Subsection Coordinated Control during Mode Transition for a Compound Power-Split System
The power-split transmission is considered as one of the major technologies for hybrid electric vehicles. It utilizes two electric motors/generators (MGs) and a power-split device (planetary gear sets) to make the speed of internal combustion engine (ICE) independent from the vehicle speed, and in that way enables the ICE to operate in a high-efficiency region under all driving cycles. In this study, a compound power-split hybrid system integrated with a two-planetary gear train is proposed. To suppress the vehicle jerk intensity and improve the driving comfort during the transition from EV (Electric Vehicle) mode to HEV (Hybrid Electric Vehicle) mode, a torque coordinated control strategy is derived. Based on the analysis of mode transition in different sections, mathematical models of each section are deduced, respectively. Then a model-based torque coordinated control method is used to solve out the target output torques of ICE, MGs and brakes in each mode transition phase.