Analysis and Prediction of Electromagnetic Interference Noise in Synchronous Buck Converter with SiC MOSFET

Compared to silicon MOSFETs, silicon carbide (SiC) MOSFETs have higher operating junction temperature and higher power density. However, due to its faster switching speed and parasitic parameters, a large switching oscillation will occur on the output waveform of SiC MOSFET. This paper derives the mathematical formulas of the time-domain switching waveforms based on equivalent circuit models for the switching transition. Then, analytical models are developed to calculate the spectra and the corresponding spectral bounds of the switching waveforms of SiC MOSFETs in a synchronous Buck converter. By comparing the experimental results with the numerical calculation results, the boundary of the switching waveform spectrum is accurately predicted, and it is found that the parasitic parameters of SiC MOSFET have significant effect on the high-frequency spectrum and its bounds. © 2021, Electrical Technology Press Co. Ltd. All right reserved.