Simulation and Calculation of Proximity Effect of Coils Under Fast Transients

Proximity effect over a broad frequency range plays an important role in analyzing transients in the coils. The frequency dependent characteristic makes proximity effect a tricky problem. This paper first introduces FEM simulation to calculate the complex impedance of proximity effect and compares different axial arrangement of two conductors, shows a good agreement. In addition, different formulas are used to compare their results with FEM simulation to verify their accuracy. Kane formula and Modified formula can both get relatively accurate results. Considering the accuracy and conciseness of Modified formula, it is preferred in the analysis of transients in coils.