Wyniki wyszukiwania - BazTech

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Robust extremum seeking for a second order uncertain plant using a sliding mode controller

Solis Cesar, Clempner Julio, Poznyak Alexander

International Journal of Applied Mathematics and Computer Science

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2019

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Vol. 29, no. 4

703--712

EN

This paper suggests a novel continuous-time robust extremum seeking algorithm for an unknown convex function constrained by a dynamical plant with uncertainties. The main idea of the proposed method is to develop a robust closed-loop controller based on sliding modes where the sliding surface takes the trajectory around a zone of the optimal point. We assume that the output of the plant is given by the states and a measure of the function. We show the stability and zone-convergence of the proposed algorithm. In order to validate the proposed method, we present a numerical example.

2

Control-oriented analysis of a lean-burn light-duty natural gas research engine with scavenged pre-chamber ignition

Hänggi Severin, Hilfiker Thomas, Soltic Patric, Hutter Richard, Onder Christopher

Combustion Engines

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2019

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R. 58, nr 1

42--53

EN

Natural gas is well-suited as a fuel in the transport sector. Due to its excellent combustion characteristics, engines operating with compressed natural gas (CNG) reach high efficiency, especially if operated at lean conditions. However, CNG engine research mainly focusses on stoichiometric conditions in order to use a three-way catalytic converter for the exhaust gas after treatment system. With the objective to explore the potential of CNG engines operated at lean conditions, a turbo-charged CNG engine with high compression ratio is developed and optimized for lean operation. In order to increase the ignition energy, the CNG engine is equipped with scavenged pre-chambers. A specific control structure is developed, which allows to operate the engine at a pre-defined (lean) air-to-fuel ratio. Further functionalities such as the combustion placement control and algorithms to estimate the conditions inside of the prechamber are implemented. The first part of this paper describes this engine control structure, which is specifically developed for the lean-burn CNG engine. In the second part, the effects of pre-chamber scavenging on engine performance criteria such as the combustion stability, engine efficiency or engine emissions are analyzed. With the objective to use pre-chamber scavenging to improve engine performance, a scavenging feedback control strategy is proposed. In order to control the ignition delay, this strategy adapts the amount of CNG injected into the prechamber with a linear controller or an extremum seeking algorithm depending on the air-to-fuel ratio of the main chamber.

3

Comparison of three estimators used in a sensorless MPPT strategy for a wind energy conversion chain based on a PMSG

Echchaachouai A., El Hani S., Hammouch A.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 3

18--22

EN

In this paper a WECS (Wind Energy Conversion System) based on a PMSG (Permanent Magnet Synchronous Generator) and implementing a sensorless MPPT (Maximum Power Point Tracking ) strategy is presented using three types of generator rotor speed and angle estimators; the Angle Tracking Observer, the Extended Kalman Filter and the Synchronous Reference Frame Phase Locked Loop. The main purpose is to compare these estimators. Simulation results in Matlab-Simulink allowing this comparison can be found at the end of this work.

PL

W artykule opisano generator z magnesami stałymi PMSG wykorzystujący strategię MPPT (śledzenie maksimum mocy). Porównano trzy typy estymatorów prędkości i kąta obrotu wirnika: czujnik kąta obrotu (angle tracking observer), filtr Kalmana i synchroniczną pętlę fazową (synchronous frame phase locked loop).

4

Nonlinear stabilizing control of an uncertain bioprocess model

Dimitrova N., Krastanov M.

International Journal of Applied Mathematics and Computer Science

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2009

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Vol. 19, no 3

441-454

EN

In this paper we consider a nonlinear model of a biological wastewater treatment process, based on two microbial populations and two substrates. The model, described by a four-dimensional dynamic system, is known to be practically verified and reliable. First we study the equilibrium points of the open-loop system, their stability and local bifurcations with respect to the control variable. Further we propose a feedback control law for asymptotic stabilization of the closed-loop system towards a previously chosen operating point. A numerical extremum seeking algorithm is designed to stabilize the dynamics towards the maximum methane output flow rate in the presence of coefficient uncertainties. Computer simulations in Maple are reported to illustrate the theoretical results.