Abstract: To solve the problem of body wobbling of a hybrid electric vehicle with a new power splitting mechanism at the moment of engine ignition, experimental research and data analysis are carried out. The vibration model of transmission system is established, and the excitation source and transmission path of the system are analyzed. Without changing the type of suspension and the inherent characteristics of power transmission system, the method of reducing the excitation source is adopted to optimize the engine output torque. Based on analysis of the factors affecting the engine output torque, the calculation formula of the engine output torque is deduced and the target optimal torque curve is given. Then the optimal control parameters of the engine torque at the moment of ignition are obtained by using particle swarm optimization algorithm. Finally, the effectiveness of the method is verified on the real vehicle

Key words: power-split, ignition, wobbling, hybrid, particle swarm