Research Of Active Vibration Control Based On Active Magnetic Bearings System

Complex surfaces are widely used in advanced manufacturing, space exploration, energy engineering, national defense, etc. In recent years, the development of five-axis NC active control and the digital manufacturing technologies bring new challenges on the manufacturing of complex surfaces. Hereby, active vibration even chatter control of machining process based on intelligent spindle especially active magnetic bearings(AMB) spindle for its capacity of increasing system stiffness shows much potential in improving machining efficiency as well as surface quality.Active magnetic bearings(AMB) are typical mechatronic products which involve a lot of subjects such as mechanical engineering, electrical engineering, electronics, control engineering and computer science. Due to the advantages of no friction, no fray, free of lubrication, high speed, low power consumption as well as controllable stiffness, AMB are often used to mitigate vibrations in turbines, compressors, machining spindles, etc. However, rotor-AMB systems are inherent open-loop unstable, and hence it is an urgent yet challenging task to stabilize rotor-AMB systems with external disturbances.A specified flexible rotor-AMB system is introduced in this paper. Firstly, a ? synthesis control method including parameter uncertainty is proposed to stabilize this unstable system along with its robustness analysis. Then, the stability of the rotor-AMB system subject to input and output constraints is investigated based on a discrete-time constrained model predictive control(MPC) algorithm to illustrate the effectiveness of the proposed controller in stabilizing the system with different output constraints. Next, a constrained dual-mode predictive control method is proposed hereby, which is afterwards proved to be capable of enlarging the region of attraction, and hence can effectively mitigate more intensive vibrations excited by external disturbances, which is desirable in real applications; finally,simulation experiments are conducted on the rotor-AMB system to show the effectiveness of the proposed dual-mode predictive controller.An AMB milling spindle platform is customized to investigate its performance of vibration suppression during machining process, which has a maximum rotating speed of40000 rpm, rotating accuracy less than ±10?m, rated power of 20 kW and torque more than5N·m. This AMB spindle is designed for a five-axis NC machine tool with intention of milling active vibration even chatter control.Based on the aforementioned AMB spindle, the rotor displacements and current response of AMB coils during different levitation and rotating experiments are investigated.Then the modeling and PID control process of rotor and magnetic force dynamics is proposed. Next, a new hardware platform based on controller dSPACE1103 along with AMB driver JSP-180-20 is developed through studying the control principles of rotor-AMB systems thoroughly. A Simulink model for the levitation control structure of the AMB spindle is fulfilled afterwards. Finally, levitation experiments are performed to investigate the performance of established levitation control system of the AMB spindle along with some analysis and rational improvement proposals.