| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply unit by which general performance of the unit is improved, even when an input voltage and a load change. SOLUTION: Either of a first bridge circuit or a second bridge circuit is selectively and switchably operated according to at least one of a DC input voltage Vin or an output current Iout. When the former is selectively operated, short circuit losses at switching elements S1 to S3 are suppressed by a resonance operation of a first resonance circuit, and efficiency of the unit is improved. Moreover, rise of a reverse voltage added to rectifier diodes 4A, 4B becomes slow by a second resonance circuit and a surge voltage inhibiting circuit 2. On the other hand, when the latter is selectively operated, an inductor Lr for resonance is bypassed, by which an input voltage range which retains a certain output voltage is expanded. COPYRIGHT: (C)2007,JPO&INPIT
|
