Multiphase Isolated DC-DC Converters for Low-Voltage High-Power Fuel Cell Applications

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dc.contributor.authorMoon, Seung Ryulen
dc.contributor.committeechairLai, Jih-Shengen
dc.contributor.committeememberDe La Ree, Jaimeen
dc.contributor.committeememberHendricks, Robert W.en
dc.contributor.departmentElectrical and Computer Engineeringen
dc.date.accessioned2014-03-14T20:35:52Zen
dc.date.adate2007-05-22en
dc.date.available2014-03-14T20:35:52Zen
dc.date.issued2007-04-26en
dc.date.rdate2009-05-22en
dc.date.sdate2007-05-09en
dc.description.abstractFuel cells provide a clean and highly efficient energy source for power generation; however, in order to efficiently utilize the energy from fuel cells, a power conditioning system is required. Typical fuel cell systems for stand-alone and utility grid-tied stationary power applications are found mostly with low nominal output voltages around 24 V and 48 V, and power levels are found to be 3 to 10 kW [1][2]. A power conditioning system for such applications generally consists of a dc-dc converter and a dc-ac inverter, and the dc-dc converter for low-voltage, high-power fuel cells must deal with a high voltage step-up conversion ratio and high input currents. Although many dc-dc converters have been proposed, most deal with high input voltage systems that focus on step-down applications, and such dc-dc converters are not suitable for low-voltage, high-power fuel cell applications. Multiphase isolated dc-dc converters offer several advantages that are very desirable in low-voltage, high-power fuel cell applications. First, a multiphase is constructed with paralleled phases, which increase power rating and current handling capability for high input current. Second, an interleaving control scheme produces a high operating frequency with a low switching frequency, and the high operating frequency reduces size of passive components. Thirdly, use of a transformer provides electrical isolation and a high conversion ratio. Lastly, several multiphase converters are capable of soft-switching operation, which increases converter efficiency. This thesis examines two highly efficient, soft-switching dc-dc converters that are targeted for fuel cell applications. The thesis also describes the converters' basic operating principles and analyzes performance for low-voltage, high-power fuel cell applications. 5-kW prototypes for each converter are built and tested with a fuel cell simulator. Experimental switching waveforms and efficiency profiles are shown to support the described basic principles and the analysis. Major features and differences between these two converters are also discussed.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-05092007-174226en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05092007-174226/en
dc.identifier.urihttp://hdl.handle.net/10919/32442en
dc.publisherVirginia Techen
dc.relation.haspartETD_MS_Moon_2007.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectdc-dc convertersen
dc.subjectfuel cellsen
dc.subjectsoft switchingen
dc.subjectmultiphaseen
dc.titleMultiphase Isolated DC-DC Converters for Low-Voltage High-Power Fuel Cell Applicationsen
dc.typeThesisen
thesis.degree.disciplineElectrical and Computer Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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