| 摘要 |
Disclosed is an auxiliary power supply device generating a constant auxiliary power. The auxiliary power supply device comprises a main power supply wherein alternating current is applied to a bridge diode, full-wave rectified, smoothed and applied to a primary winding of a transformer, an excited current of a secondary winding of the transformer is rectified, smoothed and applied to a load, the direct current power source applied to the load is applied to a control section, and a control signal for driving a switching transistor for controlling the current flowing through the primary winding of the transformer; a rectifying section for rectifying voltage outputted from the bridge diode; an auxiliary power generating section for smoothing the output voltage from the rectifying section and generating an auxiliary power source to apply to the main power supply part; and a current sink section for controlling the current in the auxiliary power generating section to output an invariable auxiliary power source regardless of the output voltage of the bridge diode so that even when the output voltage from the bridge diode varies, a constant auxiliary power source is supplied to the control section so that malfunction of the control section is avoided, and also, since the start-up section is eliminated, the auxiliary power supply device becomes simple.
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