Effects of Parasitic Parameters on EMI Filter Performance

Abstract

Two filters with identical topologies and components can exhibit a significant difference in filter effectiveness when the layouts are different. The goal of this paper is to examine the effects of parasitic couplings among the filter components and the coupling between the filter components and the ground plane of printed circuit board (PCB). Specifically, six different coupling effects are investigated: the couplings between the inductor and capacitors, a filter inductor and trace loops, two filter inductors, two capacitor parasitic inductances, a filter inductor and ground plane, and two trace loops. Experiments were performed, theories were developed to investigate and characterize these parasitic couplings.

EMI Suppression in High Frequency Half Bridge Converter

“…Therefore the real high frequency characteristic of the EM1 filter will be much different from its expected value and the two identical filters may behave differently [15]. The electromagnetic couplings among the filter components and circuit layouts also affect the high frequency performance of the EMI filters [16].…”

Parasitic Capacitance Cancellation of Integrated Cm Filter Using Bi-Directional Coupling Ground Technique

“…Many works have been done to reduce the parasitic effect [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. A staggered and interleaving winding structure reduced the parasitic winding capacitance with increased winding complexity and thickness in [3][4][5].…”

“…A grounded conductive layer was embedded between the CM inductor winding coils L (1,2) to achieve EPC cancellation in [6,7]. Moreover, the techniques realized by extra discrete passive devices are also proposed in [9][10][11][12][13][14][15][16][17].…”

A novel approach for EMI design of power electronics

“…For a filter performance prediction many parasitic properties of components and setups have to be considered, which are often not specified or completely unknown. Additionally, coupling effects between the passive components gather influence when placed close to each other, as mentioned in a recent research paper [1]. Some effort was made to find out more about the coupling effects and how to calculate them [2][3][4][5].…”