VEHICLE PROPULSION SYSTEM HAVING AN ENERGY STORAGE SYSTEM AND OPTIMIZED METHOD OF CONTROLLING OPERATION THEREOF

A vehicle propulsion system includes a plurality of power sources coupled to a final drive of the vehicle propulsion system. A controller is programmed to determine a desired power demand from the power sources and operate a number of the power sources to produce the desired power demand. The controller identifies a least efficient power source of the power sources and controls the least efficient power source to produce power at an optimum operating point of the least efficient power source. The controller also identifies a power output of the least efficient power source corresponding to the optimum operating point, compares the power output of the least efficient power source to the desired power demand, identifies a remaining power demand from the comparison, and controls another power source to produce the remaining power demand.