Measurement Of Noise Source Impedance Based On EMI Filter Design

In recent years,power converters have been widely used in various power electronic devices due to their high efficiency,small size,and light weight.With the rapid development of power electronic devices,the switching speed of the inverter is also faster and faster,which further promotes the modularization of the power electronic devices and the integration of the system.The integrated modules show good heat dissipation and consistent power performance.However,as the source of electromagnetic noise,the power electronic device makes the problem of EMC more complicated.At present,the formulation of electromagnetic compatibility standards at home and abroad has become more and more regulated.Only the power electronic devices that meet the standards can work stably and reliably in complex electromagnetic environments.Until now,EMI filters are still the most widely used and effective noise suppression and elimination methods.However,there are various problems in the design process of traditional EMI filters that restrict their further improvement.Therefore,it is necessary to study these problems and put forward an effective solution.This article first gives a brief introduction to the research background,including the current research status of EMI filters at home and abroad.Second,it introduces the related concepts and principles of EMI filters,and takes the switching power supply as an example for electromagnetic noise.The analysis of the generation,propagation and elimination of the simple analysis and the existing problems in the current EMI filter design process are described.Thirdly,aiming at the problems in the design process of the traditional EMI filter,a new method of noise source impedance recognition and measurement is presented in this paper.The analysis and deduction of the port network described by S parameter are mainly introduced.The analytical solutions of the noise source impedances of equivalent differential mode and equivalent common mode are given respectively.At the same time,the idea of implementing impedance perturbation in the port network and the analysis of the optimized structure of the implementation are introduced.The simulation and practical experiments are used to verify the proposed method.Finally,the error analysis and applicability of the proposed method are analyzed.The proposed method solves the problem that the noise source impedance is difficult to identify during the traditional design process of EMI filters.This will help improve the design theory of EMI filters,enrich the design process,improve the filtering performance,and further improve the reliability of power electronic equipment,promote the miniaturization and lightweight development of power electronic equipment.