Dynamic Performance Analyses of Current Sharing Control for DC/DC Converters

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dc.contributor.authorSun, Juanjuanen
dc.contributor.committeechairLee, Fred C.en
dc.contributor.committeememberWang, Fei Freden
dc.contributor.committeememberLiu, Yiluen
dc.contributor.committeememberNelson, Douglas J.en
dc.contributor.committeememberXu, Mingen
dc.contributor.departmentElectrical and Computer Engineeringen
dc.date.accessioned2014-03-14T20:13:22Zen
dc.date.adate2007-06-26en
dc.date.available2014-03-14T20:13:22Zen
dc.date.issued2007-06-13en
dc.date.rdate2007-06-26en
dc.date.sdate2007-06-18en
dc.description.abstractParalleling operation of DC/DC converters is widely used in today's distributed power systems. To ensure balanced output currents among paralleled power modules, current sharing control is usually necessary.Active current sharing controls with current feedback mechanism are widely used in today's power supplies. However, the dynamic performance of these current sharing control schemes are not yet clearly explored. In this work, the dynamic current sharing performance is evaluated for paralleling systems with the output impedance approach. As the representative of the terminal characteristic of a power converter, output impedance is a powerful tool to study the dynamic response under load transients. The dynamic current sharing analyses are then conducted for three different active current sharing control structures and a comprehensive comparison among them helps the designer to choose appropriate controls for different applications. On the other hand, high-frequency load transients are possible to happen for voltage regulators, which are the power supplies of microprocessors. In order to study the dynamic current sharing performance for a paralleling system when the perturbation frequency is higher than half of the switching frequency,the conventional output impedance concept needs to be extended. Due to the non-linear behavior of a switching modulator, the beat-frequency phenomenon could cause unexpected failure of a power supply when the perturbation frequency is close to the switching frequency. To address this issue, an unconventional multi-frequency model is proposed for high-frequency dynamic current sharing studies. With this model, the sideband components are possible to be included and the beat-frequency oscillations can be predicted. After that, the conventional impedance concept is expanded in the form of extended describing function, so that the terminal characteristics of paralleled converters are represented by a series of impedances. Besides the analyses, this work also proposed several solutions for the beat-frequency oscillation issue which are experimentally verified. In summary, both low-frequency and high-frequency dynamic current sharing performances are studied in this dissertation. The output impedance concept and its extension in the form of extended describing function are utilized as the tools for researches. With these powerful tools, more insights are obtained to help better design of a paralleling system.en
dc.description.degreePh. D.en
dc.identifier.otheretd-06182007-154637en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06182007-154637/en
dc.identifier.urihttp://hdl.handle.net/10919/28071en
dc.publisherVirginia Techen
dc.relation.haspartETD_JuanjuanSun.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectdynamic performanceen
dc.subjecthigh frequencyen
dc.subjectdistributed power systemsen
dc.subjectcurrent sharingen
dc.titleDynamic Performance Analyses of Current Sharing Control for DC/DC 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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