Patent ID: 9660519
Date: 2017-05-23
CPC Classifications: H02M,Y02B,Y02P

Claim:
1. A switching power supply circuit configured to generate a direct current output voltage of a predetermined value and to supply the direct current output voltage to a load, comprising: a rectifier circuit configured to full-wave rectify an alternating current power supply to obtain a pulsating output; an inductor connected to the rectifier circuit and configured to receive the pulsating output; a switching element; an output capacitor; a phase angle detector circuit configured to detect a phase angle of the alternating current power supply; an inductor current detector circuit configured to detect a current of the pulsating output flowing into the inductor and to output an inductor current detection voltage; a level conversion circuit configured to convert the inductor current detection voltage into first and second current level signals of mutually differing voltage levels; a continuous control setting circuit configured to generate a set pulse regulating a turn-on timing of the switching element by generating a reference voltage signal, which changes practically in phase with an alternating current input voltage waveform full-wave rectified, from the first current level signal and by comparing the reference voltage signal with the voltage level of the second current level signal; a zero current detector circuit configured to detect whether the current of the pulsating output flowing into the inductor has reached zero; and a turn-on timing selector circuit configured to the phase angle detector circuit is configured to set, at a point of a specified phase angle of the alternating current power supply, enabling or disabling of the turn-on timing based on the determination result of the turn-on timing selector circuit, and the turn-on timing selector circuit is configured to switch the switching element to an on-state with the set pulse regulating the turn-on timing generated by the continuous control setting circuit only when the phase angle detector circuit sets the enabling of the turn-on timing regulated by the continuous control setting circuit.