Modeling and dynamic characteristics analysis of the locomotive considering the electric transmission system

The electromechanical transmission system is essential for locomotive functionality, as it regulates the output torque from the traction motor and transfers it to the wheel-rail interface for traction or braking. However, existing locomotive dynamics research often neglects the influence of the electric transmission system on critical components, such as the traction motor, supporting bearing, gear transmission system, and wheel-rail interface. This study seeks to fill this gap. We present a spatial locomotive-track dynamics model that includes the entire electromechanical transmission path. This model encompasses the electric transmission system, traction motor, motor bearing, and mechanical transmission system. By integrating the dynamics model with the electromechanical transmission system, we investigate the overall dynamic performance of both mechanical and electrical systems. This analysis considers external excitations from wheel-rail contact and internal excitations from the gear mesh and electromagnetic coupling interfaces. To validate the dynamic responses of the locomotive electromechanical system under actual tractive conditions, we compare simulation results with data collected from field tests. Theoretical findings highlight the significant effects of the electric transmission system and its control on gear mesh force, motor bearing roller-race contact force, and wheel-rail creep force. Notably, incorporating the electric transmission system for rotor speed stabilization contributes to a reduction in friction force between the motor bearing roller and race. This research enhances our understanding of the complex interaction between the electromechanical transmission system and locomotive dynamics.