Patent ID: 7375490

Claim:
A method for managing electrical power in a dragline-mining machine, said method comprising: for a plurality of Active Front End units, each Active Front End unit from the plurality of Active Front End units adapted to be electrically coupled to a DC bus and to apply a DC voltage on the DC bus, each Active Front End unit switched on at a fixed rate and for an individually variable duty cycle, a stagger angle of the plurality of Active Front Ends pre-set to manage AC harmonic distortions caused by predetermined power events on the DC bus: responsive to a determination that a voltage measurement on the DC bus is not within a first predetermined range, automatically changing at least one of the individually variable duty cycles; and responsive to a determination that a phase angle is not within a second predetermined range, the phase angle calculated from a measured voltage on an AC bus adapted to provide AC power to the plurality of Active Front End units and a measured current directly associated with a selected Active front End unit from the plurality of Active Front End units, automatically changing the duty cycle of at least the selected Active Front End unit.