Analysis of a Coordinated Engine-Start Control Strategy for P2 Hybrid Electric Vehicle 2019-01-5023

P2 hybrid electric vehicle is the single-motor parallel configuration integrating with an engine disconnect clutch (EDC) between the engine and the motor. The key point with P2 hybrid electric vehicle is to start the engine utilizing the single driving motor while still propelling the vehicle, which requires an appropriate engine-start control strategy and a high mechanical performance of EDC. Since the space for EDC is limited, EDC torque response is difficult to follow the torque command, which complicates the issue of precisely controlling the clutch. Consequently, methods proposed in massive papers are inappropriate for current EDC of target vehicle. Considering that slip control of shifting clutch also contributes to reducing impact of engine start assisted by EDC, a detailed engine-start control strategy was proposed to simplify the control of EDC for being applied to actual target vehicle. Furthermore, the control strategy proposed in this paper was utilized to realize driving mode transformation from motor-only to engine-only. In this paper, a detailed hybrid electric vehicle simulation model was established with the consideration of dynamic characteristics of engine, motor and clutch by means of MATLAB/Simulink. Moreover, control methods of engine, motor and clutch were introduced and the vehicle control architecture was also summarized in this paper. In addition, the detailed coordinated control process of engine, motor and clutch was analyzed containing the choose of different motor control mode and engine control mode due to the change of primary control objective. Simulation results were utilized to verify the coordinated engine-start control strategy proposed. Ultimately, vehicle test data was obtained to validate the simulation results utilizing CANape and the reasons for difference between simulation results and test data were analyzed.