Conduction Emission Model And Suppression Technology Researchfor A Non-isolated DC/DC Communication Power

An integrity communication power system is composed of multiple cascade power modules. Compared with the single power module, the path of conduction electromagnetic(CE) interference in this power system is more complexity and indetectable, for the interaction between power modules. Even though each power module passes CE EMI test standard, the integrity power system is possible to fail in CE EMI test. This leads to spend lots of energy and financial cost to figure out the accuracy CE noise path in the power system.The thesis studies the electromagnetic interference(EMI) mechanism of the power system. In order to clearly illustrate EMI mechanism of power system, a rated-48 V input, output-53 V / 140 W, 172 k Hz working frequency interleaved Boost converter with the improved phase-shift control mode which satisfies the requirements of phase shift and current sharing, is manufactured firstly. The high-frequency model of the passive components(including power inductors, electrolytic capacitor and the parasitic parameters of PCB) and MOS switch in the Boost circuit are established, and the accuracy of this high frequency Boost circuit model is confirmed by comparing with the simulation results and measured results. Next, CE interference mechanism of the two phase interleaved Boost power converter is studied. The differential-mode(DM) and common-mode(CM) noise sources and interference paths and their frequency spectrum characteristics is analyzed in detail.Based on the CE interference model of the single power module, the further study focuses on the interference model for power system. A new EMI test method aiming at simulating the influence that the integrity power system brings to the single power module is proposed, which is cascading the output port of the power module with the LISN(Line Impedance Stabilization Network). The CE interference model of the power system is established, including interference path change and the differential mode(DM) and common-mode(CM) noise coupling. On the basis of this model, an improved EMI filter that has better filtering performance and smaller volume is designed, which optimizes the EMC design of the power system.