Feasibility of high voltage SiC thyristor in HVDC transmission

High voltage silicon (Si) thyristors have served for the high-voltage direct current (HVDC) transmission in the past four decades, but they are reaching their physical limits for blocking voltage, and rate of change of voltage and current. It becomes difficult to implement HVDC converts with smaller volume and higher efficiency using the existing Si thyristor technology. To satisfy the stringent requirements of next generation HVDC converters, ultra high voltage wide-bandgap silicon carbide (SiC) thyristors and their application prospect in HVDC converter are investigated by calibrated simulations and theoretical analysis. It shows that 30-kV SiC thyristor can not only greatly reduce the number of connected devices in series comparing to commercial Si thyristors, but also achieve a much smaller conduction loss, resulting in simpler control circuitry and higher efficiency. Therefore, high voltage SiC thyristors are promising candidate for next generation HVDC converters.