Performance comparison of SiC Schottky diodes and silicon ultra fast recovery diodes

Abstract

Advanced control systems combined with high speed gate driver circuits enable extremely high rate of change of power devices voltages, up to hundreds of kV/us. Short rise times of power devices could cause significant EMC problems, which are unacceptable in majority of power electronics applications. It is known that voltage variations during diode switch-off depend on how long it takes for the charge stored near the p-n junction to be recovered during voltage reversing. In fast switching applications good forward recovery characteristics are needed. The silicon carbide (SiC) diodes characterize almost zero reverse recovery charge. However the lossless operation in connection with extremely high dv/dt could cause the SiC diodes less effective in damping the voltage ringing. The compromise between high efficiency and low EMI emission is therefore the actual aim of the research. The paper compares the static and dynamic characteristics of ultra fast silicon (Si) and SiC Schottky diodes and presents the study of the mechanism of parasitic high frequency oscillations during turn-off transient.