EMI modeling considering the impedance behavior of isolated off-line converter

Abstract

As everyone knows, the electromagnetic interference (EMI) modeling becomes more important over time. So far, many EMI models have been developed in power electronics. Almost all of them are composed of two to three impedances as well as two current or voltage sources. What distinguishes a model from another is especially its identification method, which in fact determines the most of its performances. In this paper, a new three-terminal EMI model is proposed for DC-DC converters. This model is very easy to identify, and takes into account the converter impedance behavior. The model thus proposed is a complete representation of the conducted emission behavior of the converter, where it takes not only the level of the interfering line and neutral signals, but also the complete impedance behavior of the converter. Experimental illustrations are also included to verify the validity of the proposed model. Comparison between measured and predicted results under different operating conditions with and without filter, shows that the proposed model is able to successfully predict conducted emissions up to 100 MHz with an error not exceeding 6 dB in the worst case.