| 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 pairs of coils 32A and 32E, 32B and 32F, 32C and 32G, and 32D and 32H on low voltage side mutually equal in number of turns, corresponding to four switching circuits 41-44 each. 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 coil 31 and the coils 32A-32H becomes larger in the order of four series connection, two series two parallel connection, and four parallel connection. COPYRIGHT: (C)2007,JPO&INPIT
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