Research And Application Of Electromagnetic Interference Analysis Method

With the development of power electronics technology, the switching frequency of the switching devices become more higher, electronic noises were produced by the electronics devices via cable transmission, the conducted electromagnetic interference (EMI) noise issues become increasingly prominent. So it is a key point for researching the conducted electromagnetic interference technology to study how to measure and diagnose the conducted EMI noise. As a result, "Research and application of the conducted electromagnetic interference" has been proposed in this paper.Firstly, for the performance of line impedance stabilization network (LISN), analyzed its circuit structure and its high frequency characteristics parameters, and established high-frequency model of LISN. The impact of high frequency parasitic components of LISN was studied. For the noise separation performance of conducted noise discrimination network (NDN), this paper was extracted the parameter models of NDN, and the discrimination characteristics for NDN parameters was researched. The effectiveness and accuracy on the common-mode noise extraction was studied by the theory and experiment. In addition, the components parasitic parameters was studied by the theory and experiment. And the differences between two topologies of NDN was studied by the theory and experiment.Secondly, conducted EMI noise source identification methods were researched in this paper. The basic theory of Classical Informax_ICA was analyzed,and summed up the concrete steps of the algorithm.Besides,it proposed conducted EMI noise source identification method based on ICA algorithm of the voltage parameter test,and the experiment results verify the feasibility and accuracy of the methods. On the basis of the conducted noise source impedance extraction theory based on double current probes, the single current probes impedance method and the scattering parameter method were proposed to extract the noise source impedance, and analyzed the theoretical derivation and experimental validation, the experiment results verified the feasibility and accuracy of the methods.Finally, the comprehensive analysis, diagnosis and suppression on conducted EMI noise were researched in this paper. The method of measuring and diagnosing the conducted EMI noise in this paper was applied for medical electronic equipments, meter electronic equipments and smart grid equipments.And it analyzed the conducted EMI problems of these electronic equipments.Besides. according to the different mechanism. it produced different specific suppression scheme. And the equipments could all pass the standard test after applying the suppression methods. The experiment’s results could validate the present method effectiveness and efficiency.