Communications - Scientific Letters of the University of Zilina, 2001 (vol. 3), issue 2-3
Articles
Research of New Sensorless Speed Controlled Drives with Induction Motors for Traction Applications
Jan Vittek, Juraj Altus, Bernard Bednarik, Rastislav Tabacek, Stephen J. Dodds, Roy Perryman
Communications - Scientific Letters of the University of Zilina 2001, 3(2):5-15 | DOI: 10.26552/com.C.2001.2-3.5-15 
The research, aimed at an area of electric drives for electric traction, is based on a new approach to the speed control of electric drives employing induction motors without the aid of a shaft-mounted speed sensor. A novel feature of the proposed control system is that responses to the reference speed demand and the rotor magnetic flux norm reference input are mutually independent. The design control structure consists of an inner loop, which is a stator current control loop and outer loop, which is a shaft sensor-less speed control loop. A first order linear closed-loop response based on feedback linearization was chosen to derive basic control law....
Synergic Influence of Power Electronics, Electric Traction and Electro-Energetics
Branislav Dobrucky, Juraj Altus, Pavol Spanik
Communications - Scientific Letters of the University of Zilina 2001, 3(2):16-28 | DOI: 10.26552/com.C.2001.2-3.16-28
The contribution addresses the implementation of new progressive technologies in the field of electric traction in order to reduce feedback influence on the power network. First of all, it concerns Flexible Alternating Current energy Transmission Systems (FACTS), which, on the one hand, limit negative influence of the electric traction; on the other hand, they improve parameters of the power network by an electronic method. Taking their effects into account, the Power Active Filters (PAF) muddle through at most, because they allow compensation of fundamental harmonics, higher harmonics and also help to adapt energetic systems to Electromagnetic Compatibility...
Fuzzy Logic in Railway Vehicle Control - A Necessity or a Mode?
Ales Lieskovsky, Ivo Myslivec
Communications - Scientific Letters of the University of Zilina 2001, 3(2):29-37 | DOI: 10.26552/com.C.2001.2-3.29-37
The paper addresses features imputed by literature with real features of applied conventional (non-fuzzy) regulators for automation of railway vehicles control. It demonstrates with examples from everyday operation on the Czech Railways that conventional regulators are not only able for everyday operation, but they have parameters that fuzzy regulators will achieve only with difficulties. The authors support their assertions not by the results of simulations but by the results of real, long-term, everyday use of conventional speed regulators and target braking ones.
Switched Reluctance Motor and its Utilization in Traction Applications
Pavol Rafajdus, Valeria Hrabovcova, Ladislav Janousek, Peter Hudak
Communications - Scientific Letters of the University of Zilina 2001, 3(2):38-47 | DOI: 10.26552/com.C.2001.2-3.38-47
This paper deals with the performances of switched reluctance motor (SRM) and with its utilization in electric traction. The investigation of SRM equivalent circuit parameters by measurement and by finite element method is described. The calculated and measured values of parameters are used in the mathematical model of SRM, which was simulated. The simulation outputs are time profiles of the phase currents, voltages and torque and also the torque/speed characteristic, which can be used for the traction characteristic calculation. The dependencies of the losses and efficiency on the speed are shown. The comparison of performances of induction machine...
Quality Parameters of Electricity Supplied to Electric Railways
Juraj Altus, Milan Novak, Alena Otcenasova, Michal Pokorny, Adam Szelag
Communications - Scientific Letters of the University of Zilina 2001, 3(2):48-60 | DOI: 10.26552/com.C.2001.2-3.48-60
The paper analyses the most relevant unfavourable impact of AC electric traction on the quality parameters of supplied electric energy. These are: power factor of fundamental harmonic and power factor, voltage a current harmonic components, unbalance and power factors in asymmetrically loaded lines and flicker. To confirm some propositions, the paper presents results of measurements in traction transformer substation ŽSR Nové Zámky. Also, the possibilities of unfavourableimpact elimination using filtering and compensating substation and power active filters are mentioned.
Linear Motors Utilization for Oth Maglev and Railway Vehicles
A. Binder, Th. Werle
Communications - Scientific Letters of the University of Zilina 2001, 3(2):61-67 | DOI: 10.26552/com.C.2001.2-3.61-67
Traction Systems with Linear Machines have been under investigation for a long time. There were and are several applications with synchronous long stator linear machines, e.g. the maglev demonstration line in Berlin MAGNETBAHN (built in 1983), the high speed maglev line TRANSRAPID where the TR06 has been tested since 1984 or the YAMANASHI Test Line in Japan, built in 1990. The linear - motor technology cannot only be used for propulsion of new linear trains. When thinking of adhesion problems of conventional locomotives under wet weather conditions, it is also possible to use the magnetic attraction force produced by linear machines to increase the...
Speed-Sensorless Stator Flux-Oriented Control of Induction Motor Drives in Traction
Manfred Depenbrock, Andreas Steimel, Christian Foerth, Frank Hoffmann, Markus Weidauer, Stefan Koch
Communications - Scientific Letters of the University of Zilina 2001, 3(2):68-75 | DOI: 10.26552/com.C.2001.2-3.68-75
Indirect Stator-Quantities Control (ISC) combines the principle of stator flux-orientation proven successful in Direct Self Control (DSC) with Pulse Width Modulation (PWM). High torque dynamics and robust behavior against input voltage disturbance are achieved in the whole operation range including field-weakening. After careful correction of inverter voltage errors the difference of the stator current space vectors in the machine and in the control model is employed for speed estimation, allowing dispensing with speed sensors. A special flux management allows an infinitely slow change between driving and braking.
Electrical Transmission of Modernized Locomotives of Indepedent Traction Power
Jozef Kuchta, Miroslav Fulier
Communications - Scientific Letters of the University of Zilina 2001, 3(2):76-88 | DOI: 10.26552/com.C.2001.2-3.76-88
The contribution addresses diesel-electric power transmission of modernized locomotives for independent motor traction. It describes the approach to development; the solution of modernized locomotives with hybrid AC/DC power transmission, desiqued and realized locomotive with full AC/AC power transmission. Advantages and reasonability of modernization with an advanced transmission degree (namely as AC/AC) is confirmed by total efficiency calculation as well as by benefits in basic fuel savings, which have been carried out from the real operation.
Stochastic Time Series and Possibilities of their Use for Selected Modal Characteristics Determination of Mechanical Structures
Bohus Leitner
Communications - Scientific Letters of the University of Zilina 2001, 3(2):89-105 | DOI: 10.26552/com.C.2001.2-3.89-105
The paper deals with the possibilities of using mathematical apparatus of a stochastic time series for stochastic systems description and modeling, especially mechanical ones. Its purpose is to briefly characterise fundamental terms and equations of mathematical apparatus of time series, to describe the algorithm of a statistically adequate discrete model of a stochastically dynamic system to develop relationship between parameters of discrete and continuous modelsand to show some possibilities of developed strategy applications for solution of selected modal characteristics of mechanical structures.
Electrified Transport Systems - Perspective of Transport for the Third Millennium
Jiri Drabek
Communications - Scientific Letters of the University of Zilina 2001, 3(2):106-113 | DOI: 10.26552/com.C.2001.2-3.106-113
Energetics and transport in the contemporary world are based mostly on exploitation of fossil fuels (petroleum, coal, natural gas). Enormous consumption of fossil fuels causes emissions of CO2 and Nox and global atmosphere warming. The supply of fossil fuels in the future is mainly limited by petroleum used for combustion machines of road vehicles and aeroplanes. Under these circumstances, the electric-propelled guided transport systems (electrified railways, maglev) are energetically - and ecologically-suitable solutions for quick and safe transport in the future because electrical energy can be produced also from renewable sources (water potential,...
The Electric Equipment of Traction Vehicles Current Development and Perspectives
Rastislav Tabacek, Jan Vittek
Communications - Scientific Letters of the University of Zilina 2001, 3(2):114-120 | DOI: 10.26552/com.C.2001.2-3.114-120
The electric equipment of traction vehicles has undergone very fast development during the last period. Traction drive was changed dramatically where induction motors took over. Control of induction motors needs sophisticated control circuitry for control of static converters, which produce three-phase current of variable frequency and variable voltage. Performance of the drives and vehicles are then determined by the control techniques, which enable complete automation ofthe train motion, as it is demanded mainly for high-speed service.
A Review of Vector Filtering Schemes for Color Images Corrupted Y Impulse Noise
Rastislav Lukac, Stanislav Marchevsky
Communications - Scientific Letters of the University of Zilina 2001, 3(2):121-127 | DOI: 10.26552/com.C.2001.2-3.121-127
The development of modern communication technologies such as video phones, video conferencing systems, HDTV, Internet and digital television requires color image digital processing. Concerning the fact that color images represents vector-valued signals, the use of vector techniques is demanded. In the case of noise removing the problem is related with vector filters. On that reason, this paper is focused on reviewing the most frequently used vector filters for impulsenoise suppression in color images.