Dragan Jevtić

University of Belgrade, Beograd, Central Serbia, Serbia

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Publications (6)0 Total impact

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    ABSTRACT: Cross cutter for paper or board is a facility that produces sheets of the desired length from a reel of web coming from the paper or board production line. Reliable operation, high speed of the web during cutting, and high accuracy of the sheet dimensions are common requirements. Mechanical assemblies of many existing machines are in good condition, offering possible extension of the service life, provided that drives and control system are modernized. The paper presents the characteristics and requirements of basic subsystems of the paper-board cross cutter from the control system perspective. Drag-link mechanism which provides the variation of the instantaneous speed of the cutter blades, necessary for proper operation of the cutter is described and analyzed. Experimental results obtained on a real, commercial paper-board cross cutter are presented in the paper. The results show that high accuracy of the sheet length can be achieved.
    Power Electronics and Motion Control Conference (EPE/PEMC), 2012 15th International; 01/2012
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    ABSTRACT: There are two possibilities for energy savings in belt conveyors: first affects efficiency of drive components and second applies different control strategies of multi motor drives on belt conveyors. The paper presents control strategy for the system of belt conveyors with variable speed drives based on principle of reduced energy consumption. The algorithm is developed to generate the reference speed for the system of belt conveyors with remote control on an open pit mine and implemented in control center. A new improved algorithm is proposed in the paper. Simulation results presented in the paper confirm increased energy savings of the bulk material transportation system.
    Proceedings of the 15th WSEAS international conference on Systems; 07/2011
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    ABSTRACT: The paper presents the algorithm for speed control of belt conveyors, in terms of optimal energy consumption. The algorithm is based on principle “minimal speed means minimum power”. The minimal speed is calculated as a ratio of transported capacity of bulk material and maximum possible material cross section on the belt.
    Power Electronics and Motion Control Conference (EPE/PEMC), 2010 14th International; 10/2010
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    ABSTRACT: The main demand for construction of new belt conveyors in open pit mines (OPM) is the increase of safety and system capacity, minimization of personal, reduction of maintenance cost, consumed energy, etc. The paper presents the algorithm for speed control of the system of belt conveyors, in terms of improved system efficiency. The algorithm is based on the principle of optimum utilization of the available material cross section on the belt. The algorithm is developed and tested on the detailed mathematical model of the drive system with the rubber belt, transporting variable capacity of the bulk material, measured at the input of the system. The simulation results are verified through performed measurements of characteristic values, which best illustrates the response of the system to the applied control strategy in the control center of the belt conveyor system with remote control.
    Electrical Machines (ICEM), 2010 XIX International Conference on; 10/2010
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    ABSTRACT: The paper presents a new method for load equalization of high power wound rotor induction motors driving the drums of belt conveyors. During exploitation, the diameters of the drums become unequal, due to the abrasion of rubber layer or sticking of dirt, leading to unequal load distribution between motors. The proposed solution of this problem implies the application of the ldquorotor resistor converterrdquo with the existing starting resistors. The rotor resistor converter consists of the group of three rotor resistors and the unit for their short-circuiting. For that purpose, the stator current of all motors is measured, and the instantaneous average value is used for the reference. This leads to the regime where one motor operates with the short-circuited rotor, with the semiconductor switch in the rotor resistor converter - always on. The currents of the remaining motors will be controlled by the PLC and the rotor resistor converters operating in the PWM regime, periodically short-circuiting the rotor terminals, i.e. the rotor resistors. In this way, the speed of the controlled motors will be reduced, to achieve equal load on all drives (load equalization). The results recorded on the laboratory model of the drive will be presented in the paper.
    Power Electronics, Electrical Drives, Automation and Motion, 2008. SPEEDAM 2008. International Symposium on; 07/2008
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    ABSTRACT: In order to develop a universal control system for synchronous machine starts (UUSSM), the research in the Electrical Drives Laboratory at the Faculty of Electrical Engineering of the University of Belgrade is performed. The system will be founded on Intel's 80C196KC microprocessor. A part of the research and experimental results are presented in the paper.