Patent ID: 8761977

Claim:
A method for optimizing an engine idle speed in a vehicle having an engine, a motor generator unit (MGU), and an energy storage system (ESS), the method comprising: determining a set of vehicle electrical values, including at least one of: an electrical load on the MGU, a temperature of the MGU, an efficiency of the MGU, and a state of charge (SOC) of the ESS; measuring a speed of the MGU; calculating a torque capacity curve for the MGU using the measured speed of the MGU; selecting a maximum of the calculated torque capacity curve and a calibrated torque capacity curve; calculating a set of engine speed values using the set of vehicle operating values; and using a controller to command the engine idle speed as a function of the set of engine speed values, including controlling the MGU via the selected maximum of the calculated torque capacity curve and a calibrated torque capacity curve.