| 摘要 |
For use with plasma arc welding apparatus, a control system is set forth. The plasma arc welding apparatus includes a plasma arc power supply (12), a contactor (20), and an electrode assembly for moving the electrode (32) relative to a work piece (22). The electrode assembly is raised or lowered by a drive motor (24). The present apparatus includes plasma arc adapter (48) connected across the power supply to measure the voltage across the plasma arc. The plasma arc adapter forms a DC output signal input to a differential amplifier (60). A second input (58) is defined by an adjustable resistor (56) connected to a DC voltage supply to enable operator control. The differential amplifier forms an output difference signal provided to an adder circuit (64). The adder circuit then connects with a power amplifier (68) which forms the driving signal for the motor. In addition, the motor connects to a tachometer (70) which forms a feedback signal delivered to the adder to provide damping, thereby avoiding servo loop overshoot.
|
