Critical Speed and Unbalance Response of the Locomotive Motor Rotor

Background: Due to the harsh working condition of the locomotive traction motor rotor, two common faults prevail, resonance and unbalance vibration, which might cause instability and even serious accidents. Objective: The research results of calculating critical speed and analyzing unbalance response are references for dynamic design of the locomotive traction motor. Method: Certain methods are adopted: modeling of rotor for a locomotive traction motor, calculation of critical speed, influence of support stiffness and analysis of unbalance response are studied. Firstly, the rotor model is established based on the lumped mass method. Then, the critical speed is obtained using Riccati transfer matrix method, and the influence of support stiffness on critical speed is also discussed. Finally, the unbalance response is analyzed to evaluate the accuracy and feasibility of the adopted method in the calculation of the critical speed. Results: It is shown that the working speed is far lower from critical speed margin and the validity of the solution is verified by analyzing unbalance response and by comparing different calculation methods of the critical speed. Conclusion: Recent study of patent product on critical speed and unbalance response is investigated to illustrate the method. An analysis of the reviewed patents allows conclusion of the expected future developments in this domain.