| 摘要 |
PURPOSE:To reduce the variation of output voltage of an SCR due to a change of the power supply voltage, by controlling the firing angle of the SCR in response to the dropping change of the power supply voltage. CONSTITUTION:The phase of an ignition pulse of an SCR stack 2 which is applied to an AC power supply 1 is controlled by a phase controller X. The controller X consists of a sawtooth wave generating circuit Y and a gate pulse generating circuit Z. The sawtooth wave generated from the circuit Y is supplied to a plus (+) input terminal of an operational amplifier 20 of the circuit Z; while the voltage of a mobile contact of a variable resistor 21 which controls the generating phase of the ignition pulse of an SCR is supplied to a minus (-) input terminal of the amplifier 20. The output terminal 5-2 of unstabilized power supply voltage -24V of a control power supply unit 5 is connected to the resistor 21 via a Zener diode 27. When the voltage of the power supply 1 increases, the phase delay angle of the ignition pulse generated from the circuit Z is increased to the AC power supply of the ignition pulse. Then the rise is suppressed for the output voltage of an SCR2. While the drop is suppressed for the output voltage of the SCR2 when the voltage of the power supply 1 drops. |
