Experimental evaluation and FDTD method for predicting electromagnetic elds in the near zone radiated by power converter systems

Abstract

This paper presents the study of conducted electromagnetic interference (EMI) currents owing through the power cables of a DC-DC converter system and its correlation with the near eld radiated from these cables. The radiated emission measurement contains a common mode (CM) and a differential mode (DM), and accurate separation of the radiated emissions of these two modes is necessary. The nite-difference time-domain (FDTD) method is used to predict the electromagnetic radiation caused by CM currents and DM currents. An experimental bench has been designed to allow access to the measurement of EMI disturbances at various sensitive places. The CM and DM voltages resulting from the experimental measurement are implemented in the FDTD algorithm as voltage sources of disturbances, these disturbance voltages causing the generation of CM and DM currents owing through the cable. Finally, single and bi lar wire models for modeling the near eld using the FDTD method are presented and the simulation results of the neareld caused by both of the modes are evaluated and compared with the experimental ones. The main objective is to investigate the signi cance of the contribution of each of the current modes on the radiated emissions from the cable using the FDTD method, thus characterizing the level of cable radiation versus a speci c standard. This allows showing that the radiation is often caused by the CM current along the cable and the largest level is located in the switching noise zone located within the frequency range from 1 MHz to 10 MHz.