Unbalance Vibration Control For An Active Magnetic Bearing-Rigid Rotor System

Active magnetic bearing(AMB) is one of typical mechatronic products, which uses controllable electro-magnetic force to realize the rotor suspension. Rotating machinery supported on active magnetic bearings can not only achieve higher rotaional speed, has longer operating life, but also feture better preventive maintenance, no lubrication, and no friction-related mechanical damage. Since the active magnetic bearings-rotor system itself is an open-loop unstable, non-linear and time-varying system, so the active magnetic bearings must be controlled in order to enable the rotor to work in a stable suspension.In the active magnetic bearing-rotor system, the rotor imbalance, which causes the rotor produce stationary vibration during rotation, deteriorates the performance of the system and even can become a threat to the safe operation of the system. Firstly, the analysis of the basic principle of active magnetic bearing and the model of active magnetic bearings-rigid rotor system with four radial degrees of freedom are introduced. Then from the reasons arising for unbalance vibration, the unbalance vibration characteristics of the rigid rotor have been analyzed and the response of the rigid rotor in an unbalanced situation under constant acceleration has been analysed and simulated. The principles of automatic balance control algorithm and unbalance compensation control algorithm for active magnetic bearings-rigid rotor system have been respectively analysed. Then the two unbalance vibraiton control algorithm, i.e., the automatic balance system based on tracking filter and an adaptive filter based on LMS algorithm, have been introduced, and the systems’performances of the two algorithms have been analysed in simulation, then the influence of the frequency mismatch and noise problem for the LMS algorithm are discussed.In this paper, the active magnetic bearings-rigid rotor experiment platform hardware and software systems based on dSPACE 1103 control panel as the core controller is introduced. Then the automatic balance system based on the tracking filter and the adaptive filter based on LMS algorithm have been added to the active magnetic bearing-rigid rotor system for debugging respectively. The system performances of active magnetic bearings-rigid rotor system with two automatic balance control algorithm are tested. The results show that the unbalance vibration of the rigid rotor has been nicely suppressed by the two algorithms.