Topology Investigation and System Optimization of Resonant Converters

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dc.contributor.authorFu, Dianboen
dc.contributor.committeechairLee, Fred C.en
dc.contributor.committeememberWang, Fei Freden
dc.contributor.committeememberXu, Mingen
dc.contributor.committeememberBaumann, William T.en
dc.contributor.committeememberReynolds, Marion R. Jr.en
dc.contributor.departmentElectrical and Computer Engineeringen
dc.date.accessioned2014-03-14T20:12:14Zen
dc.date.adate2010-06-16en
dc.date.available2014-03-14T20:12:14Zen
dc.date.issued2010-02-04en
dc.date.rdate2010-06-16en
dc.date.sdate2010-05-18en
dc.description.abstractOver the past several years, energy efficiency and power density have become the top concerns for power conversion. Rising energy intensity leads to a higher cost of delivering power. Meanwhile, the demand for compact power supplies grows significantly. It requires power supplies with high efficiency, low profile and high power density. Dc-dc power conversion has been widely applied for industry, medial, military and airspace applications. Conventional PWM dc-dc converters have relatively low power transfer efficiency and low power density. In contrast, resonant dc-dc converters have numerous advantages for dc-dc power conversions. In this work, topologies and system optimization of resonant converters are investigated to meet challenges of high efficiency, high power density, low EMI, easy startup and over current protection. LLC resonant converters can achieve zero-voltage-switching (ZVS) for primary side devices and zero-current-switching (ZCS) for the secondary side rectifiers. The switching loss is minimized. LLC is very attractive to overcome the issues of conventional circuits. However, challenges still remain. First of all, for low-voltage high-current applications, the synchronous rectifier (SR) with lower conduction loss is a must for high efficiency. To solve the driving issues of SRs, a novel synchronous driving scheme is proposed. Experimental results demonstrate the considerable loss reduction with utilization of the proposed driving scheme. Secondly, dc-dc converters are required to meet EMI standard. This work proposes an EMI mode. Based on the proposed model, EMI analysis and noise attenuation techniques are proposed and verified by experiments. Thirdly, startup and over-load protection are another issues of LLC resonant converters. With proposed multi-element resonant converters, the current limit issues can be resolved. In addition, the proposed multi-element resonant converters can utilize higher-order harmonics to enhance power transfer. Fourthly, for high-current applications, the secondary side structure becomes very critical. An improved secondary side construction is proposed to alleviate ac termination losses and SR paralleling issues. Novel winding structures are proposed to reduce the winding loss. The magnetic integration technique is proposed and analyzed, and an optimal integrated transformer design is proposed, which has low loss and compact size.en
dc.description.degreePh. D.en
dc.identifier.otheretd-05182010-104553en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05182010-104553/en
dc.identifier.urihttp://hdl.handle.net/10919/27783en
dc.publisherVirginia Techen
dc.relation.haspartFu_D_D_2010.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectmulti-elementen
dc.subjecthigh efficiencyen
dc.subjectresonant converteren
dc.subjecthigh power densityen
dc.titleTopology Investigation and System Optimization of Resonant Convertersen
dc.typeDissertationen
thesis.degree.disciplineElectrical and Computer Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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