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

A vehicle propulsion system 10 includes a first bi-directional DC-DC converter 26 coupled to a first DC bus 36, an energy storage system comprising at least one energy storage unit coupled to the first bi-directional DC-DC converter 26, a first DC-to-AC inverter 44 coupled to the first DC bus 36, and a first electromechanical device coupled to the first DC-to-AC inverter. A controller 64 is programmed to determine a real-time operating speed of the first electromechanical device, compare the real-time operating speed of the first electromechanical device to a scheduled speed of the first electromechanical device, and selectively control the first bi-directional DC-DC converter to shift a voltage of the first DC bus based on the comparison.