A frequency modulation technique for suppressing conducted emission of SiC MOSFET based buck converter

Recently, with the development of electric vehicles and renewable energy, the use of modern wide bandgap devices (WBG) has increased tremendously due to high power density and high switching frequency. With the increase of switching frequency, switching frequency fundamentals and their harmonics overlap with the range of conducted emission. Henceforth, the converter is violating EMI standards in the switching frequency zone only. This paper proposes a frequency modulation technique to take care of the switching frequency level conducted noise of a SiC MOSFET based buck converter. 300V DC-DC Buck converter is simulated first in PLECS, the proposed frequency modulation technique is implemented, and the results have been shown. Thereafter, a 200V DC-DC buck converter has been designed, and the proposed algorithm has been implemented; spectrum analyser results has been shown and compared with the conventional constant frequency operation of the converter. Also, oscilloscope results have been included in the paper for time domain analysis.