Model Reduction for Linear Time-Varying Systems
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
The thesis treats model reduction for linear time-varying systems. Time-varying models appear in many fields, including power systems, chemical engineering, aeronautics, and computational science. They can also be used for approximation of time-invariant nonlinear models. Model reduction is a topic that deals with simplification of complex models. This is important since it facilitates analysis and synthesis of controllers.
The thesis consists of two parts. The first part provides an introduction to the topics of time-varying systems and model reduction. Here, notation, standard results, examples, and some results from the second part of the thesis are presented.
The second part of the thesis consists of four papers. In the first paper, we study the balanced truncation method for linear time-varying state-space models. We derive error bounds for the simplified models. These bounds are generalizations of well-known time-invariant results, derived with other methods. In the second paper, we apply balanced truncation to a high-order model of a diesel exhaust catalyst. Furthermore, we discuss practical issues of balanced truncation and approximative discretization. In the third paper, we look at frequency-domain analysis of linear time-periodic impulse-response models. By decomposing the models into Taylor and Fourier series, we can analyze convergence properties of different truncated representations. In the fourth paper, we use the frequency-domain representation developed in the third paper, the harmonic transfer function, to generalize Bode's sensitivity integral. This result quantifies limitations for feedback control of linear time-periodic systems.
Place, publisher, year, edition, pages
Lund: Lund University , 2004. , 174 p.
, Institutionen för reglerteknik, Lunds universitet, ISSN 0280-5316 ; 1071
Model reduction, Linear systems, Time-varying systems, Error bounds, Frequency-domain analysis, Convergence analysis, Performance limitations
IdentifiersURN: urn:nbn:se:kth:diva-74698OAI: oai:DiVA.org:kth-74698DiVA: diva2:489875
2004-12-03, M:B, Maskinhuset, Lunds tekniska högskola, Lund, 10:15 (English)
Lall, Sanjay, Professor
Rantzer, Anders, Professor
QC 201202062012-02-062012-02-032012-02-06Bibliographically approved
List of papers