| 摘要 |
<p>A programmable power control (68) and line voltage monitoring/compensation system (101) for resistance spot welding machines of varying configurations provides maximum time for computer calculation of SCR triggering times and compensates in real time for these input power line fluctuations that affect the welding operation. The power control (68) employs a single programmable delay element (86, 88) the delay time of which is set while the delay is timing out to generate SCR trigger pulses. The commutation effect in three phase welding machine configurations is taken into account by the power control (68) in determining trigger times. The line monitor (101) synthesizes replica signals of both the primary voltage and current transmitted by the SCRs and processes these replica signals to provide various circuit parameters which can be used as feedback to compensate for only those line variations which affect the welding process.</p> |
