Research Of Electromagnetic Compatibility In Aperture Cavity Based On Improved FDTD

Because of the need of heat dissipation, ventilation and the connection with outer circuits for electronic and electrical appliances, shielding cavity has various apertures inevitably. And aperture is the main way of electromagnetic coupling effects for electronic and electrical appliances. In order to predict the ability of electromagnetic compatibility(EMC) of electronic and electrical appliances, the electromagnetic coupling effects issue brought by aperture must be taken into consideration. As a result, deep understanding of the issue has a great constructive meaning for EMC design of electronic and electrical appliances and system. This thesis has the background of Northeastern University's second term sub project of "985" project "Integrated automation of industrial process innovation platform". This thesis systematically studies the electromagnetic compatibility issue of cavity with apertures.This thesis systematically studies the electromagnetic field theory, shielding technology of electromagnetic field and finite difference time domain(FDTD). It deeply analyzes the FDTD's core technology:including mesh decomposition, stability of Numerical, absorption of boundaries and incentive sources'setting. When analyzing the EMC issue, it brings the time iteration variable "At", which transforms the 3D static field equation to 4D dynamic real time equation to analyze the time and frequency's characteristics.According to the problems of calculating time and space, this thesis provides an improved extended mesh decomposition method. And this thesis calculates and simulates EMC issue with classical mesh decomposition method and improved method. The results show the accuracy and superiority of the extended mesh decomposition method.This thesis studies the usual narrow aperture's coupling FDTD algorithm, and presents an improved arrow aperture's coupling FDTD algorithm. This algorithm does some analysis and calculation of the coupling of metallic cavity with apertures and radiation field when current flowing into thin wire, and the results are similar with actual coupling situation. This thesis uses the improved narrow aperture FDTD method and extended mesh decomposition to analyze the electromagnetic coupling effects of metallic cavity in different situations.This thesis analyzes the electromagnetic shielding ability of three actual high frequency switching power supply boxes in different situations. According to the conclusion, some constructive suggestions are proposed for improving the ability of electromagnetic shielding effectively. These studies'results provide theoretical basis for the EMC design of aperture cavity and electronic circuits.