Prediction of Near Field EMI Interference in Power Converters via the Induced EMF Method

In this paper an approach to predict the electromagnetic interference generated by a switched-mode power supply (SMPS) on a victim circuit is presented. The electromagnetic field coupling between the main sources of electromagnetic interference of the SMPS and the victim is represented by mutual impedances which are calculated using the induced EMF method. The noise voltage on a circular loop representing a magnetic field probe used for electromagnetic interference troubleshooting is then predicted. Measurements on two switched-mode power supply converters with different layouts are carried out to assess the prediction capability of the approach.