Study on nonlinear vibration frequency response and characteristics analysis of EHT system under high-speed and heavy-duty conditions

With the continuous advancement of vehicle electromechanical hybrid transmission (EHT) systems toward high-speed and high-power-density operation, nonlinear vibration induced by multi-source excitations, such as gear meshing has become increasingly pronounced. To elucidate the causes of intensified nonlinear vibration in EHT systems under high-speed and heavy-duty conditions, a comprehensive approach involving semi-analytical solutions, bifurcation characteristic analysis, numerical simulation and experimental verification was adopted to study the nonlinear vibration characteristics. Firstly, we derived a semi-analytical solution for nonlinear vibrations in the EHT system using the multi-scale method, and investigates the frequency response characteristics and parameter influence mechanisms of the system’s nonlinear vibrations. Subsequently, by employing analytical tools such as bifurcation diagrams, Poincare maps, and phase plot, the effects of motor speed and load torque on bifurcation characteristics and the routes to chaos are examined. Thirdly, numerical simulations under variable speed and load conditions are conducted to analyze the time-varying meshing force, dynamic load factor, and vibration acceleration characteristics. Finally, a dynamics experiment is also implemented to verify the nonlinear vibration characteristics. The results identify specific issues and key influencing factors of nonlinear vibrations under high-speed and heavy-duty conditions, thereby clarifying directions for dynamics optimization design.