In this thesis, coupled inductors have been applied to multiphase DC-DC converters. Detailed analysis has been done to investigate the benefits of directly coupled inductors and inversely coupled inductors, compared to conventional uncoupled inductors. In general, coupled inductors for multiphase DC-DC converters have inherent benefits such as excellent current sharing characteristics, immunity to component tolerance and reduction in current control complexity. Specifically, by employing directly coupled inductors for multiphase DC-DC converters, overall current ripple can be effectively reduced, compared to that of uncoupled inductors. For inversely coupled inductors, phase current ripple can be reduced if operating points and coupling coefficients are carefully chosen. As for small-signal characteristics, inversely coupled inductors have the advantages of broadening the bandwidth of multiphase DC-DC converters and being more immune to load variation at low frequencies. On the other hand, directly coupled inductors have the benefit of low sensitivity to input variation at high frequencies. In addition, the proposed new structure for multiphase DC-DC converters has excellent current sharing performance and reduced current ripple. Computer simulations have been done and hardware prototypes have been built to validate the concepts.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 97-106). Also available on the World Wide Web.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Abstract. Vita. Also available via the Internet

Thesis (MS)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: James P. Becker. Includes bibliographical references (leaves 147-148).

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 50-54). Also available on the World Wide Web.

Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Prof. Rao Tummala; Committee Member: Prof. G.K. Chang; Committee Member: Prof. Maysam Ghovanloo.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references. Also available in electronic version.

MnZn ferrites are widely used in power electronics applications where the switching frequency is in the range of several tens of kilohertz to a megahertz. In this range of frequencies the combination of relatively high permeability and relatively low conductivity found in MnZn ferrite helps to minimize the size of magnetic devices while maintaining high efficiency. The continuing improvement in semiconductor switches and circuit topologies has led to use of high-frequency switching circuits at ever increasing power levels. The magnetic devices for these high-power, high-frequency circuits require magnetic CORES that are significantly larger than standard ferrite-core devices used at lower power levels. Often such large ferrite cores must be custom designed, and at present this custom design is based on available material information without regard for the physical size of the structure. This thesis examines the issues encountered in the use of larger MnZn ferrite cores for high-frequency, high-power applications. The two main issues of concern are the increased power dissipation due to induced currents in the structure and the change in inductance that results as the flux within the core is redistributed at higher frequencies. In order to model these problems using either numerical or analytical methods requires a reliable and complete set of material information. A significant portion of this work is devoted to methods for acquiring such material information since such information is not generally available from the manufacturers. Once the material constants required for the analysis are determined, they are used in both closed-form and numerical model to illustrate that large ferrite cores suffer significant increases in loss and significant decreases in inductance for frequencies as low as several hundred kilohertz. The separate impacts of the electrical and magnetic losses in the core are illustrated through the use of linear finite element analyses of several example core structures. The device impedances calculated using the FEA tools show fair agreement with measurement. An analysis of gapped structures and segmented cross-sections shows that these design options can reduce the severity of the dimensional problems for some designs. / Ph. D.