Zero voltage switching characterization of 12 kV SiC N-IGBTs

This paper reports experimental zero voltage switching (ZVS) characteristics of the state-of-the-art 12 kV SiC N-IGBTs with 2 μm and 5 μm field-stop buffer layer thicknesses. Extensive results up to 7 kV and 150°C are presented for both IGBTs with and without an external snubber capacitor. The 12 kV SiC IGBTs have been found to have significantly larger magnitude of turn-off current bump in comparison to the results reported for the commercial (≤ 6.5 kV) Si IGBTs, because of deep punch-through design. The turn-off current shape is majorly influenced by slower voltage rise before the punch-through, followed by faster voltage rise after the punch-through voltage. In addition, the difference in current gain resulting from different buffer layer thicknesses has considerable effect on the overall switching behavior and energy loss of the two IGBTs. A detailed explanation of all these phenomena is presented along with the considerations for power converter design while employing the ZVS technique with these ultrahigh voltage IGBTs.