A hybrid method combining static and full wave techniques to solve conducted emissions problems

Frequency dependent models are required to address most of the conducted emissions problems when any circuit or system simulator is used. High frequency 3D full wave solvers are often employed to extract S parameters from passive components, generating a frequency dependent model, which in this case, is known as a Touchstone file format. This extraction process uses a numerical technique to solve the complete set of Maxwell´s equation for higher frequencies and then extrapolates the results at DC. This work presents a methodology that uses a static solver to actually calculate the DC resistance at 0Hz, yielding a more accurate S parameter matrix of the model. A commercial washing machine is used as an example for a conducted emissions analysis (according to CISPR 14-1). Measurements results are also presented, showing a reasonably good match with the proposed technique.