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COMI, MICHELA. "Unravelling the fingerprint and regulatory functions of human tolerogenic DC-10." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2016. http://hdl.handle.net/10281/137397.
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Dendritic cells (DC) are critically involved in initiating adaptive immune responses but they also play a pivotal role in promoting and maintaining tolerance. We identified DC-10, a subset of human tolerogenic DC characterized by the ability to produce high levels of IL-10. DC-10 can be generated in vitro from monocytes in the presence of IL-10 and are currently used for generating CD4+ T regulatory type 1 (Tr1) cells for Treg cell-based therapies.
The aims of my PhD project are:
1)To define the molecular signature of DC-10;
2)To investigate modulation of in vitro and in vivo allogeneic T cell responses by DC-10.
To achieve the first aim, we compared DNA microarray-based transcriptional profiling of in vitro generated DC-10 and of immunogenic mature (mDC) or immature DC (iDC). DC-10 display a molecular signature of immuno-modulation and anti-inflammation with up-regulated IL-10- and Tissue Growth Factor (TGF) beta-dependent pathways, and down-modulated signaling of pro-inflammatory cytokines. Moreover, DC-10 have an interesting matrix remodeling profile that places them as hypothetical determinants of the tolerogenic environment in peripheral tissues. Through the screening of gene differentially expressed, we also identified two DC-10-specific markers, CD141 and CD163 that in combination with CD14 and CD16 allow their identification and isolation in vivo. CD141+CD163+CD14+CD16+ cells isolated from peripheral blood of healthy donors produce IL-10 at steady state and upon activation, in the absence of IL-12, and prime allogeneic naïve CD4+ T cells. Furthermore, preliminary results indicate that allogeneic naïve CD4+ T cells primed with ex vivo isolated DC-10 produce IL-10 when re-stimulated with the same allo-antigen.
To achieve the second aim, we studied the ability of DC-10 to modulate allogeneic CD8+ T cells. DC-10 activate allogeneic CD8+ T cells at lower levels compared to mDC, as demonstrated by the expression of activation markers and IFN-γ production. Despite the expression of HLA class I and co-stimulatory molecules, DC-10 poorly stimulate the proliferation of allogeneic CD8+ T cells, which is partially rescued by the addition of exogenous IL-12. Moreover, DC-10 inhibit mDC-induced proliferation of allogeneic CD8+ T cells in a dose-dependent manner, suggesting an active mechanism of suppression mediated by DC-10. This immunomodulatory effect is contact-independent, as shown by transwell experiments. In parallel, we assessed the ability of DC-10 to prime allogeneic T cells in vivo in NSG mice co-injected with DC-10 and allogeneic PBMC. Upon in vitro re-stimulation of spleen cells with allo-antigens, CD4+ and CD8+ T cells from mice injected with DC-10 proliferate less compared to T cells isolated from control mice injected with mDC. Conversely, response to 3rd party allo-antigens is comparable. These data indicate that DC-10 prime T cells in vivo and induce anergic allo-antigen specific T cells.
In conclusion, we identify the biomarkers of DC-10 that allow their study in vivo in healthy and pathological conditions. Moreover, we demonstrate the ability of DC-10 to modulate allogeneic CD8+ T cell responses, supporting the use of DC-10 as DC-based therapy in transplantation. DC-10 may indeed promote tolerance via allo-specific CD4+ Tr1 cells, and, concomitantly, limit allo-reactive CD8+ T cell responses.
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Teaster, Neal D. Chapman Kent Dean. "A regulatory role for N-acylethanolamine metabolism in Arabidopsis thaliana seeds and seedlings." [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/permalink/meta-dc-10978.
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ZeRuth, Gary T. "Isolation and Functional Characterization of a Dioxin-Inducible CYP1A Regulatory Region From Zebrafish (Danio rerio)." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002447.
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Ruzek, Mitch James. "Evolution of a conserved gene regulatory network among echinoderms : a comparison of genes expressed in the skeletogenetic lineage of the ophuroid Ophiocoma wendtii and the echinoid Strongylocentrotus purpuratus." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003181.
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Jackson, Erin M. "Integrating Leader-Member Exchange and Organizational Justice: Why Justice Depends on Relationship Quality." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002366.
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Blumenthal, Pamela M. "Local Land Use Regulatory Regimes and Residential Development Outcomes| An Analysis of Subdivision Review in Four Counties in the DC Region." Thesis, The George Washington University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3598490.
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Land use regulations affect housing prices, with more restrictive regulatory environments associated with higher prices. Yet, regulations are only a part of the regulatory regime in which land use decisions are made, leading to the question: how do land use regulatory regimes affect housing prices? This study examines and compares the land use regulatory regimes of four counties, Frederick, MD, Montgomery, MD, Fairfax, VA, and Loudoun, VA through interviews, project files, and regulatory review to learn how the combination of structures, rules, norms, principles, and expectations, relate to housing prices. State differences in the tools available lead to Virginia counties having a more predictable, but not faster, subdivision review process than Maryland counties. More importantly, local differences in developer contributions for mitigating the impact of development, community involvement, and perspectives on development affect the cost and predictability of the residential development review process. These jurisdictional differences support the need to focus research on regulatory regimes rather than simply regulations to identify changes to reduce unnecessary costs that increase house prices.
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Karnam, Anupama. "Role of Wnt/β-catenin pathway in the anti-inflammatory mechanism of therapeutic normal immunoglobulins Wuchereria bancrofti filaria activates human dendritic cells and polarizes T helper 1 and regulatory T cells via toll-like receptor 4 Regulatory T cells induce activation rather than suppression of human basophils." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS642.
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Les immunoglobulines polyclonales intraveineuses (IVIG) sont préparées à partir de plasmas provenant de plusieurs milliers de donneurs sains et utilisées comme traitement dans de nombreuses maladies inflammatoires et autoimmunes. Lors de ma thèse, j’ai investigué si cette thérapie pouvait interférer avec la détection sérique du virus Zika chez des patients atteints du syndrome de Guillain-Barré (GBS). J’ai démontré que la thérapie par IVIG n’interférait pas avec la détection sérique du virus dans le plasma des patients atteints de GBS suivant un traitement aux IVIG. Contrairement aux souris, les IVIG peuvent activer les basophiles humains par une voie différente que celle de l’IL-33. Les IVIG induisent la sécrétion d’Il-4, IL-6 et IL-8 par interaction directe avec les IgE à la surface des basophiles. Cette fonction est dépendante de la fraction F(ab’)2 et implique l’activation de Syk. Ces résultats montrent un nouveau mécanisme dans l’activation des basophiles humains par les IVIG. La dernière partie de ma thèse m’a permis d’étudier le rôle de la voie de signalisation β-caténine sur les effets anti-inflammatoires médiées pars les IVIG. La β-caténine, composante de la voie Wnt, joue un rôle important dans la tolérogénicité des cellules dendritiques (DC) et dans la protection contre l’encéphalomyélite auto-immune expérimentale (EAE). Les données générées montrent que les IVIG activent la voie β-caténine chez les DC humains en plus de la production de Wnt 5a nécessitant une IgG complète ainsi que les co-récepteurs LRP5/6. En dépit de l’induction de β-caténine par les IVIG, cette voie est dispensable pour ses actions anti-inflammatoires in vitro et in vivo dans le modèle EAEIntravenous immunoglobulin (IVIG) is a therapeutic preparation of pooled normal IgG obtained from the several thousand healthy donors. It is established as first-line therapy for many autoimmune and inflammatory diseases. In the first part of my thesis, I have investigated if IVIG therapy interferes with the serological detection of Zika virus infection in Guillain–Barré syndrome (GBS) patients. By analyzing the plasma of GBS patients treated with IVIG for anti-Zika IgG, I have demonstrated that IVIG therapy in GBS patients does not interfere with the serological Zika detection. The second part addresses the immunoregulatory role of IVIG on human basophil function. Unlike in mice, IVIG does not require DC-SIGN-dependent IL-33 for the activation of human basophils. IVIG directly induces the activation of IL-3-primed human basophils and secretion of IL-4, IL-6, and IL-8 by directly interacting with the basophil surface-bound IgE. This function was F(ab’)2-dependent and involves Syk activation. These results demonstrate a novel mechanism of human basophil activation by IVIG. The last part unravels the signaling pathways associated with IVIG-mediated anti-inflammatory effects specifically the Wnt/β-catenin pathway, which imparts tolerogenic properties to dendritic cells (DCs) and protection against experimental autoimmune encephalomyelitis (EAE). My data shows that IVIG activates β-catenin in human DC along with upregulation of Wnt 5a. Activation of β-catenin requires intact IgG and LRP5/6 co-receptors. However, despite the activation of β-catenin by IVIG, this pathway is dispensable for its anti-inflammatory actions both in vitro and in vivo in the EAE model
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Nghe, Brandon K. "Cascaded Linear Regulator with Positive Voltage Tracking Switching Regulator." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2173.
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This thesis presents the design, simulation, and hardware implementation of a proposed method for improving efficiency of voltage regulator. Typically, voltage regulator used for noise-sensitive and low-power applications involves the use of a linear regulator due to its high power-supply rejection ratio properties. However, the efficiency of a linear regulator depends heavily on the difference between its input voltage and output voltage. A larger voltage difference across the linear regulator results in higher losses. Therefore, reducing the voltage difference is the key in increasing regulator’s efficiency. In this thesis, a pre switching regulator stage with positive voltage tracking cascaded to a linear regulator is proposed to provide an input voltage to a linear regulator that is slightly above the output of the linear regulator. The tracking capability is needed to provide the flexibility in having different positive output voltage levels while maintaining high overall regulator’s efficiency. Results from simulation and hardware implementation of the proposed system showed efficiency improvement of up to 23% in cases where an adjustable output voltage is necessary. Load regulation performance of the proposed method was also overall better compared to the case without the output voltage tracking method.
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Ge, Ting. "Resonant Cross-Commutated Dc-Dc Regulators with Omni-Coupled Inductors." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/84936.
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The switching noise in a hard-switched point-of-load (POL) converter may result in false turn on, electromagnetic interference issues, or even device breakdown. A resonant cross-commutated buck (rccBuck) converter operates with low noise since all MOSFETs are turned on with zero voltage within a wide load range. A state-space model was developed to calculate the voltage gain, voltage stresses, and current stresses. Design guidelines for the rccBuck converter operating at continuous voltage mode or discontinuous voltage mode are provided. The design methodology of a one-turn inductor with significant ac and dc fluxes is given. Four fabricated one-turn inductors achieved 2.1% higher efficiency and 50% smaller total magnetic volume than the commercial inductors in the same rccBuck converter. The Omni-coupled inductors (OCI), composed of a twisted E-E core and PCB windings, further improve power density and efficiency. The core loss and inductances were modeled from a complex reluctance network. According to the loss-volume Pareto fronts, the total inductor loss was minimized within a smaller volume than that of discrete inductors. The expectations were validated by an OCI-based rccBuck converter switched at 2 MHz with 12 V input, 3.3 V at 20 A output, and peak efficiency of 96.2%. The small-signal model with a good accuracy up to half switching frequency was developed based on the averaged equivalent circuit. The transient performance of an rccBuck regulator is comparable to that of a second-order buck regulator with the same switching frequency, output capacitance, and closed-loop bandwidth.Ph. D.
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Bevrani, Hassan. "Modeling, Nonlinear and Robust control of DC-DC Switching Regulators." Thesis, K. N. Toosi University of Technology, 1997.
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It is generally known that DC-DC switching regulators are highly nonlinear systems which are subjected to significant variation in the line voltage and load, uncertainty in the circuit parameters and perturbations in switching times. To assure stable operation and acceptable performance despite the disturbances and inevitable uncertainty associated with such systems, highly accurate regulation schemes must be devised. Indeed the routine application of most classical compensation techniques are severely limited when tight regulation measures have to be achieved. These considerations in conjunction with increasing demand for high quality DC-DC switching regulators has necessitated more systematic and precise methodologies in modeling and control design for such systems.
The first step in the present thesis is to introduce various techniques for modeling switching regulators specifically models which account for parametric uncertainty and the nonlinear switching effects are intended.
Using the models obtained in this fashion, the next step will be to apply nonlinear (input-output feedback linearization) and robust control (Mu-synthesis, Hinf and Kharitonov theorems) techniques to obtain controllers which guarantee satisfactory operation of the system under realistic operating conditions. The resulting controllers are shown to minimize the effect of disturbances and achieve acceptable regulation. The potential superiorities of these methods over classical methodologies are also discussed.
At least, two approaches based on Mu-analysis and Kharitonov’s theorem are proposed for the analysis of switching regulators. Applications to practical circuits with buck and cuk converters are illustrated as case studies.
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Nisar, Kashif. "DC to DC converter for smart dust." Thesis, Linköpings universitet, Institutionen för systemteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77247.
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This work describes the implementation of DC to DC converter for Smart Dust in 65 nm CMOS technology. The purpose of a DC to DC converter is to convert a battery voltage of 1 Vto a lower voltage of 0.5 V used by the processor. The topology used in this DC to DC converteris of Buck type which converts a higher voltage to lower voltage with the advantage of givinghigh efficiency about 75%. The system uses PWM (Pulse width modulation) technique. It usesnon-overlapping clock generation technique for reducing the power consumption. The systemprovides up to 5 mA load current and has power consumption of 2.5 mW.
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Chiaruttini, Giulia. "Identification of vesicular SNARE proteins involved in the secretoryintracellular trafficking of IL-12 in dendritic cells." Doctoral thesis, Università degli studi di Trieste, 2013. http://hdl.handle.net/10077/8636.
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2011/2012Dendritic cells (DCs) are professional antigen presenting cells. They have the unique ability of recognizing antigens, internalizing and processing them for presentation on MHC complexes. DCs also express pattern-recognition receptors like Toll-like receptors (TLRs), which recognize pathogen-associated molecular patterns and induce DCs maturation. As a consequence DCs increase their antigens presenting ability, their levels of co-stimulatory molecules on the cell surface, and their production of cytokines, which are critical for inducing specific T cell activation. All these functions make DCs key elements in the immunological response against pathogens, viruses and tumors. One of the most important cytokines in T cell priming, interleukine-12 (IL-12), begins to be largely transcribed immediately after TLR activation. We have previously shown that in DCs engaged in antigen specific immunological synapses (IS), IL-12 is found enriched in the proximity of the contact site between DC and T cells, and several evidences suggest that its secretion is polarized towards the T cell. These data indicate that polarized trafficking of cytokines containing vesicles in DCs is a mechanism to optimize T cell priming. Polarized trafficking of soluble mediators through defined subcellular areas has been described as fundamental for the function of several other immune cells, but at present a clear characterization of the pathways and organelles implicated in the regulation of cytokine secretion in dendritic cells is still missing. The family of SNARE (soluble-N ethylmaleimide sensitive-factor accessory-protein (SNAP) receptor) proteins, which regulate the membrane fusion process during the intracellular trafficking of soluble mediators, has emerged as the most informative for the identification of such pathways. Indeed different SNAREs regulate diverse mechanisms such as the constitutive secretion of immune mediators, phagocytosis and endocytosis, or also the release of inflammatory mediators and products from secretory granules. During my thesis I have investigated the role of SNAREs in IL-12 secretion by DCs. I have analyzed the expression and modulation during maturation of three SNAREs, Syntaxin6, VAMP3 and VAMP7, that were previously shown to play a role in other immune cells. The subcellular localization and co-localization with the IL-12 subunits were analyzed in DCs alone and in the context of IS by immunofluorescence. I performed functional analyses by silencing SNAREs with the siRNA strategy to detect impairment in DC cytokines secretion and in T cell priming. These studies led to the identification of the lysosomal-late endosomal VAMP7 as a specific regulator in the polarized secretion of IL-12 during T cell priming. This suggest a role, in the secretion of soluble newly synthesized mediators, of late endosomal organelles, until now thought to be implicated only in the regulated secretion of pre-constituted mediators such as cytotoxic granules. Furthermore VAMP3 was found to downregulate the production of all the cytokines tested; we propose this SNARE as regulator of the TLR9 signaling pathway. The second part of the work stems from the concept that DCs properties become suppressed by the tumor microenvironment and many evidences suggest that tolerogenic DCs may be a crucial element in the development of tumor-mediated immune anergy. Different steps in the antigen presentation process are impaired, but also the pattern of secreted cytokines is skewed. In particular, how secretion of inflammatory cytokines becomes impaired in tumor-exposed DCs has not been investigated. I set up a model of mice bearing Lewis lung carcinoma (3LL) to analyze DCs in vitro (co-colture) and in vivo (spleen and tumor-bearing lungs). In all the models I observed a strong impairment in IL-12 production, upon restimulation with TLR agonists. In spleen DCs subtypes remained unchanged during tumor progression, whereas in tumor-bearing lungs the DC composition varied, with an expansion of CD11bhi DCs and a reduction in CD103+ DCs. DCs were isolated from all the three models to analyze the expression of trafficking proteins, and I found that tumor-exposed DCs downregulate all the SNAREs and in particular VAMP3. Moreover Rab27a, a GTPase implicated in the regulation of the exocytosis of secretory granules and lysosome-related organelles is also downregulated at protein level. These preliminary observations suggest that regulation of trafficking proteins in DCs may represent a novel pathway targeted during immunosuppression.
Le cellule dendritiche (DC) sono una importante classe di cellule presentanti l'antigene. Hanno l'esclusiva abilità di riconoscere gli antigeni, internalizzarli e processarli per la loro presentazione con il complesso maggiore di istocompatibilità. Le DC esprimono anche recettori "riconoscitori di pattern" come i recettori Toll-like (TLR), che riconoscono pattern molecolari associati ai patogeni e inducono la maturazione delle DC. Come conseguenza le DC aumentano la loro capacità di presentare gli antigeni, i loro livelli di molecole costimolatorie sulla superficie cellulare, e la loro produzione di citochine, che sono fondamentali per indurre l'attivazione specifica delle cellule T. Tutte queste funzioni rendono le DC elementi chiave nella risposta immunologica contro i patogeni, i virus e i tumori. Una delle più importanti citochine per l'induzione delle cellule T, l'interleuchina 12 (IL-12), inizia ad essere estensivamente trascritta immediatamente dopo l'attivatione dei TLR. Il nostro gruppo ha precedentemente mostrato che nelle DC impegnate in sinapsi immunologiche-antigene specifiche (IS), l'IL-12 si trova arricchita in prossimità del sito di contatto tra la DC e le cellule T, e varie evidenze suggeriscono che la sua secrezione è polarizzata verso la cellula T. Questi dati indicano che il traffico polarizzato di vescicole contenenti citochine nelle DC è un meccanismo per ottimizzare l'induzione delle cellule T. Il traffico polarizzato di mediatori solubili attraverso definite aree intracellulari è stato descritto come fondamentale per la funzione di varie cellule immunitarie, ma attualmente una chiara caratterizzazione delle vie di secrezione delle citochine nelle cellule dendritiche è ancora mancante. La famiglia delle proteine SNARE (soluble-N ethylmaleimide sensitive-factor accessory-protein (SNAP) receptor), che regolano il processo di fusione tra le membrane durante il traffico intracellulare di mediatori solubili, è emersa come la più informativa nell'identificazione di questo tipo di vie. Infatti diverse SNARE regolano diversi meccanismi, come la secrezione costitutiva di mediatori immunologici, la fagocitosi e l'endocitosi, o anche il rilascio di mediatori infiammatori e di prodotti sui granoli secretori. Durante la mia tesi ho investigato il ruolo delle SNARE nella secrezione dell'IL-12 nelle DC. Ho analizzato l'espressione e la modulazione durante la maturazione delle SNARE syntaxin6, VAMP3 e VAMP7, precedentemente descritte in altre cellule immunitarie. La localizzazione subcellulare e la colocalizzazione con le subunità dell'IL-12 sono state analizzate nelle DC da sole e nel contesto dell'IS attraverso l'immunofluorescenza. Ho svolto studi funzionali silenziando le SNARE con la strategia dei siRNA, per osservare diminuzioni nella secrezione delle citochine nelle DC. Questi studi hanno portato all'identificazione della lisosomale VAMP7 come regolatore specifico nella secrezione polarizzata dell'IL-12 durante l'induzione delle cellule T. Questo suggerisce un ruolo nella secrezione di mediatori solubili neosintetizzati, degli organelli endosomiali tardivi , finora ritenuti implicati solo nella secrezione regolata di mediatori pre-costituiti come i granuli citotossici. Inoltre si è visto che VAMP3 deregola la produzione di tutte le cotochine testate; proponiamo che questa SNARE sia un regolatore della via di segnalazione del TLR9. La seconda parte del lavoro parte dal concetto che le proprietà delle DC sono soppresse dal microambiente tumorale e molte evidenze suggeriscono che le DC tollerogeniche sarebbero un elemento fondamentale nello sviluppo dello spegnimento immunologico mediato dal tumore. Diversi punti nel processo di presentazione dell'antigene sono deregolate, ma anche il pattern di citochine secrete è modificato. In particolare, come la secrezione di citochine infiammatorie diventi deregolata nelle DC esposte al tumore non è stato investigato. Ho messo a punto un modello di topi con carcinoma polmonare di Lewis (3LL) per analizzare le DC in vitro (con co-colture) e in vivo (nella milza e nel polmone). In tutti i modelli ho osservato una forte diminuzione nella produzione dell'IL-12, dopo stimolazione con agonisti del TLR. Nella milza i sottotipi di DC sono rimasti simili durante la progressione tumorale, mentre nei polmoni affetti da tumore la composizione delle DC è variata, con un'espansione delle DC CD11b e una riduzione delle DC CD103. Le DC sono state isolate da tutti e tre i modelli per analizzare l'espressione delle proteine di traffico e ho osservato che le DC esposte al tumore deregolano tutte le SNARE e in particolare VAMP3. Inoltre anche Rab27a, una GTPasi implicata nella regolazione dell'esocitosi dei granuli secretori e degli organelli lisosomiali è trovata de-regolata a livello della proteina. Queste osservazioni preliminari suggeriscono che la regolazione delle proteine di traffico nelle DC potrebbe rappresentare una nuova via bersagliata durante lo sviluppo tumorale.
XXV Ciclo
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Raley, Jack. "Efficient DC-DC switch regulator applied iterative learning and anti-windup control /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p1457288.
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Thesis (M.S.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed November 14, 2008). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 65-66).
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Ying, Tianrui. "Area efficient charge pumps and post low dropout regulators /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202002%20YING.
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Wan, Kai. "Advanced current-mode control techniques for DC-DC power electronic converters." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Wan_09007dcc80642d38.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 4, 2009) Includes bibliographical references.
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Lei, Ernest. "Cascaded Linear Regulator with Negative Voltage Tracking Switching Regulator." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2176.
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DC-DC converters can be separated into two main groups: switching converters and linear regulators. Linear regulators such as Low Dropout Regulators (LDOs) are straightforward to implement and have a very stable output with low voltage ripple. However, the efficiency of an LDO can fluctuate greatly, as the power dissipation is a function of the device’s input and output. On the other hand, a switching regulator uses a switch to regulate energy levels. These types of regulators are more versatile when a larger change of voltage is needed, as efficiency is relatively stable across larger steps of voltages. However, switching regulators tend to have a larger output voltage ripple, which can be an issue for sensitive systems. An approach to utilize both in cascaded configuration while providing a negative output voltage will be presented in this paper. The proposed two-stage conversion system consists of a switching pre-regulator that can track the negative output voltage of the second stage (LDO) such that the difference between input and output voltages is always kept small under varying output voltage while maintaining the high overall conversion efficiency. Computer simulation and hardware results demonstrate that the proposed system can track the negative output voltage well. Additionally, the results show that the proposed system can provide and maintain good overall efficiency, load regulation, and output voltage ripple across a wide range of outputs.
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Gummi, Karteek. "Derivation of new double-input DC-DC converters using the building block methodology." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Gummi_09007dcc804fa7b9.pdf.
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Thesis (M.S.)--Missouri University of Science and Technology, 2008.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 12, 2008) Includes bibliographical references (p. 102-107).
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Hunter, Daniel Scott. "Variable-frequency pulse-width-modulation for zero-voltage switching in a boost DC-DC regulator." Thesis, Monterey, California. Naval Postgraduate School, 1990. http://hdl.handle.net/10945/37543.
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Approved for public release; distribution is unlimited.A technique for operating a pulse-width-modulated (PWM) dc-dc regulator in the boost mode while switching the MOSFET when the drain-to-source potential is near zero volts was developed and is described in this thesis. This is accomplished by using frequency-modulation in addition to pulse-width-modulation. Zero-voltage switching will provide power converter designers an alternative for designing high-frequency converters with minimal transient turn-on losses, the predominant form of converter losses experienced in high frequency operation. High frequency operation will result in smaller reactive components, which produce higher power density converters, as well as increasing the transient response of the regulated converter. In addition to allowing for high frequency operation, the design exhibits many desirable power switch properties, such as limiting the peak voltage to the output voltage level and operating with the minimum possible current levels for a given power requirement. A circuit built and tested utilizing zero-voltage switching in a regulated boost converter verified the principles of operation for yielding a high-efficiency, high-frequency converter.
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Åberg, Emil. "Optimering av styrsystem för DC-servo." Thesis, Uppsala universitet, Signaler och System, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-346489.
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Automatic control is used to operate all kinds of processes: everything from temperature in houses to the control of robots. The course in automatic control in Uppsala University includes laboratory experiments where students conduct tests on a wheel controlled by a, so called, PID-controller which is one of the most widely used control mechanisms. This is a prime opportunity for students to get practical experience of working with PID-regulators and test how different parameters influence results. That system has been improved in this project as there were previously several issues with the system. The system was buggy and one of the tasks where the students are to test the systems’ reaction to oscillating input signals was cancelled because that feature had not been implemented yet. These issues were successfully fixed in this project and all tasks are now doable. Another problem was (and is still to some degree) that a lot of measurement noise occurs when measuring speed. This in turn causes the part of the controller that is sensitive to noise (the derivative part, for those familiar with PID-controllers) to function poorly. Some improvement has been made to this by using low-pass filtering for control purposes and the least square method for display purposes, but the signal is still noisy. The key to solving this issue lies in implementing an algorithm that can precisely estimate the speed without distorting any other information, or alternatively buy sensors with higher precision.
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Manh, Vir Varinder. "An Integrated High Efficiency DC-DC Converter in 65 nm CMOS." Thesis, Linköpings universitet, Elektroniksystem, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-61237.
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This thesis work describes the implementation perspective of an integrated high efficiency DC-DC converter implemented in 65 nm CMOS. The implemented system employs the Buck converter topology to down-convert the input battery voltages. This converter offers its use as a power management unit in portable battery operated devices. This thesis work includes the description of a basic Buck converter along with the various key equations involved which describe the Buck operation as well as are used to deduce the requirements for the various internal building blocks of the system. A detailed description of the operation as well as the design of each of the building blocks is included. The implemented system can convert the input battery voltage in the range of 2.3 V to 3.6 V into an output supply voltage of 1.6 V. The system uses dual-mode feedback control to maintain the output voltage at 1.6 V. For the low load currents the PFM feedback control is used and for the higher load currents the PWM feedback control is used. This converter can supply load currents from 0 to 300 mA with efficiency above 85%. The static line regulation of the system is < 0.1% and the load regulation of the system is < 0.3%. A digital soft-start circuit is implemented in this system. The system also includes the capability to trim the output voltage in ~14 mV steps depending on the 4-bit input digital code.
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Abdelfattah, Moataz. "Switched-Capacitor DC-DC Converters for Near-Threshold Design." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500631539574741.
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Ay, Gokce Mehmet. ""." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605283/index.pdf.
Full textAbstract:
This thesis focuses on the design of an electrical drive system for the purpose of
high precision motion control. A modern electrical drive is usually equipped with a
current regulated voltage source along with powerful motion controller system
utilizing one or more micro-controllers and/or digital signal processors (DSPs).
That is, the motor drive control is mostly performed by a dedicated digital-motion
controller system.
Such a motor drive mostly interfaces with its host processor via various serial
communication protocols such as Profibus, CAN+, RS-485 etc. for the purpose of
receiving commands and sending out important status/control signals. Considering
that the motor drives lie at the heart of every (multi-axis) motion control system, the
aim of this thesis is to explore the design and implementation of a conventional DC
motor drive system suitable for most industrial applications that require precision
and accuracy. To achieve this goal, various underlying control concepts and
important implementation details are rigorously investigated in this study.
A low power DC motor drive system with a power module, a current regulator and
a motion controller is built and tested. Several design revisions on these subsystems
are made so as to improve the overall performance of the drive system itself.
Consequently, important &ldquoknow-how&rdquo
required for building high performance (and high power) DC motor drives is gained in this research.
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Shao, Hui. "System design and power management for ultra low energy applications using energy harvesting techniques /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?ECED%202009%20SHAO.
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Forghani-zadeh, Hassan Pooya. "An Integrated, Lossless, and Accurate Current-Sensing Technique for High-Performance Switching Regulators." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/16164.
Full textAbstract:
Switching power converters are an indispensable part of every battery-operated consumer electronic product, nourishing regulated voltages to various subsystems. In these circuits, sensing the inductor current is not only necessary for protection and control but also is critical to be done in a lossless and accurate fashion for state-of-the-art advanced control techniques, which are devised to optimize transient response, increase the efficiency over a wide range of loads, eliminate off-chip compensation networks, and integrate the power inductor. However, unavailability of a universal, integrable, lossless, and accurate current-sensing technique impedes the realization of those advanced techniques and limit their applications. Unfortunately, use of a conventional series sense resistor is not recommended in high-performance, high-power switching regulators where more than 90% efficiency is required because of their high current levels. A handful of lossless current-sensing techniques are available but their accuracies are significantly lower than the traditional sense resistor scheme.
Among available lossless but not accurate techniques, an off-chip, filter-based method that uses a tuned filter across the inductor to estimate current flow and its accuracy is dependent on the inductance and its equivalent series resistance (ESR) was selected for improvement because of its inherent continuous and low-noise operation. A schemes is proposed to adapt the filter technique for integration by automatically adjusting bandwidth and gain of an on-chip programmable gm-C filter to the off-chip power inductor during the system start-up through measuring the inductance and its ESR with on-chip generated test currents.
The IC prototype in AMI s 0.5-um CMOS process achieved overall DC and AC gain errors of 8% and 9%, respectively, at 0.8 A DC load and 0.2 A ripple currents for inductors from 4 uH-14 uH and ESR from 48 mOhm to 384 mOhm when lossless, state-of-the-art schemes achieve 20 40% error and only when the nominal specifications of power component (power MOSFET or inductor) are known. Moreover, the proposed circuit improved the efficiency of a test bed current-mode controlled switching regulator by more than 2.6% at 0.8 A load compared to the traditional sense resistor technique with a 50 mOhm sense resistor.
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Molepo, Seaga Abram. "A multilevel inverter for DC reticulation." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53253.
Full textAbstract:
Thesis (MScEng)--Stellenbosch University, 2003.ENGLISH ABSTRACT: This report presents the design and development of a multilevel inverter for DC reticulation. Two main multilevel inverter topologies are introduced and discussed. The research focusses on the flying capacitor multilevel topology, since it became evident that it is more suitable for DC reticulation than the diode clamped multilevel topology. A bootstrap power supply for the gate drive circuits of a multilevel inverter is developed and its feasibility verified experimentally. A self-starting auxiliary power supply, that aims at addressing the power supply problem of DC to AC and DC to DC converters, is designed and its functionality demonstrated on a flying capacitor multilevel inverter. An FPGA based digital controller for implementing the inverter's control algorithms is also discussed. This controller incorporates a feed-forward output voltage regulation technique. Experimental results obtained with the four-level flying capacitor multilevel inverter, using the FPGA based digital controller and the self-starting auxiliary power supply, are presented in this report.
AFRIKAANSE OPSOMMING: In hierdie verslag word die ontwerp en ontwikkelling van 'n multivlak omsetter vir GS retikulasie bespreek. Twee hoof multivlak omsetter topologië word voorgestel en bespreek. Die navorsing fokus op die "vlieënde-kapasitor" multivlak topologië omdat dit duidelik geword het dat dit 'n beter opsie is vir die GS retikulasie as die diode-klamp multivlak topologië. 'n Kragbron vir die hekaandryfbane van die multivlak omsetter is ontwikkel en die werking daarvan is met experimentele toetse bevestig. 'n Self-begin kragbron, wat die probleem van die kragtoevoer aan die GS na WS en die GS na GS omsetters aanspreek, is ontwerp en die funksionaliteit is gedemonstreer met die "vlieënde-kapasitor" multivlak . omsetter. 'n Digitale beheerder, gebaseer op 'n FPGA, wat gebruik word om die omsetter se beheer algoritmes te implementeer, word ook bespreek. Hierdie beheerder inkorporeer 'n vorentoe-voer uittree spannings regulasie tegniek. Eksperimentele resultate wat gekry is met 'n vier-vlak "vlieënde-kapasitor" multivlak omsetter, wat van die FPGA gebaseerde digitale beheerder en die self-begin kragbron gebruik maak, word ook in die verslag bespreek.
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Gunaydin, Zekiye. "Analysis And Design Of A Cuk Switching Regulator." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610606/index.pdf.
Full textAbstract:
This theses analyzes Cuk converter, that is one of the dc to dc switching converters. For continuous inductor current mode and discontinuous inductor current mode, stedy state operation is analysied. Characteristic parameters are determined. Through State Space Averge Models, Small Signal Models are obtained. Parasitic Resistance effects on steady state and small signal models are determined. Efficency of the switching converter is derived. Open loop transfer functions for continous and discontinuous inductor curret mode are obtained. Parmeters for small signal behaviour is determined and stability is analysied. Parasitic resistance effects on transfer functions is determined. Therotecial analysis are verified with a simulations of designed converter.
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Zrikem, Nezha. "Circuiti per il miglioramento della qualità di sorgenti dc." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8103/.
Full textAbstract:
Tutti gli apparati elettronici richiedono un'alimentazione in tensione continua. Qualunque sia la fonte di energia elettrica, una batteria (in DC) o la rete di distribuzione (in AC), l’alimentatore ha il compito di regolare la tensione continua di uscita per consentire il corretto funzionamento del dispositivo alimentato. La stabilizzazione della tensione DC in uscita deve avvenire nonostante la presenza di ripple e di disturbi sulla alimentazione primaria, di ampie variazioni sulle correnti assorbite dal carico, di ampie escursioni di temperatura e deve essere garantita nel tempo, anche a fronte di sostituzione di alcuni componenti del circuito.
In questa tesi si prenderanno in considerazione i regolatori lineari. Sebbene si tratti di circuiti che operano in condizioni di linearità e quindi, quasi per definizione, poco efficienti, in realtà il loro impiego diventa quasi obbligatorio per applicazioni in cui è richiesta una tensione di alimentazione poco rumorosa. Se utilizzati a valle di un alimentatore switching possono aumentare notevolmente la qualità della tensione di uscita operando con livelli di efficienza e di dissipazione del tutto accettabili e con minimo aumento di costo del sistema.
Gli alimentatori lineari non sono dunque “superati” dai più recenti alimentatori switching ma sono, piuttosto, “alternativi” e, in molti alimentatori moderni, di complemento. Per questo motivo, anche di recente, sono stati sviluppati e trovano importanti quote di mercato innovative architetture di regolatori lineari dalle prestazioni molto migliorate e vi sono circuiti come il regolatore di John Linsley Hood che non possono non suscitare il più vivo interesse della comunità audiofila
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Papargyris, Loukas. "Mécanismes de génération des macrophages immunorégulateurs humains : rôle de l’axe IL-27 / Adénosine / PGE2 The ecto-ATPDase CD39 is involved in the acquisition of the immunoregulatory phenotype by M-CSF-macrophages and ovarian cancer tumor-associated macrophages: Regulatory role of IL-27 Faecalibacterium prausnitzii Skews Human DC to Prime IL10-Producing T Cells Through TLR2/6/JNK Signaling and IL-10, IL-27, CD39, and IDO-1 Induction." Thesis, Angers, 2019. http://www.theses.fr/2019ANGE0038.
Full textAbstract:
Ce projet de thèse s’inscrit dans l’étude des mécanismes moléculaires associés à la polarisation des macrophages humains vers un phénotype immunorégulateur similaire à celui des macrophages tumoraux (TAM). Des données du laboratoire avaient montré le rôle de l'IL-27 dans ce processus, notamment au travers de sa capacité à moduler l'expression de CD39 qui contrôle, au moins en partie, l’acquisition d’un phénotype immunorégulateur par les macrophages humains. L’objectif de ce travail a été de préciser les mécanismes moléculaires impliqués dans l’acquisition du phénotype régulateur, en aval de l’IL-27. Les résultats confirment le rôle central de l’adénosine, et donc de l’ectonucléotidase CD39, et identifient la molécule PGE2 dans la polarisation fonctionnelle des macrophages immunorégulateurs. Ces données confirment l'importance de l'IL-27 dans la génération des macrophages immunorégulateurs humains et précisent les mécanismes moléculaires impliqués. A plus long terme, ces résultats permettront d’évaluer de nouvelles stratégies dans le traitement de tumeurs solides dont l’immunosuppression locale est associée à un fort infiltrat de macrophages exprimant CD39The purpose of the present thesis is to study the molecular mechanisms associated with the polarization of human macrophages towards an immunoregulatory phenotype, similar to that of tumor associated macrophages (TAM). Laboratory data have shown the role of IL-27 in this process, mostly by its capacity to modulate CD39 expression, which controls, at least in part, the acquisition of an immunoregulatory phenotype by human macrophages.The purpose of this work was to specify the molecular mechanisms involved in the acquisition of the regulatory phenotype, downstream IL-27. The results confirm the central role of adenosine, and therefore of the ectonucleotidase CD39, and identify the molecule PGE2 in the functional polarization of immunoregulatory macrophages. These data confirm the importance of IL-27 in the generation of human immunoregulatory macrophages and specify the involved molecular mechanisms. Over the long term, these results will allow to evaluate new strategies in the treatment of solid tumors, whose local immunosuppression is associated with a strong infiltrate of CD39-expressing macrophages
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Sammons, Wendy L. "Generation and characterization of an attenuated mutant in a response-regulator gene of Francisella tularensis live vaccine strain (LVS)." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002268.
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Duz, Aleksei. "Modul pro řízení stejnosměrných motorů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413030.
Full textAbstract:
This thesis focuses on the design and creation of control unit for DC motors drives. A principle on which the DC motor is based, a method of its control and a possibility to obtain current information about the position are briefly described in this work. After that, the different types of buses for communication with a superior system and justification of the chosen one, are presented. In the next section, there is a special emphasis on creation of the suitable driver model and a design of the elecrical schematic and PCB. The end of the thesis contains a description of commission a PCB and testing the main functions.
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Wu, Jia. "Implementation of a 100kW Soft-Switched DC Bus Regulator Based on Power Electronics Building Block Concept." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/32468.
Full textAbstract:
Power electronics building blocks (PEBBs) are standardized building blocks used to integrate power electronics systems. The PEBB approach can achieve low cost, high redundancy, high reliability, high flexibility and easy maintenance for large-scale power electronics systems. This thesis presents the implementation of a 100kW PEBB-based soft-switched bus regulator for an 800V DC distributed power system. The zero current transition (ZCT) soft-switching technique is used to improve the performance of the bus regulator by minimizing switching loss and improving overall efficiency.
PEBB modules and a digital control building block are the subsystems of the DC bus regulator. This thesis addresses the design issues at subsystem and system levels. These include: operational principles and design of ZCT PEBB modules; design and implementation of the digital control block, based on DSP and EPLD; and modeling and control design of the DC bus regulator.
There are several considerations when using the ZCT soft-switching technique in three-phase applications: the timing of the auxiliary switch gate signals must be arranged differently; there are low-frequency harmonics caused by the pulse width limits; and there is high thermal stress on the resonant capacitors. These issues are resolved by utilizing the sensed phase current information and the design freedom in the PWM modulator. A PWM modulation technique is proposed that can considerably reduce the switching events and further remove the associated loss while keeping THD low. Reduced switching events alleviate the thermal issue of the resonant capacitors. The same modulation technique can avoid the low-frequency harmonics caused by the pulse width limits and double the sampling frequency. The phase current information is used to deal with the control timing issue of the auxiliary switches and to control the three-phase soft-switching operation in order to achieve better efficiency. Additionally, the phase current information is used to implement dead time compensation to reduce THD.
The soft-switched DC bus regulator has been tested up to a 100kW power level with 20kHz switching frequency. Experimental results demonstrate that high performance of the DC bus regulator is accomplished in terms of wide control bandwidth, low THD, unity power factor, high efficiency and high power density.Master of Science
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Kadic, Safet, Alen Kazazic, and Florim Mustafa. "Exempel på användning av LabVIEW vid : mätning, reglering och signalbehandling." Thesis, Växjö University, School of Mathematics and Systems Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-636.
Full textAbstract:
Arbetet handlar om hur man med hjälp av LabVIEW 8.0 kan lösa olika uppgifter. Uppgifterna löses med hjälp av ett DAQ-kort. DAQ-kortet gör det möjligt att mata in signaler, som sedan behandlas efter behov i programmet och därefter skickas ut genom DAQ- kortet till olika komponenter som man vill styra. DAQ-kortet klarar att behandla både analoga och digitala signaler. LabVIEW 8.0 och dess historia, DAQ-kortet samt de olika processerna/uppgifter beskrivs mer utförligt i arbetet.
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Jeong, Timothy. "Zero Voltage Switching Hybrid Voltage Divider Converter." DigitalCommons@CalPoly, 2021. https://digitalcommons.calpoly.edu/theses/2290.
Full textAbstract:
This project proposes a new hybrid voltage divider DC-DC converter that utilizes switching capacitors and inductors to produce zero voltage switching (ZVS) at the turn on state of its switches. By achieving ZVS, the switching losses are significantly reduced; thus, increasing the overall efficiency of the converter at various loads. The goal for this thesis is to perform analysis of the operation of the converter, derive equations for sizing the main components, and demonstrate its functionality through computer simulation and hardware prototype. Results of the simulation and hardware testing show that the proposed converter produces the desired output voltage while providing the zero voltage switching benefits. The converter’s efficiency reaches above 92% starting from 1A load and continues to increase to 97.6% at 4A load. Overall, results from this thesis verifies the potential of the proposed converter as an alternative solution to achieve a very efficient DC-DC solution when half of the input voltage is required at the output without the use of complex feedback control circuitry.
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Ahmed, Muhammad Swilam Abdelhaleem. "Highly-efficient Low-Noise Buck Converters for Low-Power Microcontrollers." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1542277717997166.
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Werkstetter, Mario. "Hocheffizienter DC/DC-Wandler auf Basis von GaN-Leistungsschaltern für Hochleistungs-Leuchtdioden im Kraftfahrzeug." Universitätsverlag der Technischen Universität Chemnitz, 2017. https://monarch.qucosa.de/id/qucosa%3A20870.
Full textAbstract:
In der vorliegenden Arbeit werden Möglichkeiten zur Maximierung der Effizienz von stromregelnden DC/DC-Wandlern für den Betrieb von Hochleistungs-LEDs in PKW-und Motorrad-Beleuchtungseinrichtungen untersucht, mit dem Ziel, das Gewicht und den Energieverbrauch der Steuergeräte zu reduzieren und so zu dem stetigen Bestreben der Minimierung der Gesamtfahrzeugemissionen beizutragen.
Dafür werden verschiedene, teils sequenziell aufbauende Maßnahmen in Topologie, Bauelementen, Dimensionierung und Betriebsart betrachtet. Eine grundlegende Herausforderung für die Auslegung der Schaltung stellt dabei deren universelle Verwendbarkeit als Gleichteil in einem großen Bereich an Ausgangsstrom und -spannung in den individuellen Scheinwerfersystemen der verschiedenen Fahrzeugderivate dar.
Die Grundlage für die Verringerung der Verlustleistung bildet die Vereinfachung der Schaltreglertopologie hinsichtlich des Bauteilaufwands. Dies wird durch die Versorgung der Schaltung aus dem 48 V-Energiebordnetz und die Verwendung der Topologie des Tiefsetzstellers erreicht.
Elementarer Anteil dieser Arbeit ist die Untersuchung der Wirksamkeit des Einsatzes neuartiger Galliumnitrid-Leistungsschalter (GaN-HEMTs) anstelle der konventionellen Silizium-MOSFETs, was zunächst an Hand von Berechnungen und schaltungstechnischen, parasitärbehafteten und zeitvarianten Simulationen durchgeführt wird. Bereits bei herkömmlichen Schaltfrequenzen und hartgeschaltetem Betrieb können signifikante Verbesserungen des Wirkungsgrades erreicht werden.
Weitergehend wird der Nutzen der durch die GaN-Transistoren ermöglichten höheren Schaltfrequenzen eruiert. Die um bis zu Faktor 20 erhöhte Schaltfrequenz macht den Einsatz einer resonanten Betriebsart (Zero-Voltage-Switching) und einer Luftspule als Hauptinduktivität notwendig.
Auf Steuergeräteebene kann somit die Verlustleistung auf unter ein Drittel reduziert werden, was zudem ein deutlich einfacheres und kompakteres Gehäuse ermöglicht, wodurch das Gesamtgewicht etwa halbiert werden kann.
Abschließend wird die Schaltung in einem Prototypen praktisch umgesetzt und die Funktionsfähigkeit im ZVS-Betrieb bei Schaltfrequenzen von bis zu 10 MHz verifiziert.This thesis deals with the research of possibilities for maximising efficiency of current-regulating DC/DC-Converters for driving high-power-LEDs in passenger-car- and motorcycle-lighting-devices. The ambition is to reduce weight and energy-consumption of the electronic-control-units, to contribute to reach the continuously decreasing target-values for vehicle-emissions. Therefor different approaches in topology, components, design and operating mode are considered. A key-challenge for the circuit-design is the common-part-strategy for usage in many individual vehicle-headlamp-systems with a wide range of output-current and LED-string-voltages. Basis for the reduction of power-losses is the simplification of the converters topology in terms of quantity of components. This is achieved by using the 48 V -vehicle-electrical-system as voltage-supply and a step-down-topology. Mainpart of this research is about the potential benefits of applying novel Galliumnitride High-electron-mobility-transistors (GaN-HEMTs) instead of silicon MOS-FETs. Initially this is done by calculations and parasitic-afflicted, timevariant circuit-simulations. Already in hardswitching operation under conventional switching-frequencies significant improvements in converter-efficiency can be achieved. Furthermore the advantages of higher switching-frequencies, offered by the GaN-transistors, are investigated. Up to 20 times higher switching-frequencies necessitate a resonant operating mode of the circuit (Zero-voltage-switching) and the use of an aircoil as main-inductor. On ECU-level power-losses can be reduced down to less than one third, which enables a more simplified and compact housing-concept, so that the overall weight can drop to about the half. Finally the designed circuit is build up in a prototype and the functional capability is verified in ZVS-mode with up to 10 MHz switching-frequency.
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Jong, Owen. "Multi Resonant Switched-Capacitor Converter." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/88019.
Full textAbstract:
This thesis presents a novel Resonant Switched-Capacitor Converter with Multiple Resonant Frequencies, abbreviated as MRSCC for both high density and efficiency non-isolated large step-down Intermediate Bus Converter (IBC). Conventional Resonant Switched-Capacitor Converter (RSCC) proposed by Shoyama and its high voltage conversion ratio derivation such as Switched-Tank Converter (STC) by Jiang and li employ half sinusoidal-current charge transfer method between capacitors to achieve high efficiency and density operation by adding a small resonant inductor in series to pure switched-capacitor converter's (SCC) flying capacitor. By operating switching frequency to be the same as its resonant frequency, RSCC achieves zero-current turn off operation, however, this cause RSCC and its derivation suffer from component variation issue for high-volume adoption. Derived from RSCC, MRSCC adds additional high frequency resonant component, operates only during its dead-time, by adding small capacitor in parallel to RSCC's resonant inductor. By operating switching frequency higher than its main resonant frequency, MRSCC utilizes double chopped half-sinusoidal current charge transfer method between capacitors to further improve efficiency. In addition, operating switching frequency consistently higher than its resonant frequency, MRSCC provides high immunity towards component variation, making it and its derivation viable for high-volume adoption.MS
Following the recent trend, most internet services are moving towards cloud computing. Large data applications and growing popularity of cloud computing require hyperscale data centers and it will continue to grow rapidly in the next few years to keep up with the demand [4]. These cutting-edge data centers will require higher performance multi-core CPU and GPU installations which translates to higher power consumption. From 10MWatts of power, typical data centers deliver only half of this power to the computing load which includes processors, memory and drives. Unfortunately, the rest goes to losses in power conversion, distribution and cooling [5]. Industry members look into increasing backplane voltage from 12V to 48V in order to reduce distribution loss. This thesis proposes a novel Resonant Switched-Capacitor Converter using Multiple Resonant Frequencies to accommodate this increase of backplane voltage.
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Chewele, Youngie Klyv. "Model predictive control of AC-to-AC converter voltage regulator." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86339.
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Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The development of fast and efficient processors, programmable devices and high power semiconductors has led to the increased use of semiconductors directly in the power supply path in order to achieve strict power quality standards. New and advanced algorithms are used in the process and calculated on-line to bring about the required fast response to voltage variations. Losses in high voltage semiconductors increase with increased operating frequencies. A balance between semiconductor power losses and power quality is achieved through control of power semiconductor switching frequencies. A predictive control algorithm to achieve high power quality and limit the power losses in the high power semiconductor switches through switching frequency control is discussed for a tap switched voltage regulator. The quality of power, voltage regulator topology and the control algorithm are discussed. Simulation results of output voltage and current are shown when the control algorithm is used to control the regulator. These results are verified by practical measurements on a synchronous buck converter.
AFRIKAANSE OPSOMMING: Die ontwikkeling van vinnige en doeltreffende verwerkers, programmeerbare toestelle en hoëdrywings halfgeleiers het gelei tot 'n groter gebruik van halfgeleiers direk in die kragtoevoer pad om streng elektriese toevoer kwaliteit standaarde te bereik. Nuwe en gevorderde algoritmes word gebruik in die proses en word aan-lyn bereken om die nodige vinnige reaksie tot spanningswisselinge te gee. Verliese in hoë-spannings halfgeleiers verhoog met hoër skakel frekwensies. 'n Balans tussen die halfgeleier drywingsverliese en spanningskwalteit is behaal deur die skakel frekwensie in ag te neem in die beheer. 'n Voorspellinde-beheer algoritme om ‘n hoë toevoerkwaliteit te bereik en die drywingsverliese in die hoëdrywingshalfgeleier te beperk, deur skakel frekwensie te beheer, is bespreek vir 'n tap-geskakelde spanning reguleerder. Die toevoerkwaliteit, spanningsreguleerder topologie en die beheer algoritme word bespreek. Simulasie resultate van die uittree-spanning en stroom word getoon wanneer die beheer algoritme gebruik word om die omsetter te beheer. Hierdie resultate is deur praktiese metings op 'n sinkrone afkapper.
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Gavagsaz, Ghoachani Roghayeh. "Comportement dynamique non-linéaire dans les convertisseurs statiques : régulateurs de courant et stabilité des réseaux DC." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0102/document.
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Ce mémoire s'intéresse à l'étude des comportements dynamiques dans les systèmes d'électronique de puissance. La nature des cycles définis par les variables d'état du système peut être établie soit grâce à un diagramme de bifurcation soit grâce aux multiplieurs de Floquet obtenus par le modèle discret du convertisseur. Cependant, pour certaines structures de convertisseur statique, un modèle discret ne peut être obtenu sans introduire de fortes hypothèses. Les bifurcations de type flip (à l'échelle des hautes fréquences) ne peuvent pas être prédites par le modèle moyen alors qu'elles apparaissent dans de nombreux convertisseurs statiques. Une nouvelle formulation d'un modèle moyen continu permettant d'estimer le premier point de bifurcation (flip, Hopf...) a été présentée. La méthodologie proposée a été appliquée à un convertisseur boost, en mode de conduction continu, contrôlé en courant par différents types de contrôleur à fréquence fixe de commutation. Ensuite, ce modèle moyen a été utilisé pour le dimensionnement des paramètres du régulateur de courant associé à un système de filtrage actif. Les résultats obtenus par le modèle proposé ont été validés par simulation numérique ainsi que par des résultats expérimentaux.Les méthodes d'analyse des cycles limites ont été étendues pour étudier la stabilité des réseaux DC lorsque la fréquence de coupure du filtre LC reliant la source de tension avec le convertisseur statique est proche de la fréquence apparente de commutation des convertisseurs utilisés. Différents modèles discrets ont été développés pour pouvoir considérer ou non le caractère échantillonné de la commande des convertisseursThis thesis discusses the study of dynamic behavior in power electronics systems. The nature of cycles defined by the state variables of the system can be settled either by a bifurcation diagram or by Floquet multipliers obtained from the discrete model of the converter. However, for certain structures of static converters, a discrete model cannot be obtained without introducing large assumptions. The flip bifurcations (fast-scale) cannot be predicted by the averaged model whereas they appear in many statics converters. A new formulation of a continuous averaged model is presented to estimate the first bifurcation point (flip, Hopf ...). The proposed methodology is applied to a boost converter, operated in continuous conduction mode, controlled by different types of fixed frequency switching current controllers. Then, this averaged model is used for the design of the current controller parameters associated with an active filter system. The variables obtained by the proposed model have been validated by numerical simulation and experimental results. Methods of analysis of limit cycles are extended to study the stability of DC networks when the cutoff frequency of the LC filter between the voltage source and the converter is close to the switching frequency of converters. Different discrete-time models have been developed in order to consider whether to use sampled or no-sampled converter control
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Štaffa, Jan. "Jednofázový pulzní měnič DC/AC s digitálním řízením." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217881.
Full textAbstract:
This work is focused on single phase inverters, which are used for the conversion of the direct current to the alternating current and are nowdays used especially in systems of back-up power supply. The specific aim of this work is implementation of design hight power circuit of inverter include calculation of control algorithm. It describes the complete solution of power circuit. Next step is a analysis of problems concerning the digital control with help of signal processor which is used for solution of regulator structure. Check of the design and checkout of control algorithm is made in the form of simulation in the MATLAB Simulink. Debugged program algorithm is subsequently implemented into the signal microprocessor. The work results rate estimation functionality of inverter and solution of control algorithm.
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Régnier, Paul. "Effet des interactions homéostatiques entre cellules dendritiques, lymphocytes effecteurs et régulateurs sur les réponses immunitaires anti-tumorales : étude du rôle de différentes cellules dendritiques in vivo chez la souris, et étude algorithmique des relations complexes entre transcriptome tumoral, populations immunitaires et survie in silico chez les patients A paradoxical role for Flt3 ligand in tumor immune response reveals homeostatic control of NK and treg cells by dentritic cells Tumor infiltration by immune cells favors patient survival in some cancers bur is highly detrimental in immune-privileged sites." Thesis, Sorbonne Paris Cité, 2018. https://wo.app.u-paris.fr/cgi-bin/WebObjects/TheseWeb.woa/wa/show?t=2244&f=15657.
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Le cancer, l'une des principales causes de décès dans le monde, peut apparaître dans presque tout type de tissu, et est caractérisé par la prolifération anarchique de cellules et l'établissement d'une réponse immunitaire tolérogène favorisant la croissance tumorale, rendant souvent toute intervention médicamenteuse peu efficace. Les cellules dendritiques (DCs), véritables sentinelles de l'organisme, semblent jouer un rôle dans l'établissement à la fois d'une réponse anti-tumorale efficace et d'une tolérance face au cancer. Malgré tout, le rôle des différents sous-types de DCs dans le développement tumoral reste mal connu. Au cours de cette thèse, j'ai étudié différents acteurs cellulaires dendritiques et lymphocytaires, leurs relations et leur implication dans la réponse ou la tolérance immunitaire aux tumeurs. Durant la première partie de ma thèse, j'ai abordé l'effet de la modulation artificielle de l'homéostasie des DCs sur les autres cellules immunitaires ainsi que sur la réponse anti-tumorale in vivo chez la souris. J'ai montré qu'il existait un rôle paradoxal de la cytokine Flt3-L (FL) - un facteur de croissance essentiel à la différentiation et à l'homéostasie des DCs dites classiques/conventionnelles (cDCs) et des DCs plasmacytoïdes (pDCs) - sur la croissance du mélanome B16. En effet, sa surexpression ou son absence mènent à un meilleur contrôle du développement tumoral, accompagnées par une survie accrue des souris. L'absence de FL induit, en sus d'une disparition des cDCs et pDCs, une réduction drastique des lymphocytes T régulateurs (Tregs) protégeant la tumeur, ainsi qu'un renforcement général de la réponse immunitaire anti-tumorale adaptative via les lymphocytes T helpers. Sa surexpression induit une augmentation du nombre de cDCs et pDCs, et malgré une présence accrue de Tregs, un fort recrutement intra-tumoral de lymphocytes natural killer (NK) activés, un des acteurs majeurs de la réponse anti-tumorale innée. L'étude de souris déficientes en cDCs m'a également permis de démontrer l'existence d'un contrôle de l'homéostasie des NK par les DCs. De plus, la combinaison d'un traitement par FL et un anticorps déplétant les Tregs a un effet thérapeutique exacerbé chez la souris. Ensuite, par l'analyse bio-informatique de transcriptomes provenant de 35 types de cancers différents, j'ai montré que le paradoxe du FL existe également chez l'Homme, du moins pour certains cancers, et que les signatures géniques spécifiques de sous-populations de DCs peuvent être corrélées de manière paradoxale, bénéfique ou préjudiciable à la survie. En parallèle, j'ai évalué la présence de diverses cellules immunitaires dans l'infiltrat tumoral et leurs effets sur la survie des patients. Grâce aux algorithmes en langage R que j'ai développés, j'ai pu analyser pour tous les cancers étudiés les signatures géniques spécifiques de populations cellulaires immunitaires ainsi que les gènes et fonctions biologiques (pathways) les plus fortement dysrégulés ou impliqués dans le contrôle de la survie à 5 ans. Les résultats indiquent que les cellules immunitaires de l'infiltrat tumoral dans leur ensemble peuvent jouer, selon le cancer, un rôle bénéfique ou délétère. Cet infiltrat et les pathways immunitaires associés se sont révélés généralement de mauvais pronostic dans les cancers des organes dits immuno-privilégiés, mais en revanche bénéfiques dans les cancers du sein et de la peau. Pour chaque type de cancer, j'ai déterminé l'impact individuel sur la survie de différents types de cellules immunitaires et ai établi les corrélations entre les pathways impliqués et certaines de ces populations cellulaires. L'ensemble de ces résultats permet de mieux comprendre les relations complexes entre chaque cancer et son infiltrat cellulaire, et permettra à terme d'aider à développer des stratégies immuno-thérapeutiques plus adaptées à un environnement tumoral donné, en ciblant les populations immunitaires pouvant réellement impacter la survie des patientsThe cancer, one of the main causes of death in the world, can appear in almost any type of tissue, and is characterized by an anarchic proliferation of cells and the establishment of a tolerogenic immune response favouring the tumour growth, leading to low efficiency of drug interventions. Dendritic cells (DCs), real sentinels of the body, seem to play a role in the establishment of both efficient anti-tumoral immune response and tolerance against cancer. Nevertheless, the role of the different DCs subtypes in the tumoral development stays poorly known. During this thesis, I studied different dendritic and lymphocytic cellular actors, their relationships and their involvement in the immune response or tolerance to tumours. During the first part of my thesis, I studied the effect of the artificial modulation of DCs homeostasis on other immune cells and also on anti-tumoral response in vivo in mice. I proved the existence of a paradoxical role of the Flt3-L (FL) cytokine - a growth factor essential to the differentiation and the homeostasis of classical/conventional dendritic cells (cDCs) and plasmacytoid dendritic cells (pDCs) - on the B16 melanoma growth. In fact, its overexpression or absence both lead to a better control of the tumoral development, accompanied by an increased survival of mice. FL deficiency induces, together with the loss of both cDCs and pDCs, a drastic reduction of regulatory T lymphocytes (Tregs) protecting the tumour, and also a global reinforcement of the anti-tumoral adaptive immune response via helper T lymphocytes. Its overexpression induces an increase of the numbers of cDCs and pDCs, and despite a raised presence of Tregs, also a strong intra-tumoral recruitment of activated natural killer (NK) cells, one of the major actors of the anti-tumoral innate response. The study of cDCs-deficient mice allowed me to demonstrate the existence of a DCs-mediated control of the NK cells homeostasis. Furthermore, the combination of both FL treatment and antibody-mediated Tregs depletion has an exacerbated therapeutic effect in mice. Next, using bioinformatic analysis of transcriptomes of 35 different cancer types, I showed that the FL paradox also exists in humans, at least for some cancers, and that gene signatures specific of DCs subsets can be correlated in a paradoxical, beneficial or detrimental manner to survival. In parallel, I evaluated the presence of several immune cells in the tumour infiltrate and their effects on patients survival. Thanks to R language algorithms I developed, I was able to analyse for each studied cancer the immune cell populations-specific gene signatures and the most involved or dysregulated genes and biological functions (pathways) in the control of the 5 years survival of patients. My results indicate that the immune cells of the tumour infiltrate can play, according to the cancer, a beneficial or deleterious role. This immune infiltrate and the associated pathways were generally of bad prognosis in cancers of immune-privileged organs, but on the other hand were beneficial in skin and breast cancers. For each cancer type, I determined the individual impact on survival of several types of immune cells and established correlations between involved pathways and some of these cell populations. Altogether, the results allow to better understand the complex relationships between each cancer and the associated immune infiltrate, and will later lead to help the development of immunotherapeutic strategies more adapted to a given tumour environment, by targeting the immune populations that could really impact the survival of patients
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Januška, Adam. "Model laboratorního pohonu pro výukové účely." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413132.
Full textAbstract:
This thesis is focused on simulation of laboratory stand located on University of technology in Brno which is containing DC and asynchronous motor. This thesis includes mathematical model of DC motor, regulator of current, regulator of speed and DC convertor. It also contains model of asynchronous squirrel cage motor and models for scalar and vector control. Whole simulation is calculated in Simulink which is part of program Matlab.
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Huang, Bin. "Convertisseur continu-continu à rapport de transformation élevé pour applications pile à combustible." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL021N/document.
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Ce travail concerne l’étude, le dimensionnement et la réalisation d’un convertisseur continu-continu, associé à une source de type pile à combustible. Pour l’application envisagée, ce convertisseur a un rapport de transformation élevé voisin de 12. De plus l’ondulation de courant est limitée à 1% du courant moyen maximal. La mise en cascade de deux convertisseurs a été retenue pour obtenir un rapport de transformation élevé. Le premier étage est un Boost entrelacé associé à un filtre d’entrée de type L-C, qui permettent de réduire fortement l’ondulation du courant de source. Le second étage est un Boost à trois niveaux qui permet de diminuer les contraintes en tension sur les interrupteurs, et de réduire ainsi les pertes du convertisseur. La commande du convertisseur est ensuite définie en se basant sur l’utilisation d’un régulateur non linéaire. La gestion globale du système est effectuée par la régulation de la tension intermédiaire et de la puissance transitée à la charge en utilisant les principes des commandes « plates ». Enfin un banc de tests à puissance réduite (3 kW) a été réalisé, afin de valider le fonctionnement du convertisseur et les régulations proposéesThis work deals with the study, design and building of a DC-DC converter, which is associated with a fuel cell source. According to the application, this converter should have a high voltage ratio which is about 12, and it is able to limit the ripple current of source below 1% of the maximum average current. A cascaded structure composed by two converters has been chosen and allows obtaining a high voltage ratio. The first stage is an interleaved Boost associated with a L-C input filter, to reduce ripple of the current delivered by the source. The second stage is a three-level Boost which reduces the voltage stress of the switches, thereby reducing losses of the converter. The control of the converter is defined basing on the use of a non-linear regulator. Thanks to use the flatness control, the global control is realized through the regulation of the intermediate voltage and of the power transited to the load. Finally, a small power test converter (3 kW) has been realized, in order to validate the converter operation and the proposed control
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Netáhlo, Tomáš. "Palubní multifunkční jednotka pro motocykly." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219822.
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Master’s thesis deals with a design and a realization of multifunction board computer for motorcycles. The goal of the device is measuring speed, rotation speed of engine, temperature of ambient, temperature of engine, temperature in intake including signalization of overvoltage and hightemperature. The device is completed by above standard function such as measuring titl of motorcycle, climbing of route, route recording and data transmission to the computer. The thesis includes a complete solution of hardware and software part of the device.
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Hess, Lukáš. "Návrh dvoukolového autonomního robota." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230806.
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The goal of this diploma thesis is a proposal of autonomous two wheeled balancing robot, differentially driven. This kind of robot is especially suitable in confined space, where it can utilize its maneuver skills. Many criteria as operational conditions, materials, size and weight of the robot, suitable hardware and sensors must to be considered, when designing the robot. Development and implementation of autonomous balancing control system is also part of the thesis.
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Freitas, Pedro Augusto Ramos de. "Proposta de um compensador sériie de tensão de elevada dinâmica para a correção da tensão instantânea da carga diante de afundamentos ou elevações da tensão da rede elétrica." Universidade Federal de Uberlândia, 2014. https://repositorio.ufu.br/handle/123456789/14580.
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This paper proposes two new topological arrangements consisting in connecting the AC power supply in series with two DC converters, one operating during the positive half-cycle and the other during the negative half cycle. It is noteworthy that these DC converters in series in a case are Buck EIE converters and on the other a buck. The results obtained with both arrangements are analyzed and compared. The control strategy is developed with the goal of imposing an AC voltage output within the limits imposed by the rules in order to mitigate the problems associated with Sags and Swells from the AC power supply . The principles of operation as well as the experimental and simulation results obtained in both steady and transient state are presented and validated for a 1kVA experimental prototype. Finally, some works still on progress related to this dissertation are presented, like the multilevel compensation and the three phase compensation.Este trabalho propõe dois novos arranjos topológicos que consistem em se conectar a alimentação CA em série com dois conversores CC, um para operar durante o semiciclo positivo e o outro durante o semiciclo negativo. Vale ressaltar que estes conversores CC em série, em um caso são conversores Buck EIE e no outro um conversor Buck. Os resultados obtidos com ambos os arranjos são analisados e comparados. A estratégia de controle é desenvolvida com o intuito de impor uma tensão de saída CA dentro dos limites impostos pelas normas de forma a mitigar os problemas associados com Sags e Swells da rede de alimentação CA. Os princípios de operação, os resultados experimentais e de simulação obtidos, tanto em regime permanente quanto em condições transitórias de operação, são apresentados e validados para um protótipo experimental de 1kVA. Por fim apresentam-se os trabalhos relacionados a esta dissertação que ainda estão em desenvolvimento, que são a compensação em multinível e a compensação trifásica.
Mestre em Ciências
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Alepuz, Menéndez Salvador Simón. "Aportación al control del convertidor CC/CA de tres niveles." Doctoral thesis, Universitat Politècnica de Catalunya, 2004. http://hdl.handle.net/10803/6330.
Full textAbstract:
La presente tesis estudia, propone y realiza sus principales aportaciones en el campo del control para el convertidor CC/CA de tres niveles, sobre la topología denominada Neutral-Point-Clamped, aunque se puede extender a otras topologías y/o número de niveles. Se presenta una metodología de modelado que emplea funciones de conmutación de fase, el operador de promediado y la transformación D-Q, tal que los modelos obtenidos en el dominio D-Q contienen una información completa sobre la dinámica del sistema. La estrategia de conmutación se puede entender como una extensión de la estrategia PWM senoidal de dos a tres niveles. Esta estrategia es simple y no realiza el control de ninguna de las variables del sistema. En esta tesis, el controlador se encarga de regular todas las variables del sistema, incluido el equilibrio del bus de continua. Este es un enfoque diferente del convencional, donde el equilibrio del bus de continua se consigue mediante la elección adecuada de los estados redundantes del convertidor en la estrategia de conmutación, mientras que el resto de variables se regulan a través del controlador. Para la realización del controlador, se propone la técnica de control lineal multivariable LQR (Linear Quadratic Regulator), complementada con la técnica de control no lineal adaptativo denominada programación de ganancia (Gain Scheduling). Se presenta, además, una metodología de cálculo del controlador. Este control es versátil, abierto y adaptable. En cualquier caso, el controlador se puede adaptar a las necesidades concretas de cada aplicación. El cálculo del controlador se realiza mediante simulación con MatLab-Simulink. Los modelos matemáticos que emplean las funciones de conmutación del convertidor son aquellos que ofrecen un mejor compromiso entre velocidad de simulación y precisión. Para validar el control propuesto, se ha diseñado y construido un equipo experimental donde el controlador se ha mostrado aplicable, útil y eficaz en la regulación de las distintas cargas y aplicaciones experimentadas, incluso con carga no lineal, bajo diferentes condiciones de trabajo y variables a controlar, tanto en régimen permanente como en procesos transitorios. La rapidez y calidad de la respuesta transitoria es comparable a la de otros sistemas de control publicados. Es especialmente interesante el excelente control conseguido del equilibrio del bus de continua. Además, la robustez del control permite cancelar el error estacionario aunque diferentes parámetros del sistema presenten desviaciones significativas respecto los valores esperados. El uso de la programación de ganancia junto con la técnica LQR se ha mostrado muy efectivo, puesto que permite realizar diferentes tipos de control. Se ha comprobado la congruencia entre simulaciones y resultados experimentales obtenidos, lo que valida los modelos de simulación empleados y el proceso de diseño del controlador mediante simulación.This dissertation study, propose and carry out the main contributions in the field of three-level inverter control, using the topology Neutral-Point-Clamped, although results can be extended to other topologies and/or number of levels. A procedure for modelling is presented, based on line-switching functions, moving average operator and D-Q transformation. Then, the obtained models in D-Q frame contain complete information about system dynamics. Switching strategy is simple and can be considered as an extension of two-level sinusoidal PWM to three level. The system variables are not controlled by the switching strategy. In this work, all the system variables are controlled by the regulator, including DC-link balance. This control approach is different than the conventional one, where DC-link balance is achieved by means of a proper selection of redundant states in the switching strategy, and the other variables are controlled by the regulator. The regulator is based on the multivariable linear control technique LQR (Linear Quadratic Regulator), in combination with the non-linear adaptive control technique Gain Scheduling. Moreover, a methodology for the calculation of the controller is presented. This controller is versatile, open and adaptable. However, the controller can be built depending on the concrete specifications of each application. The controller is calculated by means of simulation using MatLab-Simulink. The mathematical models based on the switching functions of the converter give the best trade-off between simulation speed and precision. In order to validate the proposed controller, an experimental prototype has been designed and implemented. Experimental results show that the controller is useful and effective for the regulation of different loads and applications, even with non-linear loads, different operation points and variables to control, in steady-state and transitory operation. Dynamic response speed and quality are similar to other control systems in the literature. The DC-link balance control achieved is specially interesting. Furthermore, steady-state error is cancelled due to the robustness of the controller, even though significant deviation of different system parameters are present. The use of Gain-Scheduling in combination with LQR is effective, allowing the calculation of regulators with different control strategies. Good agreement between simulations and experimental results has been found. This result validates simulation models and the design method for the controller, based on simulations.
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Alepuz, Menéndez Salvador Simón. "Aportació al control del convertidor CC/CA de tres nivells." Doctoral thesis, Universitat Politècnica de Catalunya, 2004. http://hdl.handle.net/10803/6330.
Full textAbstract:
La presente tesis estudia, propone y realiza sus principales aportaciones en el campo del control para el convertidor CC/CA de tres niveles, sobre la topología denominada Neutral-Point-Clamped, aunque se puede extender a otras topologías y/o número de niveles. Se presenta una metodología de modelado que emplea funciones de conmutación de fase, el operador de promediado y la transformación D-Q, tal que los modelos obtenidos en el dominio D-Q contienen una información completa sobre la dinámica del sistema. La estrategia de conmutación se puede entender como una extensión de la estrategia PWM senoidal de dos a tres niveles. Esta estrategia es simple y no realiza el control de ninguna de las variables del sistema. En esta tesis, el controlador se encarga de regular todas las variables del sistema, incluido el equilibrio del bus de continua. Este es un enfoque diferente del convencional, donde el equilibrio del bus de continua se consigue mediante la elección adecuada de los estados redundantes del convertidor en la estrategia de conmutación, mientras que el resto de variables se regulan a través del controlador. Para la realización del controlador, se propone la técnica de control lineal multivariable LQR (Linear Quadratic Regulator), complementada con la técnica de control no lineal adaptativo denominada programación de ganancia (Gain Scheduling). Se presenta, además, una metodología de cálculo del controlador. Este control es versátil, abierto y adaptable. En cualquier caso, el controlador se puede adaptar a las necesidades concretas de cada aplicación. El cálculo del controlador se realiza mediante simulación con MatLab-Simulink. Los modelos matemáticos que emplean las funciones de conmutación del convertidor son aquellos que ofrecen un mejor compromiso entre velocidad de simulación y precisión. Para validar el control propuesto, se ha diseñado y construido un equipo experimental donde el controlador se ha mostrado aplicable, útil y eficaz en la regulación de las distintas cargas y aplicaciones experimentadas, incluso con carga no lineal, bajo diferentes condiciones de trabajo y variables a controlar, tanto en régimen permanente como en procesos transitorios. La rapidez y calidad de la respuesta transitoria es comparable a la de otros sistemas de control publicados. Es especialmente interesante el excelente control conseguido del equilibrio del bus de continua. Además, la robustez del control permite cancelar el error estacionario aunque diferentes parámetros del sistema presenten desviaciones significativas respecto los valores esperados. El uso de la programación de ganancia junto con la técnica LQR se ha mostrado muy efectivo, puesto que permite realizar diferentes tipos de control. Se ha comprobado la congruencia entre simulaciones y resultados experimentales obtenidos, lo que valida los modelos de simulación empleados y el proceso de diseño del controlador mediante simulación.This dissertation study, propose and carry out the main contributions in the field of three-level inverter control, using the topology Neutral-Point-Clamped, although results can be extended to other topologies and/or number of levels. A procedure for modelling is presented, based on line-switching functions, moving average operator and D-Q transformation. Then, the obtained models in D-Q frame contain complete information about system dynamics. Switching strategy is simple and can be considered as an extension of two-level sinusoidal PWM to three level. The system variables are not controlled by the switching strategy. In this work, all the system variables are controlled by the regulator, including DC-link balance. This control approach is different than the conventional one, where DC-link balance is achieved by means of a proper selection of redundant states in the switching strategy, and the other variables are controlled by the regulator. The regulator is based on the multivariable linear control technique LQR (Linear Quadratic Regulator), in combination with the non-linear adaptive control technique Gain Scheduling. Moreover, a methodology for the calculation of the controller is presented. This controller is versatile, open and adaptable. However, the controller can be built depending on the concrete specifications of each application. The controller is calculated by means of simulation using MatLab-Simulink. The mathematical models based on the switching functions of the converter give the best trade-off between simulation speed and precision. In order to validate the proposed controller, an experimental prototype has been designed and implemented. Experimental results show that the controller is useful and effective for the regulation of different loads and applications, even with non-linear loads, different operation points and variables to control, in steady-state and transitory operation. Dynamic response speed and quality are similar to other control systems in the literature. The DC-link balance control achieved is specially interesting. Furthermore, steady-state error is cancelled due to the robustness of the controller, even though significant deviation of different system parameters are present. The use of Gain-Scheduling in combination with LQR is effective, allowing the calculation of regulators with different control strategies. Good agreement between simulations and experimental results has been found. This result validates simulation models and the design method for the controller, based on simulations.
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Šoupal, Ondřej. "Programování mikrokontrolérů c2000 v programu MATLAB/Simulink." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413221.
Full textAbstract:
The aim of this thesis is to explore possibilities of rapid control prototyping, describe the concept of creating the software application in MATLAB/Simulink environment with use for development kit Texas instruments LaunchPad and create an application for DC and induction motor control in this environment. This work describes the application for unipolar/bipolar control H-Bridge of power converter for DC motor, measurement of output currents, speed and its displaying in real time using serial control interface. This thesis also desribes scalar and vector control of induction motor. All software applications with measurements are created in MATLAB/Simulink and attached to the thesis.
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Masoud, Khalid Hasan. "Circuits and controls for grid-connected inverters." Thesis, Queensland University of Technology, 2002.
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Fedoric, Boris. "Generation of tolerogenic human DC through Rapamycin conditioning and genetic modification with HLA-G." 2009. http://hdl.handle.net/2440/56027.
Full textAbstract:
Dendritic cells (DC) are potent antigen presenting cells involved in the initiation of the alloimmune response and organ transplant rejection. This thesis, has investigated pharmacological and genetic approaches to manipulate DC in order to generate tolerogenic DC which elicit poor allostimulatory activity as potential cell therapy agents to treat allograft rejection. In the first aspect of this study, human monocyte-derived DC were used to study the influence of Rapamycin (RAPA) on DC phenotype and function. This study showed that RAPA when added to monocytes prior to DC differentiation or after DC maturation generated tolerogenic DC as evidenced by the ability of these cells to induce T cell hyporesponsiveness. However, T cell hyporesponsiveness was associated with downregulation of costimulatory molecules only when added prior to differentiation and surprisingly was not influenced by the induction of CD4 ⁺FoxP3 ⁺ T cells. To assess the effects of RAPA on DC function in the transplant setting an in vivo chimeric model of ovine vascularised skin allograft transplantation was established in immunocompromised NOD/SCID mice as a host. This model was established as a preliminary model to acquire in vivo data prior to testing the effect of pharmacologically modified DC in the preclinical ovine model of renal allograft transplantation, also established in the host laboratory. Firstly, comparison of ovine DC obtained from cannulation of the prefemoral lymphatic vessels in sheep demonstrated that RAPA-modified ovine DC acted as poor stimulators of allogeneic ovine T cells similar to human DC treated with RAPA. Secondly, in NOD/SCID mice engrafted with ovine skin, the infusion of allogeneic ovine T cells together with RAPA-modified ovine DC reduced histological rejection in comparison to control DC. In the second aspect of this study, the effects of genetic manipulation of DC were investigated. In order to investigate the effects of genetic modification of DC, two isoforms of the human HLA-G molecule, HLA-G1 (membrane bound) and HLA-G5 (soluble isoform) were used to generate adenoviral vectors. Unexpectedly, both HLA-G isoforms expressed by human DC transfectants were unable to induce allogeneic T cell hyporesponsiveness in the mixed lymphocyte reaction (MLR). Surprisingly, in the MLR the allogeneic T cells acquired HLA-G1, but not HLA-G5, indicating that direct cell contact and membrane transfer from DC to T cells occurred (Trogocytosis). In addition to HLA-G1, costimulatory molecules (CD40, CD80, CD86 and MHC Class II) were also cotransferred from DC to allogeneic T cells. Accordingly, in secondary proliferation assays T cells immunoselected after co-culture with allogeneic untransfected DC (TUT) demonstrated potent antigen presenting activity when used as stimulators of autologous T cells (analogous to the indirect pathway of antigen presentation). In contrast to TUT, immunoselected T cells that acquired HLA-G1 (THLA-G1) upon co-culture with DCtransfectants showed poor stimulatory capacity. Thus the data reported in this thesis supports the proposed novel concept that HLA-G acquired by T cells through genetically modified DC, functions to autoregulate T cells via T-T cell interaction through the HLA-G receptor ILT2 (negative signalling receptor) expressed on T cells. In conclusion, this thesis has firstly provided supportive evidence that the pharmacological modification of human and ovine DC with RAPA has potential therapeutic effects on allograft rejection. Secondly, the genetic modification of DC to induce expression of HLA-G has specifically allowed the transfer of this molecule to T cells by trogocytosis and the inhibition of alloreactive T cell expansion.Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2009