Dynamics Research Of Wind Turbine Gearbox With Flexible Planet Gear Pins

The research subject of the dissertation stems from the projects “The study of keytechnologies of high-speed heavy-duty precise transmission”(2006BAF01B07-02) and“The study of Key technologies of industrialization for7MW wind turbine gearbox andspindle bearing”(2012BAA01B05) in the National Science and Technology PillarProgram during the11th Five-Year Plan period of China and the12th Five-Year Planperiod of China, respectively.Currently, the development of wind turbine technology is towards the single-stageand high-power wind-driven equipment. Correspondingly, higher-power gearbox has anincreasing demand. However, rigid-design type gearbox goes against load sharing ofplanets, and, it also has a higher requirement in design, manufacture and assembly. As aresult, it has become an important trend to increase flexibility in gearbox design. In thetraditional design, the floating sun gears or carrier have gradually failed to meet therequirements of the design of higher-power wind turbine gearbox while the load sharingtechnology of cantilever flexible pin used together with planet gears is an effective wayto solve this problem. Moreover, in order to increase power density, the number ofplanet gears will be increased, which can be restricted by the straddle planet pin incarrier. Instead, the cantilever-type flexible pin in carrier can increase the number ofplanet gears without more space requirements in carrier structure. Consequently, thisstructure has inherent advantage in increasing the number of planet gears and adjustingphase angles. However, the lack of researches on dynamics of planetary transmissionsystem with flexible pins leads to the difficulty in the design of this kind of gearbox. Forabove-mentioned, based on the dynamic research method combining withcharacteristics of structure with floating sun gears and flexible pins, the influence of pindesign parameters, dynamic load sharing, coupling characteristics, dynamic responsecharacteristics were investigated. For design optimization of transmission system withflexible pin and development of much higher power wind turbine gearbox, it has boththeoretical and project practical significance. The main contents of this dissertation areshown as follows:①The dynamic model of wind turbine planetary gear system with multi floatingcomponents was built. According to this model, the research on dynamic load sharingwas conducted. Based on energy method, equations of pin stiffness and meshing stiffness as well as time-varying equations of mesh stiffness and mesh phasing with pinerror were analyzed.②The research on influences of pins errors and gear errors on planet gear dynamicload sharing was conducted. Based on excitation characteristics of pin position error andrunout error, and combined with pin stiffness, input load and practically common errorsconfiguration, influences of these two type of errors on planet gear dynamic loadsharing were analyzed.③On the basis of boundary coordination conditions, the dynamic model ofwind-generator gearbox transmission system with flexible pins was built and researcheson modal identification, modal strain energy and dynamic response were conducted.Taking advantage of coupled dynamic model, five kinds of model characteristicsexisting in transmission system were summarized, analyzing the differences betweensingle-stage model and coupled model as well as the influence of pin stiffness on modalfrequencies. According to the distribution law of modal strain energy, the peak featureof dynamic response and the further research on the influence of design parameters ondynamic response were analyzed.④Based on dynamic theory and coupled boundary condition, the coupled methodbetween transmission system and gearbox body was proposed. On the strength of thismodel, a nonlinear dynamic model including flexible box-supporting, gear contact lossand bearing gap was derived. Researches on system-inherent characteristics, dynamicresponse and non-linear characteristics were conducted. Together with the FiniteElement Method, gearbox vibration condition was calculated.⑤The experimental studies on the comparison of planet gear dynamic loaddistribution characteristics with different loads were performed through the loaded testfor wind turbine gearbox with flexible pin structure on the professional test setup. Thedynamic characteristics of the gearbox system was also performed. The experimentalresults compared well with the theoretical dynamic results, verifying the theoreticalmethod.