Dynamic Analysis on Rotor System Supported by Active Magnetic Bearings based on Sliding Mode Control

In this research, the sliding mode control is introduced to solve the dynamic analysis of rotor system supported by active magnetic bearings (AMB) with the inherently unstable, nonlinear and strong coupling characteristics. Firstly, the rigid rotor-bearing system model is built. By linearizing the magnetic of AMB about the operating point, a four-degree of freedom rotor system supported by the radial AMB is established. Furthermore, to consider the effects of the magnetic thrust bearings on the lateral vibration of the rotor, a five-degree of freedom rotor system model is presented. Secondly, the sliding mode controller of rotor system is configured. Based on the rotor system model, switching function of the sliding mode controller is designed by the quadratic regulator so that the sliding mode controller is asymptotically stable and the sliding motion has good quality. The input of the control system is designed by the exponential reaching law to satisfy the reaching condition and to reduce the buffeting in control process. Finally, the simulation results show that the rotor's quick adjusting and steady levitating is achieved and the controller presents good dynamic performance and strong robustness.