Driving mode shift control for planetary gear based dual motor powertrain in electric vehicles

Abstract

To reduce the vehicle jerk in mode shift, this paper investigates the driving torque control strategies of the planetary gear based dual motor powertrain. The rigid dynamic model of powertrain is built to formulate a general energy management strategy (EMS) and a robust EMS which avoids the drastically change of motors speed. A flexible dynamic model considering the flexible shafts is then built to accurately simulate the vehicle jerk. Based on the linear and polynomials function, two types of coordinated speed trajectories of motors are designed to transfer the discrete speed signals produced by EMS to continuous signals. A speed feedback control strategy and a combination control strategy of speed feedback and torque feedforward are proposed to implement the mode shift. The comparisons between EMS and robust EMS, linear and polynomials speed trajectories, speed feedback control and combination control are demonstrated by simulation. The results indicate that the robust EMS and polynomials speed trajectories can reduce vehicle jerk. The speed feedback control strategy is more stable than the combination control strategy when the model parameters are inaccurate.