| 摘要 |
PURPOSE:To enable feedback control of output of welding machine at high accuracy using both 50Hz and 60Hz in common by providing a timing controlling device that delays starting of integration of output feedback signal when using 50Hz compared with the case where 60Hz is used. CONSTITUTION:In the case of 50Hz, a switch 9 works later than zero cross point of power source voltage and keeps on state for (Ta+Tb) time until next zero cross point. Out of this, Tb time in which switches 8a, 8b are made off is integrating time, and Ta time in which switches 8a, 8b are made on is reset time. Integration voltage just before reset is Vb. The value of Vb held by a sampling hold circuit 7 is compared with an output setting signal from an output setting circuit 1, and this output signal is transmitted to an output controlling section 3 through an error amplifier circuit 2 at reset time Ta to control the object 4 of controlling. Accordingly, by making (Ta+Tb) time coincide with zero cross period of power source voltage at the time of 60Hz, common use of 50Hz and 60Hz of a feedback circuit becomes possible. |
