Comparison of intrinsic energy losses in unipolar power switches

Abstract

We explore the intrinsic loss in power switches seen when they undergo charging and discharging of their output capacitance. The intrinsic loss occurs even if switching is carried out at zero current and no on-state current is conducted, and accidental turn-on is avoided. The intrinsic loss cannot be eliminated by using soft-switching schemes and essentially sets an upper limit for the switching speed of the soft-switching converters. This work measures and compares the intrinsic energy losses in the popular commercial unipolar power switches including Si superjunction MOSFETs, GaN cascode, SiC cascode, and SiC MOSFETs. The intrinsic loss mechanisms of these devices are also discussed. A simple experiment setup is proposed and used to measure the intrinsic energy losses. The experimental results show that the SiC cascode has the lowest intrinsic energy loss.