Design and Study of Interleaved and Face to Face Magnetic Microtransformers

The aim of this paper is to compare two types of microtransformers using the High Frequency Structural Simulation simulator. Interleaved and face to face transformers were studied for applications in dc/dc converters and variable speed drive. These transformers have a magnetic material core (yttrium iron garnet) and square spiral windings. The main purpose of the use of magnetic material is to increase the magnetizing inductance L_F and the coupling factor k. For this, L_F and k were studied by simulation as a function of turn spacing, magnetic, and insulating layer thicknesses. The results presented were compared with recently published works. An important improvement of the main properties was observed in the frequency range (10-100 MHz). The interleaved transformer properties are equal to 0.95 and 0.80 μH for k and L_F parameters, which corresponds to an 0.05 μH/mm² inductance area ratio (L_F/A), whereas for the face to face transformer k and L_F are equal to 0.9 and 0.78 μH for an 0.08 μH/mm ² inductance area ratio. Interleaved transformers were manufactured and characterized. Results show close agreement between simulation and measurement results.