| 摘要 |
PROBLEM TO BE SOLVED: To suppress the incorrect ignition of a thyristor converter by generating a gate signal for controlling the ignition phase of a thyristor, based on a zero-cross signal and feeding it to a gate. SOLUTION: In a phase control device, the input AC power supply voltage of a thyristor converter 1 is detected by a voltage detector 4 of a phase control circuit 20, is inputted to a notch filter 11 for eliminating harmonics with a specific order, and is inputted to a zero-cross detection circuit 6. Then, the zero-cross phase of a fundamental wave voltage being outputted from the notch filter 11 is detected and a zero-cross signal is inputted to a Schmitt trigger circuit 7, a discharge circuit 8 starts discharging a capacitor when the Schmitt trigger circuit 7 starts operating, and the voltage between terminals gradually drops. Then, a gate signal 10 for controlling an ignition phase when the voltage between capacitor terminals reaches a control voltage is fed to the gate of the thyristor of the thyristor converter 1, thus achieving initiation at a proper phase angle and suppressing the incorrect ignition. |
