Dissertations / Theses on the topic 'PMG and rectifier system'

Wave energy converter (WEC) harnesses energy from the ocean to produce electrical power. The electrical power produced by the WEC is fluctuating and is not maximized as well, due to the varying ocean conditions. As a consequence, without any intermediate power conversion stage, the output power from the WEC can not be fed into the grid. To feed WEC output power into the grid, a two-stage power conversion topology is used, where the WEC output power is first converted into DCpower through rectification, and then a DC-AC converter (inverter) is used to supply AC power into the grid. The main motive of this research is to extract maximum electrical power from the WEC by active rectification and smoothing the power fluctuation of the wave energy converter through a hybrid energy storage system consisting of battery and flywheel. This research also illustrates active and reactive power injection to the grid according to load demand through a voltage source inverter.

Lithium-ion based battery energy storage system has become one of the most popular forms of energy storage system for its high charge and discharge efficiency and high energy density. This dissertation proposes a high-efficiency grid-tie lithium-ion battery based energy storage system, which consists of a LiFePO4 battery based energy storage and associated battery management system (BMS), a high-efficiency bidirectional ac-dc converter and the central control unit which controls the operation mode and grid interface of the energy storage system. The BMS estimates the state of charge (SOC) and state of health (SOH) of each battery cell in the pack and applies active charge equalization to balance the charge of all the cells in the pack. The bidirectional ac-dc converter works as the interface between the battery pack and the ac grid, which needs to meet the requirements of bidirectional power flow capability and to ensure high power factor and low THD as well as to regulate the dc side power regulation. A highly efficient dual-buck converter based bidirectional ac-dc converter is proposed. The implemented converter efficiency peaks at 97.8% at 50-kHz switching frequency for both rectifier and inverter modes. To better utilize the dc bus voltage and eliminate the two dc bus bulk capacitors in the conventional dual-buck converter, a novel bidirectional ac-dc converter is proposed by replacing the capacitor leg of the dual-buck converter based single-phase bidirectional ac-dc converter with a half-bridge switch leg. Based on the single-phase bidirectional ac-dc converter topology, three novel three-phase bidirectional ac-dc converter topologies are proposed. In order to control the bidirectional power flow and at the same time stabilize the system in mode transition, an admittance compensator along with a quasi-proportional-resonant (QPR) controller is adopted to allow smooth startup and elimination of the steady-state error over the entire load range. The proposed QPR controller is designed and implemented with a digital controller. The entire system has been simulated in both PSIM and Simulink and verified with hardware experiments. Small transient currents are observed with the power transferred from rectifier mode to inverter mode at peak current point and also from inverter mode to rectifier mode at peak current point. The designed BMS monitors and reports all battery cells parameters in the pack and estimates the SOC of each battery cell by using the Coulomb counting plus an accurate open-circuit voltage model. The SOC information is then used to control the isolated bidirectional dc-dc converter based active cell balancing circuits to mitigate the mismatch among the series connected cells. Using the proposed SOC balancing technique, the entire battery storage system has demonstrated more capacity than the system without SOC balancing.<br>Ph. D.

A wide variety of group III-Nitride-based photonic and electronic devices have opened a new era in the field of semiconductor research in the past ten years. The direct and large bandgap nature, intrinsic high carrier mobility, and the capability of forming heterostructures allow them to dominate photonic and electronic device market such as light emitters, photodiodes, or high-speed/high-power electronic devices. Avalanche photodiodes (APDs) based on group III-Nitrides materials are of interest due to potential capabilities for low dark current densities, high sensitivities and high optical gains in the ultraviolet (UV) spectral region. Wide-bandgap GaN-based APDs are excellent candidates for short-wavelength photodetectors because they have the capability for cut-off wavelengths in the UV spectral region (λ < 290 nm). These intrinsically solar-blind UV APDs will not require filters to operate in the solar-blind spectral regime of λ < 290 nm. For the growth of GaN-based heteroepitaxial layers on lattice-mismatched substrates, a high density of defects is usually introduced during the growth; thereby, causing a device failure by premature microplasma, which has been a major issue for GaN-based APDs. The extensive research on epitaxial growth and optimization of Al_x Ga _1-x N (0 ≤ x ≤ 1) grown on low dislocation density native bulk III-N substrates have brought UV APDs into realization. GaN and AlGaN UV <i> p-i-n </i> APDs demonstrated first and record-high true avalanche gain of > 10,000 and 50, respectively. The large stable optical gains are attributed to the improved crystalline quality of epitaxial layers grown on low dislocation density bulk substrates. GaN <i>p-i-n </i> rectifiers have brought much research interest due to its superior physical properties. The AIN-free full-vertical GaN<i> p-i-n </i> rectifiers on<i> n </i>- type 6H-SiC substrates by employing a conducting AIGaN:Si buffer layer provides the advantages of the reduction of sidewall damage from plasma etching and lower forward resistance due to the reduction of current crowding at the bottom<i> n </i> -type layer. The AlGaN:Si nucleation layer was proven to provide excellent electrical properties while also acting as a good buffer role for subsequent GaN growth. The reverse breakdown voltage for a relatively thin 2.5 μm-thick<i> i </i>-region was found to be over -400V.

Near-field wireless power transfer (WPT) technology facilitates the energy autonomy of heterogeneous systems, significantly augmenting complementary metal-oxide-semiconductor field-effect-transistor (CMOS) technology. In low-power wearable devices, existing power conditioning integrated circuits do not maximize the power factor (PF) for rectification and power conversion efficiency (PCE) due to multiple conversion. Additionally, there is no core power management for the entire power flow. The majority of the research focuses on active rectifiers, which reduce the turn-on voltage for rectification. Certain studies target the output voltage regulation via feedback to the transmitter or direct battery charging without power maximization. Firstly, this study investigates a high-power factor WPT front-end circuit that is namely the mono-periodic switching rectifier (MPSR) and implemented in a 0.18µm 1.8V/5V CMOS process. Integrated phase synchronizers are used to align the waveshape of a wirelessly-coupled sinusoidal voltage source in a receiving coil to the corresponding conducting current. Using this approach, the PF can be increased from roughly 0.6 to unity without requiring any wireless or wired feedback to the transmitter. The proposed MPSR can also provide AC-DC rectification, and step up and down the sinusoidal voltage source's peak amplitude using a pulse-width modulator. Measured voltage conversion ratios range between 0.73X and 2X, and the PF can be boosted up to unity. Secondly, the wireless power system-on-chip (WPower-SoC) is proposed and implemented in a 0.18µm 1.8V/3.3V CMOS process. The WPower-SoC integrating power management can provide rectification, output voltage regulation, and battery charging. Additionally, the implementation of feedforward envelope detection (FED) can reduce the variation in a wireless power link and improve load transient responses. Simulated results demonstrate that 5% of the output voltage regulation is improved when an output load changes. Moreover, the FED reduces approximately 40% of the transient response time. Overshoot and undershoot voltages are decreased by 23% and 26.5%, respectively. The measured output voltage regulates at 3.42V and can supply output power up to 342mW. A temperature sensor as part of the power management core remains active when the WPT receivers enter sleep mode to prolong the battery usage time. In the final part of this study, a nano-watt high-accuracy temperature sensing core is implemented in a 0.18µm 1.8V/3.3V CMOS process that can self-compensate the temperature shift without the need for additional compensating techniques that consume extra power.

Ce mémoire montre la faisabilité d'une technique de commande des convertisseurs statiques, utilisant les réseaux de Petri (RDP). L'originalité de ce travail réside dans l'utilisation de RDP colorés et temporisés pour la modélisation. Deux exemples sont retenus. Le modèle du redresseur triphasé à thyristors est présenté de manière que l'on puisse analyser les valeurs de l'angle de retard d'allumage ; des temporisations de durées variables permettent de simuler la variation de la tension redressée. Le modèle de l'onduleur autonome évolue dynamiquement à la fréquence souhaitée ; le changement de la durée des temporisations associées aux transitions conduit au changement de la fréquence de sortie de l'onduleur. L'étude effectuée sur l'ensemble redresseur-onduleur machine-asynchrone nous permet d'envisager une stratégie de fonctionnement en vitesse de rotation variable, fondée sur une commande algorithmique des temporisations, conformément à l'asservissement donné. Nous avons réalisé une maquette de redresseur à thyristors liée à un ordinateur. La commande est gérée par RDP synchronisé. Elle ouvre des perspectives pour une nouvelle technique de commande des convertisseurs statiques.

Esta dissertação apresenta uma proposta de integração sistêmica da automação das subestações retificadoras do sistema metrô-ferroviário brasileiro. Esta dissertação também apresenta os ganhos de confiabilidade que podem ser obtidos, caso a mesma seja implementada, e a priorização da eficiência de operação do sistema em questão. A motivação deste trabalho deve-se à necessidade de atender à perspectiva de aumento de demanda de energia elétrica nos processos de expansão e modernização deste sistema, amplamente usado pela população brasileira. A partir do estudo e análise do atual sistema de automação existente nas subestações do sistema metrô-ferroviário brasileiro, da arquitetura de hardware e software, foi possível investigar como a integração dos dados pertencentes aos sistemas de controle da subestação e do Centro de Controle Operacional CCO - pode permitir o aumento da confiabilidade e da flexibilidade de operação. Para quantificar estes ganhos de confiabilidade é apresentado o desenvolvimento do modelo de confiabilidade de Markov aplicado ao sistema de automação de subestações retificadoras. A metodologia utilizada procedeu ao levantamento e análise das ocorrências abertas nos anos de 2006, 2007 e 2008 nas subestações retificadoras do metrô de São Paulo, calculando o seu MTBF (Mean Time Between Failures). O estudo conclui que o ganho de confiabilidade é significativo no que se refere à melhoria do transporte público com a aplicação da integração da automação das subestações retificadoras.<br>This dissertation there presents a proposal for the integrated automation of the Brazilian subway system rectifier substations, supported on the gains of reliability which may be obtained in case it is implemented, and in the improvement of the efficiency of operation of the system open to question. The inquiry was supporting in the necessity of paying attention to the perspective of increase of demand of electric energy in the processes of expansion and modernization of this system, widely used by the Brazilian population. From the study and analysis of the current system of existent automation in the substations of the system Brazilian subway, of the architecture of hardware and software, was possible to investigate like the integration of the pertaining data to the systems of control of the substation and of the Centre of Operational Control CCO can allow the increase of the reliability and of the flexibility of operation. To quantify these profits of reliability there is presented the development of the model of reliability of Markov devoted to the system of automation of rectifying substations. The used methodology proceeded to the lifting and analysis of the incidents when they were opened in the years of 2006, 2007 and 2008 in the rectifier substations of the subway of Sao Paulo, calculating the MTBF (Mean Time Between Failures). The study ends that the profit of reliability is significant in what it refers to the improvement of public transport with the application of the integration of the automation of the rectifying substations.

DC power systems have a constant DC-link voltage, as well as the advantages such as high stability, high efficiency, small size and light weight; therefore, they are widely used in stand-alone power systems, e.g. the power systems in aircrafts and automobiles, isolated wind power generation systems, etc. Permanent-Magnet Synchronous Generators (PMSGs) possess the advantages including high power density, high efficiency, and high control precision, and have obtained great attention and have been widely used in military, inductry, and daily life. Pulse Width Modulation (PWM) rectifier has been one of the main power conversion topologies thanks to its full controllability. The key point in the dissertation is to study the DC power system consisting of a PMSG to be the main power input device and a PWM rectifier to be the main power conversion topology. The objective of control is to output a constant DC-link voltage in a wide PMSG speed range. Since the PM-excited flux linkage is constant, when the PMSG is working at a high speed, field-weakening is needed to stabilize the stator voltage, further to stabilize the DC-link voltage. Hybrid excitation may be used to realize the field-weakening, but it has complex structure; no auxiliary devices are needed in the field regulation with the armature current, and can be easily realized with the PWM recifier and field-regulation control strategies. In this dissertation, the typical applications of the DC power systems are first introduced, with a comprehensive analysis and elaboration on the relevant research throughout the world. The research work is focused on the DC power system and its stabilization control, which is composed of a PMSG and a PWM rectifier. The involved research content in this dissertation includes the following aspects: 1. DC power system design with a wide-speed-range PMSGAs for the common DC power systems, PMSG with high power density, high efficiency is selected to the system power input device, usually with a variable-speed prime mover. The PWM rectifier with fully controlled switches is chosen to be the power conversion topology, which converts the AC power generated by PMSG into DC power, and supplies the DC load after the DC filter. The matching between the system requirements and the generator parameters are determined. Through finite-element analysis (FEA), a PMSG with strong field-weakening ability and suitable for wide-speed-range operation has been designed and manufactured, and the system test bench has been built based on dSPACE. 2. Study, analysis, optimization and experimental verification of the traditional control strategiesAccording to the PMSG designed in part 1, the DC-link model has been built, as well as the control model of the traditional control strategies, e.g. field-oriented control (FOC), direct torque control (DTC), and the effectiveness of the DC-link voltage stabilization control has been verified in a wide speed range. The theory of active damping has been proposed and analyzed, and has been utilized in the DC-link voltage control. When the load on the DC-link changes, the dynamic response of the DC-link voltage has been greatly accelerated, and it recovers quickly to its reference value. In the meantime, the performance influence of the prime mover speed on the actual system test bench should be considered. Finally, the performance of FOC and DTC has been compared and analyzed. 3. Analysis and experimental verification of the direct voltage control (DVC), and the comparative study of all the studied control strategiesThe derivation process of DVC has been theoretically analyzed: the inner current loops in FOC have been eliminated to obtain the direct voltage field-oriented control (DVFOC); the reference value of d-axis voltage in DVFOC has been replaced by the product of the stator voltage calculated by the speed and the load condition, and the sine value of load angle generated by the DC-link voltage PI controller, in order to form the DVC-1. Further, the DC-link voltage PI controller directly outputs the reference value of load angle and it becomes DVC-2. Finally, the comparative study has been carried out among all the studied control strategies.<br>Doctorat en Sciences de l'ingénieur et technologie<br>info:eu-repo/semantics/nonPublished

I denna rapport utreds hur systemdesignen av lågspänningsfördelningen för järnvägen kan kostnadseffektiviseras. I dagsläget har det utarbetats en norm kring systemdesignen som tenderar att efterbildas från år till år vilket har medfört brist på innovation inom området. Syftet med arbetet var att designa två typstationer med signalställverken M11 respektive M95, där placering samt nominell storlek av UPS:er skulle fastställas för att tillhandahålla en kostnadseffektiv lösning. Dessutom skulle kablage dimensioneras för typstationerna samt se över möjligheten att ersätta UPS:er med likriktarsystem. Stationerna baserades på två redan existerande driftplatser, Fagersta C (M11) och Skänninge (M95). Slutligen skulle olika energilagringsalternativ för UPS-system jämföras för att tillhandahålla det lämpligaste alternativet. Genom simuleringar och beräkningar i bland annat datorprogrammet El-Vis har lågspänningsfördelningen dimensionerats för typstationerna. Arbetet visar på att ett distribuerat UPS-system är att föredra ur ett ekonomiskt perspektiv gentemot ett centraliserat UPS-system. Vidare har det konstaterats att likriktarsystemet Rectiverter kan ersätta UPS:er samt att ackumulatorer är det mest passande energilagringsalternativet.<br>This report identifies how the system design of low voltage power distribution of the railway can be more cost effective. In the current situation there is a norm on the system design that tends to be replicated each year. This has brought a lack of innovation in the field. The purpose of the thesis was to come up with two model stations with the interlocking system M11 respectively M95, where the positioning and nominal size of the UPS:s would be determined to provide a cost effective solution. Furthermore, the cable dimensioning of the model stations was computed as well as the possibility of replacing UPS-systems with rectifier-systems. The model stations were based on two already existing operating sites, Fagersta C (M11) and Skänninge (M95). Lastly, different energy storage alternatives for UPS-systems were compared to acquire the most appropriate choice. Through simulations and calculations in, inter alia, the computer program El-Vis, the low voltage power distribution was dimensioned for the model stations. The thesis shows that a distributed UPS-system is preferred in an economical point of view compared to a centralized UPS-system. Furthermore, the thesis establishes that the rectifier system Rectiverter can replace UPS:s. It also states that accumulators are the most suitable alternative for energy storage.

This diploma thesis is focused on the design of a rotating rectifier for a synchronous generator. Based on defined requirements, the new rotating rectifier concept has been created that allows a greater current range than existing rectifier used by Siemens Electric Machines s.r.o. The thesis is divided into five parts. The first part deals with the search of existing rotating rectifiers and other design possibilities. The requirements for the rotating rectifier were defined in the second part of the thesis. The following section deals with both electrical design of rectifier elements and varistors. The fourth part of the diploma thesis describes the thermal analysis. On the basis of thermal analysis the operating conditions of the rotating rectifier were determined. The last part of the thesis is devoted to mechanical and modal analysis. Based on these analyses, the strength and operability of the new rotating rectifier concept were verified.

Méthode de résolution des équations du système modélisé, indépendante de son environnement électrique, donnant un programme modulaire, utilisable dans un ensemble plus complexe. Extension de la méthode et procédure d'identification des paramètres. Expérimentation en fonctionnement redresseur et gradateur

Made available in DSpace on 2016-08-17T14:53:10Z (GMT). No. of bitstreams: 1 Bernardo Nogueira Neto.pdf: 936161 bytes, checksum: 8cae25f84e9e07f78244f10040d97213 (MD5) Previous issue date: 2010-06-04<br>In this dissertation, we explore the application of the Theory of System Identification to develop a mathematical model that represents the behavior of the electrical current rectifier used to power the traction motors of a locomotive diesel-electric, based on mathematical manipulation of its temperature data. It was developed an ARX model and, using the aid of the computational system identification toolbox of MATLAB ®, simulations were made for estimation and validation of the order of the model that best describes the dynamic response of the physical system. The input and output data of the rectifier are obtained from the direct measurement of the output current of main generator, which is the input, and from the measurement of the temperature on the rectifier, which corresponds to the output. These data are used in developing the mathematical model of the system under study. The goal is to obtain a model that best represents the behavior of the main engine rectifier, allowing control actions to optimize the relation between supplied and required power of locomotive, so that downtime events resulting from self-protection mechanisms against high temperatures during operation of the rectifier in severe operations are minimized. As a result, we have a more advanced and efficient model that allows a strategy to monitoring the equipment at the various points of operation, considering their variation and ensuring a stable and safety locomotive's operation.<br>Nesta dissertação, aborda-se a aplicação da Teoria de Identificação de Sistemas para escolha de um modelo polinomial, que represente o comportamento do retificador de corrente elétrica, utilizado para suprimento dos motores de tração de uma locomotiva dieselelétrica, a partir da manipulação matemática de seus dados de temperatura. Desenvolve-se um modelo ARX e, com auxílio da ferramenta computacional do toolbox de identificação do MATLAB®, são feitas simulações para estimação e validação da ordem do modelo que melhor descreva a resposta dinâmica do sistema físico. Os dados de entrada e saída do retificador são obtidos a partir da medição direta da corrente de saída do gerador principal, que corresponde à entrada, e da medição da temperatura na bancada retificadora, que corresponde à saída. Estes dados são utilizados na elaboração do modelo matemático do sistema em estudo. Busca-se obter um modelo matemático que represente o comportamento do retificador principal da locomotiva, possibilitando ações de controle para uma melhor otimização entre a potência fornecida e a requerida para tração, de tal forma que os eventos de downtime, decorrentes da atuação da proteção contra altas temperaturas do retificador durante operações em regimes severos, sejam minimizados. Como resultado, tem-se um método mais avançado, eficaz e que possibilita uma estratégia de monitoramento nos diversos pontos de operação do equipamento, considerando suas variações e garantindo uma operação estável e segura do sistema.

L'augmentation considérable ces dernières années du nombre de convertisseur sur le réseau d'alimentation se traduit par la nécessite de s'intéresser a la compatibilité entre les convertisseurs et le réseau. Le redresseur à mli est un convertisseur dont les caractéristiques lui permettent d'absorber des courants réseaux sinusoïdaux, et d'échanger de la puissance active et réactive avec le réseau. Le présent travail concerne l'étude de la modélisation et la commande de ce convertisseur ainsi que l'extension au cas d'un réseau déséquilibre. Le redresseur est contrôlé par une régulation cascade: des boucles internes régulent les courants réseaux, une boucle externe régule la tension de capacité. Les conséquences de l'apparition d'une perturbation de type creux de tension (distorsion harmonique sur les courants réseaux, oscillation a l'harmonique 2 des composantes continues) sont analysées puis simulées et vérifiées expérimentalement. Deux solutions sont étudiées: - une compensation s'appuyant sur une étude théorique du système. - la construction d'un régulateur robuste appliquant le principe du modèle interne de Wohnam et la méthode de placement de pôles par -stabilité. Les avantages obtenus permettent d'envisager une meilleure continuité de fonctionnement face aux creux de tension, un dimensionnement réduit du convertisseur, et la conservation des performances. Les domaines d'application concernes sont varies. Dans le domaine industriel, il s'agit des alimentations à bon facteur de puissance ou des procédés nécessitant le réglage du réactif

The growth of embedded generation and portable electrical installations has led to an increased demand for low cost, flexible and reliable generator systems for military and commercial applications. An interior permanent magnet (IPM) machine has high power density due to its reluctance torque and magnetic torque components so it can produce a large constant power-speed range. However, an IPM machine needs demagnetizing current at high-speed during the flux-weakening region and thus develops an inverter shutdown problem in an uncontrolled generator mode operation. In order to overcome the disadvantages of the IPM machine, the permanent magnet assisted synchronous reluctance generator (PMa-SynRG) can be a good solution for low cost, high efficiency reliable generator systems. A PMa-SynRG can produce a high efficiency drive by utilizing the proper amount of magnet and reluctance torque. This work proposes a PMa-SynRG with two flux barriers and permanent magnets embedded in the second layer of the rotor. A neodymium magnet (NdFeB) was used as permanent magnets in the rotor to prevent demagnetization. Finding the minimum amount of magnet is one of the goals of the optimization process. The objectives of this work are to build an optimal design for the 3kW generator and an advanced power electronics converter for the PMa-SynRG drive system. In order to find the optimized 3kW machine, a Lumped Parameter Model (LPM) was used to achieve fast computation, and Differential Evolution Strategy (DES) was used to embed the LPM in an efficient numerical optimization routine to identify optimum designs. Finite Element Analysis (FEA) was used for test performance of optimum designs. On the basis of differences between LPM and FEA, model predictions were used to fine tune the LPM model. For new optimum design converges, numerical optimizations and iterations were performed to produce LPM and FEA predictions. For the drive system, the thyristor based, current-fed drive is much simpler and has lower power losses compared to the pulse width modulation (PWM) drive. Eliminating the requirement for self-controlled switches is a distinct advantage for lower cost. Another feature of the developed current-fed drive is its inherent capability to provide generating action by making the PMa-SynRG operates as a generator, rectifying the phase voltages by means of the three-phase rectifier and feeding the power into the load. These features make the current-fed drive a good candidate for driving any type of synchronous generators including the proposed PMa-SynRG.

Thesis (M.S.)--University of Wisconsin--Madison, 1995.<br>Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 57-59).

Line current distortion is an important issue to a high-power current source rectifier(CSR) system. There are two main challenges related to this issue. First, the CSR input LC resonance can be affected by the variation of the source inductance from the power system and the effects of the CSR DC side circuit, which may lead to a line current distortion higher than expected. Another challenge is that the traditional high-power CSR using Selective Harmonic Elimination (SHE) pulse-width modulation (PWM) technique attempts to eliminate certain harmonics in the PWM current, which limits its ability for line current harmonic control. To control the CSR line current harmonics, this thesis focuses on two aspects: 1) the analysis and design of CSR input filter to avoid unexpected input LC resonance, and 2) the development of a new PWM scheme that can compensate the effects of the grid voltage harmonics and DC link current ripples. The thesis work has been validated by simulations and on an experimental CSR prototype.<br>Power Engineering and Power Electronics

碩士<br>義守大學<br>電子工程學系<br>91<br>This thesis presents the Study and Implementation of DSP-Based Internet-Remote-Control Distributed Telecommunication Power System. The conventional power factor correction circuit has fixed output voltage. It was almost used diode converter. But, the input current is not real and causing low power factor. Power factor correct circuit with a changeable output voltage range is needful. The proposed control implemented using DSP chip EVM control card. The controller uses the TMS320F240 of TI company as the main control unit and produces the on and off and PWM signal. Combined with protecting signal chopping signal, it can control the IGBT on and off. The control software was programmed. The modular program can make the program universal and readable.

碩士<br>國立中正大學<br>電機工程研究所<br>104<br>This thesis completes a rectifier. It applied to the input of the piezoelectric energy harvesting and has a tracking system of fast maximum power point. The piezoelectric material is converted into AC power through deformed way. Therefore the alternating current into direct current power needs to the rectifier for the back-end energy processing. The conventional rectifier is as rectifying element by diode, its properties will be affected by the threshold voltage. It results in poor efficiency of rectification. The most important solution of the research is how to improve the conversional efficiency of the rectifier. Therefore, this thesis presents a technique about Synchronized Switch Harvesting on Inductor, (SSHI). To overcome the barrier voltage of traditional diode circuit causes poor efficiency of conversion. Then rectifier architecture uses active diodes with cross-coupled. Compared to other literature, this thesis proposed control circuits. It has the lower complexity of circuit, and produces optimal on-time to control the resonant circuit inductor for operating in optimum switching state. It gets the maximum efficiency. This high efficiency rectifier circuit with maximum power tracking circuit increases the availability of the overall energy harvesting system. Mostly, the conventional method of the maximum power point tracking circuit uses perturbation and observation method. But this approach needs to take tens to hundreds of cycles until track the maximum power point, causing unnecessary power consumption. Therefore, this thesis discusses the characteristics of the piezoelectric energy maximum power point. According to its characteristic design, it provides fast maximum power point tracking in one cycle of PE transducer. Compared to other MPPT method, the thesis achieved maximum power point tracking technology quickly. It can improve the efficiency of processing power and can achieve in energy harvesting systems suitably. Finally, the chip is implemented by Taiwan Semiconductor Manufacturing Company (TSMC) 0.35μm 2P4M CMOS mixed-signal polycide process. The package of chip is 40S/B and the die area of the proposed chip is 1.500×1.499 mm2.

碩士<br>國立臺灣大學<br>工程科學及海洋工程學研究所<br>107<br>With the rise of the Internet of Things (IoT), there are more and more sensors applied around us. These sensors collect data from the environment, and further form a smart network if connected to other devices. In recently years, the total number of active device connections worldwide is reaching 7 billion. If the sensors are powered by batteries, the limited lifetime can cause numerous abandoned batteries, which may seriously polluting the environment. To solve these issues, installing piezoelectric transducers around vibration sources such as motors or engines can help us to harvest the environmental energy to the storage capacitor, which can further power the IoT wireless sensors. The piezoelectric energy harvesting system includes piezoelectric transducer, interface circuits and storage capacitor, where interface circuits are usually contain rectifier, AC-DC converter and DC-DC converter. Firstly, piezoelectric transducer converts the vibrational energy into AC electric signal through piezoelectric effect. Then convert the AC signal into a DC signal through the rectifier. Finally, the energy is output to the storage capacitor through a DC-DC converter in order to provide a stable DC source to the connected sensors. The common AC-DC converters for piezoelectric energy harvesting system include standard interface circuit, SSHI, SECE etc. On the other hand, the common DC-DC converter include buck converter, low-dropout regulator(LDO regulator), switched-capacitor circuit, and so on. This paper dedicates to circuit design and chip implementation of AC-DC converter. In 2017, our research team and French research team in INSA Lyon jointly proposed a piezoelectric energy harvesting interface circuit, Synchronous Inversion and Charge Extraction (SICE) circuit, which performs breakthrough output power gain, load independent characteristic and wider range of applications. The author of this paper further propose a novel SICE interface circuit architecture, and successfully implement the first SICE circuit chip. The proposed architecture achieve load independence, HV (High-voltage) process and high output power gain by only four MOSFET switches and one inductor. The chip is implemented by TSMC 0.25μm HV CMOS process, realized by research methods such as circuit simulation, discrete circuit experiment and chip design. According to post-simulation results, the output power of the chip is 42.4μW and the FOM value is 78.2% when operating with a piezoelectric transducer under a certain condition as follow: current source amplitude 22.5μA, operating frequency 120Hz and internal parasitic capacitance 15nF. By the proposed SICE architecture, the chip can draw more power from piezoelectric transducers. Compared to the standard interface circuit, the proposed novel SICE circuit provides 586% power gain. On the chip measurement side, the discrete components have undesirable parasitic effects, which can reduce the inversion factor. The output power of the implemented chip is 27.3μW, and the FOM value is 75.6%. Finally, measurement and function verification of a SECE (Synchronous Electric Charge Extraction) rectifier chip, which had been implemented by our research team member, will be done in this paper. Some sub-circuits optimization will be finished as well.

碩士<br>國立中興大學<br>電機工程學系所<br>106<br>There has been increasing attention to the issue of energy problem, more and more people pay concern on energy harvesters. Thus how to extract power from the environment become a discussed issue. There are two ways for using these energy, first way is to save it in the battery. Second way is to harvest stable energy from the environment and supply to chips. As an instance, this thesis takes vibration as the topic and focus on the piezoelectric energy harvesting systems. Besides, energy harvest from piezoelectric material is normally ac power, energy is also small. As a result, how to design a high-efficiency rectifier to reduce energy loss during the rectifying region is an important problem. In this thesis introduces two high-efficiency ac to dc rectifiers. Besides, the designed circuits can start up without other batteries, the energy used in circuits is all provided by piezoelectric material. The first circuit proposed in this thesis is an active AC-DC rectifier with synchronous comparators controlled circuit. With four common-gate comparators to detect the relation between input and output voltage. Then synchronous controlled circuit will control the signal used on power MOS in order to reduce the power loss of piezoelectric source. The circuit is fabricated with TSMC 0.25μm 1P3M processes. The experimental results show that when input voltage is 5V and 240Hz, the maximum voltage conversion ratio can reach 93% at 200kΩ loading, and the maximum power efficiency is 86.6% at 10kΩ loading. The second circuit proposed an active AC-DC rectifier with non-overlap circuit. This circuit detect positive and negative cycle by a voltage comparator, and output N power MOS signal. Then the circuit detect the input and output voltage by two common-gate comparators to control P power MOS. Besides, there is a non-overlap circuit used on N power MOS to prevent power loss when two N power MOS conduct at the same while. The circuit is also fabricated with TSMC 0.25μm 1P3M processes. Compared to the previous work, the measurement results show that the maximum voltage conversion ratio can reach 99% at 200kΩ loading, and the maximum power efficiency is 93.85% at 20kΩ loading.

碩士<br>國立中興大學<br>電機工程學系所<br>104<br>In this thesis, it focuses on the relevant circuit design of receiver in wireless power transfer system. In wireless power transmission, the transmission terminal transmits power to coil, and the coil will transmits those power to receiver by induction or resonance effect to achieve non-contact power transmission. There are two main designs in receiver circuit. One is AC/DC converter that makes the ac voltage from coil be changed to dc voltage. And another is DC/DC converter that changes the dc voltage into another dc voltage that we need. In DC/DC converter, I use the architecture of switching regulator and adopt the pulse width modulation to control the power MOS on or off to achieve effective regulator. It is designed using TSMC 0.25um high voltage process, which input voltage is 60 V, output voltage is 5 V, and withstanding current capability is 1 A. In addition, it also designs the buck regulator by PCB component in the thesis, which input voltage is 10 ~65 V, output voltage is 5 V, withstanding current capability is 1.5 A, and its efficient is up to 84%. In AC/DC converter, I use the class-E rectifier rather than traditional circuit of bridge rectifier. In bridge rectifier, it will cause switching loss because of diode with frequency rising. And class-E rectifier will reduce the switching loss to achieve higher efficiency.

碩士<br>中原大學<br>電機工程研究所<br>95<br>This thesis is focused on developing a rectifier and inverter structure for a grid-connected solar photovoltaic (PV) system. The three-armed type of rectifier and inverter is adopted as the main structure of the system, due to its high efficiency、easy operating strategy, and voltage regulating properties. The solar energy can be more effectively employed as a reliable power supply. In order to reduce complexity of circuit design and system control, the digital signal processor (DSP) is used by means of its high calculating speed, simple syntax for programming as a control core of the system. Anticipated is the effective control of the rectifier and inverter structure for a grid-connected solar photovoltaic system. As the grid supplies the load demand through the three-armed type of rectifier and inverter, energy conversion losses therein occurs. As a result, efficiency of the whole system is degraded. To improve the drawback, four switching modes are proposed and implemented in the system as control strategies. In addition to eliminating the drawback and ameliorating the system efficiency, the integration of battery in the system further equips the system with the characteristics of the uninterruptible power supply (UPS). To verify the performance of the proposed system, effectiveness of the energy balancing among solar PV, grid power, and load demand is examined. On the other hand, to investigate the function of load voltage regulating, an auto-transformer is used to change the voltage on the grid terminal. The performance of reliable voltage supplying capability of the system can thus be demonstrated. Experimental results reveal that the feasibility of the proposed system is proved in the automatic energy balancing and the load voltage regulating characteristics.

碩士<br>國立交通大學<br>電控工程研究所<br>107<br>Personal health care is gaining popularity due to advances in wearable devices and IoT technology. Medical devices can detect personal physiological conditions at any time for long-term observation and analysis. To prevent the user from misaligning between the wearable device and the tested part during the activity, and cause physiological signals to have errors during reading. The biomedical sensor can be designed as an electronic skin patch that will be attached to the skin for accurate physiological signals. In addition, the electronic patch with flexibility and thinness also brings comfort and convenience to the user. Since the battery is bulky and cannot be fabricated on a flexible substrate, the power source of the electronic patch will be replaced by wireless power transfer. Magnetic resonance transmission power to the patch at 13.56 MHz in the ISM band. By transmitting power at high frequency resonance, in addition to increasing the transmission distance, the area of the resonant coil can be reduced to conform to the size of the patch. This thesis presents a single-stage regulating rectifier which is wireless power transfer receiver of the electronic patch. Active switching full-wave bridge rectifier reduces conduction loss and increases voltage conversion rate. Delay lock loop feedback controller improves the disadvantages of switching delay times at high frequencies that significantly affect power conversion efficiency. Not only the efficiency of wireless power receiver but also large chip area is limited by the two-stage design, which constitutes rectifier and voltage regulator. The voltage rectification and regulation are achieved simultaneously in a single-stage rectifier through 1X/0X mode control. The PFM control is utilized to select the switching frequency of the system in order to maximize the transient response during heavy-load and to minimize the switching power losses during light-load. All circuits are fabricated in TSMC 0.35 μm process. The whole chip area is 2.72 mm2. The output voltage is maintained at 3.3V at steady state to supply power to the biomedical sensor. The peak efficiency is about 86% with output power = 200mW.

This thesis aims to simulate and find out more about the electrical dynamics of a six-phase exciter for hydropower generators. Because ordinary electric circuit-based simulation software only simulate three-phase electrical systems, a FEM-based software is used for the electrical dynamics simulations of the six-phase system. The objective is to analyse the pulsation behaviour of the rectified electrical output on the six-phase system and compare it to the three-phase system. The three-phase system is also simulated with filters with the aim of decreasing the amplitude of the pulsations on the electrical output. It is expected that an upgraded system from a three-phase system to a six-phase system should double the pulsation frequency on the rectified electrical output. However, the result shows that the rectified electrical output of the six-phase system consists of pulsations with unexpected frequencies. The simulated RL-filter on the three-phase system shows only insignificantly small changes on the rectified electrical pulsation amplitude.

In the past two decades the core aircraft technology is going through a drastic change. The traditional technologies that is almost half a century old, is going through a complete revamp. In the new “More Electric Aircraft” technology many mechanical, pneumatic and hydraulic systems are being replaced by electrical and power electronic systems. Airbus-A380, Boeing B-787 are the pioneers in the family of these new breed of aircrafts. As the aircraft technology is moving towards “More Electric”, more and more electric motors and motor controllers are being used in new aircrafts. Number of electric motor drive systems has increased by about ten times in more electric aircrafts compared to traditional aircrafts. Weight of any electric component that goes into aircraft needs to be low to reduce the overall weight of aircraft so as to improve the fuel efficiency of the aircraft. Hence there is an increased need to reduce weight of motors and motor controllers in commercial aircraft. High speed ironless axial flux permanent magnet brushless dc motors are becoming popular in the new more-electric aircrafts because of their ability to meet the demand of light weight, high power density, high efficiency and high reliability. However, these motors come with very low inductance, which poses a big challenge to the motor controllers in controlling the ripple current in motor windings. Multilevel inverters can solve this problem. Three-level inverters are proposed in this thesis for driving axial flux BLDC motors in aircraft. Majority of the motors in new more electric aircrafts are in the power range of 2kW to 20kW, while a few motor applications being in the range of 100kW to 150kW. Motor controllers in these applications run from 270Vdc or 540Vdc bus which is the standard in new more electric aircraft architecture. Multilevel Inverter is popular in the industry for high power and high voltage applications, where high-voltage power switching devices like IGBT, GTO are popularly used. However multilevel inverters have not been tried in the low power range which is appropriate for aircraft applications. A detail analysis of practical feasibility of constructing three-level inverter in lower power and voltage level is presented in this thesis. Analysis is presented that verify the advantages of driving low voltage and low power (300Vdc to 600Vdc and less than 100kW) motors with multilevel inverters. Practical considerations for design of MOSFET based three-level inverter are investigated and topological modifications are suggested. The effect of clamping diodes in the diode clamped multilevel inverters play an important role in determining its efficiency. SiC diodes are proposed to be used as clamping diodes. Further, it is realised that power loss introduced by reverse recovery of MOSFET body diode prohibits use of MOSFET in hard switched inverter legs. Hence, a technique of avoiding the reverse recovery losses of MOSFET body diode in three-level NPC inverter is conceived. The use of proposed multilevel inverter topology enables operation at high switching frequency without sacrificing efficiency. High switching frequency of operation reduces the output filter requirement, which in turn helps reducing size of the inverter. In this research work elaborate trade-off analysis is done to quantify the suitability of multilevel inverters in the low power applications. For successful operation of three-level NPC inverter in aircraft electrical system, it is important for the DC bus structure in aircraft electric primary distribution system to be compatible to drive NPC inverters. Hence a detail study of AC to DC power conversion system as applied to commercial aircraft electrical system is done. Multi-pulse rectifiers using autotransformers are used in aircrafts. Investigation is done to improve these rectifiers for future aircrafts, such that they can support new technologies of future generation motor controllers. A new 24-pulse isolated transformer rectifier topology is proposed. From two 15º displaced 6-phase systems feeding two 12-pulse rectifiers that are series connected, a 24-pulse rectifier topology is obtained. Though, windings of each 12-pulse rectifiers are isolated from primary, the 6-phase generation is done without any isolation of the transformer windings. The new 24-pulse transformer topology has lower VA rating compared to standard 12-pulse rectifiers. Though the new 24-pulse transformer-rectifier solution is robust and simple, it adds to the weight of the overall system, as compared to the present architecture as the proposed topology uses isolated transformer. Non-isolated autotransformer cannot provide split voltage at the dc-link that creates a stable mid-point voltage as required by the three-level NPC inverter. Hence, a new front-end AC-DC power conversion system with switched capacitor is conceived that can support motor controllers driven by three-level inverters. Laboratory experimental results are presented to validate the new proposed topology. In this proposed topology, the inverter dc-link voltage is double the input dc-link voltage. An intense research work is performed to understand the operation of Trapezoidal Back EMF BLDC motor driven by three-Level NPC inverter. Operation of BLDC motor from three-Level inverter is primarily advantageous for low inductance motors, like ironless axial flux motors. For low inductance BLDC motor, very high switching frequency is required to limit the magnitude of ripple current in motor winding. Three-level inverters help limiting the magnitude of motor ripple current without increasing the switching frequency to very high value. Further, it is analysed that dc link mid-point current in three-level NPC inverter for driving trapezoidal BLDC motor has a zero average current with fundamental frequency same as switching frequency. Because of this, trapezoidal BLDC motors can easily be operated from three-level NPC inverter without any special attention given to mid-point voltage unbalance. One non-ideal condition arrives in practical implementation of the inverter that leads to non-zero average mid point current. Unequal gate drive dead time delays from one leg to other leg of inverter introduce dc-link mid-point voltage unbalance. For the motoring mode operation of trapezoidal BLDC motor drive, simple gate drive logic is researched that eliminates need of the gate drive dead-time, and hence solves the mid-point voltage unbalance issue. Simple closed loop control scheme for mid-point voltage balancing also is also proposed. This control scheme may be used in applications where very precise control of speed and torque ripple is warranted. All the investigations reported in this thesis are simulated extensively on MATHCAD and MATLAB platform using SIMULINK toolbox. A laboratory experimental set-up of three-Level inverter driving axial flux BLDC motor is built. The three-level inverter, operating from 300Vdc bus is built using 500V MOSFETs and 600V SiC diodes. All the control schemes are implemented digitally on digital signal processor TMS320F2812 DSP platform and GAL22V10B platforms. Experimental results are collected to validate the theoretical propositions made in the present research work. At the end, in chapter 5, some future works are proposed. A new external voltage balance circuit is proposed where the inverter dc-link voltage is same as the input dc-link voltage. This topology is based on the resonant converter principle and uses a lighter resonant inductor than prior arts available in literature. Detail simulation and experimentation of this topology may be carried out to validate the industrial benefits of this circuit. It is also thought that current source inverters may work as an alternative to voltage source inverters for driving BLDC motors. Current source inverters eliminate use of bulky DC-link capacitors. Long term reliability of current source inverters is higher than voltage source inverters due to the absence of possibility of shoot-through. Further, in voltage source inverters, the voltage at the motor terminal is limited by the source voltage (dc-link voltage). This issue is eliminated in current source inverters. An interface circuit is conceived to reduce the size of dc-link inductors in current source inverters, pending detail analysis and experimental verification. The interface circuit bases its fundamentals on the principles of operation of multilevel inverters for BLDC motors that is presented in this thesis.

碩士<br>國立中央大學<br>機械工程研究所<br>100<br>This paper applied the digital signal processor combined with motor drives and measurement modules to realize field oriented control method. For control of permanent magnet synchronous motor , we can use the speed feedback error and the coordinate inverse transform to calculate the q-axis current command by proportional integral controller . The d-axis current command is zero. We used the space vector pulse width modulation to calculate the command of IGBT module to achieve the current and speed control of PMSM. We detected the maximum speed of each cycle of the generator mode to adjust the speed command for the system maintaining a steady speed also achieve the purpose of active damping control. Through the Full-bridge SMR, the generator can apply DC voltage. We detected the relationship of three-phase currents to control the power switch. The power switch and generator equivalent inductance can consist the voltage boost circuit. We detected the DC-side voltage feedback error , can use the proportional integral controller to calculates the voltage command, and then control the stability of the DC-side voltage.

碩士<br>國立成功大學<br>電機工程學系碩博士班<br>101<br>The design and analysis of the MPPT controller for small-scale wind energy conversion system is presented in the thesis. Different from applying a conventional boost rectifier as an AC/DC converter, this work applies the full-controlled rectifier as an AC to DC interface to achieve low current total harmonic distortion (THD) and high conversion efficiency. The low current THD in generator output can reduce the mechanical oscillation introduced by torque ripple, and high conversion efficiency can shorten the system payback period. The proposed rotational speed detection (RSD) circuit provides an elegant and accurate way to detect generator speed without the help of microprocessor or DSP which makes the system more reliable, compact and cost effective. Finally, a test rig is proposed with moment of inertia simulator to verify the performance of proposed controller more accurately. A 200W prototype is presented, and the experimental results shows the average current THD is less than 3% and with 95.2% maximum conversion efficiency. The die area is 1.107 x 1.117 mm2, and it is accomplished with TSMC 0.35m 2P4M 3.3V/5V CMOS process.

碩士<br>國立臺灣大學<br>工程科學及海洋工程學研究所<br>105<br>With the advent of “Internet of Things (IoT)”, there will be numerous wireless sensors around human kinds to help us monitor different status of the environment. Powering these wireless devices is an important issue. If the wireless sensors are powered by batteries, the reliability and performances of the device will be limited by battery lifetime. Furthermore, batteries can cause serious pollution if they are not recycled properly. To overcome these issues, piezoelectric energy harvesters can be installed around vibration sources to harvest energy from ambient vibrations and power IoT devices. The output from a piezoelectric energy harvester is in alternating current (AC) form, and needs to be transformed into direct current (DC) form to supply electronic devices by an interface circuit. An interface circuit usually consists of a rectifier and a DC/DC convertor. The rectifier is used for rectifying the output from the harvester from AC to DC form and storing output energy into a buffer capacitor. The DC/DC convertor is used for converting the energy in the buffer capacitor into a stable DC power supply with proper voltage level to power electronic devices. In this thesis, we analyze different kinds of rectifying interface circuit, propose a synchronous inversion and charge extraction (SICE) rectifier topology, and design a rectifier chip and a DC/DC buck convertor chip. Both chips are implemented in a TSMC 0.25 μm HV CMOS process. The rectifier adopts synchronous electric charge extraction (SECE) technique to boost output power and being load independent. It can be powered solely by a piezoelectric harvester and has cold start-up function. According to simulation results, this chip has an output power of 53 μW when operating with a piezoelectric harvester with current amplitude 30 μA, operating frequency 120 Hz and internal static capacitance 6.7 nF. Compared to the standard interface circuit, this chip provides 261% output power gain. The DC/DC buck convertor adopts digital pulse frequency modulation (PFM) control and operates in discontinued current mode (DCM) operation to achieve the design goals of low control power and good light load efficiency. According to the measurement results, this chip has a peak efficiency of 82.8 % with 5 V input voltage, and the light load (output current 10μA) efficiency is over 75 %. The chip has an output voltage of 1.8 V ~ 1.92 V, and can be used to power sensor modules and other IoT electronic devices required 1.8 V power supply.

碩士<br>國立清華大學<br>電機工程學系<br>99<br>This thesis develops a digital signal processor (DSP) based air-conditioning system, it consists of a sensorless permanent-magnet synchronous motor (PMSM) driven compressor, a sensorless PMSM driven cooling fan and a common switch mode rectifier (SMR) front end. The system compactness is achieved through power circuit modularization and common digital control environment. Besides, for making comparative driving performance evaluation, the standard PMSM drives for the compressor and the fan are also established. In the developed PMSM driven compressor, both high-frequency signal injection (HFI) and the extended-EMF (EEMF) sensorless control methods are applied and evaluated to comprehend their distinct merits and weak points. Then accordingly, a hybrid sensorless control scheme combining these two methods is developed to yield improved driving performance within wide speed range. In the developed control scheme, while the motor is started and driven under lower speed using HFI method, it is changed smoothly and operated using EEMF method as the speed is increased to a preset value. As to the PMSM driven cooling fan, the direct duty-ratio voltage-mode PWM scheme is adopted for the less stringent performance requirements. The standard and sensorless controls for sine-wave and square-wave PMSM drives are all studied and evaluated. In the proposed sensorless control schemes, only one-phase motor terminal voltage is sensed and properly signal processed. Better driving performance is further achieved via commutation advanced shift technique. Finally, a common front-end switch-mode rectifier (SMR) is formed to establish the boostable and well-regulated DC-link voltage for the followed two PMSM drives. Both the standard and the newly evolved bridgeless boost type SMRs are comparatively assessed. Owing to the limitation of pulse width modulation (PWM) channel number of the DSP TMS320F28335, the analog PWM circuit is employed as an alternative for realizing the front-end SMR.

博士<br>國立臺灣科技大學<br>電機工程系<br>88<br>This dissertation presents a novel method of instantaneous power control for the integrated rectifier/inverter fed three-phase induction servo motor. Two identical pulse-width modulation (PWM) converters are used to serve as power regulator with unity power factor and servo motor drive using indirect field-oriented control, respectively. By introducing the synchronous rotating-frame current regulators and the voltage decouplers, both the input and output currents of the integrated system are characterized by fast current response and low harmonic distortion. A novel input-output instantaneous power balancing approach is proposed to improve the dynamic response of input power regulation during load variation in order to minimize the dc-link capacitance. The analytic power models are established for the different input power control methods. The effects of the dynamic responses using different input power control methods are compared and the systematic design and analysis of the proposed method are also presented. The proposed system is implemented with a 1.5kW induction motor. The experimental results show that a near-unity power factor is achieved and the regenerative power can be sent back to the source while motor is braking. By the feedforward power control strategy, only a small dc capacitance about 470 mf is needed for the dc-link capacitor. The dynamic dc-link voltage response of the proposed power estimation method is superior to that of the power feedback method in the transient state. Finally, the analytic results obtained are verified experimentally.

碩士<br>國立臺灣科技大學<br>電機工程系<br>89<br>The purpose of this thesis is to apply a fuzzy logic controller (FLC) to instantaneous power balancing control for a three-phase induction servo system. The system contains a cascade of pulse-width-modulation (PWM) rectifier and inverter to serve as the front- and back-stage, respectively. By using synchronous rotating-frame current regulators, unity power factor in AC side is achieved and the input currents of the system are characterized by low harmonic distortion as well as fast current response. Besides, the indirect rotor field-oriented control strategy is adopted in the speed control system of induction servo to improve the speed response. A novel input-output instantaneous power balancing approach with FLC is proposed to improve the dynamic response of input power regulation during load variation in order to minimize the dc-link capacitance. Furthermore, the design of FLC is also aimed to lower the harmonic distortion and power ripple of the input. The proposed system is implemented with a 1.5-kW three-phase induction motor. The experimental results show that unity power factor is achieved and power regeneration performs successfully when the motor is braked. In addition, experimental evaluation also indicates that the proposed instantaneous power balancing control system with FLC is superior to that with proportional-integral controller in refraining the variation of dc-link voltage. The feasibility and practicability of the proposed system are verified by experiments.

An algorithm that is capable of estimating the parameters of non-stationary sinusoids in real-time lends application to various branches of engineering. Non-stationary sinusoids are sinusoidal signals with time-varying parameters. In this dissertation, a nonlinear filter is applied to power system applications to test its performance. The filter has a structure which renders it fully adaptive to tracking time variations in the parameters of the targeted sinusoid, including its phase and frequency. Mathematical properties of the differential equations which govern the proposed filter are presented. The performance of the proposed filter in the field of power systems is demonstrated with the aid of computer simulations and practical experimentations. The filter is applied to synchronous generator excitation control, voltage dip mitigation as well as the real-time estimation of symmetrical components. The parameter settings of the filter are tested and optimized for each of the applications. This dissertation demonstrates the simulation and experimental results of the filter when applied to the various power system applications. AFRIKAANS : 'n Filter wat bevoeglik is met die beraming van die parameters van beweeglike sinusoïdale in ware-tyd, kan bruikbaar aangewend word in verskeie takke van ingenieurswese. Beweeglike sinuskrommes is sinusoïdale seine met tyd-wisselende parameters. In hierdie verhandeling word `n nie-liniêre filter aangewend in verskeie kragstelseltoepassings om die werksverrigting van die filter te toets. Die filter het 'n struktuur wat dit toelaat om wisselende tydvariasies in die parameters van die teikensinusoïdaal op te spoor, insluitende die fase en frekwensie. Wiskundige eienskappe van die differensiaalvergelykings wat die voorgestelde filter beheer is ondersoek. Die werksverrigting van die voorgestelde filter in die veld van kragstelsels is gedemonstreer met die hulp van rekenaarsimulasies asook praktiese eksperimente. Die filter is toegepas tot opgewekte, sinkrone eksitasie-beheer, spanningsverlaging versagting, asook die ware tyd estimasie van simmetriese komponente. Die parameter verstellings van die filter is getoets en geoptimeer vir elk van die toepassings. Hierdie verhandeling demonstreer die simulering en eksperimentele resultate van die filter wat aangewend is vir verskeie kragstelseltoepassings. Copyright<br>Dissertation (MSc)--University of Pretoria, 2010.<br>Electrical, Electronic and Computer Engineering<br>unrestricted