On a future for silicon carbide in power electronics applications

Abstract

Silicon-based MOSFETs and IGBTs have long been the premiere options for semiconductor switches in power converter applications. However, each of these Si based device structures has limitations that constrain the performance capabilities of their intended applications. The recently commercialized SiC MOSFET allows for optimized application designs that are not constrained by the limitations of Si semiconductor switches as in traditional designs. This thesis will explore the device properties of SiC MOSFETs and compare them to the properties of Si MOSFETs and Si IGBTs. Device characterization methods for experimentally determining switching losses and conduction losses will be presented, along with special considerations to be made when dealing with wide band-gap devices. In order to demonstrate SiC MOSFETs’ system level optimization opportunities, this thesis will present a hard-switched 5 kW DC-to-DC converter that leverages the SiC devices in question to reach a system level efficiency of 99%. This converter will also be used as a platform to perform a head-to-head comparison of Si IGBTs and SiC MOSFETs in terms of overall system efficiency. (Published By University of Alabama Libraries