Design,Fabrication And Characterization Of Common Mode Current Suppressor Made Of Electromagnetic Lossy Materials

Common mode interference(CMI)is a research hot spot in the field of electromagnetic compatibility(EMC).It exists widely in switching power supply,electric vehicle and other electronic and power equipment.Due to the use of high-power integrated devices,these devices will be switched on and off quickly,result in a strong common-mode current,lead to significant CMI,thus the normal operation of electronic and power equipment may be affected seriously if the CMI is not suppressed effectively.This paper is divided into six parts.Firstly,we introduce the the concept of EMC and the basic knowledge of EMI,the research status at home and abroad,and several common methods to suppress CMI.Then we introduce the theoretical basis and equipment involved in the paper.Thirdly,the influence of sample position on the measurement result and the method to correct the error are studied by applying transmission/reflection method to measure the electromagnetic parameters of materials.In the fourth part,based on transmission line theory and transfer matrix method,combining experimental measurement,distribution characteristics of common-mode current are discovered,the idea of suppressing common-mode current by using electromagnetic losses is clarified,and capacitor and resistance series circuit is proposed to be used to provide the required electric losses.In the fifth part,we design and fabricate a common-mode current suppressor with electromagnetic losses,and discuss its performance from two aspects of numerical simulation and experimental measurement.The results show that the device can significantly suppress common-mode current,and has the characteristics of broadband and low cost.Finally,the summarizes and possible way to improve the researches are provided.