Anticipating Common-Mode Conducted Emission of DC-DC Converter from Electric Near-Field Scan

Abstract

This paper aims at proposing a method based on electric near-field measurement to estimate common-mode conducted emission produced by DC-DC converter along a cable harness. The method is evaluated on two case studies: an academic board with simple rectangular copper island and buck converter board.

In-Situ and Contactless Evaluation of Performance of Power Converter EMC Filter based on Near-Field Scan Measurement

“…This assumption remains acceptable as the LISN used in CE tests has an input impedance close to 50 Ω. The attenuation Att provided by the filter modeled by the matrix [Zf] can be expressed according to (4), and simplifies to (5) if Zin << Zout, which is a design target to limit CE. Merging (3) and ( 5) leads to (6), which expresses 𝑆 21 𝑃 according to the converter input impedance Zin (seen at the coupled capacitor) and filter attenuation.…”

“…However, this analysis remains only qualitative (a direct estimation of CE is not possible) and the identification of a hot spot does not indicate necessarily where and how a design correction has to be brought. These last years, numerous research works have been led to develop processing methods of NFS results, for example to estimate current distribution [2], extrapolate radiated emission [3], or common-mode (CM) CE [4]. Recently, [5] proposes an NFSbased method to quantify the impact of decoupling capacitors on power integrity on an unpowered PCB.…”