Title page for ETD etd-08072003-141703


Type of Document Master's Thesis
Author Wang, Shen
Author's Email Address shwang@vt.edu
URN etd-08072003-141703
Title Modeling and Design of Planar Integrated Magnetic Components
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Boroyevich, Dushan Committee Co-Chair
Odendaal, Willem Gerhardus Committee Co-Chair
van Wyk, Jacobus Daniel Committee Member
Keywords
  • planar litz
  • finite element analysis (FEA)
  • eddy current
  • high frequency (HF)
  • planar magnetic
Date of Defense 2003-07-21
Availability unrestricted
Abstract
Recently planar magnetic technologies have been widely used in power electronics, due to good cooling and ease of fabrication. High frequency operation of magnetic components is a key to achieve high power density and miniaturization. However, at high frequencies, skin and proximity effect losses in the planar windings become significant, and parasitics cannot be ignored. This piece of work deals with the modeling and design of planar integrated magnetic component for power electronics applications.

First, one-dimensional eddy current analysis in some simple winding strategies is discussed. Two factors are defined in order to quantify the skin and proximity effect contributions as a function of frequency. For complicated structures, 2D and 3D finite element analysis (FEA) is adopted and the accuracy of the simulation results is evaluated against exact analytical solutions.

Then, a planar litz structure is presented. Some definitions and guidelines are established, which form the basis to design a planar litz conductor. It can be constructed by dividing the wide planar conductor into multiple lengthwise strands and weaving these strands in much the same manner as one would use to construct a conventional round litz wire. Each strand is subjected to the magnetic field everywhere in the winding window, thereby equalizing the flux linkage. 3D FEA is utilized to investigate the impact of the parameters on the litz performance. The experimental results verify that the planar litz structure can reduce the AC resistance of the planar windings in a specific frequency range.

After that, some important issues related to the planar boost inductor design are described, including core selection, winding configuration, losses estimation, and thermal modeling. Two complete design examples targeting at volume optimization and winding parasitic capacitance minimization are provided, respectively.

This work demonstrates that planar litz conductors are very promising for high frequency planar magnetic components. The optimization of a planar inductor involves a tradeoff between volumetric efficiency and low value of winding capacitance. Throughout, 2D and 3D FEA was indispensable for thermal & electromagnetic modeling.

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