| 摘要 |
The present invention provides a switching power supply circuit including a rectifying and smoothing section, a converter section, and a power factor improving section. The rectifying and smoothing section includes a primary side rectifying element (Di) and a smoothing capacitor (Ci). The converter section includes a choke coil (PCC), a converter transformer (PIT), a main switching element (Q1), an oscillating and driving circuit (2), a primary side series resonant capacitor (C2), a primary side parallel resonant capacitor (Cr), and an active clamping circuit (Q2,Cc). The power factor improving section adds and passes a current corresponding to a voltage generated in the primary side series resonant capacitor to the smoothing capacitor via the primary side rectifying element.
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