Patent ID: 8457860

Claim:
An electric power management system for a vehicle, the electric power management system comprising: a power plant configured to generate electrical power and to supply a voltage to a power bus; a battery connected with the power bus to also supply voltage to the power bus; a propeller drive unit connected with the power bus, and drawing power from the power plant and the battery via the power bus to cause movement of the vehicle at different speeds depending on a mode of operation comprising fast and slow modes of operation, where the fast mode results in a higher power bus voltage than the slow mode, the higher power bus voltage coming from additional voltage supplied by the battery; and a command limiting controller configured to generate a bus current to drive the propeller drive unit according to a command limiting, voltage-versus-current curve that adjusts the bus current depending on an amount of voltage on the power bus; where the command limiting curve includes a minimum voltage portion, a maximum voltage portion and a control range therebetween having upper and lower voltage limits and upper and lower current limits for enhanced reliability and stable control of the propeller drive unit.