Common Mode Noise Analysis for Cascaded Boost Converter With Silicon Carbide Devices

In the paper, an electromagnetic interference (EMI) model for a two-stage cascaded boost converter is presented to distinguish its noise sources. To illustrate the effects of switching speeds on EMI generation potential, the relationships between the time domain and the frequency domain with all-SiC and SiC-Si device combinations are provided. It is found that the voltage ripples and spikes at turn-OFF generate common mode (CM) noise in the high-frequency range, above the cutoff frequency determined by the short switching time of the SiC MOSFET. Several methods are presented for minimizing the noise sources using a ferrite bead and a modified gate driver. Experimental measurements of SiC switching waveforms and CM EMI taken from a 600-W prototype two-stage cascaded boost converter operating at 100 kHz are presented to validate the CM noise analysis.