Accurate segmented equivalent circuit-based calculation approach for non-ideal stranded Litz wire leakage energy

Existing calculations of leakage energy in the Litz wire winding region of high-frequency transformers usually ignore the influence of Litz wire stranded structures. Therefore, a new approach is established in this paper to accurately calculate Litz wire leakage energy through the segmented equivalent circuit approach and the two-dimensional finite element method. That is, a single Litz wire in a complete stranded pitch is segmented and equated to the linear structure of multiple inductance cells. First, the two-dimensional finite element method calculates the impedance of each strand of Litz wire. Then the strand current vector is solved according to the system equation. Finally, the current vector is substituted back into the 2D Litz wire transverse-sectional model to calculate the leakage magnetic field energy under the skin effect and internal proximity effect, which is combined with the analytical expression of the external leakage magnetic field to calculate the total magnetic leakage energy of the Litz wire winding. Calculation results indicate that the new approach has an average relative deviation of less than 2.154% and a maximum relative deviation of no more than 4.953%.