| 摘要 |
PROBLEM TO BE SOLVED: To take countermeasures such as exactly setting weighting of PID control elements (proportion, integration, differentiation), etc. in a negative feedback circuit by predicting poor welding to be generated due to inappropriate setting of a negative feedback amount of PID control, or disturbance of welding conditions, etc.SOLUTION: In a control method of a resistance welder which performs welding by converting direct output into AC by an inverter 42 to be guided to a primary side of a welding transformer 28, and guiding secondary side AC output reduced by the welding transformer 28 to a welding electrode 24 via a full wave rectifier 30, PWM control is performed to the inverter 42 so as to set welding conditions including a current setting pattern of the welding electrode 24, and on the other hand, negatively feeding applied voltage and welding current of the welding electrode 24 back to the inverter 42 to fit to the welding conditions, and stability of control is discriminated by integrating frequencies N in which deviation D between the welding current and the current setting pattern performs zero cross and comparing the frequencies N with a setting value N. |
