IEEE Workshop on Wide Bandgap Power Devices and Applications in Asia (WiPDA Asia 2018)

220 / 2017-11-21 16:15:44

Investigation of the Effects of Snubber Capacitors on Turn-on Overvoltage of SiC MOSFETs

SiC MOSFETs; turn-on overvoltage; snubber capacitor; small signal model

Plenary track > Gate drive and other auxiliary circuits

Fast turn-on transition induced over-voltage
between drain and source of the opposite device in a SiC
MOSFET phase-leg is investigated. A simplified but effective
model considering the parasitic inductances, stray resistances,
devices’ junction capacitances is proposed to study the turn-on
transient of SiC MOSFETs. The factors that determine the
overvoltage of the complementary device are then derived, which
is the basis of designing the snubber circuit to suppress it.
Therefore, a small signal model is used to investigate the effects
of snubber capacitors on suppressing the turn-on overvoltage
based on the frequency-domain analysis. In addition,
experiments are conducted which shows the snubber capacitors
achieve good performance in suppressing the turn-on overvoltage
with introducing a low-frequency oscillation.