High-power thyristor switching via an overvoltage pulse with nanosecond rise time

High-power thyristor switching from the blocking to conducting state via an overvoltage pulse with nanosecond rise time is studied. Low-frequency tablet thyristors with an operating voltage of 2 kV are used in the experiments. An external pulse providing a voltage rise rate from 0.5 to 6 kV/ns was applied to the thyristors main electrodes. Under these conditions, the time of thyristor switching to the conducting state is 200–400 ps. Empirical relations between the main switching characteristics, i.e., the turn-on voltage, pulse rise time before switching, and time of thyristor switching to the conducting state, are obtained. Numerical simulation shows that the ionization of deep technological defects should be taken into account to explain the results obtained.