Last issue
2016 (vol. 26) - Number 4


Andrzej Ruszewski:

Practical and asymptotic stability of fractional discrete-time scalar systems described by a new model



D. Krokavec, A. Filasova, P. Liscinsky:

On fault tolerant control structures incorporating fault estimation



Sundarapandian Vaidyanathan:

Hyperchaos, adaptive control and synchronization of a novel 4-D  hyperchaotic system with two quadratic nonlinearities



H. Górecki, M. Zaczyk:

Analytic solutions of transcendental equations with application to automatics



F. Mnif:

Predictor-based stabilization for chained form systems with input time delay



S. Daniar, R. Aazami, M. Shiroei:

Multivariable predictive control considering time delay for load-frequency control in multi-area power systems



T. Kaczorek:

Analysis and comparison of the stability of discrete-time and continuous-time linear systems



M. Rachik, M. Lhous:

An observer-based control of linear systems with uncertain parameters



L. Malinski:

Identification of stable elementary bilinear time-series model



V.V. Huynh:

New observer-based control design for mismatched uncertain systems with time-delay




ACS Abstract:

2010 (Volume 20)
Number 3
1. Observer state feedback control of discrete-time systems with state equality constraints
2. Computation of positive realization of MIMO hybrid linear systems in the form of second Fornasini-Marchesini model
3. Numerical simulation of feedback controlled fluid-induced instabilities in rotor system supported by hydrodynamic bearings
4. Robust output feedback Model Predictive Control design
5. Feedback control of three-Level PWM rectifier: Application to the stabilization of DC Voltages of five-level NPC active power filter
6.

Decomposition of the pairs (A,B) and (A,C) of positive discrete-time linear systems

7. Stator inter-turn fault detection of an induction motor using neuro-fuzzy techniques


Observer state feedback control of discrete-time systems with state equality constraintsDownload full PDF article
D. Krokavec
(Technical University of Kosice, Kosice, Slovak Republic)
A. Filasova
(Technical University of Kosice, Kosice, Slovak Republic)

Design conditions for existence of observer-based memory-less feedback control for stabilization of discrete-time systems with equality constraints given on the state variables are presented in the paper. These conditions are associated with eigenstructure assignment based on the singular value decomposition principle. The validity of the proposed method is demonstrated by a numerical example with the equality constraint tying together all state variables.

keywords: equality constraints, eigenstructure, assignment, state feedback

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Computation of positive realization of MIMO hybrid linear systems in the form of second Fornasini-Marchesini modelDownload full PDF article
T. Kaczorek
(Bialystok Technical University, Bialystok, Poland)
L. Sajewski
(Bialystok Technical University, Bialystok, Poland)

The realization problem for positive multi-input and multi-output (MIMO) linear hybrid systems with the form of second Fornasini-Marchesini model is formulated and a method based on the state variable diagram for finding a positive realization of a given proper transfer matrix is proposed. Sufficient conditions for the existence of the positive realization of a given proper transfer matrix are established. A procedure for computation of a positive realization is proposed and illustrated by a numerical example.

keywords: hybrid, 2D system, positive, realization, existence, computation

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Numerical simulation of feedback controlled fluid-induced instabilities in rotor system supported by hydrodynamic bearingsDownload full PDF article
P. Ferfecki
(Center of Advanced Innovation Technologies, SIMD, VSB-TUO, Ostrava, Czech Republic)
R. Sikora, Z. Poruba
(Department of Mechanics, VSB-TUO, Ostrava, Czech Republic)

In certain operating conditions, the oil-film forces, by which the hydrodynamic bearings act on the rotor, destabilize and induce a self-excited vibration. There are many solution based on modifications of the bearing geometry to enlarge the operational range of the hydrodynamic bearing as a tilting pad bearing, lemon bore, etc. or usage of the dampers whose operation is based only on the dissipation of mechanical energy. In this paper several concepts based on controlled kinematic excitation of the bearing shells is investigated by computer simulation and by experimental test. The mathematical model of the uncontrolled and controlled rotor system contains the nonlinear hydrodynamic forces determined by the solution of the Reynolds equation assuming short case of bearing. To solve the equation of motion the Runge-Kutta method of the 4th order with Dormand-Prince modification and variable length of the integration step is used. The computer simulations were performed for rotor system without feedback control and with feedback controller. The main objectives of the numerical analysis were determination of the stability regions of the vibration excited by the imbalance forces. Results of the computer simulations proved that the analyzed approaches reduce amplitude of the rotor vibration caused by the imbalance forces. Experimental test and computer simulations demonstrate that the active vibration control increases considerably the rotation speed when the self-excited vibration of the oil-film occurred.

keywords: rotor system, hydrodynamic bearing instability, kinematic excitation

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Robust output feedback Model Predictive Control designDownload full PDF article
V. Vesely
(Slovak University of Technology, Bratislava, Slovak Republic)
D. Rosinova
(Slovak University of Technology, Bratislava, Slovak Republic)

The paper addresses the problem of designing a robust output/state  model predictive control for linear polytopic systems without constraints. The new robust BMI stability condition for given predictive and control horizon is derived which guarantees the parameter dependent quadratic stability and guaranteed cost.The proposed condition is appropriate for centralized and decentralized control design, as illustrated on example.

keywords: model predictive control, robust control, parameter dependent quadratic stability, Lyapunov function, polytopic system, decentralized control

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Feedback control of three-Level PWM rectifier: Application to the stabilization of DC Voltages of five-level NPC active power filterDownload full PDF article
T. Abdelkrim, K. Benamrane
(Applied Research Unit on Renewable Energies, Industrial Zone, Ghardaia, Algeria)
E.M. Berkouk
(Polytechnic National School, Algiers, Algeria)
T. Benslimane
(University of Msila, Algeria)

One of the most important drawbacks of the three phases five-level NPC (Neutral Point Clamped) Active Power Filter (APF) is the neutral point balance. As the consequence, the capacitors voltages of the input DC bus of the APF are not equal which constitutes the major limitation for the use of this power converter. In order to stabilize these DC voltages, it is proposed in this paper to study the cascade constituted by three phases three-level PWM rectifier-clamping bridge filter-five-level NPC APF. In the first part, the authors present a topology of five-level NPC Voltage Source Inverter (VSI), and then, they propose a model of this converter and its PWM control strategy. In the second part, the modeling and control of three-level PWM current rectifier is presented. In the third part, to remedy to instability problem of the input capacitors DC voltages of the APF, the authors propose feedback control of the three-level PWM rectifier followed by clamping bridge filter. After that, the sliding mode regulator sed to control the active filter is developed. The obtained results are full of promise to use this topology of APF in high voltage and high power applications.

keywords: active power filter, NPC multilevel inverter, feedback control, PWM current rectifier, clamping bridge filter

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Decomposition of the pairs (A,B) and (A,C) of positive discrete-time linear systems

Download full PDF article
T. Kaczorek
(Bialystok Technical University, Bialystok, Poland)

A new test for checking the reachability (observability) of positive discrete-time linear systems is proposed. Conditions are established under which the unreachable pair (A,B) and the unobservable pair (A,C) of positive discrete-time system can be decomposed into reachable and unreachable parts and observable and unobservable parts, respectively. It is shown that the transfer matrix of the positive system is equal to the transfer matrix of its reachable (observable) part.

keywords: decomposition, positive linear, discrete-time, reachability, observability

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Stator inter-turn fault detection of an induction motor using neuro-fuzzy techniquesDownload full PDF article
R.N. Dash
(National Institute of Technology, Rourkela, India)
B. Subudhi
(National Institute of Technology, Rourkela, India)

Motivated by the superior performances of neural networks and neuro-fuzzy approaches to fault detection of a single phase induction motor, this paper studies the applicability these two approaches for detection of stator inter-turn faults in a three phase induction motor. Firstly, the paper develops an adaptive neural fuzzy inference system (ANFIS) detection strategy and then compares its performance with that of using a multi layer perceptron neural network (MLP NN) applied to stator inter-turn fault detection of a three phase induction motor. The fault location process is based on the monitoring the three phase shifts between the line current and the phase voltage of the induction machine.

keywords: inter-turn short circuit fault, phase shifts, adaptive neural fuzzy inference systems (ANFISs), neural network, induction motor

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