电力电子系统的电磁兼容

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Power Electronics Electromagnetic Compatibility

The electromagnetic compatibility issues in power electronic systems are essentially the high levels of conducted electromagnetic interference (EM I) noise because of the fast switching actions of the power semiconductor devices. The advent of high-frequency, high-power switching devices res ulted in the widespread application of power electronic converters for hu man productions and livings. The high-power rating and the high-switchi ng frequency of the actions might result in severe conducted EMI. Particu larly, with the international and national EMC regulations have become m ore strictly, modeling and prediction of EMI issues has been an important research topic.

By evaluating different methodologies of conducted EMI modeling and p rediction for power converter systems includes the following two primary limitations: 1) Due to different applications, some of the existing EMI m odeling methods are only valid for specific applications, which results in i nadequate generality. 2) Since most EMI studies are based on the qualitati ve and simplified quantitative models, modeling accuracy of both magnit ude and frequency cannot meet the requirement of the full-span EMI qua ntification studies, which results in worse accuracy. Supported by Nationa l Natural Science Foundation of China under Grant 50421703, this dissert

ation aims to achieve an accurate prediction and a general methodology. S everal works including the EMI mechanisms and the EMI quantification c omputations are developed for power electronic systems. The main conte nts and originalities in this research can be summarized as follows.

I. Investigations on General Circuit Models and EMI Coupling Modes In order to efficiently analyze and design EMI filter, the conducted EMI n oise is traditional decoupled to common-mode (CM) and differential-mod e (DM) components. This decoupling is based on the assumption that EM I propagation paths have perfectly balanced and time-invariant circuit stru ctures. In a practical case, power converters usually present inevitable uns ymmetrical or time-variant characteristics due to the existence of semicon ductor switches. So DM and CM components can not be totally decouple d and they can transform to each other. Therefore, the mode transformatio n led to another new mode of EMI: mixed-mode EMI. In order to underst and fundamental mechanisms by which the mixed-mode EMI noise is exc ited and coupled, this dissertation proposes the general concept of lumped circuit model for representing the EMI noise mechanism for power electr onic converters. The effects of unbalanced noise source impedances on E MI mode transformation are analyzed. The mode transformations betwee n CM and DM components are modeled. The fundamental mechanism of the on-intrinsic EMI is first investigated for a switched mode power suppl y converter. In discontinuous