EMI Measurement and Modelling

Abstract

This thesis report focuses on how the EMI behavior of a simple step-down or buck converter can be simulated. A very basic switching circuit is first examined and the knowledge gathered from this study, in terms of how parasitic and stray components can be modeled, is applied to a more complex step-down converter. A lot of work has been placed on implementing a detailed diode model in simulations, the Lauritzen model, the implementation proved difficult and requires more work. A second diode model, the modified charge control model, was implemented in order to produce more accurate EMI behavior from simulations that should be comparable to results from simulations were the Lauritzen diode model is properly implemented. EMI measurements was performed on the step-down converter according to the guidelines recommended by IEC in their CISPR 25 standard and these measurement results were then compared to those gathered from simulations.