Fault-Tolerant Control of a Flux-switching Permanent Magnet Synchronous Machine

Je jasné, že nejúspěšnější konstrukce zahrnuje postup vícefázového řízení, ve kterém každá fáze může být považována za samostatný modul. Provoz kterékoliv z jednotek musí mít minimální vliv na ostatní, a to tak, že v případě selhání jedné jednotky ostatní mohou být v provozu neovlivněny. Modulární řešení vyžaduje minimální elektrické, magnetické a tepelné ovlivnění mezi fázemi řízení (měniče). Synchronní stroje s pulzním tokem a permanentními magnety se jeví jako atraktivní typ stroje, jejíž přednostmi jsou vysoký kroutící moment, jednoduchá a robustní konstrukce rotoru a skutečnost, že permanentní magnety i cívky jsou umístěny společně na statoru. FS-PMSM jsou poměrně nové typy střídavého stroje stator-permanentní magnet, které představují významné přednosti na rozdíl od konvenčních rotorů - velký kroutící moment, vysoký točivý moment, v podstatě sinusové zpětné EMF křivky, zároveň kompaktní a robustní konstrukce díky umístění magnetů a vinutí kotvy na statoru. Srovnání výsledků mezi FS-PMSM a klasickými motory na povrchu upevněnými PM (SPM) se stejnými parametry ukazuje, že FS-PMSM vykazuje větší vzduchové mezery hustoty toku, vyšší točivý moment na ztráty v mědi, ale také vyšší pulzaci díky reluktančnímu momentu. Pro stroje buzené permanentními magnety se jedná o tradiční rozpor mezi požadavkem na vysoký kroutící moment pod základní rychlostí (oblast konstantního momentu) a provozem nad základní rychlostí (oblast konstantního výkonu), zejména pro aplikace v hybridních vozidlech. Je předložena nová topologie synchronního stroje s permanentními magnety a spínaným tokem odolného proti poruchám, která je schopná provozu během vinutí naprázdno a zkratovaného vinutí i poruchách měniče. Schéma je založeno na dvojitě vinutém motoru napájeném ze dvou oddělených vektorově řízených napěťových zdrojů. Vinutí jsou uspořádána takovým způsobem, aby tvořila dvě nezávislé a oddělené sady. Simulace a experimentální výzkum zpřesní výkon během obou scénářů jak za normálního provozu, tak za poruch včetně zkratových závad a ukáží robustnost pohonu za těchto podmínek. Tato práce byla publikována v deseti konferenčních příspěvcích, dvou časopisech a knižní kapitole, kde byly představeny jak topologie pohonu a aplikovaná řídící schémata, tak analýzy jeho schopnosti odolávat poruchám.It has become clear that the most successful design approach involves a multiple phase drive in which each phase may be regarded as a single-module. The operation of any one module must have minimal impact upon the others, so that in the event of that module failing the others can continue to operate unaffected. The modular approach requires that there should be minimal electrical, magnetic and thermal interaction between phases of the drive. Flux-Switching permanent magnet synchronous machines (FS-PMSM) have recently emerged as an attractive machine type virtue of their high torque densities, simple and robust rotor structure and the fact that permanent magnets and coils are both located on the stator. Flux-switching permanent magnet (FS-PMSM) synchronous machines are a relatively new topology of stator PM brushless machine. They exhibit attractive merits including the large torque capability and high torque (power) density, essentially sinusoidal back-EMF waveforms, as well as having a compact and robust structure due to both the location of magnets and armature windings in the stator instead of the rotor as those in the conventional rotor-PM machines. The comparative results between a FS-PMSM and a traditional surface-mounted PM (SPM) motor having the same specifications reveal that FS-PMSM exhibits larger air-gap flux density, higher torque per copper loss, but also a higher torque ripple due to cogging -torque. However, for solely permanent magnets excited machines, it is a traditional contradiction between the requests of high torque capability under the base-speed (constant torque region) and wide speed operation above the base speed (constant power region) especially for hybrid vehicle applications. A novel fault-tolerant FS-PMSM drive topology is presented, which is able to operate during open- and short-circuit winding and converter faults. The scheme is based on a dual winding motor supplied from two separate vector-controlled voltage-sourced inverter drives. The windings are arranged in a way so as to form two independent and isolated sets. Simulation and experimental work will detail the driver’s performance during both healthy- and faulty- scenarios including short-circuit faults and will show the drive robustness to operate in these conditions. The work has been published in ten conference papers, two journal papers and a book chapter, presenting both the topology of the drive and the applied control schemes, as well as analysing the fault-tolerant capabilities of the drive.

Probing the cosmological dynamics of a logarithmic f (R) theory of gravity

Includes bibliographical referencesIn this thesis we make a contribution in the area of Extended Theories of Gravity (ETG) by studying the dynamics of the R ln R model. We draw attention to the importance of introducing complete alternative theories of gravity and studying the possible geometrical origin of Dark Energy (unknown form of energy), which is commonly thought to be responsible for the present epoch of accelerated expansion that our universe undergoes. The first chapter of the thesis is an introduction to one of the most successful models in the realm of cosmology i.e. the CDM model. At the end of the first chapter we give a brief discussion on the ground breaking news from the BICEP2 experiment. However, part of the community argues that the BICEP2 results cannot be ascribed to a primordial gravitational waves. In fact, the recent dust map was released by Planck's team lowered the chances that the signal detected by BICEP2 team can be due to primordial gravitational waves. The second chapter introduces a review of the motivations that stimulated researchers to pursue new theories of gravity. Moreover, we revisit the mathematical basis of the f (R) theory of gravity and explain how a viable model of f (R) can account for the most bizarre phenomenon in the universe, namely Dark Energy. The third chapter is dedicated to the basis and the techniques of the theory of dynamical systems. The fifth chapter includes some original work on the R ln R model dynamics in two different versions (compact and non-compact phase space). In this thesis, we show that the R ln R model cannot be considered as a viable model since it has serious flaws. These flaws will be addressed, in detail, in chapter 5

Detection of new allotypic variants of bovine antibody λ-light chain and IgG-heavy chain constant regions

In den Rinderrassen Alte Deutsche Schwarzbunte (GBP), Deutsches Fleckvieh (GS), Holstein Friesian (HF) und Aubrac (A) wurden die Transkripte der leichten λ- (IGλ) und der schweren IgG-Immunglobulinketten (IgG) analysiert. Dafür wurden Blutproben von zehn zufällig ausgewählten Tieren einer Rasse gewonnen. Die Gesamt-RNA wurde aus den peripheren mononukleären Blutzellen extrahiert und in cDNA umgeschrieben. Mittels genspezifischer Primer wurden sowohl die IGλ als auch die schweren IgG amplifiziert. Nach einer Subklonierung wurden für jede Kette 16 Sequenzen pro Tier ausgewertet. Die konstanten Regionen wurden separiert und mit Datenbankeinträgen verglichen. Für die Definition neuer allotypischer Varianten war die Lage der Substitutionen auf der Oberfläche des Moleküls essentiell. Die Aminosäuresequenzen wurden mit bekannten Kristallstrukturen humaner und muriner Antikörper verglichen und ein 3-dimensionales Model erstellt. Für die zwei transkribierten IGλ-Isotypen wurden drei allotypische Varianten für den Isotypen IGλC2 und fünf allotypische Varianten für den Isotypen IGλC3 identifiziert. Im Falle der IgG konnten die bekannten vier allotypische Varianten für IgG1, zwei allotypische Varianten für IgG2 und eine allotypische Variante IgG3 nachgewiesen werden. Zusätzlich wurde eine neue Variante durch die 3D-Strukturanalyse definiert. Allotypische Unterschiede in Rinder-IgG können die Effektorfunktion des Antikörpermoleküls beeinflussen

PV systems control using fuzzy logic controller employing dynamic safety margin under normal and partial shading conditions

Because of the unpredictable activity of solar energy sources, photovoltaic (PV) maximum power point tracking (MPPT) is essential to guarantee the continuous operation of electrical energy generation at optimal power levels. Several works have extensively examined the generation of the maximum power from the PV systems under normal and shading conditions. The fuzzy logic control (FLC) method is one of the effective MPPT techniques, but it needs to be adapted to work in partial shading conditions. The current paper presents the FLC-based on dynamic safety margin (DSM) as an MPPT technique for a PV system to overcome the limitations of FLC in shading conditions. The DSM is a performance index that measures the system state deviation from the normal situation. As a performance index, DSM is used to adapt the FLC controller output to rapidly reach the global maxima of the PV system. The ability of the proposed algorithm and its performance are evaluated using simulation and practical implementation results for single phase grid-connected PV system under normal and partial shading operating conditions.Peer ReviewedPostprint (published version

Investigating electrical drive performance employing model predictive control and active disturbance rejection control algorithms

Many issues can degrade the electrical drive performance such as cross-coupling, time delay, external disturbances, and parameter variation. The Synchronous Reference Frame (SRF) PI Current Controller (CC) is the most popular control scheme for the motor drive current control due to its simplicity. However, the PI controller does not have an optimal dynamic response due to the reasonably low transient response of the integral parts. Furthermore, the tuning of the PI controller depends heavily on the machine’s parameters. Recently, alternative control schemes such as Model Predictive Control (MPC) and Active Disturbance Rejection Control (ADRC) are studied due to their dynamic performance and disturbance rejection capability, respectively. This paper presents a comparative study between the conventional PI, ADRC, and MPC control schemes applied for Permanent Magnet Synchronous Motor (PMSM) taking into consideration the operational issues of electrical drives

Artificial intelligence-based protection for smart grids

Lately, adequate protection strategies need to be developed when Microgrids (MGs) are connected to smart grids to prevent undesirable tripping. Conventional relay settings need to be adapted to changes in Distributed Generator (DG) penetrations or grid reconfigurations, which is a complicated task that can be solved efficiently using Artificial Intelligence (AI)-based protection. This paper compares and validates the difference between conventional protection (overcurrent and differential) strategies and a new strategy based on Artificial Neural Networks (ANNs), which have been shown as adequate protection, especially with reconfigurable smart grids. In addition, the limitations of the conventional protections are discussed. The AI protection is employed through the communication between all Protective Devices (PDs) in the grid, and a backup strategy that employs the communication among the PDs in the same line. This paper goes a step further to validate the protection strategies based on simulations using the MATLABTM platform and experimental results using a scaled grid. The AI-based protection method gave the best solution as it can be adapted for different grids with high accuracy and faster response than conventional protection, and without the need to change the protection settings. The scaled grid was designed for the smart grid to advocate the behavior of the protection strategies experimentally for both conventional and AI-based protections.This work is supported by Li Dak Sum Innovation Fellowship Funding (E06211200006) from the University of Nottingham Ningbo China.Peer ReviewedPostprint (published version

Considerations on the development of high-power density inverters for highly integrated motor drives

In transportation electrification, power modules are considered the best choice for power switches to build a high-power inverter. Recently, several studies have presented prototypes that use parallel discrete MOSFETs and show similar overall output capabilities. This paper aims to compare the maximum output power and losses of inverters with different types (surface-mounted, through-hole-mounted and power modules) of commercially available switching devices, and, therefore, discuss the theoretical boundaries of each technology. The numerical analysis relies on detailed power loss and thermal models, with adjustments made for gate current and realistic parameters of the cooling system. The analysis includes two case studies with different targets, including minimum dimensional characteristics and maximum output power. The results demonstrate that discrete MOSFETs can provide improved capabilities in contrast to power modules under certain conditions.peer-reviewe

Ultrasound and radiation-induced catalytic oxidation of 1-phenylethanol to acetophenone with iron-containing particulate catalysts

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2019 do Instituto Politécnico de Lisboa. Código de referência IPL/2019/STREAM_ISELIron-containingparticulatecatalystsof0.1–1 µmsizewerepreparedbywetandball-milling procedures from common salts and characterized by FTIR, TGA, UV-Vis, PXRD, FEG-SEM, and XPS analyses. It was found that when the wet method was used, semi-spherical magnetic nanoparticles were formed, whereas the mechanochemical method resulted in the formation of nonmagnetic microscale needles and rectangles. Catalytic activity of the prepared materials in the oxidation of 1-phenylethanol to acetophenone was assessed under conventional heating, microwave (MW) irradiation, ultrasound (US), and oscillating magnetic field of high frequency (induction heating). In general, the catalysts obtained by wet methods exhibit lower activities, whereas the materials prepared by ball milling afford better acetophenone yields (up to 83%). A significant increase in yield (up to 4 times) was observed under the induction heating if compared to conventional heating. The study demonstrated that MW, US irradiations, and induction heating may have great potential as alternative ways to activate the catalytic system for alcohol oxidation. The possibility of the synthesized material to be magnetically recoverable has been also verified.info:eu-repo/semantics/publishedVersio

Intra-alveolar neutrophil-derived microvesicles are associated with disease severity in COPD

Despite advances in the pathophysiology of Chronic Obstructive Pulmonary Disease (COPD), there is a distinct lack of biochemical markers to aid clinical management. Microvesicles (MVs) have been implicated in the pathophysiology of inflammatory diseases including COPD but their association to COPD disease severity remains unknown. We analysed different MV populations in plasma and bronchoalveolar lavage fluid (BALF) taken from sixty-two patients with mild to very severe COPD (51% male; mean age: 65.9 years). These patients underwent comprehensive clinical evaluation (symptom scores, lung function, exercise testing) and the capacity of MVs to be clinical markers of disease severity was assessed. We successfully identified various MV subtype populations within BALF (leukocyte, PMN (polymorphonuclear leukocyte i.e. neutrophil), monocyte, epithelial and platelet MVs) and plasma (leukocyte, PMN, monocyte and endothelial MVs), and compared each MV population to disease severity. BALF neutrophil MVs were the only population to significantly correlate with the clinical evaluation scores including FEV1, mMRC dyspnoea score, 6-minute walk test, hyperinflation and gas transfer. BALF neutrophil MVs, but not neutrophil cell numbers, also strongly correlated with BODE index. We have undertaken, for the first time, a comprehensive evaluation of MV profiles within BALF/plasma of COPD patients. We demonstrate that BALF levels of neutrophil-derived MVs are unique in correlating with a number of key functional and clinically-relevant disease severity indices. Our results show the potential of BALF neutrophil MVs for a COPD biomarker that tightly links a key pathophysiological mechanism of COPD (intra-alveolar neutrophil activation) with clinical severity/outcome