| 摘要 |
PURPOSE:To generate a high voltage of good reliability, by providing a short circuit which has a switching element, a resistor and so forth and through which an electrical current can flow only in a prescribed direction, and by closing the switching element at the same time as the stoppage of operation. CONSTITUTION:When the operation of a chopper circuit 5 and an inverter circuit 6 has stopped, a gate signal is supplied from a gate signal generation circuit 22 to the thyristor 21a of a short circuit 21 so that the thyristor 21a is turned on. As a result, both the terminals of the short circuit 21 are electrically connected to each other, namely, a capacitor 5d and a capacitor 3 are electrically connected to each other, so that an overvoltage is prevented from being generated across the capacitor by a reactor 5a, and the drop in the voltage across the capacitor is accelerated. For that reason, a high voltage of good reliability is generated.
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