| 摘要 |
PROBLEM TO BE SOLVED: To provide an equipment advantageous in cost and space which prevents irregularity of welding equality. SOLUTION: When a start command is inputted in a current pattern circuit 26, it outputs a predetermined current pattern signal. An instantaneous PWM circuit 27 outputs PWM signal, in such a manner that a current detection signal from a current detector 321 coincides with the current pattern signal. A change- over circuit 14 alternately selects either one of gate circuits 24, 25 wherever the start command is inputted, and sends the PWM signal to the selected circuit. Thereby IGBT's (switching elements) 20a, 20d or 20b, 20c are turned on, and a discharging current from a capacitor 5 flows through the primary side of a transformer 7. A level detection circuit 23 monitors the voltage of the capacitor 5 after start of discharge. When the voltage level falls down to a discharge limit voltage, the detection circuit 23 stops the operation of the gate circuits 24, 25 to stop discharge of the capacitor 5. |
