High voltage, step-down converter design using 20-kV silicon carbide IGBTs

Single-die, silicon carbide (SiC) Insulated-Gate Bipolar Transistors (IGBTs) fabricated on wide epitaxial drift regions have been developed reaching avalanche breakdown voltages greater than 24 kV and rated currents up to 20 A. This work utilizes similar research-grade, SiC IGBT devices to investigate their continuous switching capabilities, by integrating them in a high voltage, non-isolated, step-down DC-DC converter circuit. The details on the design and construction of the buck converter test-bed and its components are covered in this document, as well as initial results on the device capabilities. The goal of our work was to explore the device capabilities beyond previously-reported levels with a focus on frequency and operating voltage. The SiC-based step-down converter was successfully operated at 10 kHz and 10 kV for a test period of 60 min. While the results found here are not conclusive, the demonstration of the system shows that SiC technology for power conversion systems is very promising.