| 摘要 |
PURPOSE:To shorten feedback working time, by providing the secondary winding of a current transformer with a tap, and by feeding back snubber energy to the DC power source of an inverter via the bridge circuit of a plurality of arms. CONSTITUTION:An inverter is built in a half-bridge form of the arm elements 1U-1X of self-arc-suppressing switching elements (GTO) which are alternately turned ON/OFF. Besides, reactors 2U-2X, snubbers 4U-4X, a diode circuit 5, a rectifier 6, and a diode rectification circuit 7 are arranged. In this case, the secondary winding terminals 6b-6c of the rectifier 6 are provided with an intermediate tap 6a, and a thyristor circuit 8 is set. Then, by changing the ratio of the secondary winding of the current transformer 6 to a primary winding according to the degree of the DC power voltage of the inverter, voltage lowering is compensated for, and so a working time in a feedback mode can be prevented from being made longer even if the power voltage is lowered.
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