Calculation model of leakage inductance of planar transformer based on image method

As a common magnetic component of small and medium power switching power supplies, planar transformers' leakage inductance is an important factor affecting the stability and efficiency of switching power supplies. The traditional one-dimensional Dowell model does not take into account the uneven current distribution of PCB windings due to the eddy current effect at high frequencies, resulting in a large error in leakage inductance calculation. To address the shortcomings of the one-dimensional Dowell model, this paper divides the PCB winding into several parallel conductors and calculates the current value of the parallel conductors. Then, the magnetic field intensity of the transformer window is obtained by using the mirror method, and next the leakage inductance of the planar transformer is calculated.