| 摘要 |
PURPOSE:To simplify a circuit constitution and protect the circuit agaist overvoltage and overcurrent, by connecting an electric valve to the capacitor of the snubber circuit, which is connected to a switching element and protects this element against surge, and by turning on the element above by the discharging current of this capacitor. CONSTITUTION:Gate turn-off thyristor SCR1 of a switch element and diode 3 of an electric valve are provided, and the anode electrode of diode 3 is connected to the anode electrode of SCR1. Capacitor 4 is connected to the cathode electrode of diode 3, and further, capacitor 4 is connected to the cathode electrode of SCR1 through resistance 5. The series circuit of capacitor 4 and resistance 5 is a snubber circuit provided for absorbing the overvoltage applied to SCR1, and transistor TR6 is connected between their connection point J1 and the gate electrode of SCR1. Control signal generating circuit 7 is connected to base electrode 6b of TR6 and the cathode electrode of SCR1. |
