| 摘要 |
PROBLEM TO BE SOLVED: To achieve the cost down and the downsizing of a circuit as a switching power supply circuit which possesses a power factor improving function. SOLUTION: Besides being equipped with a current resonance type converter by a half bridge coupling system, this switching power unit is equipped with a voltage feedback transformer which is so constituted as to input its primary switching output from primary winding. This feeds back the voltage of the above switching output excited from this primary winding to the secondary winding to a rectified current path, and intermits the rectified current, whereby this enlarges the angle of conduction of an AC input current, thereby improving power factor. It obviates the necessity of installing an active filter for improvement of power factor, and the number of parts items is reduced sharply. Moreover, likewise it obviates the necessity of installing a power choke coil used in a choke input system, too, for improvement of power factor, and in this case, the weight of the circuit can be reduced sharply. COPYRIGHT: (C)2004,JPO&NCIPI
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