Suitability and optimization of high-voltage IGBTs for series connection with active voltage clamping

The successful series combination of 5.2-kV high-voltage integrated gate bipolar transistors (HV IGBTs) is reported in this paper. The tail current cut-off encountered in punchthrough type HV IGBTs can represent a particularly severe handicap for the full control of the inductive voltage overshoot when connecting two devices in series. Advanced voltage clamping techniques are demonstrated, which can also limit the second voltage spike originating from the tail current cut off. It is shown in this paper, that IGBTs with a carrier lifetime profile localized at the anode side are particularly well suited for this application; the shorter the tail current interval, the lower the turn-off losses can be kept. The discussion focuses on the optimum on-state plasma distribution in punchthrough-type HV IGBTs with respect to series connection of these devices. The most recent trends in the development of HV IGBTs seem to be in line with the conclusions drawn in the discussion. Advanced future HV IGBT concepts may substantially ease the difficulties encountered in the series connection of first generation HV IGBTs as used experimentally in this paper.