sexta-feira, 30 de dezembro de 2016
STABILITY ANALYSIS AND VOLTAGE-SAG MITIGATION OF POWER SYSTEM IN OFFSHORE OIL RIG PLATFORM Autor:WU DI DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE
Fig A.2 Proposed DVR Design Simulink Configuration in Power System
STABILITY ANALYSIS AND VOLTAGE-SAG MITIGATION OF POWER SYSTEM IN OFFSHORE OIL RIG PLATFORM
WU DI B. Eng. (Hons.), NUS
A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF ENGINEERING
DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
NATIONAL UNIVERSITY OF SINGAPORE 2011
SUMMARY Today’s semi-submersible offshore oil rig platform uses variable-speed induction motors for station—keeping during drilling and sailing. During drilling, the platform needs to be maintained within its intended location to prevent interruption of operation and damage to the drills. Thus, it is crucially important that the induction-motor drive and the power supply feeding the drive are stable. This master thesis aims at analyzing and proposing analytical solutions to these two issues. The main contributions of the thesis are: For the first time, a Matlab Simulink model is built to simulate the detailed dynamics of the induction-motor drive in offshore oil-rig platform. The model and parameters used for the drive are verified by on-site tests of the Keppel FELS motors. Genetic algorithm is developed to the small-signal model of the induction-motor drive to identify, within the full range of speed and load, the instability region of the induction motor fed from ideal variable-frequency supply or a converter. The source of instability is also investigated from the two different supply configurations of the induction-motor drive. It is shown by eigenvalue analysis that instability exists in the induction motor itself but not in the other parts of the drive i.e. the converter supplying the motor. Accordingly, speed feedback comprising a proportional regulator is added to the drive to eliminate the instability region intrinsic to the induction motor plotted using genetic algorithm Voltage sag is known to be the most common disturbance in offshore power system, which has led to blackout in severe cases. A new design of dynamic voltage restorer (DVR) is modeled in Simulink, which deals with the influence of voltage sag on the induction-motor drive within strict harmonic limits imposed by marine standards. The new design outperforms the conventional DVR design by effectively increasing the accuracy of voltage compensation and significantly reducing the level of total voltage harmonic distortion.
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quinta-feira, 29 de dezembro de 2016
Design and Optimization of HF Transformers for High Power DC-DC Applications Mohammadamin Bahmani - Division of Electric Power Engineering Department of Energy and Environment Chalmers University of Technology Goteborg, Sweden 2014
Thesis for The Degree of Licentiate of Engineering
Design and Optimization of HF Transformers for High Power DC-DC Applications
Division of Electric Power Engineering Department of Energy and Environment
Chalmers University of Technology Goteborg, Sweden 2014
Increasing the operational frequency is the most common solution to achieve higher power densities, since the weight and volume of the magnetic part, the bulkiest element in power electronics converters, are then decreased. This solution is well established in low power high frequency applications, while in the recent decade, the possibility of utilizing high frequency at higher power and voltage levels has generated wide interest as well. This work proposes a design and optimization methodology of a high power high frequency transformer accounting for the tuned leakage inductance of the transformer, as well as high isolation requirements, particularly in DC offshore application where a converter module should withstand the MVDC or HVDC link voltage. To achieve this goal, several models were proposed and developed in order to accurately characterize such a transformer. One of these models is a so called pseudo-empirical expression derived from a rigourous regression algorithm based on an extensive 2D finite element simulation scenario, resulting in an accurate analytical expression with an average unsigned deviation of 0.51% and the extreme deviations not higher than 9%. Moreover, using the energy method, an analytical expression to precisely calculate the leakage inductance of high power density magnetic components is proposed. In addition, using the proposed modification of the Steinmetz equation for core loss calculations, general expressions are derived and presented for a rectangular waveform with its associated duty cycle and rise time. Applying the proposed design methodology, in which all the aforementioned models are implemented on a 1 MW case study transformer, indicates that such a transformer can achieve a power density of about 22 kW/L and the efficiencies as high as 99.74%. Moreover, with respect to the isolation requirements, desired leakage inductance and the magnetic material used, a critical operating frequency can be found above which the transformer does not benefit from volume reduction anymore. Keywords High Power High Frequency Transformer, Isolation Requirements, Leakage Inductance.
LINK ORIGINAL THESIS COMPLETE
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quarta-feira, 28 de dezembro de 2016
LED lighting control driver design and development of the 12V‐12W class using the voltage controlled ring oscillator Ki-Soo Kwon -Department of Electronic Engineering Graduate School Yeungnam University SOUTH KOREA
M. S. Thesis
LED lighting control driver design and development of the 12V‐12W class using the voltage controlled ring oscillator- Ki-Soo Kwon
Department of Electronic Engineering Graduate School Yeungnam University (Advised by Professor Young-suk Suh)
전압제어 링 발진기를 이용한
12V-12W급 LED 조명제어 구동회로
설계 및 개발
This paper presents a Pulse Width Modulation (PWM) controller and circuits for the high power LED (Light Emitting Diode) driver. The controller is available for the remote control through four major operation modes of ON, OFF, Emergency and Power saving using the serial communication M. S. Thesis LED lighting control driver design and development of the 12V‐12W class using the voltage controlled ring oscillator Ki-Soo Kwon Department of Electronic Engineering Graduate School Yeungnam University (Advised by Professor Young-suk Suh) Abstract This paper presents a Pulse Width Modulation (PWM) controller and circuits for the high power LED (Light Emitting Diode) driver. The controller is available for the remote control through four major operation modes of ON, OFF, Emergency and Power saving using the serial communication The entire driver circuits use a DC‐DC converter such a Boost topology with dimming, current, thermal control and communication functions for hallway lighting and automobile applications. According to the type and power of LED, a driver IC has already been developed and is produced. This driver IC makes the constant current and constant voltage available. However, if the LED driver allows delicate dimming control and thermal dissipation through allowance of LED off time, PWM control is needed. Therefore, a MCU (Microcontroller unit) for the PWM control as well as a driver IC for driving LEDs is needed. If this operation is embedded at this driver IC, the expense can be reduced. The LED controller integrated circuit (IC) was designed, simulated and fabricated in 0.35μm Magnachip/Hynix.
sábado, 24 de dezembro de 2016
DR. Slobodan Cuk
I am Yugoslav/Serbian who came to United States as an immigrant on flight from Belgrade, Yugoslavia on February 29, 1972 sponsored by NASA. NASA first supported at Santa Clara my MS thesis: “Stability Investigations of the Spinning Skylab” and my 2-year doctorate at Caltech from Sept. 1974 to Dec. 1976. This latter work is now part of the new Vol. 4: “State Space Averaging and Cuk converters”. Vol.1 and Vol. 4 are now combined into a 624-page 40-th anniversary paperback edition while Vol.2 and vol. 3 are combined into 631-page paperback. Kindle editions are also available now individually and as four volume bundle. 1. teslaco.com 2. YouTube.com/c/slobodancukTESLAco 3. Amazon.com/author/slobodancuk 4. linkedin.com/groups/7045487. 5. firstname.lastname@example.org; 6. Linkedin.com/in/slobodancuk. Many generations of engineers used these books to get into emerging Power Electronics field and more than 4,000 used them as textbooks in courses I presented. One of my 35 PhD students, now professor, endorsed these books on Amazon with: “This Power Electronics Series is a record of a Big Bang in the History of Power Electronics!” The combined vol.1 and vol.4 paperback and my past research work led me to conclude that a critical re-evaluation is badly needed of the conventional buck, boost, flyback, forward, bridge-type, LLC and other converters which dominated industry for the last 60 years! This is now addressed in the upcoming volume 5! The time has now also come for their replacement by new Power Electronics System Technology based on three new Resonant/PWM type switching methods, related host of novel converter topologies and new magnetics structures I introduced in last 6 years via patents, articles and presentations! They and my contemporary column with articles on teslaco.com home page are slated for upcoming Volume 6 of this series! A well respected Power Electronics expert recently commented to his LinkedIn group: “You should all read everything that Dr. Ćuk has ever written!”.
sexta-feira, 23 de dezembro de 2016
terça-feira, 20 de dezembro de 2016
Efficiency Improvement of Flyback Converter Using Stepped-Airgap Inductor 계단형 공극 인덕터를 이용한 Flyback Converter의 효율 개선 Yong-Hwan Shin - Department of Electrical Engineering - Gyeongsang National University-South Korea
Efficiency Improvement of Flyback Converter
Using Stepped-Airgap Inductor
계단형 공극 인덕터를 이용한 Flyback Converter의 효율 개선
Department of Electrical Engineering
Gyeongsang National University
This thesis deals with the efficiency improvement of flyback converter using stepped-airgap transformer, in order to improve the efficiency and/or power density of power electronic systems. The stepped-airgap inductor has been proposed for the flyback converter in order to improve the efficiency over the entire load range, especially light load. The design procedure is also presented. The center leg has typical air gap while the outer gap has a step-shape core. The inductance of the flyback transformer is increased at light load, so that CCM operation can be extended to lighter load. In addition, both the air gaps in the center and outer legs operate at heavy load, so that the AC winding loss can be reduced. The usefulness of the proposed flyback transformer is experimentally verified and compared with the conventional flyback transformer with one inductance value. The experimental results show that the proposed stepped-airgap transformer has higher efficiency at not only light load but also heavy load. Especially, light load efficiency can be much improved. The first part of the thesis introduced method improving flyback converter at light load. Improving efficiency is introduced by many other methods at the entire load. Efficiency is also compared with switching frequency and variable inductance at the entire load. To improve efficiency at light load, stepped-airgap core was suggested. The second part of the thesis introduces how to model stepped-airgap for reluctance circuit. Stepped-airgap is calculated by stepped air gap length and stepped core area. Inductance is analyzed by relative permeability. According to current, stepped-airgap inductor have linear, saturated and hard saturated region. To analyze stepped-airgap is also calculated by flux intensity. Finally, stepped-airgap inductor is summarized by the inductance and relative permeability according to inductor current. The third part of the thesis deals with design of stepped-airgap inductor and flyback transformer. Stepped-airgap is simulated by Maxwell 3D and PSIM simulation tools according to inductor current. To improve efficiency of flyback converter can extend the CCM range with changeable inductance value. Before experiment of flyback converter, simulation is preceded using Maxwell 3D program to confirm permeance, relative permeability value and flux density at stepped core. The operation of flyback converter with varying load current is also simulated by PSIM program. The fourth part of the thesis deals with measurement of inductance about stepped-airgap inductor. Inductance is measured by circuit that can measure the inductance according to current. When input current is changed, inductance is measured by LCR Meter using DC power supply. Inductance is also measured to change part of stepped core area. Until now, there is no relative permeability data of PC95 according to current. Relative permeability of PC95 is gathered by measurement in lab. Stepped-airgap inductor is analyzed and modeling about length of air gap and core area by PC95 relative permeability data. Relative permeability of PC95 is also described that inductance curve about change of current and compared with normal air gap inductor. The fifth part of the thesis deals with experiment of flyback converter with stepped-airgap transformer. Efficiency of converter is measured when the load is changed from high to low or low to high. The waveform is measured when the converter is entered the CCM, CRM and DCM. To verify theory the experimental results is confirmed by measured ring of vds voltage for extended CCM range over the entire load. The sixth part of the thesis deals with conclusion of flyback converter with stepped-airgap transformer. Stepped-airgap inductor advantage to improve the efficiency of flyback converter over the entire load range. The thesis researches the pros and cons of the stepped-airgap transformer. Stepped-airgap transformer using variable inductance will improve efficiency of other many converters, especially efficiency of magnetics components.
domingo, 18 de dezembro de 2016
segunda-feira, 12 de dezembro de 2016
Contribuições ao controle eletrônico inteligente de reguladores de tensão para sistemas de distribuição de energia em 13,8 kV - RODRIGO RIMOLDI DE LIMA- Dissertação (Mestrado)-Universidade Federal de Uberlândia, Uberlândia- BRASIL
Título: Contribuições ao controle eletrônico inteligente de reguladores de tensão para sistemas de distribuição de energia em 13,8 kV Outros títulos: Contributions to the intelligent electronic control of voltage regulators for systems of energy distribution in 13,8 kV .
Data de publicação: 20-Jul-2007
Citação: LIMA, Rodrigo Rimoldi de. Contribuições ao controle eletrônico inteligente de reguladores de tensão para sistemas de distribuição de energia em 13,8 kV. 2007. 143 f. Dissertação (Mestrado)-Universidade Federal de Uberlândia, Uberlândia, 2007.
Resumo: O desenvolvimento proposto neste trabalho excede à operação convencional até então praticada por apresentar em seu dorso um circuito eletrônico microcontrolado que atua sobre a carga do sistema por intermédio de 09 taps de regulação (02 de abaixamento, 06 de elevação e o central) de modo totalmente independente e com grande velocidade de resposta, posto que a regulagem foi procedida com tempo limite de 04 ciclos da rede elétrica. Cada estágio de regulação proporciona uma variação de 5% sobre o valor nominal da tensão entregue à carga, estabelecendo um amplo controle para valores entre 70% e 110% do sinal fornecido à mesma. A comunicação desta com o módulo de controle mencionado é feita através de tiristores (SCR’s) com refrigeração a ar.
Arquivos neste item:
|ContribuiçõesControleEletrônico_parte 1.pdf||2.38 MB||Adobe PDF||ver/abrir|
|ContribuiçõesControleEletrônico_parte 2.pdf||3.7 MB||Adobe PDF||ver/abrir|
|ContribuiçõesControleEletrônico_parte 3.pdf||3.85 MB||Adobe PDF||ver/abrir|
domingo, 11 de dezembro de 2016
Automatic Test System for Type Tests of the Uninterruptible Power Supply -Esa Nummijoki - Aalto University School of Electrical Engineering-HELSINKI-FINLAND
Title: Automatic Test System for Type Tests of the Uninterruptible Power Supply
School of Electrical Engineering Thesis submitted for examination for the degree of Master of Science in Technology.
AALTO SCHOOL UNIVERSITY OF ELECTRICAL ENGINEERING
Abstract of the master's thesis
Testing is an essential part of product development. In UPS product development, di erent tests are made every day. Testing requires large variety of measurement instruments and other equipment such as large load systems and di erent kind of test con gurations. Signi cant number of performed tests are based on the UPS type tests de ned in the IEC-62040 standard. Testing consumes a lot of time and that way also resources. To solve this problem, an automatic test system for type tests is considered. The aim of this thesis was to clarify the need for the automatic test system, and clarify requirements needed to realize it. The work was done by reviewing the type tests and di erent parts of an automatic test system. In addition, an experimentation was made, resulting a prototype. The prototype is able to automatically perform an indicative e ciency test for the UPS. Furthermore, a possibility to automate the most complex type test, a dynamic output performance test, was examined. This examination resulted a description of the test process and LabVIEW programs, supporting the execution of the test. However, the conclusion was that it is not sensible to automate the test, due to the fact that it is not often performed and automating the test requires a lot of time and resources. The review and the experimentation proved that realization of an automatic test system, able to perform all the type tests, requires large amount of time and resources. Due to this, the automatic test system for type tests is not the best solution to reduce the time and resources consumed by testing.
Keywords: Automatic Test System, Uninterruptible Power Supply, Product Development, LabVIEW, TestStand, Prototype
Electrónica de potencia: componentes, topologías y equipos Por Salvador Martínez García,Juan Andrés Gualda Gil
EXCELENTE LIBRO DE ELECTRÓNICA DE POTENCIA DE LOS INGENIEROS
Salvador Martínez García,Juan Andrés Gualda Gil
LINK BOOK DEMO GOOGLE:
https://books.google.com.br/books?id=izwxn8edxhAC&lpg=PR3&hl=pt-BR&pg=PR3#v=onepage&q&f=false BOOK DEMO GOOGLE
sábado, 10 de dezembro de 2016
Transformer Shielding Technique for Common Mode Noise Reduction in Switch Mode Power Supplies Yuchen Yang -Virginia Polytechnic Institute and State University
Transformer Shielding Technique for Common Mode Noise Reduction in Switch Mode Power Supplies Yuchen Yang
Thesis submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering.
Switch mode power supplies are widely used in different applications. High efficiency and high power density are two driving forces for power supply systems. However, high dv/dt and di/dt in switch mode power supplies will cause severe EMI noise issue. In a typical front-end converter, the EMI filter usually occupies 1/3 to 1/4 volume of total converter. Hence, reducing the EMI noise of power converter can help reduce the volume of EMI filter and improving the total power density of the converter. For off-line switch mode power supplies, DM noise is dominated by PFC converter. CM noise is a more complicated issue. It is contributed by both PFC converter and DC/DC converter. While many researches have focused on reducing CM noise for PFC converter, the CM noise of DC/DC converter still remains a challenge. The main objective of this thesis is provide a solution to have best CM noise reduction for DC/DC converters. The shielding concept and balance concept are combined to propose a novel balance double shielding technique. This method can have an effective CM noise reduction in the circuit level. In addition it is easy to design and implement in the real production. The balance condition is easily controlled and guarantees effective CM noise reduction in mass production. Then, a novel one-layer shielding method for PCB winding. transformer is provided. This shielding technique can block CM noise from primary side and also cancel the CM noise from secondary side. In addition, shielding does not increase the loss of converter too much. Furthermore, this shielding technique can be applied to matrix transformer structure. For matrix transformer LLC converter, the inter-winding capacitor is very large and will cause severe CM noise problem. By adding shielding layer, CM noise has been greatly reduced. In addition, by modifying the secondary winding, the loss on shielding layer is minimized and experiments show that the total efficiency of converter has almost no impact. Furthermore, although this thesis uses flyback and LLC resonant converter as example to demonstrate the concept, the novel shielding technique can also be applied to other topologies that have similar transformer structure.
LINK ORIGINAL WEB
sexta-feira, 9 de dezembro de 2016
High Frequency-Link Cycloconverters for Medium Voltage Grid Connection -Shattock, Nicholas -PhD thesis, University of Nottingham.
High Frequency-Link Cycloconverters for Medium Voltage Grid Connection Nicholas Shattock BEng. (Hons) Thesis submitted to the University of Nottingham for the degree of Doctor of Philosophy
As the deployment of renewable generation increases in the worldwide electrical grids, the development of distributed energy storage becomes more and more of an essential requirement. Energy storage devices connected at Medium Voltage allows for much higher powered deployments and this Ph.D. will focus on the power converter used to interface the energy storage device to the electrical grid. Multi-level converters can be used to provide this interface without huge ltering requirements or the need of a Low Frequency step up transformer. However traditional Multi-level converter topologies require a large number of electrolytic capacitors, reducing the reliability and increasing the cost. Multi-level converters constructed from a Cycloconverter Topology do not require any additional electrolytic capacitors, however the High Frequency transformer, used to provide isolation has to be considerably larger. This Ph.D. will investigate a novel hybrid converter topology to provide an interface between an energy storage device, such as a super-capacitor or battery, to the Medium Voltage grid, designed for high reliability and power density. This topology is called The Hybrid Cycloconverter Topology and is based on a Cycloconverter Topology connected to an auxiliary 3-Phase VSI. A comprehensive simulation study is carried out to investigate the semiconductor losses of this novel converter topology and compared against two alternative topologies. An experimental converter is constructed to validate the theory of operation and to justify its e ectiveness.
quinta-feira, 8 de dezembro de 2016
Manual de Engenharia para Sistemas Fotovoltaico - Cresesb - Cepel - JOÃO TAVARES PINHO- MARCO ANTONIO GALDINO-BRASIL-2014
LINK ORIGINAL DE ACCESO LIBRE EN LA WEB
sábado, 3 de dezembro de 2016
Communication Circuits: Analysis and Design by Kenneth K. Clarke ESTUDIE CIRCUITOS ELECTRONICOS III CON ESTE LIBRO EN LA FACULTAD DE INGENIERIA ELECTRÓNICA DE LA UNIVERSIDAD NACIONAL MAYOR DE SAN MARCOS SIENDO MI PROFESOR EL ILUSTRE PROF. Carlos Sanchez Tarnawiecki hoy Profesor del Postgrado at Universidad Nacional Mayor de San Marcos
LINK ORIGINAL EN LA WEB