Line-Interactive Transformerless Uninterruptible Power Supply (UPS) with a Fuel Cell as the Primary Source Muhammad Iftikhar , Muhammad Aamir, Asad Waqar , Naila, Fahad Bin Muslim and Imtiaz Alam Department of Electrical Engineering, University of Engineering and Technology,Peshawar, Pakistan

Line-Interactive Transformerless Uninterruptible Power Supply (UPS) with a Fuel Cell as the Primary Source 
 Muhammad Iftikhar , Muhammad Aamir, Asad Waqar , Naila, Fahad Bin Muslim and Imtiaz Alam Department of Electrical Engineering, University of Engineering and Technology,Peshawar, Pakistan

 Abstract: This paper presents line-interactive transformerless Uninterruptible Power Supply (UPS) with a fuel cell as the prime energy source. The proposed UPS consists of three major parts (i.e., an output inverter, a unidirectional DC–DC converter, and a battery charger/discharger). Non-isolated topologies of both the unidirectional converter and battery charger/discharger ensure transformerless operation of the UPS system. A new topology of high gain converter is employed for boosting the low voltage of the fuel cell to a higher DC link voltage, with minimum semiconductor count, and high efficiency. A high-gain battery charger/discharger realizes the bidirectional operation between the DC link and the battery bank. Besides, it regulates the DC link voltage during the cold start of fuel cells and keeps the battery bank voltage to only 24 V. A new inverter control scheme is introduced that regulates the output voltage and minimizes the total harmonic distortion for non-linear loading condition. The proposed control scheme integrates proportional-resonant control with slide mode control, which improves the controller’s performance in transient conditions. The proposed UPS system is validated by developing a 1-kVA experimental prototype.

 Keywords: fuel cell; line-interactive; uninterruptible power supply; transformerless; DC–DC ORIGINAL LINK
https://www.mdpi.com/1996-1073/11/3/542/pdf

INPUT STAGE WITH DOUBLE FUNCTIONALITY APPLIED TO A HIGH PERFORMANCE THREE-PHASE UPS-William A. Venturini, Henrique Jank, Fábio E. Bisogno, Mário L. S. Martins, Humberto Pinheiro Universidade Federal de Santa Maria, Santa Maria – RS-BRASIL

ESTÁGIO DE ENTRADA COM DUPLA FUNCIONALIDADE APLICADO A UMA UPS TRIFÁSICA DE ALTO DESEMPENHO
 William A. Venturini, Henrique Jank, Fábio E. Bisogno, Mário L. S. Martins, Humberto Pinheiro Universidade Federal de Santa Maria, Santa Maria – RS, Brasil

 Resumo – Este trabalho apresenta uma configuração topológica que permite utilizar o estágio de entrada de uma UPS de dupla conversão como retificador trifásico, em modo normal de operação, e como conversor CC/CC elevador de tensão, em modo bateria. Dessa forma, evita-se o uso de um circuito específico para a descarga do banco de baterias, o qual deve ser dimensionado para a potência nominal da UPS. É apresentada a análise de funcionamento do estágio de entrada proposto, bem como a modelagem matemática e o sistema de controle que garantem a aplicabilidade na correção do fator de potência de entrada, no controle da tensão de barramento e ainda no equilíbrio das tensões sobre os capacitores de barramento. A metodologia desenvolvida e a boa performance do sistema proposto são validados através de resultados obtidos em uma plataforma hardware-in-theloop, modelo Typhoon HIL402. Os resultados são adquiridos para uma UPS trifásica de 20 kVA.

Abstract – This work presents a topological configuration that allows the input stage of a double conversion UPS to be used as a three-phase rectifier and a DC/DC voltage boost converter in normal and backup operating mode, respectively. Thus, the use of a specific circuit for the discharge of the battery bank, which would be rated for UPS nominal power, is avoided. The operation analysis of the proposed input stage is presented, as well as the mathematical modeling and the control system that guarantee the applicability in the input power factor correction, DC bus voltage control and for the DC bus capacitors voltage balance. Hardware-in-the-loop results are acquired for a 20 kVA three-phase UPS to validate the developed analysis besides to demonstrate the good performance of the system.

VII. CONCLUSÕES
 Este trabalho apresentou uma configuração topológica de estágio de entrada com dupla funcionalidade aplicado a uma UPS de alto desempenho. A característica de dupla funcionalidade é evidenciada pelo uso do mesmo circuito para condicionar a energia demandada pela carga, tanto em modo normal, quanto em modo bateria de operação, operando como um retificador trifásico e como um conversor CC/CC elevador de tensão para a descarga do banco de baterias, respectivamente. Esta característica não é observada na literatura, sendo usualmente utilizado um conversor específico para a descarga do banco de baterias, o qual deve ser dimensionado para a potência nominal da UPS. É apresentada a modelagem de pequenos sinais e o projeto dos controladores que garantem a funcionalidade do estágio de entrada proposto. A metodologia de projeto e o desempenho da topologia em questão são validados a partir de resultados obtidos através de uma plataforma
hardware-in-the-loop de alta fidelidade para uma UPS de 20 kVA.

AGRADECIMENTOS Os autores gostariam de agradecer ao CNPq, CAPES e grupo LEGRAND pelo suporte financeiro a esta pesquisa.

  Palavras-Chave – Correção do Fator de Potência, Fonte Ininterrupta de Energia, Retificador Trifásico.
LINK FULL PAPER
https://www.sobraep.org.br/site/uploads/2018/06/rvol23no2p21.pdf

Optimal Design of Switching Power Supply Por Zhanyou Sha, Xiaojun Wang, Yanpeng Wang, Hongtao Ma

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Pulsed Plasma Thrusters for Small Satellites -Peter Vallis Shaw - Surrey Space Centre Faculty of Engineering & Physical Sciences University of Surrey -United Kingdom.

Pulsed Plasma Thrusters for Small Satellites Peter Vallis Shaw
 Submitted for the Degree of Doctor of Philosophy from the University of Surrey Surrey Space Centre Faculty of Engineering & Physical Sciences University of Surrey -United Kingdom.

 Abstract
 Since the Russian launch of the Zond-2 satellite in 1964 there have been over fifty years of research dedicated to the understanding of the first electric propulsion device to be flown in space, the Pulsed Plasma Thruster. The Pulsed Plasma Thruster originates from the evolution of the vacuum arc switch, but due to its microsecond operation time, the internal dynamics and nature of operation have remained unclear. The Pulsed Plasma Thruster is generally cheap to manufacture and to operate, which keeps it a popular device to research within institutes worldwide and has contributed to its longevity. As a satellite propulsion device it has unique capabilities that other propulsion systems cannot provide. The thruster operates by accelerating plasma formed in the accelerating electrodes (or nozzle) in short discrete packets of thrust or impulse. The pulsed nature of the thruster means that between pulses energy can be stored in capacitors, ready for the next discharge. The storage of energy over time means the power draw is variable and is only dependant on the frequency that the system is pulsed at. This property of the thruster makes the Pulsed Plasma Thruster extremely versatile, allowing the thruster to perform both velocity correction and control manoeuvres and attitude control manoeuvres. The Pulsed Plasma Thruster is mechanically scalable but the performance of the thruster has been shown to depend linearly on the energy storage ability of the thruster’s capacitor. The work presented here covers two areas. Firstly is the critical analysis of the physical mechanisms that occur within a Pulsed Plasma Thruster through a review of literature, experimentation and the development of a high current plasma flow model. The second area is the design, development, manufacture and evaluation of the Pulsed Plasma Thruster for use on a nanosatellite platform known as the CubeSat. Several novel observations and contributions were made during the critical analysis of the physical mechanisms of the Pulsed Plasma Thruster. The most significant was realising how the erosion of the metal electrodes affected the overall discharge process. It is postulated that the expulsion of material from emission sites (or cathode spots), the ionisation of that material and the resulting freed electrons, create a pinched plasma column between the electrodes. It is postulated that the interaction of the electrode sheath region and the intersecting plasma column cause the current flow to become limited. This was then shown to affect the efficiency with which the stored energy of the capacitor was converted to energy to accelerate the plasma. Understanding this issue is key in improving future designs of the Pulsed Plasma Thruster. The observations and conclusions made during this work were put into practice to create an eight µPPT propulsion module for a 3U CubeSat. Initial results show that a µPPT with a specific impulse of 321s, an impulse bit of 0.56µNs and a mass bit of 0.17µg has been developed. The thruster was developed for two technology demonstration CubeSats. STRaND-1 is a joint collaboration between Surrey Space Centre and Surrey Satellite Technology Limited and UKUBE-1 is a joint collaboration between Surrey Space Centre and the UK Space Agency. Both CubeSats are scheduled for launch late 2011, early 2012. The propulsion module for the STRaND-1 CubeSat will be the first to provide full axis control and the first to provide electric propulsion on this class of satellite, showing the advantages of the Pulsed Plasma Thruster for Small Satellites.
LINK THESIS
http://epubs.surrey.ac.uk/745999/1/Thesis_P_Shaw.pdf

Analog Electronic Circuits-Prof. Jeong, Deog-Kyoon-Electrical and Computer Engineering-SEOUL NATIONAL UNIVERSITY

LINK
http://ocw.snu.ac.kr/node/27126