Evaluation of direct force control for AMB's rotor system

Abstract

AMB allows contactless support of a rotating body. AMB requires an active control as it is inherently unstable. Classical current control scheme that con-sists of outer position and inner current control loops can be used. Another way is to use flux control in the inner loop, in this case flux, estimated from measured currents, is applied. A scheme developed in this thesis is based on DTC principle that is mostly used in electrical drives. This principle is DFC that does not contain inner controller and does not contain current and posi-tion stiffnesses that results in faster dynamics. Flux estimator is built for de-termining force, flux and currents acting in the electromagnets. Controller is LQG with disturbance estimator built for current control, flux control and DFC models. All models are built and compared. Results are analyzed and it can be seen that DFC control has faster dynamics.