitable for the disc rotor system although the 2DOF-PID controller can assuredly improve the dynamic characteristics of each control path. The coupling caused by gyroscopic moment is proved to be the main reason of bad rotational stability.