A New Quantity to Describe Power Semiconductor Subcycle Current Ratings

A new quantity for predicting the subcycle surge current ratings of silicon diodes and thyristors is presented. The quantity I2¿t is shown to be much more valid than the more conventional I2t rating in coordinating power semiconductors with fast-acting current-limiting fuses. The requirement of the device to block reverse voltage on the next half-cycle following the surge current is reviewed and shown to be quantitatively significant in the subcycle current capability of power semiconductors.