| 摘要 |
PURPOSE:To make welding always in the same state possible despite the change in power supply characteristics in a short time by controlling a DC welding power supply in such a way that the difference between the arc electric power rate determined from the electric power at the moment of short circuiting and the electric power at the moment of the arc and the set value thereof is made zero. CONSTITUTION:The arc voltage value VA detected with a voltage detecting circuit 5 and the current value IA detected with a current detecting circuit 7 are converted to respectively to corresponding digital quantities with the circuits 10, 11 of an electric power calculating circuit 8 and these digital quantities are inputted to a circuit 12. The circuit 12 multiplies both and outputs the same to a circuit 14. The circuit 14 compares the set voltage value VL from a circuit 12 and the voltage value VA from the circuit 5 and obtains a switching signal. By this signal, the integrated values corresponding to the two states VA>=VL and VA<VL are selectively outputted as electric power Pa at the moment of the arc and electric power Ps at the moment of short circuiting to a circuit 15. In the circuit 15, arc electric power rate zeta=Pa/(Ps+Pa) is calculated, and a comparator 17 compares this with set arc power rate zeta, and controls a DC welding power supply 6 so that these attain zeta-zeta'=0. |
