No abstract

For hybrid electric vehicles, there are output shaft torque fluctuations during the working condition switching process, which reduce the driving comfort of the vehicle. Therefore, corresponding control is necessary to eliminate the torque fluctuations. In this paper, for a dual-mode power-split hybrid system, the steady state energy management strategy under the typical power flow in two modes is studied and an operational condition switching control strategy based on engine torque control and motor speed control is proposed for the system characteristics. Meanwhile, the reason for fluctuations on the switching process based on engine torque control is found out to be the too large inertia moment in the coupling power mechanism. Considering the characteristics of fast speed and torque response of the motor, dynamic coordinated control strategy is proposed to eliminate the torque fluctuations and improve the accuracy of the actual torque relative to the target torque for the two models (i.e., the motor torque compensation control strategies). The model of dual-mode hybrid system was built and the simulation results show that the proposed control strategy has a positive effect on eliminating the torque fluctuations and the target torque of the driver can be accurately tracked.