A coupled thermal-magnetic model for high frequency transformers. I. Model formulation and material properties

A novel model for analyzing high-frequency transformers is presented. The model is based on the simultaneous solution of the coupled, nonlinear thermal and electromagnetic equations. The modeling and assumptions used to derive the governing equations are explained. A set of integrodifferential constraints are developed to apply the proper input voltage and output impedance to the transformer windings. Next, a method of modeling the magnetic material properties as a function of temperature and magnetic flux density is given. A novel technique for modeling the complex 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. A quasi-steady formulation of the heat-conduction equation eliminates the time dependence of the thermal problem.<<ETX>>

[1]  Ronald F. Soohoo,et al.  Theory and application of ferrites , 1960 .

[2]  N. Takahashi,et al.  Efficient solving techniques of matrix equations for finite element analysis of eddy currents , 1988 .

[3]  J. Patrick Jessee.  A coupled thermal-magnetic finite element model for high frequency transformers , 1990 .

[4]  Magneto-thermal coupled finite element calculations in multiconductor systems , 1987 .

[5]  C. G. Koops.  On the Dispersion of Resistivity and Dielectric Constant of Some Semiconductors at Audiofrequencies , 1951 .

[6]  Osama A. Mohammed,et al.  A new technique for transformer design in power electronics applications using nonlinear magnetic field solutions , 1987, IEEE Power Electronics Specialists Conference.

[7]  W. Shockley,et al.  Studies of the Propagation Velocity of a Ferromagnetic Domain Boundary , 1950 .

[8]  J. P. Jessee,et al.  A coupled thermal magnetic model for high frequency transformers. II. Finite element implementation and validation , 1992 .

[9]  J. B. Klaassens,et al.  Design of a high-frequency planar power transformer in multilayer technology , 1991 .

[10]  A. Konrad,et al.  Eddy currents and modelling , 1985 .

[11]  John G. Kassakian,et al.  Issues related to 1-10-MHz transformer design , 1989 .

[12]  J. D. Lavers,et al.  Numerical solution methods for electroheat problems , 1983 .

[13]  Fred C. Lee,et al.  Design of high-frequency hybrid power transformer , 1988, APEC '88 Third Annual IEEE Applied Power Electronics Conference and Exposition.

[14]  R. D. Findlay,et al.  The variational treatment of the diffusion equation for vector field problems , 1987 .

[15]  Z. Cendes,et al.  Efficient finite element solution of multipath eddy current problems , 1982 .

[16]  D. F. Snelling,et al.  How long is a MegaFlop , 1991 .

[17]  A. Konrad,et al.  New finite element techniques for skin effect problems , 1982 .

[18]  N. R. Coonrod.  Transformer Computer Design Aid for Higher Frequency Switching Power Supplies , 1984, IEEE Transactions on Power Electronics.

[19]  Larry L. Hench,et al.  Principles of electronic ceramics , 1990 .

[20]  J. Jessee,et al.  MODELING BIVARIABLE-DEPENDEIUT MATERIAL PROPERTIES USING AN EXPLICIT BICUBIC SPLINE , 1991 .

[21]  A. Konrad.  The numerical solution of steady-state skin effect problems--An integrodifferential approach , 1981 .

[22]  P. Massé,et al.  A finite element prediction correction scheme for magneto-thermal coupled problem during curie transition , 1985 .

[23]  A. Goldberg.  High field properties of nickel-zinc ferrites at 1-10 MHz , 1988, APEC '88 Third Annual IEEE Applied Power Electronics Conference and Exposition.

[24]  K. Preis.  A contribution to eddy current calculations in plane and axisymmetric multiconductor systems , 1983 .