| 摘要 |
PROBLEM TO BE SOLVED: To improve working quality of resistance welding by realizing constant-current control with high definition at high speed in the resistance welding. SOLUTION: A power source for resistance welding has a large-capacitance capacitor 10 which stores energy for resistance welding as electric charge, a charging circuit 12 which recharges this capacitor 10 to the predetermined voltage, switching elements Q (TR1-TRn) which are electrically connected in between the capacitor 10 and a pair of welding electrodes 14 and 16, and a control part 20 which operates the switching elements Q through a drive circuit 18 during welding energization and controls welding current I. When the welding current I is less than set current value at the time of a leading edge of a clock CK, the control part 20 maintains control pulses CS to the switching elements Q at an active H level from that time to the time when the welding current will be more than the set current value without being influenced by cycle of the clock CK. When the welding current I is more than the set current value at the time of the leading edge of the clock CK, the control part 20 maintains the control pulses CS at a non-active L level until at the time of the leading edge of next clock CK.
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