I. Introduction
The power transformer is the key component in MF isolated dc-dc converters, especially in applications with volume and weight restrictions. It can perform different functions apart from voltage and current transformations. In Dual-Active-Bridge (DAB) or in Series-Resonant-Converters (SRC), the series connected inductor and/or the transformer leakage inductance is critical for a proper operation of the power converter. Moreover, the parallel inductor and/or the transformer magnetizing inductance is essential in topologies which operate in zero-voltage-switching (ZVS) conditions, such as the LLC resonant converter, since they can assure soft-switching in all the operating range. The converter design can be optimized by integrating all these inductive elements within the transformer (see Fig. 1), but increasing the complexity of transformer design.