Abstract
In the interests of global environmental preservation and resource conservation, it is increasingly important to improve the fuel consumption of automobiles. One existing solution which is receiving a lot of attention is the hybrid electric vehicle (HEV). This combines an internal combustion engine and electric motor-generators. In HEVs, for better fuel economy, engine starting and stopping occurs frequently and may cause undesirable vibrations. Additionally, the fast torque response of the electric motors can easily cause drivetrain vibration. Reducing these vibrations in HEV applications is a challenging issue.
Control methods for motor-generators to reduce vibrations in front wheel drive and rear wheel drive hybrid vehicles have been presented in previous papers [1][2]. These motor control systems consist of two parts; one controller controls the transmission of engine torque pulsation to the driveshaft at engine turn-over. The other controls torsional vibrations of the driveshaft generated by a rapid increase or decrease of the drive torque. In this paper, these motor control methods are expanded to include reduction of vehicle vibrations in an electrical 4WD hybrid vehicle. The electrical 4WD hybrid vehicle has a hybrid powertrain incorporating an engine and two motor-generators to propel the front driveshaft and a rear motor-generator to propel the rear driveshaft. The vibration reduction controller presented herein for electrical 4WD hybrid vehicles simultaneously controls the three motor-generators to reduce torsional vibrations of the front driveshaft, rear driveshaft and torsional damper. This can also improve ride comfort. Experimental results presented herein verify the efficiency of these control methods.
Keywords:Hybrid, Engine, Vibration, Motor, Control