Patent ID: 8253357

Claim:
A method of load demand and power generation balancing within an electric drive system comprising one or more electric drive motors supplying torque used to propel a machine, the electric drive system including a fuel-driven prime mover for driving an electrical power generator including a field circuit through which a controlled excitation current flows, the electrical power generator providing electrical power for a DC link having a voltage characteristic and a current characteristic, the method comprising: determining a voltage value of the DC link; determining a torque command by an operator of the electric drive system; determining a speed for each of the one or more electric drive motors receiving power provided from the DC link at the voltage value; normalizing the determined speed to derive an average motor speed; deriving a mechanical power that is being commanded based on the average motor speed and the torque command; determining, using an excitation current predictor function, a predicted excitation current value, for the controlled excitation current flowing through the field circuit of the electrical power generator, based on the derived mechanical power and the voltage value of the DC link, wherein the excitation current predictor function references excitation current data providing, for each of a plurality of constant excitation current levels for the field circuit, a current output produced by the electrical generator at the voltage value of the DC link; and applying an actual excitation current to the field circuit of the electrical power generator, the actual excitation current being based on the predicted excitation current.