| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply controlling device which prevents the fluctuation of a DC voltage to be supplied to a load even if an AC voltage supplied from a commercial AC power supply contains distortion. SOLUTION: A DC regulated power supply 400 is provided with an input current detecting circuit 407, which detects an alternating current supplied from a commercial power supply 100, an output voltage detecting circuit 408, which detects a given DC voltage supplied to a load RL and a switching pulse generating circuit 410, which outputs switching pulses to a switching FET 405, and so forth. The switching pulse generating circuit 410 contains a zero-cross detecting circuit 411, which detects the zero-cross point of the AC voltage supplied from the commercial power supply 100, and a ROM 413, which generates the sine waves of a half period with the zerocross point identical to the detected one and of the same phase with the AC voltage. Based on the sine waves of a half period generated by the ROM 414, etc., the pulse width of the switching pulses to be outputted to the switching FET 405 is controlled so that the AC voltage becomes constant. |
