| 摘要 |
A switching power supply circuit achieves improvement of the power conversion efficiency while a high power factor is maintained, in which the power factor of a current resonance converter is improved by feeding back a switching output to a rectification current path to selectively interrupt the rectification current, thereby to expand the conduction angle of ac input current. This allows elimination of a power choke coil to achieve improvement of the power conversion efficiency. Further, the magnetic flux density of an insulating converter transformer is set lower than a predetermined level, so that secondary side rectification current normally maintains a continuous mode irrespective of a variation of the load or the input voltage. This decreases the power loss that appears when the secondary side rectification current is placed into a discontinuous mode and thereby achieves further improvement of the power conversion efficiency. |
