| 摘要 |
<p>PURPOSE:To eliminate a reverse side overvoltage preventing device by protecting by discharge resistor against reverse overvoltage by a bypass pair of a bridge circuit for a forward overvoltage. CONSTITUTION:A forward field overvoltage detector 10 applies a fire signal to a set of P-side and N-side arms for forming a bypass pair of a main thyristor rectifier 5 when detecting a forward field overvoltage to prevent the overvoltage by the bypass pair. A reverse field overvoltage detector 9 applies a fire signal to a thyristor switch 7 when detecting a reverse field overvoltage to prevent an overvoltage by a discharge resistor 8. Thus, reverse direction overvoltage preventing device can be omitted to reduce the size.</p> |
