| 摘要 |
PURPOSE:To make it possible to prevent excessive charging current flowing through a main thyristor, by giving a gate signal to a thyristor when the output voltage is lower than a reference value at chopper starting and gradually charging a capacitor used for smoothing. CONSTITUTION:After chopper starting, the ouput voltage of a chopper section 2 is detected by a voltage sensor 15, and a comparator 22 compares the detected voltage with the set voltage of an output voltage reference value 21 that is set up, and while a detected voltage is lower than the set voltage value, a relay 23 is excited and the fixed contact point a of a change-over contact point 24 is closed. During this the output signal from an oscillator 27 for starting is input into a logic circuit 19, and a main thyristor 3 and an auxiliary thyristor 4 are driven by this signal. Then gradually a smoothing capacitor 10 is charged. When the output voltage goes over a reference value, the output of the comparator 22 is reversed, and relay coils 23 and 25 are turned off, and a fixed contact point b of the change-over contact point 24 is closed to control the output voltage at the set value. Further, a contact point 26 is also closed and DC current is supplied to a load 13. |
