Hybrid prediction method for conducted electromagnetic interference in AC-DC converters
摘要
For accurately evaluating the conducting electromagnetic interference (EMI) characteristics of AC-DC converters, a hybrid prediction method is proposed in this paper. The method is carried out in two steps: conducting path modeling and interference source modeling. For the conducting path modeling, high-frequency models of the key components inside the converter are developed, and a simplified EMI model is constructed to analyze the interference sources and conduction paths separately. In terms of the interference source modeling, a simplification approach is introduced for the front-end three-phase Vienna rectifier (TPVR) to establish a time-domain interference source model that considers slope variations and ringing effects. Meanwhile, for the rear-end three-level isolated converter (TLIC), a corresponding time-domain interference source model is built based on charging and discharging of capacitors. Simulation results of the spectrum of the time-domain interference source show good agreement with experimental results. The difference within a wide frequency range is less than 8 dB. Subsequently, a hybrid prediction method integrating time-domain to frequency-domain transformation of interference sources with conducting path analysis was employed to predict the conducted EMI of AC-DC converters. Comparisons indicate that the predicted results are similar to experimental measurement, and the difference in magnitude is less than 10 dB during a wide frequency range.