
1-6 Power Electronics and Motor Drives
Typical forward blocking and on-state current–voltage characteristics of high-power thyristors are
depicted in Figure 1.5. e hysteresis in the on-state characteristic results from the fact that the current
has to distribute across the extended main cathode area aer turn-on. In the 5 in. thyristor considered
here, the current distributes over the entire cathode area, not until the current exceeds approximately
3 kA. Current spreading during the turn-on process and the nal on-state voltage V
T
can be controlled
by several measures: For large-area thyristors, the outermost AG is typically designed in such ...