Study On The Conducted Electromagnetic Interference Modeling And Restraint Of Electric Automotive DC/DC Converter System

The DC/DC converter system is main source of electromagnetic interference (EMI)in electric vehicle, because the electromagnetic emission from the system has thecharacteristics of high-energy and wide-bandwidth, the EMI of DC/DC convertersystem becomes one of the biggest obstacles for meeting the EMC standard. Thissubject supported by the National Natural Science Foundation of China," EMC basicresearch，the electromagnetic environment analysis and optimization in the high voltagesystems of electric vehicle "（No51177183）,studied on analysis and suppression ofconducted electromagnetic interference of DC/DC converter system, the main researchcontents are following:①Grasping the DC/DC converter system’s working principles and through thesimulating of saber to the full bridge DC/DC circuit we made a DC/DC, which providea basic condition to the coming study.②According to the DC/DC convertor’s working character,this paper analyzed themechanism of the conducted electromagnetic interference and the coupling path as wellas the main factor of affecting the common-mode and differential-mode interference。Atwo probes approach was used to measure the impedance of the interference source. Thecircuit model of the impedance of the interference source was established by vectorfitting method. At last, a circuit model of conducted electromagnetic interference is builtin Saber.③Built conducted electromagnetic interference EMI bench of the DC/DCconverter system. In0.15-30MHz range, the simulation predicted the common-mode(CM) and differential-mode (DM) interference on the LISN, and was compared with theexperimental results. The validity and feasibility of the method which could predictconducted electromagnetic interference of DC/DC converter system in this paper wasverified by combining experiment and simulation.④The suppression of conducted interference also was studied in this paper and thesuppression methods’validity was verified based on the experiments. The leakageinductance of the transformer is proposed for the influence of interference sources,through changes in the structure of transformer suppressed interference sources. Inaddition, a EMI passive filter was made to suppress the interference, and some eliminatemethod to parasitic parameters of EMI filter were proposed. Finally the effectiveness of EMI filter was verified by experiment.