Прегледај по Аутор "Lubura, Slobodan"
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- СтавкаAdaptive Delay Bank Filter for Selective Elimination of harmonics in SRF-PLL structures(2015) Lubura, Slobodan; Šoja, Milomir; Lale, Srđan; Ristović, Milica; Ikić. MarkoThis paper proposes the usage of adaptive delay bank (ADB) based on cascaded delayed signal cancellation (CDSC) structure for selective elimination of the harmonics in the synchronous reference frame phase locked loop (SRF-PLL) structures. The ADB is inserted inside the SRF-PLL structure and it is frequency adaptive, which is the advantage over CDSC structures which are used in PLL as pre-filters, not being adaptive at all. Detailed mathematical analysis and simulation results confirmed suggested method for selective harmonic elimination in PLL.
- СтавкаAnalysis of discretization methods applied on DCSOGI block as part of SRF-PLL structure(2016) Ristović Krstić, Milica; Lubura, Slobodan; Lale, Srđan; Šoja, Milomir; Ikić. Marko; Milovanović, DragišaPhase Locked Loop (PLL) is wide used for grid parameters estimation, as well for grid-converters synchronization. Key block at single-phase Synchronous Reference Frame PLL (SRF-PLL) structure is two-phase generator which is used for generation of two quadrature signals, which are necessary for SRF block. One of the issues that could appear during estimation of grid parameters is appearance of DC offset in measured grid voltage. In this paper is described second order generalized integrator (SOGI) which is capable to fully reject DC offset and noise which could appear in measured input grid voltage. This two-phase generator is named DC-SOGI. Analog DC-SOGI is made of two second order filters. While these structures are mostly digitally implemented, then it is interesting to analyze discretization method and sampling time impact on two-phase generator. Simulation results confirm given assumption.
- СтавкаAnalysis of single-phase PLL with novel two-phase generator for gridconnected converters(2011) Lale, Srdjan; Lubura, Slobodan; Šoja, Milomir; Ikić. MarkoIt is very important for proper work of gridconnected converters to have accurate detection of phase angle, frequency and amplitude of grid voltage. Estimation of these grid parameters can be achieved using PLL (phase locked loop) based on SRF (synchronous reference frame) theory. This PLL should have robustness against noise and offset introduced by measurement and data conversion. This paper proposes an improved PLL alorithm that has excellent noise and offset rejection property. The main part of the proposed PLL is a novel two-phase generator which is used to obtain two quadrature signals for SRF block and PI regulator in closed control loop.
- СтавкаExperimental verification of single-phase PLL with novel two-phase generator for gridconnected converters(2012) Lubura, Slobodan; Šoja, Milomir; Lale, Srđan; Ikić. MarkoFor proper work of grid-connected converters it is important to have accurate detection of phase angle, frequency and amplitude of grid voltage. Estimation of these grid parameters can be achieved using PLL (phase locked loop) based on SRF (synchronous reference frame) theory. This PLL should have robustness against noise and offset introduced by measurement and data conversion. This paper proposes an improved PLL algorithm that has excellent noise and offset rejection property. The main part of proposed PLL is a novel two-phase generator which is used to obtain two quadrature signals for SRF block and PI regulator in closed control loop. Performances of proposed PLL are verified through experimental results given in this paper.
- СтавкаImplementation of CORDIC Algorithm on FPGA Altera Cyclone(2012) Ristović, Milica; Lubura, Slobodan; Jokić, DejanIn paper is presented HDL Code generation of Cordic Algorithm in MATLAB/Simulink, using HDL Code generation tool, and its implementation on FPGA Altera Cyclone, using Altera Quartus II. There are also tested data types which Cordic uses, as well as time which is need for sine or cosine calculation of given angle, depending on these data types. With this information Cordic can be easily implemented in any digital system.
- СтавкаSingle-phase phase locked loop with DC offset and noise rejection for photovoltaic inverters(Wiley, 2014) Lubura, Slobodan; Šoja, Milomir; Lale, Srđan; Ikić. MarkoProper work of grid-connected converters requires an accurate detection of phase angle, frequency and amplitude of grid voltage. Phase locked loops (PLLs) based on synchronous reference frame theory can be used for estimation of these grid parameters. One of the issues that could appear during estimation of grid parameters is appearance of DC offset in measured grid voltage. This DC component (offset) is usually entered in PLL structure via measurement and A/D conversion process. Undesirable induced DC offset could appear as part of the reference sine current of photovoltaic inverters or other grid-connected converters. A lot of standards define allowed PV inverter’s DC current injection in the grid. In this study, we propose an improved PLL structure with capability to fully reject DC offset and noise which could appear in measured input grid voltage. The key component of the proposed PLL is two-phase generator with a closed control loop for DC offset and noise rejection. Obtained simulation and experimental results show that the proposed PLL structure can solve important issues of presence of noise and DC offset in measured grid voltage. The proposed PLL structure shows excellent dynamical performances in conditions of fast changes of grid parameters.
- СтавкаTwo Open Solutions for Industrial Robot Control: The Case of PUMA 560(MDPI, 2020) Jokić, Dejan; Lubura, Slobodan; Rajs, Vladimir; Bodić, Milan; Šiljak, HarunIn this paper we present two di erent, software and reconfigurable hardware, open architecture approaches to the PUMA 560 robot controller implementation, fully document them and provide the full design specification, software code and hardware description. Such solutions are necessary in today’s robotics and industry: deprecated old control units render robotic installations useless and allow no upgrades, advancements, or innovation in an inherently innovative ecosystem. For the sake of simplicity, just the first robot axis is considered. The first approach described is a PC solution with data acquisition I/O board (Humusoft MF634). This board is supported with Matlab Real-TimeWindows Toolbox for real-time applications and thus whole controller was designed in Matlab environment. The second approach is a robot controller developed on field programmable gate arrays (FPGA) board. The complexity of FPGA design can be overcome by using a third party software package, such as self-developed Matlab FPGA Real Time Toolbox. In both cases, parameters of motion controller are calculated by using simulation of the PUMA 560 robot first axis motion. Simulations were conducted in Matlab/Simulink using Robotics Toolbox.
- СтавкаWhat’s in the Box: Design of an Open Didactic Robot Environment(MDPI, 2020) Jokić, Dejan; Lubura, Slobodan; Ristović, Milica; Stankovski, Stevan; Rajs, Vladimir; Šiljak, HarunWe present a realization of a didactic robot environment for robot PUMA 560 for educational and research purposes. Robot PUMA 560 is probably the mathematically best-described robot, and therefore it is frequently used for research and educational purposes. Adeveloped control environment consists of a robot controller and teach pendant. The advantage of using a personally developed solution is its open structure, which allows various tests and measurements to be performed, and that is highly convenient for educational and research purposes. The motivation behind the design of this personal didactic robot control environment arose from a survey for students after the first Summer School on Mechatronic Systems. The student questionnaire revealed severe discrepancies between theory and practice in education. Even though the primary purpose of the new control environment for robot PUMA 560 was research, it was established that it is a viable lab resource that allows for the connection between theoretical and industrial robotics. It was used for the duration of four Summer Schools and university courses. Since then, it has been fully integrated into International Burch University’s Electrical and Electronics Engineering curriculum through several courses on the bachelor and master levels for multidisciplinary problem-based learning (PBL) projects.