“Sixty years ago I knew everything; now I know nothing; education is a progressive discovery of our own ignorance. Will Durant”



terça-feira, 28 de outubro de 2014

Non-isolated Single Phase Uninterruptible Power Supply (UPS) System Muhammad Aamir Department of Electronics, Electrical, Control, & Instrumentation Engineering Graduate School of Engineering Hanyang University South Korea

( Abstract ) In this thesis, a high performance single phase transformer-less online uninterruptible power supply (UPS) is proposed. The use of the bidirectional buck-boost converter with high conversion ratio not only reduces the number of batteries but also ensures a transformer-less system. The rectifier has capability of power factor correction and provides regulated DC link voltage whereas the inverter provides a regulated sinusoidal output voltage to the load. In order to control the transient effect, efficient control scheme is adopted in the system. The overall efficiency of the system is improved with significant reduction in size and weight of the system due to decrease number of batteries. Qualitative analysis and experimental results obtained with a 500VA prototype shows a normal efficiency of over 94% and an input power factor of over 99%.

Filtering Methods for DC Link Voltage Control of Common-neutral-type Transformerless Single-phase UPS

Filtering Methods for DC Link Voltage Control of Common-neutral-type Transformerless Single-phase UPS UPS is largely divided into passive-standby, line-interactive, and double-conversion types. Commonly a double-conversion type is used at a site requiring a high reliability. These days, important factors of UPS are high efficiency, low input current distortion, high input power factor, small cabinet size and low price. In this thesis, a common-neutral type transformerless UPS is proposed. A proposed UPS is composed of PFC with 1-switch voltage doubler strategy, half-bridge inverter, separate battery charger and separate battery discharger. PFC with 1-switch voltage doubler strategy and half-bridge inverter are configured as commom-neutral type so that they can convert power without input and output transformer. Therefore input and output transformers can be removed, so the efficiency can be improved and cabinet size can be reduced. Also advantage of PFC with 1-switch voltage doubler strategy and half-bridge inverter is that they need a small number of switching devices so they can simplify driving circuitry and reduce the price. Advantage of separate battery charger and separate battery discharger is that they can make battery voltage lower than DC link voltage so they can reduce the quantity and cost of battery which is an important part of UPS. PI controller was used as voltage controller and current controller of PFC. In order to compensate imbalance of positive and negative DC link voltages, imbalance voltage PI controller was used. In order to compensate leading effect of input current, duty feedforward method was used. Several methods to eliminate 120Hz ripple component in DC voltage feedback were compared with each other. Moving Average resulted in better performance than other methods. Half-bridge was used as inverter circuit. In order to achieve stable static output voltage and improve dynamic characteristic multi-loop control method was used. Finally, the value of proposed UPS was confirmed in the method of simulation and experiment.

A study on Development of an algorithm for reducing neutral current in three-phase four-wire PWM rectifier of UPS Kim,SeungHo Dept. of Electrical Engineering Graduate School of Industry and Engineering Seoul National University of Science and Technology


A Study on the Hybrid UPS with Electrical Energy Storage Function Seung-Beom Lim Department of Electrical Engineering Graduate School, Dankook University

A Study on the Hybrid UPS with Electrical Energy Storage Function

A Study on the Hybrid UPS with
Electrical Energy Storage Function
Seung-Beom Lim
Department of Electrical Engineering
Graduate School, Dankook University
Advisor: Professor Soon-Chan Hong

EES(Electrical Energy Storage) is the system which stores the remaining energy during the time of light load or night time with the cheap electricity price, and then discharges the stored energy during the time of peak load or electric power shortage. This system improves usage efficiency and stabilizes the power supply system. UPS(Uninterruptible Power Supply) can be divided into three parts according to dependency between input and output voltage : Passive-Standby, Line-Interactive, and Double-Conversion. Double- Conversion type UPSs are used to supply the stable power to industrial high-tech/medical equipments and finance/data centers, where loads are sensitive to the blackout and voltage fluctuation. In this paper, it is proposed a double-conversion hybrid UPS with EES function. The proposed hybrid UPS is operating in four states, which are normal state, battery state, bypass state, and EES state. When the AC input source is normal, the system operates in normal state which supplies the stable power to the load through the PFC and inverter, and charges batteries simultaneously. In case of black out or unstable input, the system operates in battery state which supplies the energy from the batteries to the load. In bypass state in case of overload or failure of the inverter, the system supply the input power to the load directly. When the system is needed to operate in EES state, AC input is cut off by the user command and the energy stored in the batteries is supplied to the load. Thereby the system can manage the power efficiently and make the power system more stable. The proposed system is composed of a rectifier, an inverter, a battery charger, and batteries. The rectifier operates as the PFC in normal state and as the battery discharger in battery state and EES state. In the proposed system, there is no battery discharger which is essential in the conventional system. As a natural consequence, the size and weight of the system are reduced. In addition, by designing the inverter as 3-level TNPC(T-type Neutral Point Clamp) inverter, efficiency is improved compared to the conventional 2-level type. To verify the proposed system, it is simulated through the C-block of PSIM. Also, the proposed system with the output rating of 2,700 Watts is constructed and experimented. As a result, it was verified that the proposed system has excellent performances in the viewpoints of efficiency, input power factor, and THDs in input current and output.

quinta-feira, 23 de outubro de 2014


Physics, Class XII Chapter : Alternating current Topic : Transformer, Classroom lecture by Pradeep Kshetrapal. Language : English mixed with Hindi.

terça-feira, 21 de outubro de 2014

Reduction of no-load losses in distribution transformers by using amorphous ribbons Malick MOUHAMAD LME (Laboratoire des Matériels Electriques), Réseau de distribution d'électricité THESE DE DOCTORAT DE L’ECOLE NORMALE SUPERIEURE DE CACHAN

Résumé La présente étude traite l’application des rubans amorphes dans les transformateurs de distribution dans l’objectif de réduire les pertes dans le réseau d’électricité. Les matériaux utilisés sont un alliage à base de fer, silicium et bore. Les premières études sur ce matériau amorphe révèlent une très bonne compatibilité chimique de ces derniers avec les huiles de transformateur. Ces rubans possèdent des durées de vie entièrement conforme aux exigences d’ERDF.

Performance evaluation of amorphous hexa-core for distribution transformers by JOSEFIN ALMÉN & MÅNS BREITHOLTZ


The integrated Operation and Design of the DC Distribution Systems combined Wind Turbine and Photovoltaic Power Systems Shin,Soo Cheol Department of Electrical and Computer Engineering Sungkyunkwan University

The integrated Operation and Design of the DC
Distribution Systems combined Wind Turbine and
Photovoltaic Power Systems
Shin, Soo Cheol
Department of Electricaland
Computer Engineering
Sungkyunkwan University

Because DC distribution system has more numerous advantages than AC distribution system,aircraftand shipshavebeen applied to the DC distribution system.because consumer and office equipment consisting of the electronic systems use DC power,the powercan be easily supplied to the load using simple power conversion system.especially,high efficiency power transmission is possible because the power conversion step supplying the power to the electronic load is small in DC distribution system.however,due to the power grid of land consisting of AC powergrid,most of the land power system are applied to the AC distribution system except for special cases such as IDC(InternetDataCenter) and etc. In this paper,design and control method of DC distribution system which can be connected with AC distribution system of land is proposed.In addition,it proved that the connection of renewable energy can bemore easily connected with DC distribution system than AC distribution system by connecting DC distribution grid with renewable energy such as wind power of PMSG type and photovoltaic system through the simulation and experiment. Three-phase AC/DC PWM converter can supply DC 380[V]to the DC bus in case that AC power distribution voltage is AC 220[V].however,because the secondary side of the transformer consists of Y connection and 380[V]in most of the commercial building,in order to configure a DC distribution system,it is boosted to DC 700[V]using three-phase AC/DC PWM converter.And then,the DC distribution system of DC 380[V] was constructed using non-isolated bidirectional DC/DC converter

Design strategy of high power LED arrays for various applications Bong-Ryeol Park School of Electronic and Electrical Engineering Graduate School Hongik University

Design strategy of high power LED arrays for
various applications

Bong-Ryeol Park
School of Electronic and Electrical Engineering
Graduate School Hongik University

Thermal effects in LED arrays were investigated as a function of LED
power, and spacing. For high power LEDs, the increase in junction
temperature due to a high driving current plays an important role in LED
performance, e.g. conversion efficiency, optical degradation, etc. Since the
maximum driving power that determines LED brightness is limited by the
critical junction temperature, thermal influence from adjacent LEDs in an
array has to be also taken into account carefully. The relationship
between maximum allowed driving power and LED BLU design
parameters are discussed along with other factors to be concerned.

sexta-feira, 17 de outubro de 2014

Participantes destacam atualidade e excelência do Diálogo BRASIL-ALEMANHA

Realizado nos dias 30 de setembro e 1º de outubro, o 3º Diálogo Brasil-Alemanha de Ciência, Pesquisa e Inovação alcançou seus principais objetivos. Com a Matemática como tema central, o evento buscou incentivar a troca de informações e ideias entre profissionais de diversas áreas ligadas à ciência. O evento, organizado pelo Centro Alemão de Ciência e Inovação – São Paulo, aconteceu na Biblioteca Mário de Andrade.

O engenheiro Armando Cavero Miranda, presente no evento, elogiou a escolha do tema do Diálogo Brasil-Alemanha, já que vê uma grande necessidade de incentivar os jovens a seguir carreira nessa área. “Existe uma preocupação em muitos países, como o Brasil e a Alemanha, em se criar um estímulo entre os jovens para que continuem estudando Matemática, porque ela está em todas as áreas da tecnologia, na indústria ou na ciência”, afirmou Miranda, que também elogiou a organização do evento e a escolha dos palestrantes.

O engenheiro destacou a apresentação de Marcelo Viana da Silva sobre o programa Profmat, especialização para os professores de Matemática do Brasil. “É preciso difundir novas tecnologias didáticas, que estão sendo desenvolvidas tanto no Brasil quanto em outros lugares. Para os países sustentarem seu desenvolvimento, precisam de mais engenharia e matemática.”

Para o participante Odilon Otávio Luciano, professor do Instituto de Matemática e Estatística da Universidade de São Paulo, a organização do evento foi impecável e proporcionou excelentes oportunidades de contato. A qualidade do conteúdo também foi ressaltada por ele.  “O evento foi muito estimulante por tratar de um tema unificador de grande atualidade e ampla abrangência científica. Os painéis exibiram conteúdos com riqueza de diversidade e competência, evidenciando a fertilidade científica do paradigma das redes complexas.”

Para Marcio Weichert, coordenador do Centro Alemão de Ciência e Inovação – São Paulo (DWIH-SP), os objetivos do Diálogo foram atingidos. “Atraímos um público de alto nível, que incluía estudantes até pesquisadores seniores de diversas áreas do conhecimento.


quinta-feira, 16 de outubro de 2014

Brasileiro vencedor da Medalha Fields é recebido em Brasília

Control Design of Series Connected MOSFETs for High Voltage Applications

 Control Design of Series Connected MOSFETs for High
Voltage Applications
Mirko Bodach, Lutz Zacharias, Björn Veit, Ringo Lehmann, Bernd Günther, Denny Ehrler
University of Applied Sciences Zwickau, Dr.-Friedrichs-Ring 2A, D-08056 Zwickau, GERMANY,
Mirko.Bodach@fh-zwickau.de, Bjoern.Veit@fh-zwickau.de, Lutz.Zacharias@fh-zwickau.de,
Ringo.Lehmann@fh-zwickau.de, Bernd.Guenther@fh-zwickau.de, Denny.Ehrler@fh-zwickau.de

A new electro-mechanical converter concept for renewables needs a special DC / DC converter.
The converter has to transform a voltage of about 8 kV into a lower voltage of about 400 volts
covering a power range of 250 up to 1,000 W. Using this type of converter, semiconductor
switching elements are required, which can handle a voltage of about 8 kV and carrying a direct
current of about 60 mA.

WEB SEMINARY 18/10/2014 -10A.M. Switch Mode Power Supply Measurements using Oscilloscopes

Switch Mode Power Supply Measurements using Oscilloscopes

PRESENTER Johnnie Hancock, Oscilloscope Product Manager, Keysight Technologies Johnnie Hancock is an Oscilloscope Product Manager at Keysight Technologies. He began his career with Hewlett-Packard in 1979 as an embedded hardware designer, and has over 35 years test and measurement experience in various roles for HP, Agilent, and now Keysight Technologies. Johnnie is currently responsible for application support activities and he regularly speaks at technical conferences worldwide. Johnnie graduated from the Universityof South Florida with a degree in electrical engineering.


Engineers and technicians testing or debugging switch mode power supplies.

Onde e quando

PreçoData(s)LocalPara mais informações
Gratuito2014-11-18 10:00
At Your PCEnroll to view the November 18, 2014 live broadcast

segunda-feira, 13 de outubro de 2014

Design and Implementation of a Fuzzy Adaptive Sliding-Mode Voltage Control System for Three-Phase UPS Inverter Khawar Naheem DIVISION OF ELECTRONIC AND ELECTRICAL ENGINEERING DONGGUK UNIVERSITY SEOUL

 ( Abstract )
Nowadays, the nonlinear nature of electric loads leads to a strong demand of a high-quality and reliable power source both by the customers and utilities. To address this issue, the uninterruptible power supplies (UPSs) are extensively employed for the critical loads such as communication systems (i.e., data centers), medical support systems, semiconductor manufacturing systems, etc. For improving the power quality using UPS system, it is important to achieve the sinusoidal output voltage waveform with very low total harmonic distortion (THD) regardless of the load types. Typically, the inverter with LC output filter in the UPS system is a suitable solution to fulfill this requirement. The main criteria to evaluate the regulation performance of the UPS inverter output voltage are fast dynamic response, small steady-state error, and low THD. Furthermore, the various load conditions (abrupt load changes, unbalanced load, and nonlinear load) including parameters uncertainties extremely degrade the performance of the UPS inverter. Thus, an appropriate control strategy is desired to sufficiently meet the performance criteria of the UPS systems under any type of electrical loads and uncertainties.

Robust Control of a Grid Connected 3 Phase 2 Level Photo Voltaic Inverter and Development of an Inverter Operating SW Using Test Driven Development Approach Ahn, Kyung Pil

Robust Control of a Grid Connected 3 Phase 2 Level Photo
Voltaic Inverter and Development of an Inverter Operating
SW Using Test Driven Development Approach

Ahn, Kyung Pil
(Supervisor Lee, Young Il)
Dept. of Control and Instrumentation Eng.
Graduate School of Industry and Engineering
Seoul National University of Science and Technology

This study discusses robust control of grid connected three-phase two-level photo voltaic inverter where LC filter is used and its reliable implementation method for the system.
The suggested control method uses the cascaded strategy in which inner-loop controller for the ac current control and outer-loop controller for the dc-link voltage are used. In the inner-loop ac current controller, it is important to maximize convergence rate and keep the stability at the same time. So the optimal controller design method based on the LMI (Linear Matrix Inequality) is used with the integration action. Though this method, it can achieve high performance in term of tracking the reference as well as eliminate the offset-error. More over it guarantees system stability even when there are parameter mismatch by considering the parameter uncertainty set. In the outer-loop dc-link controller the PI controller is used with the dc-ac current linearization. So it can have concurrent performance though overall inverter operating condition.
On the other hand, the high power product such as three-phase photo voltaic inverter is in the mission-critical area due to its riskness of an accident. More over the photo voltaic inverter system become more an more complex with increasing requirement of functions in the grid connection rule for each country. With these trend it is difficult to keep the system integrity. This study shows the cases how the inverter operating SW can be builded using Test Driven Development (TDD) approach.