In this thesis a two-stage AC/DC/DC power converter is designed and implemented. The AC/DC input stage of the converter consists of the two&amp / #8211 / phase interleaved boost topology employing the average current mode control principle. The output stage consists of a zero voltage switching phase shifted full bridge (ZVS&amp / #8211 / PS&amp / #8211 / FB) DC/DC converter. For the input stage, main design goals are obtaining high input power factor, low input current distortion, and well regulated output dc voltage, and obtaining these attributes in a power converter with high power density. For the input stage, the interleaved structure has been chosen in order to obtain reduced line current ripple and EMI, reduced power component stresses, and improved power density. The control of the pre&amp / #8211 / regulator is provided by utilizing a new commercial monolithic integrated circuit, which provides interleaved continuous conduction mode power factor correction (PFC). The output stage is formed by utilizing the available prototype hardware of a ZVS&amp / #8211 / PS&amp / #8211 / FB DC/DC converter and mainly the system integration and controller design and implementation studies have been conducted. The converter small signal model is derived and utilizing its transfer function and employing voltage loop control, the output voltage regulator has been designed. The output voltage controller is implemented utilizing a digital signal processor (DSP). Integrating the AC/DC preregulator and DC/DC converter, a laboratory AC/DC/DC converter system with high overall performance has been obtained. The overall system performance has been verified via computer simulations and experimental results obtained from laboratory prototype.

銅銻硒礦是具有 0.3 eV狹窄能帶間隙的P型半導體，且已被發現是在中溫區下極具潛力的熱電材料。銅銻硒礦的晶體結構具有三維銅硒子框架可提供導電的電洞，而有較高的功率因子900 μW/mK2。銻硒四面體結構可藉由其他元素取代銻的位置，扭曲其鑽石結構以達到提高功率因子以及降低熱傳導的目的。理論預測可藉由 IV 族元素鍺、錫、鉛和過渡金屬鈦等元素取代銻來提供電洞載子。本研究藉由燒結與電漿放電製備樣品，探討鈦、錫、鉛、鍺取代銻的熱電效應。 在上述之元素取代效應後，鈦與鉛並沒有帶來顯卓的熱電效應提升，反之錫與鍺能有效地提升電洞載子濃度，然而與摻錫的研究相似的結果已被其他團隊發表，惟鍺的取代效應則尚未被做完整的探討。2 % 鍺的取代有1200μW/mK2的功率因子，相較於母材(900μW/mK2)有 30 % 的提升，因此我們會對鍺的取代效應做完整一系列的研究。摻雜比例從 1~8 % 的結果裡，發現晶格熱傳導係數隨摻雜比例提升減少的合金效應，然而高於 6 % 的取代造成電導大幅提升，使得熱傳導的載子貢獻高於 50% 並嚴重降低載子移動率，致使功率因子大幅衰減與優質係數降低。 4% 的鍺摻雜在提高功率因子與降低熱傳導係數上皆有顯卓的表現，使得優質係數在溫度650 K達到 0.7 相對於母材 (0.54) 有30 ％的提升。 / Cu3SbSe4 is a p-type semiconductor with a narrow band gap near 0.3 eV, and has been found to be a promising thermoelectric material at medium temperatures. The crystal structure of Cu3SbSe4 consists a three-dimensional [Cu3Se4] framework acting as electron hole conduction pathway which cause high power factor near 900 μW/mK2. The inserting guest atom to the Sb site of tetrahedral [SbSe4] framework cause a more distorted diamond-like structure, thus providing a relatively lower lattice thermal conductivity in relatively large electric conductivity. According to theoretical predication which are based on the defect formation energy and band structure calculations, p-type doping can be achieved by substituting Sb with group IV elements, as Ge, Sn, and Pb, and transition metals as Ti. This study is investigation of the doping effect in Cu3SbSe4 semiconductor which are prepared by melting and spark plasma sintering. Herein, we take a close look at the thermoelectric properties of Cu3SbSe4 which are mentioned in previous paragraph. No significant change in results of Ti and Pb. Carrier concentrations are dramatic increasing in results of Sn and Ge, but the results of Sn substitution were already reported by another group. Power factor of Ge substitution is 1,200μW/mK2 which is 30 % more than raw material. We did more study in germanium doping series because it have high power factor which did not be investigated in Cu3SbSe4. Alloy effects, as description of lattice thermal conductivity reducing with doping fraction increasing, are explored in Ge doping fraction from 1 % to 8 %. Although electric conductivity were largely enhanced, figure of merit were reducing by electric contribution of thermal conductivity were higher than 50 % and carrier mobility were significantly reducing when the doping fraction were higher than 4 %. Doping fraction in 4 % have relatively high power factor and relatively low thermal conductivity. Figure of merit in 4 % doping fraction is 0.7, as 30% more than 0.5 of raw material.

In this dissertation, two high-frequency (HF) transformer isolated single-stage integrated ac-dc converters are proposed for a small scale permanent magnet synchronous generator (PMSG) based wind energy conversion system (WECS). These two types of single-stage integrated ac-dc converters include expected functions of HF isolation, power factor correction (PFC), and output regulation in one single-stage. Fixed-frequency phase-shift control and soft-switching operation are employed in both proposed ac-dc converters. After reviewing the literature and discussing pros and cons of the existing topologies, it is preferred that three identical single-phase single-stage integrated converters with interleaved connection configuration are suitable for the PMSG. For the single-phase converter, two new HF isolated single-stage integrated resonant ac-dc converters with fixed-frequency phase-shift control are proposed. The first proposed circuit is HF isolated single-stage integrated secondary-side controlled ac-dc converter. The other proposed circuit is HF isolated single-stage dual-tank LCL-type series resonant ac-dc converter, which brings better solutions compared to the first converter, such as high power factor and low total harmonic distortion (THD) at the ac input side. Approximate analysis approach and Fourier series methods are used to analyze these two proposed converters. Design examples for each one are given and designed converters are simulated using PSIM simulation package. Two experimental circuits are also built to verify the analysis and simulation. The simulated and experimental results reasonably match the theoretical analysis. Then the proposed HF isolated dual-tank LCL-type series resonant ac-dc converter is used for three-phase interleaved connection in order to satisfy requirements of PMSG based WECS. A design example for this three-phase interleaved configuration is given and simulated for validation under several operating conditions. / Graduate / 0544 / duyimian@uvic.ca

Thesis (Ph. D.)--Ohio State University, 2005. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 Aug 15.

Σκοπός της παρούσας διπλωματικής εργασίας είναι ο σχεδιασμός και η ανάπτυξη προγράμματος ελέγχου του συστήματος ηλεκτρικών παροχών του Εργαστηρίου Ηλεκτρομηχανικής Μετατροπής Ενέργειας, με τη χρήση Προγραμματιζόμενου Λογικού Ελεγκτή. Συγκεκριμένα, κατά τη διάρκεια εκπόνησης της διπλωματικής αυτής εργασίας, αναπτύχθηκε πρόγραμμα ελέγχου ομαλής εκκίνησης ασύγχρονου τριφασικού κινητήρα, με τη βοήθεια ενός ηλεκτρομηχανικού ζεύγους αποτελούμενου από μηχανή συνεχούς ρεύματος, συνδεδεμένης σε κοινό άξονα με σύγχρονη μηχανή. Επιπλέον, αναπτύχθηκε ένα αυτοματοποιημένο πρόγραμμα ελέγχου της ισχύος της σύγχρονης μηχανής του Εργαστηρίου, καθώς και ένα πρόγραμμα για βελτίωση του συντελεστή ισχύος της εγκατάστασης, λειτουργώντας τη σύγχρονη μηχανή, είτε ως γεννήτρια παραλληλισμένη στο δίκτυο, είτε ως κινητήρα εν κενώ. Τέλος, πραγματοποιήθηκαν εκτενείς δοκιμές στα δύο αυτά προγράμματα και γενικότερα στο σύστημα παροχής τάσεων του Εργαστηρίου, με σκοπό την πλήρη ετοιμότητα του για τους εκπαιδευτικούς και εργαστηριακούς σκοπούς για τους οποίους απευθύνεται. / The purpose of this thesis is to design and develop a control system of the Electromechanical Energy Conversion Laboratory, using a Programmable Logic Controller. Specifically, during the preparation of this thesis, a control program three phase asynchronous motor soft-starter has been developed, using a electromechanical couple consisting of machine dc coupled to a common shaft with a sychronous machine. Additionally, an automated program to control power of modern machine workshop as well as a program to improve the power factor of the installation has been developed, using a modern machine, either as a generator , either as a motor.Finally, there have been extensive tests on these two programs and generally in the supply system of the laboratory, in order to the system be totally ready for use.

Submitted by RAFAEL FERNANDO MARIANO null (mariano.rafael@outlook.com) on 2017-12-21T18:42:51Z No. of bitstreams: 1 Rafael_Dissertação_Digital_Revisao_FINAL.pdf: 2427309 bytes, checksum: 032f6de48703baf01dc996ef0b00e063 (MD5) / Approved for entry into archive by Minervina Teixeira Lopes null (vina_lopes@bauru.unesp.br) on 2017-12-22T10:58:02Z (GMT) No. of bitstreams: 1 mariano_rf_me_bauru.pdf: 2366747 bytes, checksum: cbc5abe78e5f08900855037b7bf5458b (MD5) / Made available in DSpace on 2017-12-22T10:58:02Z (GMT). No. of bitstreams: 1 mariano_rf_me_bauru.pdf: 2366747 bytes, checksum: cbc5abe78e5f08900855037b7bf5458b (MD5) Previous issue date: 2017-10-31 / A preocupação com a qualidade da energia elétrica, seu uso e técnicas para redução de perdas elétrica não é mais uma tendência e sim uma necessidade, pois, tem se entendido que a energia elétrica é um bem comum e não deve ser desperdiçada. Nesse contexto, estratégias para controlar o nível de tensão e o fator de potência vêm sendo tratadas, com o objetivo de aprimorar o controle dessas variáveis. Este trabalho apresenta uma estratégia de controle integrado de regulação de tensão e do fator de potência para um sistema de distribuição de energia elétrica usando uma rede de comunicação sem fio. A estratégia de controle proposta consiste em uma rede de comunicação entre os dispositivos designados para operarem reguladores de tensão, transformadores com comutadores sob carga e banco de capacitores, concentrando as informações em um único dispositivo capaz de definir a operação dos demais dispositivos alocados no sistema, sendo a concentração das informações feita localmente, sem a necessidade de um sistema de controle centralizado, permitindo uma simplificação e uma redução significativa de custo para implementação de uma solução de controle integrado de tensão e do fator de potência. A estratégia de controle proposta foi modelada no ambiente Matlab®/Simulink® e a rede de comunicação na ferramenta TrueTime. O estudo apresenta uma comparação entre a estratégia proposta e o método de controle tradicional, abordando aspectos relacionados a qualidade de energia elétrica entregue, demanda de energia em horários de alto consumo e perdas elétricas no sistema simulado. Os resultados mostram que a estratégia de controle local integrado de tensão e fator de potência permite a aplicação de banco de capacitores a jusante de reguladores de tensão sem impactar a qualidade de energia elétrica, ainda permite a técnica de redução de tensão com o intuito de reduzir a demanda de energia principalmente em horários de pico de consumo. E por fim apresenta uma redução de perdas elétricas de quase 4%, comparado com a estratégia de controle tradicional. / The issue about power quality, its rational use, and techniques to reduce electrical losses in the distribution systems is not anymore a trend but a necessity, due to, a understanding that the electricity is a common good, then, should not be wasted. Based on this context, strategies have been studying to control the voltage and power factor with the objective to improve the control of this variables. This work presents an integrated control for voltage and power factor strategy to distribution systems using a wireless network. The purposed strategy allows a communication between the devices designed to operate voltage regulators, on load transformers tap changers, and capacitors bank, concentrating all information in only one device, which is able to define the operation of others, being the concentration information made locally, without a necessity of the a centralize system, simplifying and reducing costs related the implementation of an integrated control for voltage and power factor. The strategy presented was modeled in the Matlab®/Simulink® and the communication network using the TrueTime toolbox. The study presents a comparison between the traditional strategy and the purposed, analyzing the power quality delivered, power demand in peak time, and electrical losses in the system. The results shows that the integrated control for voltage and power factor strategy allows the use of capacitors bank downstream of voltage regulators without any impact in the power quality supplied, besides that, it is possible to reduce the power demand lowering the voltage using the conservative voltage reduction function, to finish a reducing in electrical losses about 4% is achieved with the strategy purposed when compared with the traditional.

Made available in DSpace on 2014-06-11T19:30:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-15Bitstream added on 2014-06-13T19:40:17Z : No. of bitstreams: 1 soares_jo_dr_ilha.pdf: 2703269 bytes, checksum: f51d4821a6cb2c9c52cf4d25420d0c39 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O objetivo deste trabalho é a concepção de uma lógica de controle digital com modulação por histerese variável usando um dispositivo programável FPGA (Field Programmable Gate Array) e linguagem de descrição de hardware VHDL (Hardware Description Language), aplicada em um retificador trifásico híbrido para a obtenção do Fator de Potência (FP) de entrada quase unitário. O Retificador Trifásico Híbrido (RTH) é uma estrutura composta por um retificador a diodos de 6 pulsos e por três retificadores monofásicos SEPIC conectados em paralelo. O controle digital proposto é capaz de impor a forma de onda das correntes de entrada, obtendose Distorção Harmônica Total (DHT) reduzida e fator de potência (FP) quase unitário, sendo que nesta condição, os retificadores monofásicos SEPIC conduzirão no máximo 33% da potência ativa total. Além disso, o uso de FPGAs dará ao Retificador Híbrido Trifásico uma flexibilidade adicional na operação, podendo substituir vários sistemas de múltiplos pulsos convencionais e reduzir custos para o sistema de controle por eliminar a confecção de circuitos complexos de controle analógico, para os conversores chaveados. Neste trabalho, apresenta-se uma análise detalhada e metodologia de projeto para o Retificador Híbrido Trifásico (RTH) que possibilita relacionar o valor da DHT das correntes de entrada com os valores das potências média e aparente processadas pelas estruturas controlada e não-controlada, podendo-se prever o desempenho global do sistema. Serão apresentados detalhes sobre o funcionamento do código VHDL e da modulação por histerese variável empregada e, por fim, os resultados experimentais de um protótipo implementado para 3,0 kW. O código VHDL desenvolvido, associado à lógica de controle digital proposta, foi implementado através de um dispositivo FPGA da Xilinx – Spartan XC2S200E, módulo digilab-D2E... / The objective of this work is the development of a digital control logic with variable hysteresis modulation using a FPGA (Field Programmable Gate Array) device and VHDL (Hardware Description Language), applied at a hybrid three-phase rectifier in order to obtain an almost unitary input power factor (PF). The hybrid three-phase rectifier is a structure composed by parallel SEPIC controlled single-phase rectifiers connected to each leg of a standard 6-pulses uncontrolled diode rectifier. The proposed digital control is capable to impose input current waveforms, resulting in a reduced THD (Total Harmonic Distortion) and almost unitary input power factor, being that in this operation condition the parallel SEPIC single-phase rectifiers will process only 33.0 % of total active power. Moreover, the use of FPGA will provide to hybrid three-phase rectifier an additional flexbility in its operation, making possible the replacement of same conventional systems of multiple pulses and reducing costs for the control system, through the elimination of complex analogical circuitry used in the controlled converters. In this work is presented a detailed analysis and design methodology to hybrid threephase rectifier that establishes a relationship between the THD imposed to line input currents, with the average and apparent powers processed through controlled and uncontrolled structures, making possible to know previously the global system performance. It will be presented details about the operation of the VHDL code and variable hysteresis modulation proposed, and finally the experimental results from an implemented 3.0 kW prototype. The developed VHDL code, considering the proposed digital control logic, was implemented through a Xilinx’s FPGA device – Spartan XC2S200E, digilab-D2E module, whose generated control signals resulted in input currents with practically sinusoidal waveforms... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:30:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-14Bitstream added on 2014-06-13T20:00:55Z : No. of bitstreams: 1 melo_ga_dr_ilha.pdf: 5228605 bytes, checksum: 52731e96bb6ac0861b1e6187109bafa8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Esta tese apresenta o desenvolvimento e os principais resultados para um retificador monofásico pré-regulador ”boost” para aplicação em sistema trólebus, possibilitando sua alimentação em corrente alternada (CA) ou em corrente contínua (CC), mantendose o sistema tradicional de distribuição da alimentação a dois fios. A estrutura proposta é composta por um retificador monofásico convencional, conectado a um conversor “boost” entrelaçado com cinco células, operando no modo de condução descontínua (MCD), reduzindo as perdas de comutação no diodo “boost”, interferências eletromagnéticas (EMI - electromagnetic interference) e propiciando o controle de forma simples, robusta e confiável para a estrutura. Além disso, devido às características das linhas de distribuição, a estrutura proposta pode atuar como conversor CA para CC ou CC para CC, fornecendo nível de tensão dentro da faixa adequada para o barramento CC. Quando alimentado pelo sistema em CA monofásico, o conversor propicia elevado fator de potência com reduzida distorção harmônica total de corrente (DHTi), atendendo plenamente às restrições da norma internacional IEC 61000-3-4. Adicionalmente, uma técnica de correção para a corrente de entrada, utilizando referência da tensão de entrada, é utilizada para garantir os baixos níveis de distorção harmônica, uma vez que a operação do pré-regulador retificador “boost” entrelaçado em MCD ocorre com reduzido ganho estático. Para a implementação do controle da regulação de tensão e correção da corrente de entrada, é empregado um dispositivo FPGA (field programmable gate array) utilizando linguagem de descrição de hardware (VHDL - verilog hardware description language). Utilizando o mesmo dispositivo FPGA, foi desenvolvido um controle de gerenciamento da operação, promovendo a comutação automática quando... / This thesis presents the development and experimental analysis of a special input stage converter for a Trolleybus type vehicle allowing its operation in AC (two wires, singlephase) or DC distribution networks. The proposed input stage architecture is composed by a conventional single-phase rectifier connected with a five interleaved boost rectifiers operating in discontinuous conduction mode (DCM), avoiding commutation boost diode losses, electromagnetic interference (EMI) and promoting simple control actions, robustness and reliability for the structure. Furthermore, due to the power lines characteristics, the proposed input power structure can act as AC to DC or as DC to DC converter providing a proper DC output voltage range required to the DC bus. When operating as AC to DC, the converter is capable to provide high power factor with reduced input current harmonic distortion, complying with the imposed restrictions by IEC 61000-3-4 standard. In addition, a special input current correction technique, using input voltage reference, is employed in order to achieve low harmonic distortions considering operation with low voltage static gain for the DCM interleaved boost rectifier pre-regulator. For implementation of the output voltage control and input current correction was used a field programmable gate array (FPGA) device with verilog hardware description language (VHDL). In addition using the same FPGA device, a management control system was implemented, promoting the required automatic operation changes when the vehicle is commuted from the DC power supply to the AC power supply and viceversa, keeping the original electrical DC bus characteristics for the trolleybus. After a brief review, a development work process is presented, containing the design methodology with all needed mathematical expressions, simulations, control circuits, as well as a 3D Computer-Aided Designs... (Complete abstract click electronic access below)

Este trabalho apresenta o estudo, projeto e análise de um conversor monofásico-trifásico com compensação ativa de potência série-paralela, o qual é denominado de UPQC-Mono-Tri e indicado para aplicações em sistemas de eletrificação rurais monofásicos. O UPQC-Mono-Tri é composto por dois inversores PWM, um monofásico operando como filtro ativo de potência série (FAPS) e outro trifásico, no qual um dos braços inversores é conectado à carga e opera como filtro ativo de potência paralelo (FAPP). É adotada a estratégia de compensação dual para a topologia do UPQC proposta, na qual as malhas de controle de tensão e corrente operam com referências de controle senoidais. Desta forma, o FAPS opera como fonte de corrente senoidal, sincronizada com a tensão da rede elétrica monofásica, enquanto o FAPP opera como fonte de tensão senoidal equilibrada e regulada. São realizadas simulações computacionais com o objetivo de avaliar o desempenho da topologia proposta, bem como um protótipo experimental é construído a fim de confirmar o desenvolvimento teórico e validar a proposta deste trabalho. / This work presents a study, design and analysis of a single-phase to three-phase converter with series-parallel active power line compensation, which in this work is called UPQC-Mono-Tri. The proposed topology is indicated for application in rural areas, where only single-phase electric power distribution system is available. The UPQC is composed of two PWM converters, where the first operates as series active power filter (SAPF), while the second is composed of a three-phase inverter, which is implemented by means of three half-bridge inverters. One of the half-bridge inverters is connected to the load and also operates as parallel active power filter (PAPF). The dual compensation strategy is adopted for the proposed UPQC topology, in which both series and parallel controllers handle only sinusoidal references. The SAPF operates as sinusoidal current source synchronized with the utility grid voltage, while the PAPF operates as sinusoidal voltage source providing sinusoidal, balanced and regulated voltages to single or three-phase loads. Simulations are performed in order to evaluate the proposed topology performance, as well as an experimental prototype is built to confirm the theoretical development, and validate the proposed work.

O motor de indução é, talvez, o mais robusto e, certamente, um dos motores mais comumente usados. Graças à simplicidade de sua construção, do seu baixo custo, confiabilidade e rendimento relativamente alto com carga nominal é provável que ele permaneça sendo a principal fonte de transformação de energia elétrica em energia mecânica nas aplicações industriais e comerciais por um futuro previsível. O estudo de economia de energia pela redução de perdas é o objetivo do presente estudo. Os motores de indução operam regularmente com fluxo quase constante no entreferro e, portanto, com perdas magnéticas quase constantes. A utilização de um circuito gradador de tensão em série com a alimentação do motor para reduzir o fluxo no entreferro pela redução da tensão aplicada quando a carga não requer fluxo total é o objeto de análise neste estudo. Com a redução da tensão, para manter o conjugado de operação, a velocidade de rotação diminui, ou seja, há um aumento no escorregamento até um valor ótimo para reduzir as perdas totais. Então, esperaria-se que com a redução da tensão aplicada, as perdas magnéticas decresceriam e a eficiência total cresceria. Via de regra, no motor de indução, dada a característica mergulhante de sua curva Conjugado x Velocidade na região em torno da velocidade nominal, o conjugado varia muito mais que a velocidade. Para operação eficiente, a sua tensão aplicada deve ser função da carga que traciona. É objetivo desse trabalho estudar um dispositivo que, colocado em série com a fonte de alimentação de um motor de indução de CA, promove a redução de potência fornecida ao motor, quando a carga aplicada ao motor é menor que a carga nominal. Uma análise da redução da tensão senoidal aplicada através de um auto-transformador de tensão variável é comparada com a redução da tensão através de um circuito gradador baseado em tiristores. A melhor tensão a ser obtida é a que reduz as perdas magnéticas ao mínimo, para cargas que não requerem o fluxo total no entreferro como quando da tensão nominal aplicada. As limitações do processo são estudadas e apresentadas. / The induction motor is perhaps the most rugged, and certainly one of the most commonly used motors. With simply construction, low cost, reliability and efficiency relatively high with rated-load it seems to be a good way to convert electric energy into mechanical energy for industrial and domestic applications for a predictable future. An economy in energy consumption by loss reduction is the goal of this study. The induction motors as normal operate with constant flux in the air-gap and, hence with almost constant losses in the core. The use of a voltage gradador circuit in series with the voltage source applied to the motor for flux reduction in the air-gap by reduction of the voltage when the load do not need full-flux is this study proposal. Hence, with applied voltage reduction, to keep the operational torque, the motor rotation decreases or the slip increases to an optimum value to reduce the total core losses and increase the efficiency. As a rule, the induction motor, by the dip characteristic of the torque x speed curve in the region near the nominal speed, the torque changes much more then the speed. For efficient operation, the applied voltage should be a function of the load. It is the goal or aim of this work to study a device which, when placed in series with the power input of an alternating current induction motor, will produce a reduction in power normally provided to the motor when operated in either a condition where motor loading is less than a rated load. An analysis of voltage ideal sine wave supply reduction applied by an autotransformer with variable voltage is compared with the voltage reduction using a gradador circuit based on thyristors. The optimal voltage operation is the one that decrease the iron losses to minimum, for partial-load that do not need full-flux in the air-gap as when the full voltage is applied. Limitations in the process are investigated and will be showed.