We have developed a high-voltage, high-power converter prototype (300 kVA single-phase three-level power converter) using switching modules with SiC-PiN diodes and Si-IEGTs. The switching frequency of the modules is 2 kHz, which is four times higher than the conventional switching module.

The new switching module uses 4 × 4 mm SiC diodes (6 kV-class), developed through AIST's technology for large-area SiC devices, and Toshiba's Si-IEGTs. In switching modules using Si-IEGTs and Si diodes, the switching frequency is limited to about 500 Hz because of the limitations of Si diodes performance. The use of SiC diodes, with their excellent switching characteristics, results in a higher switching frequency of the switching modules (2 kHz). Due to the high switching frequency, the three-level converter can be adopted and the insulating transformer can be eliminated. In addition, the filter capacity can be reduced. Great size reduction of power converter systems (one-fifth compared to the conventional system) becomes possible with this technology.