An Improved Calculation Method of Leakage Inductance for High-frequency Transformer Based on Precise Analysis of Magnetic Field

In high-frequency transformers (HFTs), Litz wire is widely adopted to reduce eddy current loss and improve efficiency. Despite the advantages that Litz wire brings, calculating the leakage inductance is also more difficult. As one of the key parameters of high-frequency transformer, leakage inductance directly affects the power transmission performance. This paper proposes a new model to estimate the leakage inductance of transformers accurately in a wide frequency range. Unlike traditional models, the new model makes comprehensive analysis of leakage field and more accurate estimate of leakage inductance. In order to verify the precision of the proposed model, five transformers are built and analyzed by performance comparison. By comparing the results of measurement, finite element analysis (FEA) simulation and existing model, it is proved that the proposed model is more precise. Finally, the effect of winding layers and wire density on the variation of leakage inductance with frequency is revealed.