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