In hybrid electric vehicles, engine starting and stopping occur frequently to provide better fuel economy. Specifically, the structure of the series-parallel hybrid system transmits engine torque pulsations to the driving wheels during engine starting and stopping, which may degrade the quality of the ride. In addition, the quick response of the electric motor can easily cause drivetrain vibration.
This paper presents a motor control system for a series-parallel hybrid vehicle designed to reduce these vibrations.
The proposed motor control system consists of two parts; one controller functions to compensate the engine torque pulsation during engine starts, and the other controller functions to control torsional vibration of the propeller shaft and drive shaft generated by rapid increases or decreases in driving torque.
The proposed vibration reduction motor control method was added to the motor controller on the first rear wheel drive hybrid vehicle (Lexus GS450h). Experimental results revealed that the new control method effectively reduces the vibrations of the vehicle.