Characterization of power-line filters and electronic equipment for prediction of conducted emissions

With present-day standards and measurement techniques, it is very difficult to accurately predict the conducted interference levels of an electronic device connected to a power-line filter (PLF). In this paper, a new modal model (which takes into account common- and differential-mode interactions) for an electronic device is presented and tested. This model is used to develop a new methodology for the accurate prediction of the conducted emissions generated by a filtered electronic device. The modal point of view clarifies such phenomena as the loss of efficiency of PLFs and the modal energy exchange due to mismatches and asymmetries in the circuits. This methodology allows an automatic software selection or design of the optimum PLF for a given electronic device. It has been successfully tested using both test devices and actual electronic equipment.