Analytical determination of the first resonant frequency of differential mode chokes by detailed analysis of parasitic capacitances

In this paper the important parasitic capacitances of chokes are analyzed and defined. This work contributes to a general understanding of capacitive coupling in wound elements. Based on calculations from previous studies a more precise, wide range algorithm is proposed to calculate these parasitic capacitances of toroidal chokes. With these results a method is presented to analytically predict the first resonant frequency of a differential mode choke with high precision. Furthermore, the retrieved capacitance network offers the possibility to forecast resonant frequencies of higher order with high accuracy avoiding the need of measurement or field simulation.