This thesis begins with a literature review focusing on electric vehicle (EV) applications. Systems used for steering, braking and energy storage are investigated, with specific concentration on torque control in various DC and AC motors commonly used in EVs. A final solution for a low range personal transportation EV in the form of a wheelchair is proposed. The theme for this thesis is motion control, focusing on a two axis (or two wheel drive) brushless DC hub motor (BLDCHM) EV, with torque and direction control tracking a user reference. The operation principle for a BLDCHM is documented and the dynamic and electrical equations derived. Simulation results for motor response under different load and speed conditions are compared to practical measurements. Current and torque control loops are designed, implemented and tuned on a single-axis test-bed with an induction motor (IM) load coupled via a torque transducer. A Texas Instrument DSP development kit is used for the control algorithm bench testing. The final control algorithm is then duplicated and expanded in simulation to form a dynamic two axis system for an electric wheelchair. It incorporates both motor drive and regenerative capabilities. After demonstrating two axis controls for BLDCHMs, a control algorithm is designed simulated and compared to traditional systems. The final solution focuses specifically on an intuitive response to the driver input whilst maintaining direction tracking, even when there is a difference in smoothness of the individual terrains traversed by the left and right wheels. In addition the motor drives are equipped with controllers that ensure regenerative braking in order to recover as much energy as possible when the wheelchair is commanded to decelerate. / M. Sc. Eng. University of KwaZulu-Natal, Durban 2014.

Electric power engineering, as it applies to low-voltage power reticulation in buildings and industrial sites, is ripe for a ‘paradigm shift’ to bring it properly into the Electronic Age. The conventional alternating-current approach, now over a hundred years old, is increasingly unsatisfactory from the point of view of plant and appliance requirements. Alternative approaches can deliver substantial cost savings, higher efficiencies, power quality improvements, and greater safety. Power reticulation systems in the future can be expected to differ from present systems in two key respects. The first is a greatly increased role for direct current; the second is the augmentation of the power system with a wide range of ‘management’ technologies. Combining these two trends, which can already be observed today, leads to consideration of ‘managed DC’ power reticulation systems, operating from AC bulk supply mains via AC-DC converters.

Thesis (M.S.)--Ohio University, November, 1996. / Title from PDF t.p.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (p. 169-182) Also available in print.

Thesis (M.S.)--University of Wisconsin--Madison, 1974. / Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

by Pierre Dersin, Alexander H. Levis. / "August 1982." / Bibliography: leaf [4]. / Support by the Division of Electric Energy System of the U.S. Dept. of Energy under Contract no. AC01-77-ET29033

Η παρούσα διπλωματική εργασία πραγματεύεται την μελέτη, τον σχεδιασμό και την κατασκευή ενός ηλεκτρονικά ελεγχόμενου μηχανικού φορτίου. Η εργασία αυτή εκπονήθηκε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών της Πολυτεχνικής Σχολής του Πανεπιστημίου Πατρών. Σκοπός είναι η δημιουργία ενός μηχανικού φορτίου του οποίου το προφίλ μπορεί να ελέγχεται με την χρήση ψηφιακού μικροελεγκτή. Αρχικά, εξετάζεται η θέση που κατέχει το μηχανικό φορτίο σε ένα ηλεκτρικό κινητήριο σύστημα και παρουσιάζονται οι χαρακτηριστικές καμπύλες των διάφορων τύπων μηχανικών φορτίων. Στη συνέχεια, μελετώνται η βασική αρχή λειτουργίας, οι μαθηματικές εξισώσεις καθώς και τα κατασκευαστικά χαρακτηριστικά των μηχανών συνεχούς ρεύματος αλλά και της μηχανής που χρησιμοποιήθηκε στην κατασκευή. Στο επόμενο βήμα, γίνεται μια θεωρητική ανάλυση του κυκλώματος της πλήρους γέφυρας που κατασκευάστηκε καθώς και όλων των υπόλοιπων κυκλωμάτων και στοιχείων που είναι αναγκαία για την λειτουργία της. Επιπροσθέτως, αναλύεται η μέθοδος παλμοδότησης των διακοπτικών στοιχείων του μετατροπέα, που είναι η Διαμόρφωση Εύρους Παλμών (PWM) καθώς και τα ιδιαίτερα χαρακτηριστικά του μικροελεγτή που χρησιμοποιήθηκε. Για το συνολικό σύστημα, αποτελούμενο από την μηχανή συνεχούς ρεύματος και τον μετατροπέα τύπου πλήρους γέφυρας, δημιουργήθηκε ένα μαθηματικό μοντέλο στο περιβάλλον Simulink για να ελεγχθεί η συμπεριφορά του. Τέλος, αναλύονται τα τεχνικά χαρακτηριστικά όλων των κυκλωμάτων που κατασκευάστηκαν και παρατίθενται τα παλμογραφήματα που προέκυψαν από τα πειράματα που διενεργήθηκαν μετά την ολοκλήρωση της κατασκευής. / This thesis deals with the study, design and construction of an electronically controlled mechanical load. The work was conducted in the Laboratory of Electromechanical Energy Conversion, Department of Electrical and Computer Engineering School of Engineering, University of Patras. The aim is to create a mechanical load whose profile can be controlled using digital microcontroller. First, was considered the position of the mechanical load in an electric driving system and shows the characteristic curves of various types of mechanical loads. Then was studied the basic principle of operation, mathematical equations and the construction of DC machines and the machine used in construction. The next step is a theoretical analysis of the full bridge circuit that is constructed and all other circuits and components necessary for its operation. In addition, explains the method of interrupted pulses data converter, which is shaping pulse width (PWM) and the characteristics of icroconroler which is used. For the total system, consisting of the DC machine and type full bridge converter, a mathematical model in Simulink environment to verify its behavior. Finally, analyzing the technical characteristics of all circuits built out and the curves obtained from experiments carried out after the completion of construction.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The implementation of the Caprivi Link Interconnector (CLI) High Voltage Direct Current (HVDC) scheme in 2010 connecting the weak Namibian and Zambian Alternating Current (AC) transmission networks via overhead line is based on Voltage Source Converter (VSC) technology. This world-first combination of attributes presents a unique opportunity to study harmonic interaction between weak AC systems and VSC-based HVDC schemes. Relatively few publications exist that focus on AC and DC harmonic interaction and very few refer to VSC HVDC schemes. Because weak AC systems are much more prone to harmonic distortion than strong AC systems, there is a clear motivation for more detailed work in this field. In order to understand the context wherein AC and DC harmonic interaction exists, the fields of AC power system harmonic analysis and resonance, VSC switching theory, HVDC scheme configurations, Pulse Width Modulation (PWM) techniques and frequency domain analysis techniques are discussed. This thesis then presents the concept of Harmonic Amplitude Transfer Ratio (HATR) by a theoretical analysis of AC and DC harmonic interaction due to the fundamental component, as well as harmonic interaction due to scheme characteristic harmonics and is compared to the simulation results obtained from different software solutions. Simulation and modelling techniques for AC and DC harmonic interaction are discussed including AC and DC systems modelling. The theoretical results and simulation results are compared to the results obtained from a real life case study on the CLI HVDC scheme where a harmonic resonance condition occurred. The correlation of these three sets of results confirms the validity of the theories presented and possible mitigation of the case study resonance problems is explored. The results and conclusion highlight a variety of interesting points on harmonic sequence components analysis, VSC zero sequence elimination, AC and DC harmonic interaction due to the fundamental component and the HATR for different PWM methods, AC and DC harmonic interaction due to scheme characteristic harmonics, modelling techniques and mitigation for the resonance conditions experienced in the analysed real life case study. / AFRIKAANSE OPSOMMING: Die implementering van die Caprivi Skakel Tussenverbinder (CLI) hoogspannings- gelykstroom (HSGS) skema in 2010 wat die swak Namibiese and Zambiese Wisselstroom (WS) transmissienetwerke verbind via „n oorhoofse lyn is gebasseer op Spanningsgevoerde-omsetter tegnologie. Hierdie wêreld-eerste kombinasie van eienskappe verskaf „n unieke geleentheid om harmoniese interaksie tussen swak WS stelsels en Spanningsgevoerde-omsetter Hoogspannings GS stelsels te bestudeer. Relatief min publikasies wat fokus op WS en GS harmoniese interaksie bestaan, en baie min verwys na Spanningsgevoerde-omsetter Hoogspannings GS skemas. Omdat swak WS stelsels baie meer geneig is tot harmoniese verwringing as sterk WS stelsels, is daar „n duidelike motivering vir meer gedetaileerde werk in hierdie veld. Om die konteks te verstaan waarin WS en GS harmoniese interaksie bestaan, word die velde van WS kragstelsel harmoniese analise en resonansie, Spanningsgevoerde-omsetter skakelteorie, Hoogspannings GS skema opstellings, Pulswydte Modulasie (PWM) tegnieke, en frekwensiegebied analiese tegnieke bespreek. Hierdie tesis stel dan die konsep van Harmoniese Amplitude Oordragsverhouding voor deur „n teoretiese analise van WS en GS harmoniese interaksie na aanleiding van die fundamentele komponent, asook harmoniese interaksie a.g.v. harmonieke wat die stelsel kenmerk en word vergelyk met die simulasieresultate verkry uit verskilllende sagteware oplossings. Simulasie- en modelleringstegnieke vir WS en GS harmoniese interaksie word bespreek insluitend WS- en GS stelselmodellering. Die teoretiese resultate en simulasieresultate word vergelyk met die resultate wat verkry is uit „n werklike gevallestudie op die CLI HSGS skema waar „n harmoniese resonansie toestand voorgekom het. Die ooreenkomste tussen hierdie drie stelle resultate bevestig die geldigheid van die teorieë soos uiteengeset voor, en die moontlike verbetering van die gevallestudie resonansie probleme word verken. Die resultate en samevatting beklemtoon „n verskeidenheid punte aangaande harmoniese volgorde-komponent analiese, Spanningsgevoerde-omsetter zero-volgorde uitskakeling, WS en GS harmoniese interaksie na aanleiding van die fundamentele komponent en die Harmoniese Amplitude Oordragsverhouding vir verskillende PWM metodes, WS en GS harmoniese interaksie na aanleiding van skema-kenmerkende harmonieke, modelleringstegnieke, asook verbetering van die resonansie toestande soos ervaar in die analise van die werklike gevallestudie.

Introdução: Climatério, ou transição menopáusica, é definido como o período onde ocorre a mudança de vida reprodutiva para não reprodutiva, com extensão de duração variável. Durante esse período, e após o estabelecimento da menopausa, é comum o surgimento de diversos sintomas que expressam o esgotamento dos folículos ovarianos; sendo os sintomas vasomotores, ou fogachos, os mais comumente relatados pelas mulheres. Atualmente, Terapia Hormonal, bem como os Inibidores Seletivos da Recaptação da Serotonina, têm sido empregadas na tentativa de melhorar estes sintomas. As medicações não hormonais, apesar de apresentarem melhores respostas que placebo, ainda demonstram pouco impacto clínico na redução dos sintomas vasomotores. Esta lacuna permite avaliar outras alternativas terapêuticas, como a Estimulação Transcraniana por Corrente Direta (ou tDCS, do inglês transcranial direct current stimulation). Objetivo: avaliar a diminuição no número de episódios de sintomas vasomotores em pacientes tratadas com aplicação de tDCS e placebo-sham, além de testar os efeitos do tDCS sobre o processo de neuroplasticidade, através da medida sérica de BDNF. Métodos: foram selecionadas nove pacientes pós-menopausicas com queixa de ao menos 5 episódios diários de sintomas vasomotores. Estas pacientes foram randomizadas para um dos grupos, tDCS (tratamento ativo) ou placebo-sham. O tratamento consistiu na aplicação de sessões diárias de estimulação com corrente elétrica de 02 mili Ampere, pelo período de dez dias consecutivos. Após uma semana e um mês de tratamento, as pacientes registravam o número de fogachos ao dia, e respondiam ao Women´s Health Questionaire (WHQ). No primeiro e no último dia de tratamento, foram coletadas amostras sanguíneas para dosagem de BDNF. Resultados: comparando o número médio de sintomas vasomotores (fogachos) ao dia, durante o período de sete dias, não houve diferença significativa entre os dois grupos, assim como nos níveis de BDNF e no WHQ. Conclusão: no momento, não podemos descartar o uso de tDCS no tratamento dos sintomas vasomotores, em virtude de pequeno número de pacientes avaliadas nesta pesquisa. Será mantido o acompanhamento das pacientes avaliadas até esse momento, e o tratamento será aplicado em novas mulheres com sintomas vasomotores. / Background: Climacteric or Menopausal Transition is defined as the time period where there is a change to non-reproductive reproductive life, with extension of variable length. During this period, and after the establishment of Menopause and non-functioning ovarian, the appearance of various symptoms that express the depletion of ovarian follicles is common; among these symptoms, the most frequently reported by women are vasomotor symptoms or hot flashes. In addition to hormonal therapy, other medications have been employed in an attempt to improve these symptoms; although they present better results than placebo, yet have little clinical impact in reducing vasomotor symptoms. Therefore, this gap allows the evaluation of alternative therapies, such as Transcranial Direct Current Stimulation (tDCS). Objective: evaluate the decrease in the number of episodes of vasomotor symptoms in patients treated with tDCS and placebo –sham, beyond testing the effects of tDCS on the neuroplasticity process through measurement of serum BDNF. Methods: nine post-menopausal women with at least 5 episodes of hot flashes/day were selected. These patients were randomized to one of the groups, tDCS (active treatment) or placebo-sham. The treatment consisted in daily application sessions of stimulation with electrical current of 02 mA, for ten consecutive days. After one week and one month of treatment, patients recorded the number of hot flashes per day, and answered the Women's Health Questionnaire (WHQ). In the first and in the last day of treatment, blood samples were collected for measurement of BDNF. Results: Comparing the average number of vasomotor symptoms (hot flashes) per day during the period of seven days, there was no significant difference between the two groups, and there were no differences in the levels of BDNF and WHQ. Conclusion: we can not rule out the use of tDCS in the treatment of vasomotor symptoms, because of the small number of patients evaluated in this study. Monitoring of these patients will be kept, and treatment will be applied to other women with vasomotor symptoms.

[pt] Este trabalho apresenta a modelagem e a simulação de um dinamômetro para motores elétricos empregados nos veículos terrestres em escala, e a especificação dos principais componentes, mecânicos e eletrônicos, necessários para a constrição de um dinamômetro do tipo Flywheel. Todos os componentes que compõe um dinamômetro foram modelados matematicamente e simulados individualmente, para posterior simulação do conjunto nas condições de operação dos motores elétricos aplicados em veículos rádio-controlados. Estas simulações, que visam validar os modelos, como o monitoramento das principais variáveis de cada componente do sistema, foram empregados motores cujos parâmetros e desempenho eram conhecidos. Foi desenvolvido ainda um programa em LabView para ler e tratar dos dados gerados na simulação, a fim de manipular e exibir o desempenho dos motores em testes. / [en] The present work shows the modeling and simulation of a dynamometer for electrical Motors applied in scale vehicles and the specifications of the mair, mechanical and eletronic components needed to build a Flywheel type dynamometer. Every component was mathematically modeled and individualy simulated for futher simulation of the whole system used in a radio-controled vehicle with electrical motors in normal operational conditions. This simulations were performed to validate the models with variables monitored and motors with known parameters and performance were used. In addition, a LabWiew program was developed to read, analyse and display the tested motors performance data.