Prediction of the leakage inductance in high frequency transformers

In this paper, approximation formulas for the calculation of the leakage inductance of transformers with two winding layers or two stacked bobbins are reviewed and verified by simulation results and experiments. The accuracy of the approximation is examined for practical applications, e.g. if the available winding area is defined by a coil former. Finally, the influence of an air gap in the center leg is investigated.