A frequency-domain quantification of rotor harmonic and voltage fluctuation effects by electrical excitations

This study investigates this electro-mechanical coupling by establishing a dynamic vehicle model that explicitly incorporates electric-induced traction forces. The model is used to analyze the system’s vibration response, with a focus on excitations from the electrical drive. Simulation and experimental results under both traction and coasting conditions identify the 12th-order harmonic of the rotor fundamental frequency as a significant excitation source. This frequency component distinctly influences the vertical vibration of key bogie components, including the motor and gearbox. A key finding is that the vibration induced by this electrical harmonic persists, albeit with reduced amplitude, even after the power is cut off during coasting, demonstrating that it cannot dissipate instantaneously. Furthermore, the influence of track irregularity spectra is shown to amplify low-frequency vibrations, which can mask the prominence of the rotor-related frequency in the gearbox response. Additional simulations across a speed range of 10 to 80 km/h confirm that the vibrational effect of the 12th-order rotor harmonic exhibits a consistent relationship with velocity. These findings quantitatively demonstrate the profound impact of electrical parameters on the mechanical vibration of the bogie, providing crucial insights for optimizing the electro-mechanical coupling dynamics in modern rail vehicles.