| 摘要 |
PROBLEM TO BE SOLVED: To provide size and cost reduction for a component, while keeping a restraining effect of a voltage level applied to a main switch device. SOLUTION: An intermediate tap 20 is provided at a primary main winding 5 for exciting a power transmission main transformer 4. A winding 21 is run from one end of the main winding 5 to the intermediate tap 20, and a winding 22 is run from the intermediate tap 20 to the other end. An input voltage is applied to the one end of the primary main winding 5 formed of the windings 21, 22. The other end is grounded through a main switch device 6, and a capacitance 7 for voltage resonance is provided at the main switch device 6 in parallel. An active snubber circuit 18 is constituted of a capacitance 15, an auxiliary switch device 16 connected with the capacitance 15 in series, and a diode 17 connected with the auxiliary switch device 16 in parallel. The active snubber circuit 18 is connected with the winding 21 in parallel.
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