| 摘要 |
PURPOSE:To realize an inexpensive AC arc welding source with the high reliability by making an electric current flowing through switching elements to constiture free wheel circuits of Q4 and Q2 to the switching current in accordance with switching frequency of Q1 and Q3. CONSTITUTION:A first DC power source 1a is connected to a second DC power source 1b in series with the additive polarity. Further, a circuit to connect in series a first switching element Q1 to control ON-OFF of the reversed polarity side current to a second switching element Q3 to control ON-OFF of the straight polarity side current is connected to the DC power sources in parallel. Moreover, a circuit to connect an arc load 4 to a reactor 5 for smoothing in series, the reversed polarity side free wheel circuit to connect a first rectifying device D5 to a third switching element Q4 in series and the straight polarity side free wheel circuit to connect a second rectifying device D5 to a fourth switching element Q2 in series are provided in parallel between a connection common point of the DC power sources and a connection common point of the switching elements. The electrification is carried out on the respective circuits to supply the straight polarity side current to the arc load 4.
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