| 摘要 |
PURPOSE:To carry out switching of a power converter safely, securely and quickly during the period of time wherein a current is not working by a method wherein a gate pulse of one thyristor bridge is interrupted, and an element kept on last is detected for being applied with reverse voltage to turn other bridges on. CONSTITUTION:When switching from a thyristor bridge 3A to other thyristor bridge 3B, an output current of the bridge 3A decrease in accordance as current command value decreases. When the current command value becomes negative, a current direction command signal 8 turns to 0 from 1; when output current of the bridge 3A becomes 0, an output of a microcurrent detection circuit 7 changes, FF10 is reset and an ignition pulse of the bridge 3A is interrupted. When reverse voltage detection circuits 11-16 detect an element kept on last for being applied with a reverse voltage, an ignition controlling circuit of the bridge 3B operates to ignite the bridge 3B. Thus, switching is carried out safely, securely and quickly during the period of time in which the current is not working. |
