| 摘要 |
PROBLEM TO BE SOLVED: To protect the starting circuit of an active filter against damage, even if a main converter circuit has stopped. SOLUTION: A starting circuit 6, comprising a resistor R1, a transistor Q2, diode D2 and a constant-voltage diode 2, is provided between the cathode of a diode D1 of an active filter AF and the power supply terminal (VCC) of an AF control circuit 3. Connected to the based of the transistor Q2 of this starting circuit 6 is a protective-switching circuit 10 made up of a thyristor SS connected parallel to the constant-voltage diode 2, a resistor R6 and a capacitor C6 connected between the cathode and gate of the thyristor SS and a diode 7 connected to the gate of the thyristor SS. This protective-switching circuit 10, when receiving a control signal to stop a DC-DC converter at the gate of the thyristor SS, holds the off state of the transistor Q2 for putting the starting circuit 6 into an inoperative state. |
