Abstract: Significant longitudinal vibration is found when a China-made fuel cell passenger car accelerates and brakes. To explain this phenomenon, a nonlinear dynamical model of fuel cell vehicle powertrain system is established considering the gear backlash and tire-road friction characteristics, which includes electric motor, motor shaft, gear box and differential assembly, left and right axle shafts, tire and car body, total seven sub-models. Based on this model, the dynamical characteristics of vehicle acceleration and generative braking are simulated by using Matlab/Simulink software. The numerical results show that the fuel cell vehicle will occur longitudinal vibration and impact with powertrain system torsional vibration if there is sudden electric motor torque variation when the vehicle is being accelerated or braked, and the gear backlash can cause gear impact and increase dynamical torque load. The research can explain the mechanism of fuel cell vehicle powertrain system oscillation and longitudinal vibration, and can be helpful for dynamic analysis and design of electric vehicle powertrain system.

Key words: Electrical powertrain system, Fuel cell vehicle, Longitudinal vibration and impact