| 摘要 |
PURPOSE:To obtain welding current that responds to the change of load and power supply by calculating large current of rectified secondary DC main circuit by load simulation circuit from small current of AC primary side and enabling control of welding current. CONSTITUTION:The device consists of a current detector 13 that detects output current of an AC power source 1, a load simulation circuit 16 that converts output from the detector 13 to current equivalent to DC side current of a welding machine, a current value calculation circuit 20 that converts the output from the circuit 16 to current effective value, a circulating current calculating circuit 18 that calculates the effective value of circulating circuit basing on the output from the circuit 16, and a controlling circuit. The controlling circuit compares the composite value of respective output from the circuit 18 and circuit 20 with current reference value corresponding to welding current, and phase controls an electric valve 2 basing on the comparative output. By this device, AC is converted to DC by an electric valve 2 such as a thyristor etc., and welding current that responds to the change of load and power supply can be obtained. |
