15 kV SiC IGBT based three-phase three-level modular-leg power converter

The 15kV /20A, 4H-SiC n-IGBT is the state-of-the-art high voltage power semiconductor device. The transformerless intelligent power substation (TIPS) [1] for 13.8kV grid interfacing is built using this device. It is proposed to use a three-phase, three-level, diode clamped topology as the front end converter (FEC) in TIPS. A modular-leg structure has been employed for FEC. In modular-leg structure, each phase-leg will have its own DC-link capacitors and a low inductance bus-bar. However, modular-leg structure adds complexity in DC bus over-load protection, which is studied in this paper. Experimental results of modular-leg converter at 3kV DC link voltage and scale down prototype of AC switch for DC bus fault protection are presented.