| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply which can widen the convertible voltage range. SOLUTION: The switching power supply is provided with a transformer 3 which has four coils 31A-31D on high voltage side mutually equal in number of turns, corresponding to four switching circuits 11-14 operating synchronously with one another, and four inductors Lr1-Lr4. Four fellow current paths are put each in four parallel connection, in four series connection, or in mixed connection (two series and two parallel connection) of series and parallel, according to the target voltage value of input voltage (DC high voltage VH) at normal operation and output voltage (DC high voltage VH) at reverse operation, by a voltage detecting circuit 61, a controller 7, and connection changeover switches S51-S53 and S61-S63. The ratio of the numbers of turns between the coils 31A-31D on high voltage side and the coils 32A and 32B on low voltage side becomes larger in the order of four parallel connection, two series two parallel connection, and four series connection. Moreover, the current change within the circuit becomes slow by the action of inductors Lr1-Lr4. COPYRIGHT: (C)2007,JPO&INPIT
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