I. Introduction
Leakage inductance is a critical design element of a transformer used in a galvanically isolated power electronic converter. In a multi-layered transformer with integrated magnetics, the skin and proximity effects can disturb the homogeneity of the current density across the cross-sections of the conductors. For a given wire gauge, these eddy current effects become more pronounced as the operating frequency of the power converter is increased. Consequently, the leakage inductance seen at a higher frequency can be significantly smaller than that at a lower frequency [1]. Therefore, it is important to determine the leakage inductance at the specific operating frequency range of the transformer, especially in resonant converters with variable frequency control.