EMI generation characteristics of SiC diodes: Influence of reverse recovery characteristics

In this paper the influence of silicon carbide (SiC) diodes on electromagnetic interference (EMI) generation in hard-switched power converters is investigated. The absence of reverse-recovery behaviour in these devices is expected to result in reduced EMI generation, in addition to significantly reducing switching losses. A simplified analytical model enabling the spectral envelope of the diode current waveform to be predicted is presented and numerical simulation is employed to validate this model. It is found that reverse-recovery characteristics have greatest influence on the spectral content of the simulated diode current waveforms at frequencies above 10 MHz. Experimental measurements of switching current waveforms for both conventional Silicon (Si) diode and SiC diodes are presented and their frequency spectra are compared with the results of the numerical and analytical models.