Adaptive boost voltage for hybrid vehicle operation

A vehicle comprising:

• an electric machine configured to provide propulsive force to the vehicle at a bus voltage;
• and
• a controller configured to cause a converter to output the bus voltage at a discrete step value that is selected from a predetermined number of available discrete step values, and to change at least some of the available discrete step values in response to an operating mode of the electric machine, wherein magnitudes of at least some of the available discrete step values are based on percentages of drive-cycle time at which a powertrain that includes the electric machine operates with particular torques, speeds, and powers.

A method of controlling a DC-DC converter comprising:

• in response to a torque request to a motor coupled with the converter exceeding an available torque, outputting by the converter for at least a predetermined duration a bus voltage at a discrete step value selected from a predetermined number of available discrete step values, and updating magnitudes of at least some of the discrete step values based on historical powertrain operating data;
• and
• in response to a selected powertrain operating mode, changing the predetermined number.