Dynamic Characteristics Of Planetary Gear Transmission System Of Wind Tuibine Under Time-varying Speed Conditions

In wind turbines,the planetary gear train is an important part of the speed increasing gear box.Due to irregular wind field and frequent start and stop during normal operation,the system's working load and speed are time-varying.The resulting vibrational response has complex non-stationary impact characteristics.The research results of traditional planetary gear train powertrain dynamics cannot be applied directly.Therefore,the dynamic characteristics of wind turbine planetary gearset under variable speed are studied based on the finite element method and dynamic modeling method.The main work contents are as follows:1.A three-dimensional solid model was established.The finite element analysis software ABAQUS was used to analyze the dynamics of the planetary gear train.The change of the gear tooth surface contact stress under uniform speed conditions and three variable speed conditions was studied.It was found that the surface contact stress of the gear meshing changes periodically and the tooth surface contact stress is affected by the change of the gear speed.Under accelerated conditions,the contact stress of the larger gear surface is generally larger,and the meshing force at the time of deceleration is smaller and the contact stress at the surface is smaller.The maximum contact stress value in the meshing process under the impact of impact load at variable speed is the largest among the four working conditions.2.A time-varying meshing stiffness calculation method based on finite element is proposed.The accuracy of the method is verified by comparing with the calculation results of the same parameters with the Ishikawa method.Further study on the effect of speed change on meshing time-varying stiffness under three conditions of uniform acceleration,uniform deceleration,and variable acceleration,and found that the magnitude of the force at the meshing point has a certain influence on the time-varying stiffness of meshing in the single tooth meshing region.While the time-varying meshing stiffness of the double-tooth meshing area is less affected by the magnitude of the meshing force in the force balance state,the impact of the external force in the non-equilibrium state alternately occurs between the single tooth and the double tooth.3.Considering the factors such as time-varying meshing stiffness,damping and contact clearance,the planetary gear train dynamic model was established according to the lumped parameter method,and the Runge-Kutta method was used to solve the differential equation to obtain the planet carrier,the sun gear,and the three planetary wheels.The horizontal and vertical vibration displacements and vibration speeds can be found by comparing the amplitude of the circumferential vibration with both the horizontal and vertical vibration amplitudes.The vertical vibration amplitude isgreater than the horizontal vibration amplitude.4.Comparing the above planetary gear train vibration response results with the data corresponding to the experimental measuring points,and further verifying the accuracy of the planetary gear train dynamics model.Through the analysis of the dynamic response of the planetary gear train under variable speed conditions,it was found that the increase in the vibration amplitude of the rotation increases,which reflects that the vibration increases with the increase of the speed of the planetary gear train during the acceleration conditions.