Researchers at North Carolina State University created a high-voltage and high-frequency SiC power switch that could cost much less than similarly rated SiC power switches. The findings could lead to early applications in the power industry, especially in power converters like medium-voltage drives, solid-state transformers, and high-voltage transmissions and circuit breakers.

The new SiC power switch, however, could cost approximately one-half of the estimated cost of conventional high-voltage SiC solutions, say Alex Huang and Xiaoqing Song, researchers at NC State’s FREEDM Systems Center. Besides the lower cost, the high-power switch maintains the SiC device’s high efficiency and high switching speed characteristics. In other words, it doesn’t lose as much energy when it is turned on or off.


A new NC State high-power switch has the potential to work more efficiently and cost less than conventional solutions. Credit: Xiaoqing Song, NC State

The power switch, called the FREEDM Super-Cascode, combines 12 1.2-kV SiC power devices in series to reach a power rating of 15 kV and 40 A, compared to the highest power rating available today of 1.7 kV. The new device requires only one gate signal to turn it on and off, making it simple to implement and less complicated than IGBT-series connection-based solutions. The power switch is also able to operate over a wide range of temperatures and frequencies due to its proficiency in heat dissipation, a critical factor in power devices. The new device offers potential applications in high-voltage and high-frequency power converters. The researchers say that the FREEDM Super-Cascode solution paves the way for power switches to be developed in large quantities with breakdown voltages from 2.4 kV to 15 kV. The FREEDM Super-Cascode costs only one-third of the estimated high-voltage SiC MOSFETs and will facilitate early applications of SiC in very high-voltage and high-frequency power converters. 

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