Patent ID: 7797089
Filing Date: 2010-09-14
Classification: B60K,B60L,B60W,Y02T

Abstract:
1. A method for managing a power source in a vehicle including an engine and an electric machine, each of the engine and the electric machine being operable to output torque to at least one vehicle wheel, the engine having an engine-on power requirement for starting the engine, the power source being operable to supply power to the electric machine and having a first operating temperature range, a second operating temperature range above the first operating temperature range, and a third operating temperature range below the first operating temperature range, the method comprising: setting a first discharge limit for the power source that is substantially constant over the first operating temperature range and decreasing over the second and third operating temperature ranges, the first discharge limit being at least partly based on an amount of power that is supplied by the power source for a first predetermined period of time; setting a second discharge limit for the power source higher than the first discharge limit the second discharge limit being at least partly based on the temperature of the power source and an amount of power that is supplied by the power source for a second predetermined amount of time that is less than the first predetermined amount of time, and which is based on an amount of time required to start the engine; determining a buffer value as a function of at least the second discharge limit and the engine-on power requirement; determining a driver demand for power; and starting the engine when the engine is off and the driver demand for power exceeds the buffer value.