| 1. |
- Almér, Stefan, et al.
(författare)
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Dynamic phasor analysis of a class of PWM systems
- 2015
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Ingår i: 2007 European Control Conference, ECC 2007. - : IEEE. - 9783952417386 ; , s. 1940-1947
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Konferensbidrag (refereegranskat)abstract
- The paper makes use of the so-called dynamic phasor model for stability and performance analysis of a class of PWM systems. The dynamic phasor model allows for the state to be represented in the frequency domain where a harmonic Lyapunov function is defined. The analysis covers both periodically switched systems and non-periodic systems where the switching is controlled by feedback.
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| 2. |
- Almér, Stefan, et al.
(författare)
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Dynamic Phasor Analysis of Periodic Systems
- 2009
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Ingår i: IEEE Transactions on Automatic Control. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9286 .- 1558-2523. ; 54:8, s. 2007-2012
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Tidskriftsartikel (refereegranskat)abstract
- The paper considers stability analysis of linear time-periodic (LTP) systems based on the dynamic phasor model (DPM). The DPM exploits the periodicity of the system by expanding the system state in a Fourier series over a moving time window. This results in an L-2-equivalent representation in terms of an infinite-dimensional LTI system which describes the evolution of time varying Fourier coefficients. To prove stability, we consider quadratic time-periodic Lyapunov candidates. Using the DPM, the corresponding time-periodic Lyapunov inequality can be stated as a finite dimensional inequality and the Lyapunov function can be found by solving a linear matrix inequality.
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| 3. |
- Almér, Stefan, et al.
(författare)
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Hybrid control techniques for switched-mode DC-DC converters part I : The step-down topology
- 2007
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Ingår i: 2007 American Control Conference. - : IEEE. - 1424409888 - 9781424409884 ; , s. 5450-5457
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Konferensbidrag (refereegranskat)abstract
- Several recent techniques from hybrid and optimal control are evaluated on a power electronics benchmark problem. The benchmark involves a number of practically interesting operating scenarios for a fixed-frequency synchronous step-down dc-dc converter. The specifications are defined such that good performance only can be obtained if the switched and nonlinear nature of the problem is respected during the design phase.
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| 4. |
- Briat, Corentin, et al.
(författare)
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An axiomatic fluid-flow model for congestion control analysis
- 2011
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Ingår i: 2011 50th IEEE Conference on Decision and Control andEuropean Control Conference (CDC-ECC). ; , s. 3122-3129
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Konferensbidrag (refereegranskat)abstract
- An axiomatic model for congestion control isderived. The proposed four axioms serve as a basis for theconstruction of models for the network elements. It is shownthat, under some assumptions, some models of the literature canbe recovered. A single-buffer/multiple-users topology is finallyderived and studied for illustration.
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| 5. |
- Briat, Corentin, et al.
(författare)
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Dynamic equations on time-scale : Application to stability analysis and stabilization of aperiodic sampled-data systems
- 2011
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Ingår i: IFAC Proc. Vol. (IFAC-PapersOnline). - 9783902661937 ; , s. 11374-11379
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Konferensbidrag (refereegranskat)abstract
- The stability analysis of systems with aperiodic sampling is analyzed in the framework of dynamic equations on time-scales. Lyapunov theory is used, with sample-period-dependent and independent Lyapunov functions, to obtain stability conditions expressed in terms of parameter dependent matrix inequalities. The examples illustrate the efficiency of the approach which is able to recover, for some systems, the theoretical results for the periodic sampling case even in the aperiodic case. It is also shown that some systems may have admissible varying sampling periods located in disjoint sets. Finally, stabilization results via switching statefeedback are provided; both robust and sampling-period-dependent controllers are considered. It is shown that the latter ones, using the information on the sampling period, can improve stability properties. Stabilization examples illustrate the effectiveness of the approach.
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| 6. |
- Briat, C., et al.
(författare)
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The Conservation of Information, Towards an Axiomatized Modular Modeling Approach to Congestion Control
- 2015
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Ingår i: IEEE/ACM Transactions on Networking. - 1063-6692 .- 1558-2566. ; 23:3, s. 851-865
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Tidskriftsartikel (refereegranskat)abstract
- We derive a modular fluid-flow network congestion control model based on a law of fundamental nature in networks: the conservation of information. Network elements such as queues, users, and transmission channels and network performance indicators like sending/acknowledgment rates and delays are mathematically modeled by applying this law locally. Our contributions are twofold. First, we introduce a modular metamodel that is sufficiently generic to represent any network topology. The proposed model is composed of building blocks that implement mechanisms ignored by the existing ones, which can be recovered from exact reduction or approximation of this new model. Second, we provide a novel classification of previously proposed models in the literature and show that they are often not capable of capturing the transient behavior of the network precisely. Numerical results obtained from packet-level simulations demonstrate the accuracy of the proposed model.
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| 7. |
- Cantoni, M., et al.
(författare)
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IQC robustness analysis for feedback interconnections of unstable distributed parameter systems
- 2009
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Ingår i: Proceedings of the 48th IEEE Conference on Decision and Control, 2009 held jointly with the 2009 28th Chinese Control Conference. CDC/CCC 2009. - : IEEE. - 9781424438716 ; , s. 1124-1130
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Konferensbidrag (refereegranskat)abstract
- In recent work the authors combined integral-quadratic-constraint (IQC) based analysis with ν-gap metric based analysis to study the robustness of feedback interconnections of possibly unstable rational transfer functions. This is extended here to the case of irrational transfer functions without pure delays. Specifically, we restrict attention to the sub-algebra of Callier-Desoer class transfer functions that have a limit at infinity.
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| 8. |
- Cantoni, Michael, et al.
(författare)
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Robust Stability Analysis For Feedback Interconnections Of Time-Varying Linear Systems
- 2013
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Ingår i: SIAM Journal of Control and Optimization. - : Society for Industrial & Applied Mathematics (SIAM). - 0363-0129 .- 1095-7138. ; 51:1, s. 353-379
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Tidskriftsartikel (refereegranskat)abstract
- Feedback interconnections of causal linear systems are studied in a continuous-time setting. The developments include a linear time-varying (LTV) generalization of Vinnicombe's nu-gap metric and an integral-quadratic-constraint-based robust L-2-stability theorem for uncertain feedback interconnections of potentially open-loop unstable systems. These main results are established in terms of Toeplitz-Wiener-Hopf and Hankel operators, and the Fredholm index, for a class of causal linear systems with the following attributes: (i) a system graph (i.e., subspace of L-2 input-output pairs) admits normalized strong right (i.e., image) and left (i.e., kernel) representations, and (ii) the corresponding Hankel operators are compact. These properties are first verified for stabilizable and detectable LTV state-space models to initially motivate the abstract formulation, and subsequently verified for frequency-domain multiplication by constantly proper Callier-Desoer transfer functions in analysis that confirms consistency of the developments with the time-invariant theory. To conclude, the aforementioned robust stability theorem is applied in an illustrative example concerning the feedback interconnection of distributed-parameter systems over a network with time-varying gains.
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| 9. |
- Cantoni, Michael, et al.
(författare)
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Robustness Analysis for Feedback Interconnections of Distributed Systems via Integral Quadratic Constraints
- 2012
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Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 57:2, s. 302-317
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Tidskriftsartikel (refereegranskat)abstract
- A framework is established for directly accommodating feedback interconnections of unstable distributed-parameter transfer functions in robust stability analysis via integral quadratic constraints (IQCs). This involves transfer function homotopies that are continuous in a nu-gap metric sense. As such, the development includes the extension of nu-gap metric concepts to an irrational setting and the study of uncertainty-set connectedness in these terms. The main IQC based robust stability result is established for constantly-proper transfer functions in the Callier-Desoer algebra; i.e. finitely many unstable poles and a constant limit at infinity. Problems of structured robust stability analysis and robust performance analysis are considered to illustrate use of the main result. Several numerical examples are also presented. These include stability analysis of an autonomous system with uncertain time-delay and a closed-loop control system, accounting for both the gain and phase characteristics of the distributed-parameter uncertainty associated with the nominal rational plant model used for controller synthesis.
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| 10. |
- Fujioka, H., et al.
(författare)
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Control synthesis for a class of PWM systems for robust tracking and H ∞ performance
- 2006
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Ingår i: Proc IEEE Conf Decis Control. - 1424401712 - 9781424401710 ; , s. 4861-4866
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Konferensbidrag (refereegranskat)abstract
- Robust control with robust tracking is considered for a class of pulse-width modulated systems (PWM) that appear, for example, in power electronics applications. The control objective is to regulate a high frequency ripple signal to robustly track a constant reference signal in an average sense. To achieve this goal, a new H∞ -control problem with integral action and averaged sampling is proposed. The design procedure is verified on a synchronous buck converter.
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