COMMUTATION FAILURE PROTECTING SYSTEM FOR THYRISTOR CONVERTER

摘要

PURPOSE:To execute a stable systematic operation in a commutation failure protecting system for a thyristor converter by detecting no application of a reverse voltage to the arm thereof within a predetermined duration after the completion of the conducting period of the arm and rapidly advance the firing phase of the thyristor to a predetermined phase. CONSTITUTION:A reverse voltage detector circuit 25 detectes the reverse voltage of a thyristor to produce a reset input of the flip-flop circuit 24. A pulse control circuit 22 inputs a pulse control signal corresponding to the conducting period or bias pair period to an inverter circuit 23 and to the set terminal of a flip-flop circuit 24. A pulse circuit 27 generates a one-shot pulse at the rise of the input signal and applies it to an AND gate 28. If a reverse voltage is not detected during a predetermined period from the time of completing the pulse control signal, an AND gate 28 outputs a commutation failure protecting signal.