| 摘要 |
PROBLEM TO BE SOLVED: To provide an arc machining power supply system compatible with two different input voltages with a simple structure. SOLUTION: A change-over switch S1 is arranged between a connection point N1 of first and second smoothing capacitors C1 and C2 and a connection point N2 between seventh and eighth switching elements TR7 and TR8 in an auxiliary switching circuit 14. Voltages between terminals in the first and second smoothing capacitors C1 and C2 are alternately supplied to an inverter circuit 13 by conducting the change-over switch S1 at the time of 400V input. Voltage of the connection point N1 between the first and second smoothing capacitors C1 and C2 is prevented from being supplied to an inverter circuit 13 through diodes D17 and D18 in reverse connection, which are installed in the seventh and eighth switching elements TR7 and TR8, and the effect of soft switching control can securely be obtained by interrupting the change-over switch S1 at the time of 200 V input. COPYRIGHT: (C)2009,JPO&INPIT
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