Patent ID: 6936991

Claim:
A method for controlling motor torque of a motor in a vehicle, comprising: determining a maximum torque current that a DC source can supply to the motor; determining a present flux weakening current; determining a minimum threshold for the determined maximum torque current, below which a commanded torque current should not fall; increasing a flux current to the motor if a commanded torque requires higher current than the determined maximum torque current that the DC source can supply, by adding to the flux current the output of a first proportional-plus-integral controller operating on a difference between the commanded torque current and the determined maximum torque current that the DC source can supply; and further increasing the flux current to the motor if the determined maximum torque current that the DC source can supply is less than the minimum threshold for the determined maximum torque current, by adding to the flux current the output of a second proportional-plus-integral controller operating on a difference between the determined maximum torque current that the DC source can supply and the determined minimum threshold for the determined maximum torque current.