Patent ID: 8116958

Claim:
A driving force control system of a hybrid electric vehicle, including at least one motor-generator, a motor-generator rotational speed detection means for detecting a rotational speed of the motor-generator, a motor-generator control means for controlling the motor-generator, an engine, an engine rotational speed detection means for detecting a rotational speed of the engine, an engine control means for controlling the engine, a clutch for controlling connection and disconnection between the motor-generator and the engine, a clutch control means for controlling the clutch, and a power transmission control means for transmitting and interrupting driving forces of the motor-generator and the engine, the system comprising at least one starter-generator directly connected to the engine, wherein output torques of the engine and the starter-generator are controlled so as to make a difference between the rotational speed of the engine and the rotational speed of the motor-generator become smaller, and the clutch is engaged when the difference between the rotational speeds reaches a predetermined threshold value, and the control of the output torques is performed by at least one of a control (P control) corresponding to the rotational speed difference, a control (D control) corresponding to a differential value of the rotational speed difference, and a control (I control) corresponding to an integral value of the rotational speed difference, the P and D controls being performed so as to make a torque gain of the starter-generator become larger than that of the engine, and the I control being performed so as to make the torque gain of the starter-generator become smaller than that of the engine.