Patent ID: 7292917

Claim:
A method for attenuating vibration in a primary rotary power source in a hybrid electric vehicle powertrain, the powertrain including a secondary rotary power source and gearing defining in part, respectively, separate torque flow paths from the primary and secondary power sources to vehicle traction wheels, the secondary power source including an electric motor electrically coupled to an electric generator, the generator being mechanically coupled to the primary power source, the method comprising the steps of: measuring actual speed of the primary power source; determining a primary power source speed command; determining a generator torque command based upon a closed loop control of primary power source speed using the actual speed of the primary power source as a feedback variable, the generator torque command corresponding to generator torque transmitted to an element of the gearing; and coordinating torque of the gearing element and a motor torque commanded by a vehicle driver to develop a coordinated motor torque command whereby engine speed and dynamic acceleration fluctuations during engine start events and engine stopping events are attenuated.