Método de carga para banco de baterias em fontes ininterruptas de energia que busca garantir o estado de carga completa: corrente pulsada modificado--Cardoso, Renato Tavares (Universidade Federal de Santa Maria)

 

ABSTRACT

Esta dissertação de mestrado tem como proposta o desenvolvimento de um sistema de gerenciamento de carga de um banco de 16 baterias de chumbo ácido, com capacidade de carga de 7Ah, comumente utilizado em Fontes Ininterruptas de Energia (UPS). Este sistema visa garantir que estas baterias cheguem a um estado de carga completo e de forma mais rápida que a convencional. Para isto, foi escolhido fazer a modificação do método de carga de corrente pulsada, com o objetivo de reduzir problemas inerentes do método tomado como base, quando ocorre o intervalo de retirada de energia da bateria, tais como: elevação da tensão do barramento ao retornar a energia para ele, ou, dissipar esta energia em uma resistência, o que acarreta em baixa eficiência do sistema. Para o desenvolvimento do sistema de carga sugerido foi escolhido o conversor estático Full-Bridge Isolado com modulação Phase Shift. Foi feita a modelagem simplificada deste conversor, para a implementação do controle digital, assim como o desenvolvimento prático do mesmo em laboratório. São apresentados os resultados de simulação e experimentais para validar o método. 

 LINK: https://repositorio.ufsm.br/bitstream/handle/1/8576/CARDOSO%2c%20RENATO%20TAVARES.pdf?sequence=1&isAllowed=y

High-voltage power supply for x-ray computed tomography and time-delay compensation of cockcroft-walton circuit Yuki Kajiuchi and Toshihiko Noguchi Canon Medical Systems Corporation, Tochigi, Japan. Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu, Japan

 

High-voltage power supply for x-ray computed tomography and time-delay compensation of cockcroft-walton circuit Yuki Kajiuchi and Toshihiko Noguchi Canon Medical Systems Corporation, Tochigi, Japan. 2Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu, Japan. 

Abstract.

 In recent years, an image diagnostic apparatus using X-ray is intensively investigated to reduce the radiation exposures amount. Above all, high-speed control of the high voltage generator to control the X-ray output is a very important issue. A Cockcroft-Walton circuit (CW circuit) is one of the method to generate the high voltage output. However, it has problem of the long time delay in the output response due to the huge capacitive component of the CW circuit. Therefore, it is required to achieve the stable output voltage with a quick transient response, which can be obtained by the time delay compensation technique of the CW circuit. This paper proposes an application of a Smith method to compensate for the time delay of the CW circuit output to reduce the undesirable excessive radiation exposure. AS a result of verification through the computer simulation, it has been confirmed that the overshoot of the output voltage can effectively be suppressed and that the optimal response can be realized without sacrificing the high-speed response. The paper indicates some possibilities of further improvement of the CW circuit output response by introducing the more precise compensation technique to the X-ray computed tomography. 

LINK:https://www.researchgate.net/publication/337182375_High-voltage_power_supply_for_x-ray_computed_tomography_and_time-delay_compensation_of_cockcroft-walton_circuit

변압기 없는 고승압 직류 컨버터용 대칭형 Cockcroft-Walton 회로 (Symmetrical Cockcroft-Walton circuit for Transformerless High Step-Up DC-DC Converter) 차대중*․백지은․고광철** (Dae-Joong Cha․Ji-Eun Baek․Kwang-Cheol Ko)-Journal of the Korean Institute of IIIuminating and Electrical Installation Engineers (2015--

 

변압기 없는 고승압 직류 컨버터용 대칭형 Cockcroft-Walton 회로 (Symmetrical Cockcroft-Walton circuit for Transformerless High Step-Up DC-DC Converter) 차대중*․백지은․고광철** (Dae-Joong Cha․Ji-Eun Baek․Kwang-Cheol Ko) 

Abstract 

High Step-up DC-DC Converters have been demanded for renewable energy applications. Transformer or coupled inductor is generally used to boost output voltage of converters. This methods can relatively obtain high voltage than others, whereas have heavy weight and high cost. To complement these disadvantages, we studied transformerless high step-up DC-DC converter. In various transformerless topologies, Boost converters combined with Cockcroft-Walton have studied. In this paper, we proposed a symmetrical Cockcroft-Walton circuit for transformerless high step-up DC-DC converter. Finally, we simulated proposed converter to compare with existing converter. As a result, proposed converter has higher duty ratio or lower cost than existing transformerless converters which are discussed in this paper.

LINK VIEW FULL TEXT: https://www.koreascience.or.kr/article/JAKO201505041841025.pdf

Cockcroft-Walton Voltage Multiplier Simulation According to Diode Parasitic Capacitance for Xray Generator Designing Xray 발생장치 설계를 위한 다이오드 기생 커패시턴스에 따른 Cockcroft-Walton Voltage Multiplier 시뮬레이션 Im, Gyu-Wan (KONKUK University) ; Mok, Hyung-Soo (KONKUK University) ; Zhu, He-Lin (KONKUK University) 임규완 (건국대학교) ; 목형수 (건국대학교) ; 주학림 (건국대학교)

 ABSTRACT

Due to the recent outbreak of COVID-19 (Coronavirus disease, 2019), The demand for X-ray examinations to make a definitive diagnosis is increasing. In order to obtain high-quality Xray images, the X-ray tube A constant high voltage suitable for the purpose of shooting must be applied to the camera through control. To do this, consider the output voltage characteristics of the power converter. should be designed Therefore, it is mainly used for Xray generators. of the diode using the Cockcroft-Walton Voltage Multiplier. The parasitic capacitance component is the leakage inductance component of the transformer, and the The parasitic inductance component and the output voltage generated by resonance.

LINK VIEW FULL TEXT: https://www.koreascience.or.kr/article/CFKO202026958570456.pdf

NOVA FAMÍLIA DE INVERSORES MULTINÍVEIS ASSIMÉTRICOS COM ESTÁGIO CA-CA E COM REDUZIDO NÚMERO DE COMPONENTES EM CONDUÇÃO--SAMUEL JÓ DE MESQUITA-- Curso de Doutorado em Engenharia Elétrica -Universidade Federal do Ceará--BRASIL

 

RESUMO 

Esta tese propõe uma nova família de inversores multiníveis assimétricos baseados no uso de chaves bidirecionais. Generalizadas relações de tensão entre as fontes de entrada dos inversores cascateados são desenvolvidas e análises comparativas realizadas com as topologias convencionais demonstram uma solução atrativa com relação a redução do número de componentes em condução, além do reduzido emprego de fontes CC isoladas. Soluções topológicas empregando apenas uma fonte CC são apresentadas e a operação com estágio CA-CA desses conversores não necessita de pontes de diodos para confecção das fontes de alimentação dos inversores multiníveis assimétricos como comumente é usado pela comunidade científica. Estratégias de modulação PWM para algumas topologias são propostas e os resultados de simulações são apresentados para validar as análises teóricas. Entre as topologias propostas, foram escolhidas duas de maior complexidade para a validação experimental por meio de um protótipo de 49 níveis na tensão de saída, empregando um transformador toroidal de múltiplos secundários operando em 300 Hz, para a primeira topologia e em 60 Hz para a segunda topologia. Os resultados experimentais para as duas topologias processando 1 kW com tensão de entrada de 48 V e de saída 220 V validam os conversores aqui propostos. Também é validada a proposta dos estados otimizados de comutação dos interruptores bidirecionais. Dessa forma, este trabalho introduz novas topologias de inversores multiníveis assimétricos viáveis até mesmo para operações em baixas potências.

 Palavras-chave: Chaves bidirecionais. Estágio CA-CA. Inversores multiníveis assimétricos. Topologias isoladas. Transformador de múltiplos secundários. Modulação staircase. Modulação híbrida. Modulação PWM.

 ABSTRACT 

This thesis proposes a new family of asymmetric multilevel inverters based on the use of bi-directional switches. Generalized voltage relations among input sources of the cascaded inverters are developed and comparative analyzes with conventional topologies show an attractive solution in relation to the reduction of the number of components in conduction, as well as the reduced number of isolated DC sources. Topological solutions employing only one DC source are presented and the AC-AC operating stage of these converters does not require diode bridges to create the power supplies of asymmetric multilevel inverters as commonly proposed by the scientific community. PWM modulation strategies for some topologies are proposed and validated by simulation results. Among the proposed topologies, two topologies of higher complexity were chosen to validate the studies by means of a 49-level output voltage laboratory prototype, using a toroidal transformer with multiple secondary windings, being one topology operating at 300 Hz, and the second one at 60 Hz. Experimental results for the two topologies processing 1 kW with 48 V input voltage and 220 V output validate these converters as well as the optimized commutation states of the bi-directional switches. In this way, this work introduces new multilevel inverter topologies viable for low power and low voltage operation. 

Keywords: Asymmetrical multilevel inverters. AC-AC conversion. Bi-directional switches. Multi-winding transformers. Hybrid modulation. PWM modulation. Staircase modulation

LINK VIEW FULL TEXT :http://www.gpec.ufc.br/teses/5.pdf

ADVANCED TOPOLOGIES OF HIGH-VOLTAGE-GAIN DC-DC BOOST CONVERTERS FOR RENEWABLE ENERGY APPLICATIONS by AHMAD SAEED Y. ALZAHRANI--MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY--DOCTOR OF PHILOSOPHY in ELECTRICAL ENGINEERING 2018

 CONVERTERS FOR RENEWABLE ENERGY APPLICATIONS by AHMAD SAEED Y. ALZAHRANI MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY 

 In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY in ELECTRICAL ENGINEERING- 2018 

 ABSTRACT

 This dissertation proposes several advanced power electronic converters that are suitable for integrating low-voltage dc input sources, such as photovoltaic (PV) solar panels, to a high voltage dc bus in a 200 − 960 V dc distribution system. The proposed converters operate in the continuous conduction mode (CCM) and offer desirable features such as lowvoltage stresses on components, continuous input currents, and the ability to integrate several independent dc input sources. First, a family of scalable interleaved boost converters with voltage multiplier cells (VMC) is introduced. Several possible combinations of Dickson and Cockcroft-Walton VMCs are demonstrated and compared in terms of the voltage gain, number of components, and input current sharing. This dissertation also presents a novel VMC structure called Bi-fold Dickson. The novel VMC offers equal current sharing between phases regardless of the number of stages, voltage ripple cancellation at each stage, and does not require an output diode. A family of high-voltage-gain multilevel boost converters is presented, with detailed example of the hybrid flyback and three-level boost converter. In this family, the effective frequency seen by the magnetic element is multiple times the switching frequency, and therefore smaller magnetic devices can be used. Theory of operations, steady-state analysis, component selections, simulation, and efficiency analysis are included for each proposed converter. The operation of the proposed converters was further verified with 80 − 200 W hardware prototypes.

LINK: https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=3721&context=doctoral_dissertations

Design and Control Methodology for Improved Operation of a HV Bipolar Hybrid Switched Capacitor Converter J. Delhotal, J. Richards, J. Stewart, J. Neely, J. Flicker, R. Brocato, L. Rashkin Sandia National Laboratories Albuquerque, New Mexico, USA

Design and Control Methodology for Improved Operation of a HV Bipolar Hybrid Switched Capacitor Converter J. Delhotal, J. Richards, J. Stewart, J. Neely, J. Flicker, R. Brocato, L. Rashkin Sandia National Laboratories Albuquerque, New Mexico, USA Email: jneely@sandia.gov Jane Lehr University of New Mexico Albuquerque, New Mexico, USA 

 Abstract— In this work, a novel dc-dc converter topology, an adaptation of the Hybrid Switched Capacitor Circuit (HSCC), is considered for use in high-gain, high voltage applications that also require high efficiency and superior power density. In particular, a bipolar HSCC design is described, and a candidate control methodology is set forth and developed analytically. The converter performance is demonstrated to be consistent with analysis. In addition, the converter is demonstrated to step 460V up to 8.63 kV (gain of 19) at 3.63 kW and nearly 97.0% efficiency. 

LINK VIEW FULL TEXT IN WEB:

https://www.osti.gov/servlets/purl/1473752

DESIGN AND DEVELOPMENT OF POWER PROCESSING UNITS FOR APPLICATIONS IN ELECTRICALLY-PROPELLED SATELLITE SYSTEMS by KARTIKEYA JAYADURGA PRASAD VEERAMRAJU---Requirements for the Degree MASTER OF SCIENCE in ELECTRICAL ENGINEERING--MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY-

 

DESIGN AND DEVELOPMENT OF POWER PROCESSING UNITS FOR APPLICATIONS IN ELECTRICALLY-PROPELLED SATELLITE SYSTEMS by KARTIKEYA JAYADURGA PRASAD VEERAMRAJU

 A THESIS Presented to the Graduate Faculty of the MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE in ELECTRICAL ENGINEERING 2020 

 ABSTRACT 

Electrospray technology provides a way to ionize specialized liquids by applying high voltages across a sharp porous tip and a metallic mesh. This technology is widely used in the field of mass spectroscopy for generating ions for testing purposes. The dawn of nano-satellites posed new challenges in the miniaturization of many conventional satellite sub-systems. One significant challenge faced in such a process was the miniaturization of the propulsion system. Electrosprays have started to find their application in the field of Aerospace Engineering and now are formally known as Electrospray Thrusters. These thrusters provide high specific impulse and are attractive substitutes to conventional gas propelled thrusters as they can be scaled down in size and can also provide extended mission times. Some of the new challenges faced in such applications are the generation of high voltages from a lowvoltage onboard battery, grounding, spacecraft charging, clearance, and reliability issues for long term usage. In this work, a complete design process is developed for the realization of such high voltages suitable for interfacing with an electrospray thruster. Simulation models for a new type of converter are assessed, and its feasibility is discussed. A hardware prototype is implemented, and the practical results are assessed. An analysis of the converter is presented, and the semiconductor and passive components are selected. Magnetic components are designed based on the analysis. Parallels are drawn between the theoretical and prototype model of the concept converter. Finally, the firmware of the converter is explained, and the communication protocol of the PPU is delineated. As the boards designed for the converter have to sustain high voltages and reliably operate in unfavorable environments, special PCB layout considerations must be used, which also forces a designer to look for various other materials for the PCB fabrication.

 LINK VIEW FULL TEXT IN WEB:

https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=8938&context=masters_theses

Characterization and Design of HighSwitching Speed Capability of GaN Power Devices in a 3-Phase Inverter-Rémi PERRIN-THESE de DOCTORAT DE L’UNIVERSITE DE LYON opérée au sein de Laboratoire AMPERE

 

Characterization and design of the switching frequency rise of a 3-phase inverter with GaN transistors by Rémi Perrin

 Abstract 

The French industrial project MEGaN aims to develop a power module based on HEMT compost in GaN. One of the industrial applications concerns aeronautics with a high constraint in galvanic isolation (> 100 kV / s) and in ambient temperature (200 ° C). The thesis work was focused on a power module brick (650 V 30 A inverter arm). The objective is to achieve a prototype of thin form factor, 30 cm2 and embedding all the driver functions, driver power supply, bus capacity and phase current sensor. This objective implies high energy efficiency, and respect for galvanic insulation while the surface stress is high. The manuscript, in addition to the state of the art relating to the power module and in particular that based on GaN HEMT transistor, discusses a micro-transformer-based control signal isolation solution. Micro-transformer prototypes were characterized and aged for 3000 hours to assess the robustness of the solution. The work contributed to the characterization of several GaN components in order to mature models for circuit simulation of converter topology. Within the MEGaN collaborative work, our contribution did not concern the design of the integrated circuit (grid driver), while having participated in the validation of the specifications, but a power supply strategy for the grid driver. A first isolated power supply proposal for the gate driver favored the use of low-voltage GaN components. The resonant flyback topology with clamp makes it possible to get the most out of these GaN components but poses the constraint of the power transformer. Several technologies for the realization of the transformer have been validated experimentally and in particular an original proposal for the burial of the magnetic component within a high-temperature polymer substrate. In particular, an inexpensive manufacturing process makes it possible to obtain a reliable device (1000 h of cycling between - 55; + 200 ° C), with an intrinsic efficiency of 88% for 2 W transferred. The parasitic insulation capacity is reduced compared to previous prototypes. Two prototypes of highly integrated power supplies use either low voltage GaN transistors (2.4 MHz, 2 W, 74%, 6 cm2), or a dedicated integrated circuit in CMOS SOI technology, designed for the application (1.2 MHz, 2 W, 77%, 8.5 cm2). The manuscript then proposes an integrable solution for measuring the phase current of the bridge arm, based on a magnetoresistance. The experimental comparison with respect to a shunt resistance solution. Finally, two converter prototypes are described, one of which has been the subject of an experimental validation demonstrating reduced switching losses.

VIEW FULL TEXT :http://theses.insa-lyon.fr/publication/2017LYSEI001/these.pdf

Design and characterization of a three-phase current source inverter using 1.7kV SiC power devices for photovoltaic applications-Présentée par Luís Gabriel ALVES RODRIGUES Laboratoire de Génie Electrique de Grenoble dans l'École Doctorale Electronique, Electrotechnique, Automatique et Traitement du Signal-

 

Abstract 

Classically, the energy conversion architecture found in photovoltaic (PV) power plants includes solar arrays delivering a maximum voltage of 1kV followed by a step-up chopper connected to a three-phase Voltage Source Inverter. This multistage conversion system (DC/DC + DC/AC) is then connected to the medium-voltage grid through a low-voltage/medium-voltage transformer. In order to simplify the PV systems, this research work focuses on the study and implementation of a DC/AC topology employing a single power processing stage: the three-phase Current Source Inverter (CSI). To deal with the inconvenient of high conduction losses when implementing this topology, wide-bandgap Silicon Carbide (SiC) semiconductors are used, allowing to efficiently convert energy while keeping a relatively high switching frequency. Nonetheless, since the available power semiconductor modules on the market are not compatible with the CSI, a novel 1.7kV SiC-based voltage bidirectional module is developed in the context of this thesis. Hence, the dynamic characterization of the new SiC device is carried out and serves as the basis for the design of a 60kW CSI prototype. Finally, the inverter efficiency is evaluated at nominal operating conditions, employing both a calorimetric and electrical methods. The obtained results confirm the CSI ability to operate efficiently at high switching frequencies (η>98.5% @60kHz). The originality of this work lies mainly in the design, characterization and implementation of the new 1.7kV full-SiC power module adapted to the CSI topology. Keywords: Power electronics, DC/AC converters, Current Source Inverter (CSI).

VIEW FULL TEXT : https://tel.archives-ouvertes.fr/tel-02476261/document

A Study on a Single-phase Control Algorithm of 4-LEG type PCS (Power Conditioning System)for Micro-grid Application by Seung Ho, Kim -Department of Electronic and Electrical Engineering The Graduate School Korea University of Technology and Education

마이크로그리드용 4-LEG 방식 PCS의 각상 개별제어 알고리즘에 관한 연구

 A Study on a Single-phase Control Algorithm of 4-LEG type PCS for Micro-grid Application

BY KIM SEUNG HO

Graduate School of Korea University of Technology and Education Electrical and Electronic Communication Engineering Electrical Engineering

ABSTRACT

AC-common bus microgrid system can overcome several weaknesses of DC microgrid system by interconnecting DC/AC inverters for renewable energy with AC network. Nevertheless, unbalanced loads in island and small community electric power system can make performances of AC microgrid system getting worse. These are because of limited voltage regulation capability and mixed power flow in voltage source inverter. In other to overcome the unbalanced load condition, this paper proposes voltage and current control algorithm of 4-LEG inverter based on single phase d-q control method, and also proposes the modeling of voltage controller using Matlab/Simulink S/W. From the S/W simulation and experiment of 250kW proto-type inverter, it is confirmed that the proposed algorithm is useful tool for design and operation of AC microgrid system.

VIEW FULL TEXT:

http://kut.dcollection.net/public_resource/pdf/200000083347_20211104232924.pdf

ANALYSIS AND OPERATION OF A MICROGRID WITH PHOTOVOLTAIC SOURCES-A Thesis Presented to The Academic Faculty By Juan C. Lazarte-In Partial Fulfillment Of the Requirements for the Degree Master of Science in Electrical and Computer Engineering-Georgia Institute of Technology

 VIEW FULL TEXT: https://smartech.gatech.edu/bitstream/handle/1853/59951/LAZARTEMENDOZA-THESIS-2018.pdf