Dynamics Of Gear Trains In A Class Of Wind Turbine

With the rapid development of wind power generation, nowadays the MW level wind turbine has become the mainstream products in Chinese wind power market. As one of the key components of wind turbines, the main gear box must possess good dynamic performance to meet the requirements of high reliability and long durability. Therefore, the investigation and profound understanding on the dynamics of gear train set in wind turbine is of great importance in the stage of system design. In this thesis, a gear box containing two stages of planetary gear trains and a parallel shaft gear train in a 1.5MW wind turbine is taken as example system and its dynamic characteristics are analyzed. The research covers the following contents:A lumped-parameter dynamic model of the three-stage gear box is proposed based on the description of the system construction. The proposed model considers both transversal and torsional deflections of each component in the transmission system. By analyzing the relative displacements between each components, the motion equations of the system are derived. Meanwhile, the calculations for time-varying mesh stiffness, gear profile errors, external excitations and connection stiffness are introduced in details.The natural frequencies and corresponding mode shapes of the gear transmission system are predicted by conducting the modal analysis. The mode shapes of the system are classified as the following three categories: translation mode for single planetary, rotational mode for three stages and parallel shaft gear mode. The characteristics of each kind of mode are described and the effect of stiffness on modal properties is analyzed.The dynamic responses of the system are obtained by using the harmonic balance method. The displacements of the gearing system with input excitation, load excitation and internal excitation are explored and their relationships are demonstrated. After that, the utilization coefficient and dynamic load coefficient of each gear pair can be calculated for further design. Finally, the effects of some factors such as teeth number, sun floating and gear inertias on system dynamics are analyzed.