Characterization and loss modeling of silicon carbide based power electronic converters

Abstract

Silicon Carbide (SiC) based power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) are great candidates for high-voltage, high-frequency and high-temperature power switching applications because of their favorable material properties when compared with Silicon (Si) power MOSFETs. In this thesis, the design, characterization, and modeling of a power electronic converter based around SiC MOSFETs is investigated. The test converter circuit is designed to be general enough that it can represent a half bridge converter, a DC chopper circuit or an output phase of an inverter for flexibility in testing. A practical characterization procedure is proposed which takes a circuit-level approach, as opposed to a device-level approach, using only the actual power electronic circuit under study and no additional test circuitry. Therefore this study takes into account the inherent parasitic impedances associated with the test circuit and its influence on the SiC devices' high-speed switching behavior. The hardware setup is operated at frequencies up to 200 kHz and efficiencies up to approximately 99% were recorded.Based on the characterization data and analysis, a model is constructed using MATLAB (a mathematical modeling software) for predicting converter and gate driver losses at different load currents, DC bus voltages, and operating temperatures (for both a DC-DC synchronous buck converter and a DC-AC three phase, two-level Voltage Source Inverter). Good agreements are obtained between the model outputs and experimental results. Possible future extensions to the work are discussed.