| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a switching power supply circuit which has a power factor improving function, enhances power conversion efficiency, and reduces the number of circuit components. <P>SOLUTION: A rectified and smoothed voltage Ei is generated from an AC power source and the rectified and smoothed voltage Ei is input in a voltage/current resonance converter to obtain a secondary side DC output voltage Eo from the secondary side via a converter transformer PIT. The switching power supply circuit is equipped with a voltage clamp capacitor C3, an active clamp circuit constituted of a series connection circuit composed of a switching element Q1 of the voltage/current resonance converter and of an auxiliary switching element Q2 complementarily turned on, a first diode D1 for improving power factor, an inductor Lo for improving power factor, and a second diode D2 for improving power factor. The switching power supply circuit is operated as a boosting converter to enlarge the conductive angle of the primary side rectifying element Di, with improvement in the power factor. <P>COPYRIGHT: (C)2007,JPO&INPIT |
