| Summary: | 碩士 === 國立清華大學 === 電機工程學系 === 87 === Abstract
A variable-weighting robust two-degrees-of-freedom controller (VWR2DOFC) for the speed control of an indirect field-oriented (IFO) induction motor drive is developed in this thesis. First, an experimental IFO induction motor drive is constructed and its dynamic model at the nominal case is estimated from input/output measurements. According to the estimated model, a 2DOF controller is systematically designed to meet the proscribed speed command tracking and load regulation control specifications. As to the study about the performance improvement against parameter variations and system nonlinear behavior, the control characteristics and limitations of a simple disturbance cancellation robust controller with fixed weighting factor are first investigated. It is found that the flexibility of this type of robust controller in making compromise between control performance and control effort is low. To improve this, a VWR2DOFC is proposed in this paper. In the proposed controller, the weighting factor is automatically tuned via a variable structure (VSS) controller, wherein the estimated model mismatched error and its derivative are used as the driven inputs of the VSS controller. The simulation and experimental results show that more robust and better control performances can be obtained by the proposed controller when the parameter variations and system nonlinearities exist. A simple but practical approach for eliminating the inherent chattering phenomenon of VSS controller is also proposed in this thesis. The validities of all the designed controllers are confirmed by simulation and measured results.
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