Research On Dynamics Of Locomotive Driving System With Wheelset Quill Shaft And Bogie-Mounted Motor

The driving system is an essential component in a locomotive. The driving systems can convert mechanical energy into electrical energy and drive the locomotive. The structural design and dynamics of the driving system have become an important part of the bogie design and locomotive dynamics. Further more, the main parts of the driving system are installed at the bottom of the locomotive, they will sustain the powerful strike of the rail/wheel force while they export power. So the operating conditions of the driving system are very servere, and the conditions will get worse and the vibration of the driving system will deteriorate with the increase of the railway vehicle speed. All these will have a negative impact on the dynamic performance of the driving system and the locomotive. In order to ensure the reliability and safety of the locomotive, it is necessary and important to make an intensive study on the dynamics of the driving system.In this dissertation, the driving system of the locomotive is defined as an electromechanical coupling system including the traction motor, the wheelset, the suspension of driving equipment and the constructs of a drive system, which consider the interaction between the wheel and the rail. The work in this dissertation focuses on the driving system of locomotive with wheelset quill shaft and bogie-mounted motor. This thesis briefly reviews the history and the current situation of the structure and dynamics of the driving system. Based on these studies, this document proposes that there are self-excited vibrations in the driving system, and proves the existence of the self-excited vibrations through two aspects: one is caused by the speed feedback in the driving system (self-excited torsional vibration of locomotive drive system); another is caused by electro-mechanical coupling effects (harmonic torques of asynchronous traction motor).In railways, the adhesion force between the wheel and the track is the ultimate motivation force which drives the train forward. But because of the attenuation characteristics of the adhesion coefficient, the self-excited torsional vibration will occur when the slip velocity reaches a greater value. In order to investigate the self-excited torsional vibration of locomotive driving system, a single wheelset model is built and the mechanism of the vibration is analyzed. The investigation results indicate that the self-excited torsional vibration will occur when the initial slip velocity is located at the descending slope of the adhesion coefficient curve, and it appears in the form of stick-slip vibration.For the purpose of investigating the interrelation and interference between the locomotive dynamics and the driving system self-excited torsional vibration, a locomotive and slab track vertical coupled dynamics model is established in this dissertation based on the vehicle-track coupled dynamics and the principle of total potential energy with stationary value in elastic system dynamics. Dynamics equations are set up, a MATLAB program is applied to simulate the parameters and dynamics of the self-excited torsional vibration. The simulation results indicate that the self-excited torsional vibration has effect on dynamic performances of locomotive, especially on vertical dynamics. So it is essential to consider these effects when investigate locomotive dynamics.The driving system of the locomotive is an electromechanical coupling system. The traction torque of asynchronous traction motor includes harmonic torques. Due to the harmonic torques, rotational speed pulsation will be presented in the traction asynchronous motor, which will affect the locomotive dynamics. Firstly, this dissertation analyzs the harmonic torque of traction asynchronous motor and proposes the calculation expressions for harmonic torques. Secondly, this paper studies the frequencies of the harmonic torques and establishes a complete dynamics model of locomotive. Lastly, a simulation program is provided and the tangent dynamics and curve negotiating dynamics of locomotive are simulated.Considering that the bogie-mounted motor is massively applied in China, it is essential to use the elastic bogie-mounted suspensions instead of the rigid suspensions to meet the requirements of the new 200km/h locomotive. In order to investigate the dynamics of the locomotive with elastic bogie-mounted motor, a complete dynamics model of locomotive is established. The dynamics of elastic bogie-mounted suspension locomotive are simulated and compared with the tradition locomotive with rigid bogie-mounted motor. The key parameters of the elastic suspension and the feasibility of using the 3-points full elastic bogie-mounted driving equipment are also analyzed in this dissertation.