| 摘要 |
PROBLEM TO BE SOLVED: To prevent the impression of large voltage on an element on a circuit by using charging resistors having small heat capacity by constituting charging/ discharging circuits of a charging circuit constituted of the series connection of the charging resistors, charging switches and DC power sources and discharging resistors connected in parallel to this charging circuit. SOLUTION: Resonance circuits 16, 26 for serially connecting capacitors 11, 21, inductors 12, 22 and high frequency current starting switches 13, 23 are arranged in parallel to a main switch 2 for carrying/cutting off an electric current. Charging/discharging circuits 14, 24 connected in parallel to the capacitors 11, 21 of high frequency current circuits 10, 20 are constituted of the series connection of charging resistors 52, 521, charging switches 54, 541 and Dc power sources 51, 511 and discharging resistors 53, 531 of the parallel connection. The charging switches are turned off when the main switch 2 is cut off, and are turned on by a value of regenerative energy charged to the capacitors 11, 21. Thus, the charging resistors having small heat capacity can be used.
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