| 摘要 |
PURPOSE:To reduce production cost and realize compactness and light weight by decreasing an external surge and making usable a power semiconductor element of a relatively low breakdown voltage. CONSTITUTION:A parallel circuit of both a GTO thyristor 9 and a resistor 10 is connected in series to an input filter reactor 5 provided in a prestage of a power converter 7, and a series circuit of a resistor 11 and a thyristor 12 is connected in parallel to an input filter capacitor 6; and if an overvoltage state occurs, the GTO thyristor 9 is turned off and the thyristor 12 is turned on, thereby dividing and reducing the voltage by the resistors 10 and 11 and suppressing the voltage rise at the input filter capacitor 6. |
