The volume 2002

Table of Contents

Aurel CAMPEANU, Augustin-Iulian IONESCU, Toma CAMPEANU: Numerical Treatment Of Some Complex Dynamic Processes Of Saturated Induction Machine
Abstract   Full Text

Ion VONCILA, Nicolae BADEA, Ion DOBROTA: The Behavior Of Asymmetric Frontal Couplings With Permanent Magnets In Magnetic Powder And High Temperature Environments
Abstract   Full Text

Grigore FETECĂU ,Viorel-Eugen IORDACHE, Eric HUG: Considerations On The Effect Of Plastic Deformation Over The Magnetic Behavior Of Soft Ferromagnetic Alloy Fe-3%Si NO
Abstract   Full Text

Radu GIUCLEA, Cristian BOGUS, Liviu KREINDLER: Comparison On Sensorless Control Of Synchronous Motors
Abstract   Full Text

Decebal ALEXANDRU, Monica-Adela ENACHE, Paul MARINAS: Influence Of High Performance Voltage Converters Supply Upon The Induction Motors Behaviour
Abstract   Full Text

Ioan Serban POPA, Mihai Octavian POPESCU, Claudia POPESCU: Energetic Macroscopic Representation Applied To An Electrical Urban Transport System
Abstract   Full Text

Alexandru BITOLEANU, Mihaela POPESCU: New Power Optimization Possibilities Of Static Converter And Asynchronous Motor Driving Systems
Abstract   Full Text

Stelian JUDELE, Razvan SOLEA, Viorel DUGAN: On The Snubber Influence To The Switching And Conduction Losses In A Converter Using Switched Capacitor
Abstract   Full Text

Maria IMECS, Ioan I. INCZE, Csaba SZABÓ, József VÁSÁRHELYI: Simple Approach For Induction Motor Control Using Reconfigurable Hardware
Abstract   Full Text

Emil ROSU, Marian GAICEANU, Ion BIVOL, Dumitru CALUEANU: Energetic Optimal Control Of Adjustable Drive Systems
Abstract   Full Text

Teodor PANA, Calin RUSU: Speed And Rotor Flux Estimation In Speed Sensorless Control Of Induction Motor
Abstract   Full Text

Ion BIVOL, Traian MUNTEANU, Ionel LUPEA, Eric DESTOBBELEER: Some Considerations Regarding The Efficiency Of The Electromechanical Motion
Abstract   Full Text

Florin IOV, Frede BLAABJERG, Anca Daniela HANSEN: A Simulation Platform To Model, Optimize And Design Wind Turbines. The Matlab/Simulink Toolbox
Abstract   Full Text

Nicolaos Antonio CUTULULIS, Iulian MUNTEANU, Emil CEANGA, Mihai CULEA: Optimal Control Structure For Variable Speed Wind Power System
Abstract   Full Text

Nicolaos Antonio CUTULULIS, Mihai CIOBOTARU, Emil CEANGĂ, Mina Emil ROSU Real Time Wind Turbine Simulator Based On Frequency Controlled AC Servomotor
Abstract   Full Text

Ion BIVOL, Emil ROSU, Emil CEANGA: Detecting The Liquid Core In Continuous Casting Slabs By Load Torque Estimation In Unbending Zone
Abstract   Full Text

Radu BELEA, Liviu BELDIMAN: A Diferent Approach In The Parameters' Identification Of A JFET Using Genetic Algorithms
Abstract   Full Text

Robin de KEYSER, Clara Mihaela IONESCU: Modelling, Identification And Simulation Of A Lighting Control System
Abstract   Full Text

Cornelia TUDORIE: Imperfect Data In Database Context. How Are They Stored In Extended Relational Databases ?
Abstract   Full Text

 

 

Aurel CAMPEANU, Augustin-Iulian IONESCU, Toma CAMPEANU: Numerical Treatment Of Some Complex Dynamic Processes Of Saturated Induction Machine
Abstract: Three variants for the mathematical models of the saturated induction machine (the exact one, the classical one and the simplified one) are used for the analysis of the reversal process combined with one short mechanical overload. The limits of the classical and simplified models are emphasised and the suitability of the exact model is justified.

Keywords: induction machine, modeling, saturated model, simulation, dynamic processes.

 



Ion VONCILA, Nicolae BADEA, Ion DOBROTA: The Behavior Of Asymmetric Frontal Couplings With Permanent Magnets In Magnetic Powder And High Temperature Environments

Abstract: The main purpose of this paper is the comparative analysis of the behavior of frontal couplings with Nd-Fe-B permanent magnets in difficult environments, specific to metallurgy – such as environments with magnetic powders and high temperature – in two constructive variants: symmetric couplings and asymmetric couplings (with divided poles). The results show the superior performance of asymmetric couplings under the given conditions.

Keywords: permanent magnets, permanent magnet couplings.

 



Grigore FETECĂU ,Viorel-Eugen IORDACHE, Eric HUG: Considerations On The Effect Of Plastic Deformation Over The Magnetic Behavior Of Soft Ferromagnetic Alloy Fe-3%Si NO

Abstract: The paper synthetically presents the results obtained over the degradation of magnetic properties of soft ferromagnetic sheets Fe-3%Si NO required mechanically in plastic deformation area. Chronologically, the evolution of magnetic behavior was considered from two complementary approaches: after plastic deformation and, recently, during a uniaxial traction/pull. The analyze of the behavior refers firstly to the structure of dislocation and, secondly, to the level of internal tensions generated during cold hammering.

Keywords: soft ferromagnetic, magneto-mechanic, internal tensions, plastic deformations.

 



Radu GIUCLEA, Cristian BOGUS, Liviu KREINDLER: Comparison On Sensorless Control Of Synchronous Motors

Abstract: The paper compares two different methods for speed and position estimation in AC permanent magnet synchronous motors vector control applications. The first method implies two observer blocks — one for the speed, and the other for the electrical position, using the voltage equations in the (d,q) reference frames. The second method estimates the same variables starting from the calculation of instantaneous reactive power. The tests have proved excellent behaviour in steady state (method 1) as well as in transient state (method 2). The implementation has been made on the 16 bits fixed-point DSP - TMS320F240 from Texas Instruments.

Keywords: sensorless control, DSP controller.

 



Decebal ALEXANDRU, Monica-Adela ENACHE, Paul MARINAS: Influence Of High Performance Voltage Converters Supply Upon The Induction Motors Behaviour


Abstract: The induction motors supply by converters leads to a distorted regime accompanied by some parasite torques and some supplementary losses. These aspects are emphasized further on because their quantitative determinations have a special influence in establishing the motors performances.

Keywords: motors, converters, distored regime.

 



Ioan Serban POPA, Mihai Octavian POPESCU, Claudia POPESCU: Energetic Macroscopic Representation Applied To An Electrical Urban Transport System


Abstract: An energetic description of the electric transport urban system ASTRAIK 415T is proposed according to a specific formalism. This is used to simulate the trolleybus system, equipped with a chopper and a direct current series motor. DC series motor is still used for trolleybus and metro, driven by a GTO or IGBT chopper µC-controlled, which allows the implementation of command algorithms. From this synthetically representation a complete model of the electromechanical system was implemented using the Matlab-Simulink simulation environment. A control structure was deduced through model inversion. This will allow the study of the transient phenomena and the implementation of different command laws taking into account the minimum energy losses.

Keywords: urban system transport, transient phenomena, modeling, energetic macroscopic representation.

 



Alexandru BITOLEANU, Mihaela POPESCU: New Power Optimization Possibilities Of Static Converter And Asynchronous Motor Driving Systems


Abstract: In this paper there are given a few mathematical relations for the power analysis in un-sinusoidal regime. If the voltage is sinusoidal and the current is unsinusoidal, the apparent power will be ascertained by the active power, the fundamental displacement factor and on the current distortion factor. If the voltage and the current are un-sinusoidal, there will exist the optimum values for real parts of harmonics impedances that will minimize the apparent power. More interesting is the possibility of minimization the apparent power at constant mechanical power.

Keywords: nonsinusoidal regime, distortion power, optimal control.

 



Stelian JUDELE, Razvan SOLEA, Viorel DUGAN: On The Snubber Influence To The Switching And Conduction Losses In A Converter Using Switched Capacitor


Abstract: The paper deals to design and to compute the snubber parameters influence on the switching and conduction losses of the transistors (IGBT) used as bidirectional switches in a converter with switched capacitor. The converter was modelled with difference equations, and the transistors during turn-on and turn-off processes were simulated by dynamically varying resistance models. The energy loss per switching, commutation time, the variation of the transistor voltage etc. and the influence of snubber parameters in each of these cases are shown in the context of a converter used as a 50Hz reactive power controller unit.

Keywords: Switched capacitor converter, Bidirectional switches with IGBT, dynamically varying resistance models, Snubbers, Commutation and conduction losses.

 



Maria IMECS, Ioan I. INCZE, Csaba SZABÓ, József VÁSÁRHELYI: Simple Approach For Induction Motor Control Using Reconfigurable Hardware


Abstract: The paper deals with rotor-field-oriented vector control structures for the induction motor drives fed by the so-called tandem frequency converter. It is composed of two different types of DC-link converters connected in parallel arrangement. The larger-power one has current-source character and is operating synchronized in time and in amplitude with the stator currents. The other one has voltage-source character and it is the actuator of the motor control system. The drive is able to run also with partial-failed tandem converter, if the control strategy corresponds to the actual operating mode. A reconfigurable hardware implemented in configurable logic cells ensures the changing of the vector-control structure. The proposed control schemes were tested by simulation based on Matlab-Simulink model.

Keywords: Frequency converter, Induction motor, Field-orientation principle, Vector control, Reconfigurable logic, Simulation, Variable speed drives.

 



Emil ROSU, Marian GAICEANU, Ion BIVOL, Dumitru CALUEANU: Energetic Optimal Control Of Adjustable Drive Systems

Abstract: In the paper is developed a new control strategy for the adjustable speed drives. The strategy consists in the energetic optimal control of the dynamic regimes as starting, stopping and reversing. The main developed problems: formulation of energetic optimal problem, solution, experimental results via simulation and some considerations concerning the use of the control. The optimal developed solution can be applied for the both AC and DC drives, but only for linear systems.

Keywords: optimal control, adjustable drive systems.

 



Teodor PANA, Calin RUSU: Speed And Rotor Flux Estimation In Speed Sensorless Control Of Induction Motor


Abstract: The paper compares the performances of several adaptive rotor flux and speed estimation methods used in speed sensorless vector control of induction motor. First, a short review of Luenberger, Gopinath, MRAS, Torque Error MRAS and Kalman Filter estimation methods is presented. Then, the vector control drive using each estimation principle is simulated, using the real-time simulation techniques. The simulation results are compared and discussed by means of stability, sensitivity to parameter variation and operation in the low speed region, taking also into account the impossibility to estimate without any error both speed and rotor resistance, when the rotor equations are used as reference or adjustable model in estimation.

Keywords: Flux, speed and rotor resistance estimation, vector control, low speed region.

 



Ion BIVOL, Traian MUNTEANU, Ionel LUPEA, Eric DESTOBBELEER: Some Considerations Regarding The Efficiency Of The Electromechanical Motion


Abstract: Control techniques for servo drive which run at variable speed for prolonged time is developed on the base of minimum energy dissipation in a feed-forward structure. The optimal control laws are determinate using the estimated values of the main perturbation - the load torque. Different aspects of the electromechanical motion efficiency are presented regarding the influence of the desired time of execution, the shape of trajectory and the last torque.

Keywords: Motion control, feed-forward control, energy saving, efficiency of dynamical drive system.

 



Florin IOV, Frede BLAABJERG, Anca Daniela HANSEN: A Simulation Platform To Model, Optimize And Design Wind Turbines. The Matlab/Simulink Toolbox


Abstract: In the last years Matlab / Simulink® has become the most used software for modeling and simulation of dynamic systems. Wind energy conversion systems are for example such systems, containing subsystems with different ranges of the time constants: wind, turbine, generator, power electronics, transformer and grid. The electrical generator and the power converter need the smallest simulation step and therefore, these blocks decide the simulation speed. This paper presents a new and integrated simulation platform for modeling, optimizing and designing wind turbines. The platform contains different simulation tools: Matlab / Simulink - used as basic modeling tool, HAWC, DIgSilent and Saber.

Keywords: simulation platform, modeling and simulation, electrical machines, power electronics.

 



Nicolaos Antonio CUTULULIS, Iulian MUNTEANU, Emil CEANGA, Mihai CULEA: Optimal Control Structure For Variable Speed Wind Power System


Abstract: This paper presents an optimal control structure for variable speed, fixed pitch wind turbine. The control objective results from the optimization criterion that includes two contradictory demands: maximization of the energy captured from the wind and minimization of the damage caused by mechanical fatigue. We admit, as a modeling assumption, that wind speed has two components: a slowly varying component, named seasonal and a rapidly varying component, named turbulence. Hence, two control structures, which should function simultaneously, are identified in the optimal control problem.
The first optimization structure aims to maximize the wind turbine energetic efficiency by maintaining operational point on optimal regime characteristics (ORC). According to the slowly varying seasonal component of wind speed, a control loop adjusts system operating point in order to maintain it on ORC. In the second optimization structure, the system is considered to be operating on “static” optimal point assured by the above mentioned control loop, with the turbulence component being the input variable. The second control loop aims dynamic optimization that implies the minimization of the tip speed ratio variations around its optimal value, while minimizing the torque variations, thus the mechanical stress. Mathematically, this objective is defined as an integral criterion, belonging to linear quadratic optimization.

Keywords: wind power, variable speed operation, wind modelling, linear quadratic optimal control.

 



Nicolaos Antonio CUTULULIS, Mihai CIOBOTARU, Emil CEANGĂ, Mina Emil ROSU Real Time Wind Turbine Simulator Based On Frequency Controlled AC Servomotor


Abstract: This paper is a contribution to the development of a real time wind turbine simulator. The simulator is designed to generate wind power on its shaft, and provide the static and dynamic characteristics of a given turbine. The general structure of the simulator is composed of two subsystems: a “soft simulator” which realizes the real time simulation of the wind turbine, on the basis of the mathematical model, an electromechanical tracking system which receives the reference signal from the softsimulator, and provides a measurable output variable transmitted as response variable to the soft-simulator. The work concerns a wind turbine simulator using a tracking system realized on the basis on a frequency controlled AC servo-motor. This servo-motor is mechanically coupled with a pendulum machine, which realises the shaft torque of the electrical generator. The experimental system is built around the DS1103 PPC Controlled Board (dSPACE), which offers a rapid control prototyping, by Matlab-Simulink software tools. Experimental results from the real time WTS are presented.

Keywords: Windmills, simulator, real time system, digital signal processor, AC servomotor.

 



Ion BIVOL, Emil ROSU, Emil CEANGA: Detecting The Liquid Core In Continuous Casting Slabs By Load Torque Estimation In Unbending Zone


Abstract: The development in continuous casting process has been strongly dominated by the demands of quality improvement and reduced costs for steel products in recent years. To achieve these goals consideration has been given by increasing the velocity of casting process. In that case a portion of a cross section of the slab are still licked in the unbending zone. Information about the deformation, stress and strain in solid shells is quit important in terms of the cost quality. These information are obtained by load torque estimation using the electrical quantities of the drive system for the unbending zone. A sensor less drive system with induction motor is considerate. The electrical drive systems are controlled in torque and speed. The measurements of voltage and current components and the imposed speed are the inputs for the real time load torque estimator. The estimated load torque is compared with the calculated maximal load torque for the entirely solidified slab state. From this comparison results the thickens of the slab licked zone.

Keywords: estimated load torque, electrical drive systems.

 



Radu BELEA, Liviu BELDIMAN: A Diferent Approach In The Parameters' Identification Of A JFET Using Genetic Algorithms


Abstract: The genetic algorithms are developing in three directions: the genetic algorithms theory, the genetic algorithms programming and the study of the problems that can be solved with genetic algorithms. In this paper it is presented a study on the identification of the parameters of a JFET (Junction Field Effect Transistor). The problem is very exciting because the JFET has two mathematical models: an empirical one, and an analytic one, both of the models being nonlinear in parameters. In a parametric identification problem, it is minimized the distance between an experimental data set and an analytical function, which represent the mathematical model of the studied phenomenon. Basically, a genetic algorithm can maximize a fitness function, which is a positive defined function whose maximum is searched. However, genetic algorithms can also solve minimum problems, on condition that to the minimum problem can be applied an algebraic transform or a rank based transform in a maximum problem.

Keywords: algorithm, parametric identification, objective function, fitness-like function, Junction Field Effect Transistor.

 



Robin de KEYSER, Clara Mihaela IONESCU: Modelling, Identification And Simulation Of A Lighting Control System


Abstract: This paper presents the results of the first phase in the design of a control system for closed-loop regulation of the light amount in office-building rooms. This project is a joint development of Ghent University and Niko Lighting Company. The final objective is to regulate the light amount in a room at a constant level, irrespective of the disturbances from outside such as weather conditions. The main benefits would be a higher level of comfort and a continuous saving of energy. The system will be made commercially available as a micro-controller-based intelligent light-switch. The first phase in the project, described in this paper, is the modelling of the lighting system and the identification of a dynamic model of the system. A simulator, based on the obtained model, is also presented and validated. The simulator will be used in the second phase of the project to design, tune and test the controller and to evaluate the closed-loop system performance under varying environmental conditions (robustness tests).The project is rather challenging because undesired interaction might occur between separately controlled zones in a big room.

Keywords: Lighting Control, Modelling, Simulation, Identification.

 



Cornelia TUDORIE: Imperfect Data In Database Context. How Are They Stored In Extended Relational Databases ?


Abstract: Building a more accurate reality model requires taking into account imperfect information present in our knowledge and language. This paper presents several aspects of data imperfection in the database context and the appropriate frameworks for their treatment. It’s concluding that null value, possibility distribution and probability theory are the best solutions to represent incomplete, imprecise and uncertain data. For each of these problems there are some relational model extension proposals, including data representation and relational algebra.

Keywords: Artificial Intelligence, Database, Fuzzy Logic, Possibility Theory