Design of a model reference controller for a dual-mode power-split hybrid electric vehicle during mode shift

Abstract

This paper presents a model reference controller (MRC) of mode shift that intends to decrease the vehicle jerk and the clutch frictional loss for a dual-mode power-split hybrid electric vehicle (HEV). To design a model-based control system in this paper, simplified dynamic equations capturing mode shift dynamics of the dual-mode power-split HEV are derived. To simplify the complicated dynamic characteristics of mode shift, switched system theory is applied to partition the state space of mode shift into domains and facilitate the controller design. To deal with the friction-induced discontinuity of the clutch torque during mode shift, a MRC is proposed that coordinately manages the engine torque, the motor-generator torque and the clutch friction torque. In addition, because the control system is overactuated by three control variables (three torques) and two output variables (two angular speeds), the controller parameter selections that involves selecting the combination of the control variables and the feedback-feedforward parameters are comparatively analyzed. The simulation and the experimental results demonstrate that the proposed MRC in this paper can simultaneously reduce the vehicle jerk and the clutch frictional loss, thereby improving the shift quality, when compared with the conventional controller.