The Design of the Robust Controller for Active Magnetic Bearings on Active Disturbance Rejection Technology

Abstract

AbstractActive magnetic bearings (AMBs) have advantages of no friction, no lubrication or sealing requirements, long lifespan, low maintenance cost, and, especially, active controllability of dynamic characteristics. Thus, AMBs are now widely used in helium-turbine circle of the high temperature gas-cooled reactor and many other high-speed rotating machinery. The design of controller is the core problem of AMBs. The AMB force has high nonlinearity and the AMBs-rotor system may be influenced by external disturbance during operation, which increase the threshold of the controller robustness and make it hard to design. Based on the AMB-rigid rotor system model, this paper adopts lumped uncertainties to describe nonlinear error and external load disturbance and then the plant model of the decentralized controller is obtained. Then, a linear active disturbance rejection controller (LADRC) is designed to compensate the model error. The LADRC contains a proportional-differential controller and a three-order external state observer. The adjustable parameters of the LADRC can be selected according to pole assignment. In order to verify the effectiveness of the LADRC, levitation experiments, rotation experiments, and re-levitation experiments are carried out with traditional PID controller as comparison.