Three-Phase load current reconstruction using singleshunt current measurement and modified vector modulation for three-level DC-AC converter : doctoral dissertationHaris Kovačević
, 2022, doktorska disertacija
Opis: This doctoral thesis focuses on the development of Space Vector Modulation (SVM) techniques adjusted for single-shunt current measurement and applied to the three-level three-phase voltage source inverter. Based on the single-shunt current measurement, three-phase load currents are then reconstructed.
An overview of existing multilevel topologies and their main operating principles is provided within the thesis. To evaluate proposed SVM techniques adjusted for single-shunt current measurement, a three-level three-phase diode clamped voltage source inverter topology is selected. The main advantages of the selected topology are high efficiency, reduced semiconductor stress, the low capacitance of DC-link capacitors, etc. To reconstruct the three-phase load currents, a single-shunt is positioned inside the middle branch of the DC-link.
An overview of existing modulation techniques for two-level and multilevel inverters is provided within the thesis. To reconstruct three-phase load currents, three SVM methods are proposed within the thesis. Due to the lack of a current measurement window, while the voltage vector is positioned near sector or region boundary areas, additional modifications are required. The first SVM method shifts the SVM signals to ensure the minimum current measurement window needed for measurement with minimum additional vector injection. Such an approach ensures the high modulation index values greater than 0.8 with the smallest current ripple due to the SVM signal symmetry. The second method intentionally injects the colinear voltage vector into the existing vector combination to ensure the minimum time window required for current measurement. As a drawback, a smaller modulation index compared to the first method can be achieved. As an advantage, a very low modulation index of less than 0.2 can be achieved. The third method simplifies the second method by using a single SVM pattern. Such a method can be used only for very low modulation indexes and can be applied for two-level and three-level inverters.
The proposed SVM methods are implemented within the Digital Signal Processor (DSP). Experimental results confirm the proper operation of the proposed methods applied to the three-level diode clamped voltage source inverter.
Ključne besede: single-shunt, three-level inverter, SVM modification, current reconstruction, vector injection
Objavljeno v DKUM: 09.03.2023; Ogledov: 267; Prenosov: 30
Celotno besedilo (12,21 MB)
Standardizacija modula za prijavo v podjetju Inel : diplomsko deloŽak Paradižnik
, 2022, diplomsko delo
Opis: V diplomski nalogi smo predstavili, kako potekata izdelava modula in standardizacija prijave znotraj podjetja Inel. Standardizacija modula je bila narejena s pomočjo tehnologije Microsoft Visual Studio, tehnologije za namizne aplikacije WPF in Dependency injection, ReactiveX. V diplomskem delu so opisane vse tehnologije, ki so se uporabile pri razvoju, in postopek same izdelave modula ter reševanje problemov, ki so nastali ob tem. Opisano je tudi testiranje delovanja modula s pomočjo tehnologije enotskih testov, s strani programerjev, ki so zadolženi za testiranje, ter validacijskih inženirjev.
Ključne besede: modul, standardizacija, prijava, WPF, dependency injection, reactiveX, enotsko testiranje
Objavljeno v DKUM: 21.10.2022; Ogledov: 501; Prenosov: 52
Celotno besedilo (2,66 MB)
INJECTION MOULDING PROCESS OPTIMIZATION OF CITRUS FIBER BIOCOMPOSITES BY SIMULATIONS AND TAGUCHI EXPERIMENTAL DESIGN : magistrsko deloPeter Fajs
, 2019, magistrsko delo
Opis: The objective of the master thesis is to determine the filling properties of injection moulding process for newly created material, and to understand how the variation of processing parameters affects the flow possibilities. In thesis two materials were analysed, i.e. neat PLA material, which was used as a benchmark material and newly created composite CitrusPLA that is based on biodegradable PLA matrix and reinforced with citrus fibres. To fulfil the aim, the virtual and experimental design of experiment with the Taguchi methodology was conducted with use of spiral flow test, where the flow length of material through mould cavity was observed. The experimental results were the basis for the accuracy validation of numerical results and also to determine the optimum process parameters for injection moulding products with best flow conditions through statistical evaluation.
It has been concluded that the newly created composite has lower viscosity compared to benchmark virgin PLA which results in better flow conditions in spiral flow test analysis. Both materials have the same optimal conditions in terms of flow conditions. The contribution of mould temperature is in both cases negligible. However, other two variated parameters i.e. melt temperature and injection speed have higher influence on filling characteristics for both materials.
Ključne besede: injection moulding optimization, material characterization, Moldflow, injection moulding simulations, Taguchi DOE, bio-composites, citrus waste fibres, PLA
Objavljeno v DKUM: 07.06.2019; Ogledov: 1442; Prenosov: 27
Celotno besedilo (3,19 MB)
Impacts of different factors on seepage and land uplift due to compressed-air injectionZang Yongge
, Sun Dongmei
, Feng Ping
, Stephan Semprich
, 2017, izvirni znanstveni članek
Opis: In this study, using an in-situ, air-flow test in Essen, the impacts of different factors on multiphase flow and land uplift during and after compressed-air injection were investigated using numerical simulations. A loosely coupled, two-phase flow and geo-mechanical modeling approach, linking two numerical codes (TOUGH2/EOS3 and FLAC3D) was employed to simulate the in-situ, air-flow test for comparing the simulated and measured results. As the compressed air is injected, it flows upwards and laterally, and the vertical effective stress near and above the injection zones decreases owing to the pore pressure increasing here, causing an expansion of the soil skeleton in the corresponding zones. The land uplift, induced mainly by support actions from lower deformed soils, is relevant to the distribution of the porosity increments in the soil interior, and it increases rapidly during air injection. After the compressed-air injection stops, the land uplift decreases gradually to zero due to the overpressure dissipation. With a combination of intensive rainfall, the land uplift is slightly greater near the borehole, but it is significantly greater at a distance from the borehole than the land uplift with no or low rainfall, but the air-injection rate remains almost unchanged due to the unchangeable pore pressure near the injection region. As the intrinsic permeability increases or the air entry pressure decreases in the injected strata, both the land uplift and the air injection rate increase, but the time required for the land uplift to become zero is slightly advanced with either a small permeability or a high air entry pressure.
Ključne besede: loosely coupled two-phase flow and geo-mechanical model, in-situ, air-flow test, compressed-air injection, multiphase flow, land uplift, air loss
Objavljeno v DKUM: 18.06.2018; Ogledov: 1036; Prenosov: 125
Celotno besedilo (1,75 MB)
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Aplikacija zdravil po intraosalni potiAlen Kramberger
, 2017, diplomsko delo
Opis: Izhodišče: Pri življenjsko ogroženih bolnikih je eden izmed najnujnejših ukrepov takojšnja vzpostavitev intravenozne poti, kadar pa ti ni mogoče je smiselno uporabiti intraosalni pristop. Namen diplomskega dela je predstaviti intraosalni pristop in možnosti apliciranja medikamentozne terapije po intraosalni poti. Raziskali smo v katerem primeru je priporočljivo uporabiti intraosalni pristop pri poškodovancu ter v kakšni meri se intraosalni pristop uporablja v praksi.
Raziskovalne metode: Uporabili smo kvantitativno metodologijo in deskriptivno metodo dela. Podatke smo zbrali s pomočjo anonimne ankete, kot instrument raziskovanja smo uporabili anketni vprašalnik.
Rezultati: Ugotovili smo, da je intraosalno pot uporabilo približno polovico vseh anketirancev (48 %). Najbolj poznana pripomočka za vzpostavitev intraosalne poti sta B.I.G. in EZ/IO. Po analizi rezultatov lahko ugotovimo, da anketiranci vedo, da lahko po intraosalni poti apliciramo zdravila, infuzije ter krvne pripravke.
Diskusija in zaključek: Z ugotovitvami želimo izpostaviti, da je poznavanje intraosalnega pristopa na dobri poti, čeprav je potrebno najprej podkrepiti teoretično znanje, da bomo lahko v praksi dosegali pričakovane standarde. Potrebno je poudariti, da bi morali delodajalci zagotoviti več internih izobraževanj, kjer bi bil večji poudarek na alternativnih venskih pristopih in bi lahko zaposleni dobili teoretično in praktično znanje.
Ključne besede: intraosalni pristop, prehospitalno okolje, reševalci, terapija, bone injection gun, EZ/IO.
Objavljeno v DKUM: 19.07.2017; Ogledov: 2178; Prenosov: 321
Celotno besedilo (1,31 MB)
Experimental investigation review of biodiesel usage in bus diesel engineBreda Kegl
, Marko Kegl
, 2017, izvirni znanstveni članek
Opis: This paper assembles and analyses extensive experimental research work conducted for several years in relation to biodiesel usage in a MAN bus Diesel engine with M injection system. At first the most important properties of the actually used neat rapeseed biodiesel fuel and its blends with mineral diesel are discussed and compared to that of mineral diesel. Then the injection, fuel spray, and engine characteristics for various considered fuel blends are compared at various ambient conditions, with special emphasis on the influence of low temperature on fueling. Furthermore, for each tested fuel the optimal injection pump timing is determined. The obtained optimal injection pump timings for individual fuels are then used to determine and discuss the most important injection and combustion characteristics, engine performance, as well as the emission, economy, and tribology characteristics of the engine at all modes of emission test cycles test. The results show that for each tested fuel it is possible to find the optimized injection pump timing, which enables acceptable engine characteristics at all modes of the emission test cycles test.
Ključne besede: bus diesel engine, fuel injection, fuel spray, combustion, emission, engine performance, tribology characteristics, optimized injection pump timing
Objavljeno v DKUM: 07.07.2017; Ogledov: 1470; Prenosov: 403
Celotno besedilo (3,81 MB)
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Determination of penicillamine by batch and flow-injection potentiometry with AgI-based sensorNjegomir Radić
, Josipa Komljenović
, Danilo Dobčnik
, 2000, izvirni znanstveni članek
Opis: Potentiometric determination of penicillamine (pen) is described based on a batch experiment and flow-injection analysis (FIA) using a chemical sensor with AgI-based membrane. The membrane was prepared by pressing silver salts (AgI, Ag2S) and powdered Teflon. This membrane was incorporated in a multipurpose electrode body for batch measurements, and in a tabular flow-through sensor body for FIA measurements. For batch measurements, the equilibrium potentials recorded with continuous addition of standard penicillamine solution were considered in relation to ▫$lg(c_pen/mol L^-1)$▫. Linear response with slope of 60 mV was obtained in the concentration range from 2.5 x ▫$10^5$▫ mol ▫$L^1$▫ to 1.8 x ▫$10^-2$▫mol ▫$L-1$▫. In using the tubular sensor with a membrane of the same coposition for FIA measurements, the linear response with slope of 59 mV was recorded in the concentration range from 1 x ▫$10^4$▫ mol ▫$L^1$▫ to 1 x ▫$10^-1$▫ mol ▫$L^-1$▫. The response of the applied chemical sensor to penicillamine (designated also as RSH) is explained by the formation of sparingly soluble RSAg in the reaction solution and/or the exposed surface of the sensor. The solubility product ▫$K_s(RSAg)$▫ was determined using experimental values recorded both by batch measurements and by the continuous-flow experiment. The mean value obtained by different measurements and using a membrane of the same composition is ▫$K_s(RSAg)$▫ = (1.4+-0.1) x ▫$10^-20$▫ mol ▫$L-2$▫).
Ključne besede: analytical chemistry, batch potentiometry, flow-injection analysis, membrane electrode, tubular sensors, penicillamine
Objavljeno v DKUM: 05.07.2017; Ogledov: 1151; Prenosov: 85
Celotno besedilo (196,90 KB)
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Sensor for injection rate measurementsMilan Marčič
, 2006, izvirni znanstveni članek
Opis: A vast majority of the medium and high speed Diesel engines are equipped with multi-hole injection nozzles nowadays. Inaccuracies in workmanship and changing hydraulic conditions in the nozzles result in differences in injection rates between individual injection nozzle holes. The new deformational measuring method described in the paper allows injection rate measurement in each injection nozzle hole. The differences in injection rates lead to uneven thermal loads of Diesel engine combustion chambers. All today known measuring method, such as Bosch and Zeuch give accurate results of the injection rate in diesel single-hole nozzles. With multihole nozzles they tellus nothing about possible differences in injection rates between individual holes of the nozzle. At deformational measuring method, the criterion of the injected fuel is expressed by the deformation of membrane occurring due to the collision of the pressure wave against the membrane. The pressure wave is generated by the injection of the fuel into the measuring space. For each hole of the nozzle the measuring device must have a measuring space of its own into which fuel is injected as well as its measuring membraneand its own fuel outlet. During measurements procedure the measuring space must be filled with fuel to maintain an overpressure of 5 kPa. Fuel escaping from the measuring device is conducted into the graduated cylinders for measuring the volumetric flow through each hole of the nozzle.The membrane deformation is assessed by strain gauges. They are glued to the membrane and forming the full Wheatstonećs bridge. We devoted special attention to the membrane shape and temperature compensation of the strain gauges.
Ključne besede: thermodynamics, sensors, Diesel engines, nozzles, injection, measurements
Objavljeno v DKUM: 22.06.2017; Ogledov: 1550; Prenosov: 337
Celotno besedilo (242,99 KB)
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Acoustic emission detection of macro-cracks on engraving tool steel inserts during the injection molding cycle using PZT sensorsRajko Svečko
, Dragan Kusić
, Tomaž Kek
, Andrej Sarjaš
, Aleš Hančič
, Janez Grum
, 2013, izvirni znanstveni članek
Opis: This paper presents an improved monitoring system for the failure detection ofen graving tool steel inserts during the injection molding cycle. This system uses acoustic emission PZT sensors mounted through acoustic waveguides on the engraving insert. We were thus able to clearly distinguish the defect through measured AE signals. Two engraving tool steel inserts were tested during the production of standard test specimens, each under the same processing conditions. By closely comparing the captured AE signals on both engraving inserts during the filling and packing stages, we were able to detect the presence of macro-cracks on one engraving insert. Gabor wavelet analysis was used for closer examination of the captured AE signalsć peak amplitudes during the filling and packing stages. The obtained results revealed that such a system could be used successfully as an improved tool for monitoring the integrity of an injection molding process.
Ključne besede: injection molding, process monitoring, acoustic emission, PZT sensors, piezoelectric effect
Objavljeno v DKUM: 22.06.2017; Ogledov: 1587; Prenosov: 365
Celotno besedilo (854,94 KB)
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