Comparison of experimental techniques for determination of stray capacitances in high frequency transformers

A new approach for experimental determination of stray capacitances in high frequency transformers is proposed in this paper. This approach identifies the stray capacitances of a two winding transformer by conducting open and short circuit tests on both windings within the range of normal operation frequencies and fitting the π-shaped capacitor network model to the voltage and current readings. The experimental results of the stray capacitances in a 500 W two foil winding soft ferrite E-core high frequency transformer obtained by this two port network approach are compared with those obtained by the forced resonance and the step response approaches previously proposed by the authors. The merits and drawbacks of these approaches are also discussed