Modeling and Characterization of Parasitic Inductive Coupling Effects on Differential-Mode EMI Performance of a Boost Converter

Near-field electromagnetic couplings between an electromagnetic interference (EMI) filter and the main circuit have serious impacts on EMI performance of a power converter. In order to improve the EMI performance, it is necessary to analyze the near-field coupling effects of power converters. In this paper, a Boost power factor correction converter and a CL EMI filter are used for analysis of near-field inductive couplings. This paper presents a method to extract parasitic inductive coupling parameters by means of network gain measurement. With the extracted coupling parameters, it builds up a circuit model for the converter. The model is then used to analyze the effects of inductive couplings between the EMI filter and the main circuit on EMI performance of the converter. The analysis shows that the inductive couplings of the filter choke are harmful to a low-frequency differential-mode (DM) EMI, whereas the inductive couplings of the filter capacitor are harmful to a high-frequency DM EMI.