抄録
For the purpose of implementating a highly reliable self-commutated power converter system with gate turn-off (GTO) thyristors, we developed for the first time a triple redundant controller for the system. The triple redundant controller consists of triplicated sub-modules that generate gate pulses for each thyristor and voters that select one of the gate pulses from the triplicated sub-modules in 2 out of 3 fashion. The controller continue to provide correct gate pulse even in the presence of a single module fault. On the other hand, selecting gate pulse can cause gate pulse inaccuracy problem. Time lag between gate pulses of the triplicated sub-modules causes gate pulse inaccuracy, and consequently, causes over-voltage to the thyristors which leads to the destruction of the thyristor. We developed a new method of synchronizing the gate pulses of the three sub-modules for gate pulse accuracy, and applied it to the triple redundant controller. As a result, the maximum time lag between the gate pulses of the three sub-modules become under 0.1μs; so it is possible to produce accurate gate pulses even when single module fault occurs. Mean time between failures (MTBF) of the developed controller is shown to be ten times longer than the MTBF of an non redundant controller.
