Improving Disturbance Rejection in Nonlinear Active Magnetic Bearing Systems: Using Lur'e Formulation

Abstract

The efficacy of magnetic bearing controllers designed to reject transient disturbances is evaluated via a series of experiments. The experiment consists of a rocking beam with opposing electromagnetic actuators for control as well as an actuator for applying a disturbance torque. Controller synthesis employed a generalized Lur'e system approach to accommodate the nonlinear magnetization behavior of the electromagnetic actuator iron. Experimental results demonstrate significant improvements in disturbance rejection with controllers based upon the Lur'e system approach. Good agreement between simulation and experimental results was obtained, providing confidence that similar benefits can be achieved in industrial machinery employing active magnetic bearings.