| 摘要 |
PURPOSE:To operate switching operation safely, by a method wherein ignition pulses are given in a prearranged order by an output current detecting circuit and an output voltage detecting circuit when a regular-side thyristor bridge is OFF and a reversal-side thyristor bridge is ON. CONSTITUTION:An output current detecting circuit 6 which consists of a current detector 7 and a current polarity detector 8, an output voltage detecting circuit 12 and an ignition control circuit 9 which controls current transfer phase of thyristor bridges 3A, 3B are attached to an electric power converter which consists of an AC source and the thyristor bridges 3A, 3B connected to the source. In order to transfer current from the bridge 3A to 3B, the ignition pulse of the bridge 3A is OFF when the current of 3A is nearly zero and the OFF stage of 3A is detected by detecting that the phase is such that the potential applied to the element being ignited lastly is negative and that the regular potential is applied to the bridge 3B and then the bridge 3B is made ON. Thus the switching can be operated safely and securely without a period of zero current and without generating a short circuit loop. |
