Analyse And Restrain Of The Conducted EMI For The Power Converter System

In order to meet the development request of electron industry, all kinds of electro-equipments develop in the direction of micromation, compact,integration, intelligence,and the EMC of the electro-equipments become very complexity in the limited space,and it require the higher standard for the power converter systems.This paper do some researche in the conducted EMI comeing from power converter systems. CM and DM are the two conducted form of the conducted EMI,this paper discuss the CM and DM in the noise source and promulgated path.The measurement of conducted EMI is very importance in researching the conducted EMI,this paper analyse the methods and theories of measurement.There are CM and DM circulating in the power lines,it need separating them.This paper discuss the method of separating them.It need adopting the restrained method in order to reduce the conducted EMI.This paper do some research in the application of restraining the conducted EMI in power EMI filter.It proved that the insert loss will be different along with different source impedance,load impendence and topology.This paper introduce a method of designing the power EMI filter.First, forecast the source impedance of CM and DM;second, select the topology depend on impedance matching;third, compute the difference of original noise level and standard noise level.By experimenting,it is effect restraining the conducted EMI when inserted the power EMI filter.