Modeling and Validation of Common-Mode Emission in Silicon Carbide Based Voltage Source Converters

Abstract

Electromagnetic compatibility (EMC) issues have become one of the most difficult challenges in power converter designs. With the invention of wide bandgap (WBG) power semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) power MOSFETs, the power converter designs are provided with the potential to be significantly more power dense than older generation converters using silicone IGBTs. However, the majority of spectral contents of the switching waveforms are moved from the very-low-frequency (VLF, 3 kHz to 30 kHz) range to low-frequency and up to the very-high-frequency (VHF, 30 MHz to 300 MHz) range. Moreover, due to the design traits of WBG-based converters, common-mode (CM) emission dominates the EMC problems. Conventional electromagnetic interference (EMI) modeling methodologies in the frequency range in and above VHF were mostly developed for applications where the power level is relatively low. For high-power and highly power-dense applications, new EMI modeling methodologies, especially in CM, need to be developed to allow more accurate analysis, more efficient design processes, and more optimal designs. This doctoral dissertation documents the author's development of a novel CM emission modeling methodology with a set of CM model segments that form canonical SiC-based voltage source converters and the surrounding electrical environment, such as filter structures. The accuracy of all these model segments is validated with two applicational scenarios at frequencies up to 30 MHz. These modulized building blocks and the methodology using these blocks to construct full converter system CM models are lightweight and insightful, thus enabling more optimal design processes for SiC-enabled high-voltage and high-power-density converters such as virtual prototyping processes and multi-objective optimization. Furthermore, the discoveries of this dissertation will help power electronics designers to understand better the potential and challenges of the utilization of SiC semiconductors in voltage source converters.