Persons at STU
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Basic information about a final thesisAdditional informationAdditional information about the final thesis follows. Click on the language link to display the information in the desired language.
|Language of final thesis:||English|
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|Title of the thesis:||Nonlinear Model-Based Air-Fuel Ratio Predictive Control of Spark Ignited Engines|
|Summary:||The presented work discusses model-based air-fuel ratio predictive control of a spark ignited (SI) engine. Physically based model of air and fuel path of combustion engine is the first issue considered in the thesis. Next a theoretical background of predictive control theory and chosen approach of control are presented. Finally, the control problem definition, applied solution and registered problems are discussed. The work focuses on a control algorithms and presents nonlinear model-based predictive controller, linear controller for a simplified control problem and warm-start technique as an alternative for decreasing of computational complexity resulting from definition of the control law. Model predictive control (MPC) is a modern control technique characterized by its ability to control systems under defined limits. Complexity of control law of linear and nonlinear MPC causes that the computational requirements on storage space and online computation time have to be considered in the controller design. Especially limitations on computation time make often the optimal control law too complex to be implemented and some suboptimal solution has to be provided to meet computational requirements. In the thesis comparison of features of linear and nonlinear controllers is presented and then an approach combining both implementations is proposed to overcome their individual limitations. Presented warm-start technique applies solution of the simplified control problem as an initial solution in fully-term nonlinear problem. As a result computational effort required to control law calculation can be decreased and real-time implementation of NMPC becomes easier. Discussed approaches are applied for air fuel ratio control of SI engine. The control objective is to achieve desired (mostly stoichiometric air-fuel ratio) lambda variable under changes in the throttle position and engine's load. The applicability and limitations of the developed approaches are demonstrated through various simulations and results gathered on the engine's test bench.|
|Key words:||Predictive Control, Air-Fuel Ratio, Real Time|
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