Torque coordination control strategy in engine starting process for a single motor hybrid electric vehicle

To troubleshoot the oversized output torque ripple during engine starting process of parallel hybrid electric vehicle (HEV), the engine starting process is divided into cranking phase, speed synchronisation phase and after-ignition phase. In this paper, the expressions of the vehicle jerk are derived from the vehicle dynamic formula in each phase, and the influences of various parameters on the jerk are analysed. The coordinated control strategy between the clutch pressure and motor torque, and that between the motor torque and engine torque are proposed. The simulation for the single shaft HEV model is carried out through MATLAB/SIMULINK by which rationality of the control algorithms was checked. Finally, a bench test is implemented whose results prove the determined change rate of clutch pressure, motor torque, and engine torque can effectively coordinate to meet the need of vehicle ride performance in engine starting in-motion process.