| 摘要 |
<p>PURPOSE:To prevent the deterioration of an arc convergence and the breakdown of an auxiliary switching element by providing a high frequency invertor and a control circuit which controls the said invertor, and the auxiliary switching element and a drive circuit and a capacitor for absorbing a surge. CONSTITUTION:When a power source is closed, a switching pulse is outputted from the control circuit 34, and 1st and 2nd transistors Tr 19, 20 switch alternately, and the high frequency invertor 22 is driven. Thus, the output direct current of an input side rectification circuit 16 is converted into a high frequency. Besides, the Tr 26 switches by the switching pulse, outputted from the drive circuit 36 synchronizing with the switching pulse from the circuit 34, and the direct current, obtained by rectifying the high frequency due to the invertor 20 by means of an output side rectification circuit 20, is converted into an alternating current again, and an AC power is supplied to a load 29. At this time, at the time of the OFF of a 3rd Tr 26, the voltage of an accumulated energy, accumulated by an inductance portion of the connection cable of the load, is impressed to the Tr 26 as a surge voltage, but it is absorbed by the capacitor for absorbing a surge 39, and the breakdown of the Tr 26 is prevented.</p> |
