Hybrid vehicle energy balance control system for CO2 reduction

A hybrid electric vehicle (HEV), comprising:

• an internal combustion engine;
• an electric traction motor;
• a belt starter generator (BSG) unit configured to start the internal combustion engine;
• a low voltage battery system including a low voltage battery electrically coupled to the BSG unit;
• a high voltage battery system including a high voltage traction battery configured to power the electric traction motor;
• a DC/DC converter configured to convert high voltage from the high voltage battery system into low voltage to charge the low voltage battery and support low voltage loads;
• and
• a powertrain control system for reducing CO2 emissions of the HEV, including a controller configured to control an output voltage setpoint of the DC/DC converter and the BSG unit,
• wherein the controller is configured to selectively increase or decrease the output voltage setpoints of the DC/DC converter and/or the BSG unit to reduce high voltage battery power consumption to thereby avoid or delay turning on the internal combustion engine thereby reducing CO2 emissions, and
• wherein the controller is programmed to maintain a state of charge (SOC) of the low voltage battery within a predefined range to reduce CO2 emissions, including:
• monitoring the low voltage battery SOC to determine an increase or decrease in the SOC;
• increasing the output voltage setpoints for the DC/DC converter and/or the BSG unit when the low voltage battery SOC is increasing within the predefined range to thereby charge the low voltage battery;
• and
• decreasing the output voltage setpoint of the DC/DC converter and/or the BSG unit when the low voltage battery SOC is decreasing within the predefined range to thereby discharge the low voltage battery.