Development of a 700-V-class Reverse-Blocking IGBT for Advanced T-type Neutral Point-Clamped Power Conversion System

In this study, we developed a 700-V reverse- blocking insulated gate bipolar transistor (RB-IGBT), which is suitable for a large-capacity advanced T-type neutral- point-clamped (AT-NPC) three-level power conversion system. As this device can tolerate a larger turn-off surge voltage than the existing 600-V device, the turn-off speed can be higher and the turn-off loss can be reduced by 30%. Improving the p+ collector activation method reduces the reverse leakage current and increases the device operation temperature by 25 °C. When the 700-V devices are applied to the bidirectional switches of the rectifier stage of the AT-NPC system, the total loss of the bidirectional switch can be reduced by 10% compared with the application to 600-V devices. We have developed a power semiconductor module product mounting the 700-V RB-IGBTs for the bidirectional switches. The modules are installed in the large-capacity uninterrupted power supply machine 7300WX-T3U, achieving a high conversion efficiency of 97.5%.