Torque coordinated control in engine starting process for a single-motor hybrid electric vehicle

Abstract

To tackle the excessive output torque ripple during engine starting process of parallel hybrid electric vehicles, the engine starting process is divided into three phases in this study: engine cranking phase, speed synchronization phase, and after synchronization phase. 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 analyzed. The coordinated control strategy for the clutch pressure and motor torque and that for the motor torque and engine torque are proposed. The simulation model for the single-motor parallel hybrid electric vehicle is established using MATLAB/Simulink, and the effectiveness of the proposed control algorithms is verified. Besides, a bench test is conducted and the test results show that the selected change rates of clutch pressure, motor torque, and engine torque can effectively coordinate the relation between clutch, motor, and engine. It can be concluded that the proposed control strategy satisfies the requirement of vehicle ride performance in engine starting in-motion process.