Driving force control method during engine clutch slipping of TMED HEV

A driving force control method during engine clutch slipping of a transmission mounted electric device (TMED) for a hybrid electric vehicle (HEV) including an engine and a second motor which is a hybrid starter generator (HSG), a first motor disposed at a transmission side, an engine clutch interposed between the engine and the first motor, and a multi-clutch transmission connected with an output terminal of the first motor, the method comprising:

• verifying, by a controller, whether a control for maintaining a target speed of the engine is achieved by an engine feedback control or by a second motor torque feedback control;
• applying, by the controller, clutch pressure for the clutch slipping with hydraulic pressure;
• estimating, by the controller, when the clutch pressure is applied clutch slipping transmission torque T_clutch in which torque of the engine clutch equivalent to the pressure acts as a load;
• calculating, by the controller, second motor dischargeable limit torque;
• calculating, by the controller, second motor assist torque and engine torque;
• and
• executing, by the controller, a slip control,
• wherein in calculating the second motor assist torque and the engine torque, when the control for maintaining the target speed of the engine is achieved by the engine feedback control, torque for maintaining the engine target speed is considered for calculating the engine torque and when the control for maintaining the target speed of the engine is achieved by the second motor torque feedback control, the torque for maintaining the engine target speed is considered for calculating the second motor assist torque.