Comparison of reverse recovery behavior of silicon and wide bandgap diodes in high frequency power converters

The nature of reverse recovery losses is examined in hard-switched and soft-switched converters, using silicon (Si), silicon carbide (SiC), or gallium nitride (GaN) devices. A loss model and experimental results with a prototype 150-to-400 V, 150 W, boost converter operated at switching frequencies between 500 kHz and 2 MHz are used to characterize and quantify losses related to diode reverse recovery. It is found that reverse-recovery related losses with Si diodes cannot be neglected even when the converter is soft switched, with zero-current switching of the diode and zero-voltage switching of the transistor. The switching losses with SiC or GaN diodes are substantially smaller in all cases considered, and can be reduced to negligible values when the converter is soft switching.