A Simulation Platform For Conducted EMI Of Switched-mode Power Supply

With the execution of national and international electromagnetic compatibility (EMC) regulations, modeling and simulation of electromagnetic interference (EMI) issues attracts more research interests. This dissertation concentrates on studying EMI modeling and simulation in flyback converters. It introduces EMI receiver working principle simply, showing that the measured results are influenced by the bandwidth of IF bandpass filter. When fast Fourier transform (FFT) is used to analyze the EMI spectrum, the measurement bandwidth effect should be taken into consideration to obtain results that are consistent with the measured results from EMI receiver. A MATLAB program which uses the window function method to simulate EMI receiver bandpass filter is presented, and then the paper discusses the influence factors of predicted results. It is necessary to study the main noise sources and coupling paths in flyback converter in order that the EMI can be predicted effectively. This dissertation adopts a general modeling approach, called multi-channel "noise source-coupling path" model, to investigate the EMI from different noise sources and main influence frequency bands in flyback converters. Eventually, a simulation platform of switched-mode power supply for EMI filter design is established, which can predict a simple common-mode filter topology accurately in certain frequency range and get EMI filter performance accurately by using insertion loss analysis, providing guidance for EMI filter design of switched-mode power supply.