| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 92 === This study is dedicated to design a feedback controller for the turbo molecular pump, which center of gravity is located below the blades; therefore, its running property is different from the rotor and cannot be decoupled to simplify the system.
Formerly many scholars and experts establish the magnetic bearing system pattern or design the controller, and devoted in the magnetic domain, which neglect system uncertainties and external unanticipated disturbance, and simply applied linear controller to the linearized system.
Therefore, this thesis proposes the adaptive variable structure control theory, due to the advantage of its robustness. By applying this control theory, the system error and the system performance variety from the rotational speed change, which cause by the modeling and the linearization, can be reduced. Moreover, by designing an adaptive controller which base on the error between the plant output and the reference model, the controller can make the system come back to the running central when the system occurs external unanticipated disturbance.
From the simulation results, the general variable structure controller for regarding imbalance force and external force disturbance has the good suppression effect, but the system will be unstable when system works as internal parameter change or overload external force disturbance, while the controller possibly provides overload current or higher switching frequency to constraint the instantaneous response. On the other hands, the command output from adaptive variable structure controller follows the reference model in all kinds of circumstance. From the comparison between these two controllers, it is found that the performances are similar while the adaptive variable structure control has more robustness for external unanticipated disturbance.
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