Tuning of Planar Transformer Leakage Inductance

The leakage inductance of high-frequency (HF) transformer is a key parameter to help improve the power density of isolated DC/DC converters. Minimized, it can reduce the losses, but maximized or precisely tuned, the leakage inductance can intervene in the converter operation, avoiding supplementary HF inductor. This is the case for soft-switching converters or specific topologies like dual active bridge for example. The present work aims to adjust the value of a planar transformer (PT) leakage inductance, acting on the positioning of the conductors within the PT winding window. The methodology developed here is based on finite element analysis (FEA) simulation as well as single and multi-objective optimizations to adjust the value of the leakage inductance while minimizing the AC resistance. The optimization is carried out for different interleavings, questioning the usual choices of interleavings known to minimize or maximize the leakage inductance.