Characterising and modelling extended conducted electromagnetic interference in densely packed DC-DC converter

Abstract

High density high switching frequency power converter conducted EMC had been analysed, modelling the noise source and noise path, while providing accurate conducted EMC noise limits comparable to accredited noise measurements up to 100 MHz. The military specified DC-DC converters are applicable, spanning from 100 W handheld power managers up to 2 kW DC-DC battery chargers. Circuit layout high frequency effects as well as high frequency impedances of the power components were characterised. The effect of a higher switching frequency was demonstrated. At first, a trapezoidal noise source and lumped element noise path model was adopted, showing high frequency limitations of this technique. Thereafter, a lumped element model including a switching component was created. A Transient model circuit analysis was investigated to represent circuit noise as measured with a LISN. Common mode and differential mode signals were extracted in both the simulated results and the bench measurements.