A dragline excavating machine includes a gearless direct drive AC drive motor for driving each of the hoist and the drag drums in the system. The gearless AC motor is driven using a digital system which receives AC power from the utility system rectifies the power using active front end circuits, and converts the resultant DC to a frequency controlled AC using an inverter circuit. The resultant AC signal is employed to drive the gearless AC motor, resulting in reduced harmonic distortion, unity or leading power factor, and increased efficiency, reduced operating costs, and reduced mean time between failure.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional patent application Ser. No. 60/396,842 filed on Jul. 18, 2002 and entitled "Dragline Excavating Machine with Direct Drive Hoist and Dragline Drums".
Certain exemplary embodiments can include a static DC electric drive system for mining equipment. The drive system can include: an active front end adapted to receive an AC voltage and output a substantially constant DC voltage; and a DC chopper coupled to the active front end, the DC chopper adapted to receive the substantially constant DC voltage and output a variable DC voltage.
