| 摘要 |
<P>PROBLEM TO BE SOLVED: To constitute a switching power circuit so that it is provided with a power factor improving function and accommodates to wide ranges for cost reduction and the reduction in the size and weight of the circuit. <P>SOLUTION: A rectifying circuit generates direct-current input voltage (Ei) in a composite resonance converter obtained by combining a partial resonance voltage circuit with a current resonance converter based on half bridge connection. Switching control is carried out so that the rectifying circuit functions as a voltage doubler rectifying circuit at 150VAC or below and as a full-wave rectification circuit at 150VAC or above. For power factor improvement, a power factor improvement circuit 3 is provided. The circuit is so constituted that: switching output transmitted to tertiary winding N3 wound on an insulating converter transformer PIT is voltage fed back to a rectified current path to interrupt rectified current, and the conduction angle of alternating input current is enlarged. Further, at 150VAC or above, the number of windings of the tertiary winding constituting the power factor improvement circuit 3 and the inductance of an inductor for voltage feedback connected thereto are increased. Consequently, the power factor is improved in an 200-VAC system. <P>COPYRIGHT: (C)2004,JPO |
