| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply circuit having a power factor improving function, improving power conversion efficiency and reducing the number of circuit constituent components. SOLUTION: The switching power supply circuit improves a power factor. A converter section is a multiple resonance converter having a primary side voltage resonance circuit consisting of a leakage inductor L1 and a primary side voltage resonance capacitor C1, and a secondary side serial resonance circuit consisting of a leakage inductor L2 and a secondary side resonance serial capacitor C2. It is provided with a switching element Q1. The converter section also includes a power factor improving circuit 13 for improving the power factor, and a common mode filter between the power factor improving circuit 13 and an AC power supply AC. A capacitor CNL of the common mode filter is shared with the power factor improving circuit 13 to reduce the generation of a noise, irrespective of the small number of components. Further, a high-speed switching diode is used for a primary side rectifying element Di to reduce the number of components, thereby improving efficiency. COPYRIGHT: (C)2008,JPO&INPIT
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