Title page for ETD etd-12172008-063409

Type of Document Master's Thesis
Author Jessee, J. Patrick
URN etd-12172008-063409
Title A coupled thermal-magnetic finite element model for high frequency transformers
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Nelson, Douglas J. Committee Chair
Thomas, James R. Jr. Committee Member
Vick, Brian L. Committee Member
  • Electric transformers
Date of Defense 1990-12-20
Availability restricted

A new method for analyzing axisymmetric, high-frequency transformers is presented. The method is based on the simultaneous solution of the coupled, nonlinear thermal and electromagnetic equations using the finite element method. A novel technique for modeling the reluctivity of the soft-ferrite core material permits a time-harmonic transformation of the electromagnetic equations. This eliminates the need to step through time while maintaining the effects of hysteresis losses. Also, a quasi-steady formulation of the heat-conduction equation eliminates the time dependency on the thermal problem. A direct substitution iterative scheme is used in conjunction with the finite element method to compensate for the coupled and nonlinear nature of the equations. To verify the magnetics portion of the finite element code numerically, a linear, uncoupled test case is given which compares the magnetic results from the present method to those from a commercial software package. To investigate the accuracy of the fully coupled and nonlinear model, an example is presented which compares the results from the numerical analysis of an inductor to those obtained by experimental measurement.

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