High turn-off current capability of parallel-connected 4.5 kV trench IEGT

An injection enhancement IGBT (IEGT) is a high-power switching device that realizes low saturation voltage by the injection enhancement effect (IE-effect). The experimental results obtained by the IE-effect are presented. The trench IEGTs with 6- and 12-mum trench depth were compared with a planar IEGT. These experimental results show that the trench IEGT has a better trade-off relation between saturation voltage and turn-off loss than the planar IEGT. Moreover, the trench IEGT with 12-mum trench depth has a better trade-off relation than that with 6-mum trench depth. These results prove clearly that the IE-effect improves the trade-off relation. Turn-off characteristics of parallel-connected 4.5 kV trench IEGTs are discussed. The influence of the gate circuit parameters on a turn-off current balance was examined in order to realize high turn-off current capability. It is concluded that the reduction of the gate parasitic inductance is important for uniform turn-off operation. At optimum gate circuit condition, it is shown that the maximum turn-off current increases in proportion to the number of IEGT chips. As a result, a 1300-A turn-off current capability was obtained using nine parallel-connected IEGT chips in an inductive load circuit and without any snubber circuits. In conclusion, the IEGT has a good prospect of replacing the gate turn-off thyristor (GTO) for high-voltage applications, such as motor controls for traction, industrial motor drives, and so on.