| 摘要 |
PURPOSE:To protect a gate turn-off thyristor from breakdown and to start the thyristor stably, by turning the gate turn-off thyristor (GTO) ON and OFF with constant frequency and constant anode current regardless of the load condition for a predetermined time after supplying power source current. CONSTITUTION:In a switching system power source circuit employing a transformer 2, GTO 3 is connected through primary winding of the transformer with a DC power source 1, and power is fed from the secondary winding of the transformer through a rectifier diode or the like to a load. A control circuit 8 is connected through a capacitor 6 with the gate of GTO 3 and a starting circuit 9 is connected through a capacitor 7 thereto. Terminal voltege of a smoothing capacitor 5 is inputted to the control circuit 8, and GTO 3 is controlled such that the terminal voltage of the smoothing capacitor 5 will be constant. The starting circuit 9 disables the control circuit 8 when power source current is supplied, and controls GTO 3 with constant frequency and on-off mode for a predetermined time regardless of the load condition. The time interval is ON/OFF controlled with constant frequency regardless of the load condition.
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