Analysis of Dynamic Characteristics and Load Sharing Performance of Electric Driven Planetary Gear System Based on Electromechanical Coupling Model

Due to the multi-gear configuration and high integration of electric drive systems in electric vehicles, it is necessary to investigate the influence of drive motor torque fluctuation on the dynamic characteristics and load sharing performance of planetary gear transmission systems. Considering both motor torque fluctuation and internal excitations of the transmission system, a dynamic model of the electromechanical coupled system is established by combining the Maxwell motor electromagnetic model with the planetary gear dynamics model. Based on the proposed model, the dynamic characteristics, dynamic load performance and load sharing performance of the system considering motor torque fluctuation are analyzed, and the improvement of system load sharing performance due to sun gear floating is discussed. The results show that motor torque fluctuation leads to more complex dynamic response and causes the vibration displacement amplitude to more than doubled. Furthermore, the system exhibits an increased presence of high-frequency components in its vibration frequency spectrum. Under the conditions of eccentricity error only and both installation error and eccentricity error, motor torque fluctuation increases the load sharing coefficient of the planetary gear system by more than 11.5% and the dynamic load coefficient by more than 76%. The backlash float mechanism can improve the load sharing performance of the system by approximately 3% for both internal and external meshing pairs, but with limited effectiveness. Additionally, when the float amount reaches 5μm, the system’s load sharing performance will no longer show further improvement. This research work provides valuable insights for the optimization design of shock and noise reduction in electric-driven planetary gear systems