A Spectral Analysis Method for Modeling EMI Source Considering High-Frequency Ringing Effects in SiC MOSFETs

Silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) are extensively utilized in high-efficiency and high-frequency applications due to their exceptional performance. While the high switching speed of SiC MOSFETs significantly enhances operational efficiency, it also exacerbates electromagnetic interference (EMI) issues during the switching transient process. This study introduces a spectral analysis method for identifying interference sources, with a focus on high-frequency ringing in SiC MOSFETs. The method considers the impact of parasitic parameters during switching transients and uncovers the characteristics of high-frequency oscillations. By employing an asymmetric trapezoidal waveform, spectral and envelope models that account for high-frequency oscillations caused by parasitic parameters are derived, enabling the evaluation of main influencing factors to EMI noise. A spectral calculation approach for high-frequency ringing effects is proposed. Experimental validation demonstrates a maximum error reduction from approximately 18 dBμV to 8 dBμV when compared to traditional methods.