1. Enhancing grid stability and low voltage ride through capability using type 2 fuzzy controlled dynamic voltage restorerCh. Sajan, P. Satish Kumar, Peter Virtič, 2024, original scientific article Abstract: Introduction. The integration of Renewable Energy Sources (RESs), particularly Wind Energy Conversion Systems (WECS), is vital for reducing reliance on fossil fuels and addressing climate change. However, this transition poses challenges, including ensuring grid stability in the face of intermittent RESs. Compliance with grid codes is crucial, with a focus on Low Voltage Ride Through (LVRT) capability.
Problem. The intermittent nature of RESs, specifically in Permanent Magnet Synchronous Generator (PMSG) based WECS, presents challenges to grid stability during voltage dips.
Goal. To enhance voltage stability and LVRT capability in PMSG-based WECS by integrating a Dynamic Voltage Restorer (DVR) with an energy storage device. This involves regulating the input DC voltage to the DVR using a type 2 fuzzy controller, adapting intelligently to changing conditions.
Methodology. DVR, powered by an energy storage device, is strategically integrated with WECS. A type 2 fuzzy controller regulates the DC voltage to DVR. The rectified WECS output undergoes processing through an isolated flyback converter. A 31-level Cascaded H-Bridge Multilevel Inverter (CHBMLI) with PI control ensures high-quality AC output.
Results. The validation of developed system is executed using MATLAB/Simulink revealing a reduced Total Harmonic Distortion (THD) value of 1.8 %, ensuring significance in LVRT capability.
Originality. The strategic integration of DVR with PMSG-based WECS, addresses the LVRT challenges. The use of type 2 fuzzy controller for intelligent voltage regulation and a sophisticated multilevel inverter contributes to the uniqueness of proposed solution.
Practical value. The developed system provides benefits by ensuring reliable LVRT capability in PMSG-based WECS with reduced THD of 1.8 % indicating improved grid compatibility. References 26, tables 5, figures 20.
Keywords: permanent magnet synchronous generator, wind energy conversion systems, low voltage ride through, type 2 fuzzy controller, isolated flyback converter, 31-level cascaded H-bridge multilevel inverter, PI controller
Published in DKUM: 06.11.2025; Views: 0; Downloads: 1
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2. Hardware-in-the-loop simulations: a historical overview of engineering challengesFranc Mihalič, Mitja Truntič, Alenka Hren, 2022, review article Abstract: The design of modern industrial products is further improved through the hardware-inthe-loop (HIL) simulation. Realistic simulation is enabled by the closed loop between the hardware
under test (HUT) and real-time simulation. Such a system involves a field programmable gate array
(FPGA) and digital signal processor (DSP). An HIL model can bypass serious damage to the real
object, reduce debugging cost, and, finally, reduce the comprehensive effort during the testing. This
paper provides a historical overview of HIL simulations through different engineering challenges,
i.e., within automotive, power electronics systems, and different industrial drives. Various platforms,
such as National Instruments, dSPACE, Typhoon HIL, or MATLAB Simulink Real-Time toolboxes
and Speedgoat hardware systems, offer a powerful tool for efficient and successful investigations
in different fields. Therefore, HIL simulation practice must begin already during the university’s
education process to prepare the students for professional engagements in the industry, which was
also verified experimentally at the end of the paper.
Keywords: hardware-in-the-loop (HIL), controller-in-the-loop (CIL), power hardware-in-the-loop (PHIL), electric drives, automotive, DC-DC converters, inverter systems, grid applications, railway systems
Published in DKUM: 07.04.2025; Views: 0; Downloads: 10
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3. Enhancing manufacturing precision: Leveraging motor currents data of computer numerical control machines for geometrical accuracy prediction through machine learningLucijano Berus, Jernej Hernavs, David Potočnik, Kristijan Šket, Mirko Ficko, 2024, original scientific article Abstract: Direct verification of the geometric accuracy of machined parts cannot be performed simultaneously with active machining operations, as it usually requires subsequent inspection with measuring devices such as coordinate measuring machines (CMMs) or optical 3D scanners. This sequential approach increases production time and costs. In this study, we propose a novel indirect measurement method that utilizes motor current data from the controller of a Computer Numerical Control (CNC) machine in combination with machine learning algorithms to predict the geometric accuracy of machined parts in real-time. Different machine learning algorithms, such as Random Forest (RF), k-nearest neighbors (k-NN), and Decision Trees (DT), were used for predictive modeling. Feature extraction was performed using Tsfresh and ROCKET, which allowed us to capture the patterns in the motor current data corresponding to the geometric features of the machined parts. Our predictive models were trained and validated on a dataset that included motor current readings and corresponding geometric measurements of a mounting rail later used in an engine block. The results showed that the proposed approach enabled the prediction of three geometric features of the mounting rail with an accuracy (MAPE) below 0.61% during the learning phase and 0.64% during the testing phase. These results suggest that our method could reduce the need for post-machining inspections and measurements, thereby reducing production time and costs while maintaining required quality standards
Keywords: smart production machines, data-driven manufacturing, machine learning algorithms, CNC controller data, geometrical accuracy
Published in DKUM: 10.03.2025; Views: 0; Downloads: 14
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4. Mixed-field radiation of 3-D MLC flash memories for space applicationsLorenzo Gonzales, Salvatore Danzeca, Salvatore Fiore, Iztok Kramberger, 2024, original scientific article Abstract: This article presents the results of dynamic measurements of 3-D multilevel cell (MLC) NAND flash memories in a mixed-field radiation facility CERN High-energy AcceleRator Mixed field/facility (CHARM), CERN. The results show that the behavior of devices is comparable to tests with specific high energy particles, such as high energy protons, heavy ions, and to TID tests. The observed TID and single-event effects (SEEs) in flash memories from the existing relevant work are also observed in mixed field, making the environment suitable for an accelerated system level test. As the CHARM hadron energy spectrum is comparable to the low Earth orbit (LEO) environment, the facility is appropriate as an accelerated test for space applications. Furthermore, the volumetric characteristics of the devices can be observed in this 3-D radiation facility. Additionally, bad bit (BB) spread was observed, and the necessary radiation induced errors in NAND devices are discussed.
Keywords: bit error rate, flkash memories, memory controller, mixed field facility, multilevel cell, MLC, radiation hardness, single-event upsets, SEUs, space applications, total ionizing dose
Published in DKUM: 03.02.2025; Views: 0; Downloads: 13
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5. Event-triggered second-order sliding mode controller design and implementationAndrej Sarjaš, Dušan Gleich, 2023, original scientific article Abstract: The paper presents an event-triggered higher-order sliding mode controller design. The event-triggering technique is the alternative approach to real-time controller execution, unlike the classic time-triggering technique, which is not time-dependable and is governed by the triggering policy. The technique is suitable for system resource relaxation in case of computation burden or network usage mitigation. The paper describes the stability analysis of the super-twisted sliding mode controller based on input-to-state stability notation. The stability analysis introduces a triggering policy related directly to the ultimate boundness of the system states and preselected sliding variables. The controller time execution with the selected triggering condition prevents the exhibition of the Zeno phenomena, where the minimal inter-event time of the controller has a positive non-zero lower bound. The minimal value of the inter-event time is related directly to the controller parameters and triggering bound, the selection of which is given with the derived stability conditions regarding the designer’s objective. Preventing the fast nonlinear controller execution, especially close to the sliding manifold, also alleviates the chattering phenomena effectively, which is a primal drawback, and limits the usage of the controller on various systems. The method’s efficiency is verified with the hardware-in-the-loop system, where the dynamic and robustness of the triggering approach are compared to the standard time-triggered execution technique.
Keywords: event triggering, sliding mode control, super-twisted controller, chattering alleviation
Published in DKUM: 07.12.2023; Views: 370; Downloads: 27
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6. PALETIRANJE IN PREIZKUŠANJE ZLEPNEGA SPOJA NA UMS2 : diplomsko deloIvan Verboten Mastnak, 2020, undergraduate thesis Abstract: V diplomskem delu je predstavljena dodelava obstoječega montažnega stroja UMS2, ki je produkt podjetja Vivapen d. o. o. Gre za napravo, ki preizkuša zlepni spoj med notranjo in zunanjo pušo ustnikov ter njihovo nadaljnjo manipulacijo v namenske zalogovnike. Opisana sta mehanski in električno-pnevmatski postopek načrtovanja stroja od ideje do končnega izdelka z vsemi pripadajočimi zahtevami in omejitvami. Diplomsko delo zajema modeliranje v SolidWorks-u, projektiranje električnih in pnevmatskih načrtov ter pisanje programa krmilnika v programskem okolju CyPro v povezavi z linijskim servo pogonom SMC. Na podlagi uspešno opravljene analize dobrih kosov, ki so produkt tega diplomskega dela, se je stroj aktivno vključil v proizvodnjo.
Keywords: strojegradnja, EPLAN, CyPro, ACT Controller
Published in DKUM: 03.11.2020; Views: 874; Downloads: 76
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7. Intelligent adaptive cutting force control in end-millingUroš Župerl, Franc Čuš, Edvard Kiker, 2006, original scientific article Abstract: In this article, an adaptive neural controller for the ball end-milling process is described. Architecture with two different kinds of neural networks is proposed, and is used for the on-line optimal control of the milling process. A BP neural network is used to identify the milling state and to determin the optimal cutting inputs. The feedrate is selected as the optimised variable, and the milling state is estimated by the measured cutting force. The adaptive controller is operated by a PC and the adjusted feedrates are sent to the CNC. The purpose of this article is to present a reliable, robust neural controller aimed at adaptively adjusting feed-rate to prevent excessive tool wear, tool breakage and maintain a high chip removal rate. The goal is also to obtain an improvement of the milling process productivity by the use of an automatic regulation of the cutting force. Numerous simulations are conducted to confirm the efficiency of this architecture. The proposed architecture for on-line determining of optimal cutting conditions is applied to ball end-milling in this paper, but it is obvious that the system can be extended to other machines to improve cutting efficiency.
Keywords: end milling, adaptive force control, neuron controller, cutting conditions, adaptive control systems
Published in DKUM: 12.07.2017; Views: 1289; Downloads: 144
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8. An ℋ∞ optimal robust pole placement with fixed transparent controller structure on the basis of nonnegativity of even spectral polynomialsAndrej Sarjaš, Rajko Svečko, Amor Chowdhury, original scientific article Abstract: This paper presents the synthesis of an optimal robust controller with the use of pole placement technique. The presented method includes solving a polynomial equation on the basis of the chosen fixed characteristic polynomial and introduced parametric solutions with a known parametric structure of the controller. Robustness criteria in an unstructured uncertainty description with metrics of norm ℋ∞ are for a more reliable and effective formulation of objective functions for optimization presented in the form of a spectral polynomial with positivity conditions. The method enables robust low-order controller design by using plant simplification with partial-fraction decomposition, where the simplification remainder is added to the performance weight. The controller structure is assembled of well-known parts such as disturbance rejection, and reference tracking. The approach also allows the possibility of multiobjective optimization of robust criteria, application of mixed sensitivity problem, and other closed-loop limitation criteria, where the common criteria function can be composed from different unrelated criteria. Optimization and controller design are performed with iterative evolution algorithm.
Keywords: optimal robust controller, optimization, algorithm
Published in DKUM: 15.06.2017; Views: 1101; Downloads: 379
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9. Controllership influences on the restructuring of Slovenian companiesDanijel Lebar, Iztok Kolar, 2015, original scientific article Abstract: Controllership, as an informational activity, is becoming a multidimensional function, about which numerous doubts exist as to whether to increase its independency and integrate it tightly with the decision-making process. Financial knowledge and business-analytical capabilities of carriers of controllership activity can offer support for operational, financial, and strategic restructuring. This is important when facing frequent business dynamics in order to enhance competitiveness and especially achieve short-term as well as strategic goals.
Keywords: controllership, controller, restructuring, financial knowledge, business-analytical capabilities
Published in DKUM: 03.04.2017; Views: 1309; Downloads: 386
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10. Position control with parameter adaptation for a nano-robotic cellGregor Škorc, Jure Čas, Simon Brezovnik, Riko Šafarič, 2011, original scientific article Abstract: This paper describes the development of a nano-assembly system, built up using linear piezo motors. The so-called nano-robotic cell is based on an X/Y manipulator, supported by three serving tables, movable within a Z axis, and aposition controlled using two different types of a bang-bang control methods. The presented application has been developed as a stand-alone application with the LabVIEW Real Time software package, a PCI-7356 servo controller card and a TMCM-090 stepper driver. Our experiments focused on two major problems present during the construction of nano-robotic assembly cells. The first one is a nonlinear characteristic of a linear piezo motor, which makes the use of classical control methods very limited. The second problem appears when a nano-robotic cell needs a bigger working space and at the same time, production demands that the manipulator moves more often over longer distances. In order to position in nano-resolution, the motors have to run at higher resolutions with smaller speeds. Therefore, long distance moves slow down the entire production process. Experiments on this system have shown that positioning within the nano-scale is possible, using a simple control method such as the bang-bang control method. Although positioning using this method is possible, certain limitations and weaknesses exists, making this simple method useless in nano-scale if higher speeds and longer move distances are needed. Certain changes in the basic control algorithm are proposed, which will ensure that the bangbang control method becomes useful within higher speeds and over longer distances. All recommendations are supported and backed- up by practical experimental results.
Keywords: nanorobotske celice, nanopozicioniranje, histerezni krmilnik, proizvodnja MEMS, realno-časovni LabView, nano-robot cells, nano-positioning, bang-bang controller, MEMS assembly, LAbVIEW, real time
Published in DKUM: 10.07.2015; Views: 1815; Downloads: 145
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