Abstract: Due to the random characteristics of wind speed， the transmission system in wind turbine gearbox would produce complex vibration， which can cause internal structure fatigue of the drive system. In order to analyze the performance of the gearbox， the wind turbine gearbox system was divided into threeclass gear transmission， and the dynamical models of spur gear， helical gear and planetary gear were built. On this basis， the dynamical model of the whole wind turbine gearbox system was established. The vibration differential equations of the drive system were derived through the Lagrange’s equation， considering the meshing stiffness， meshing damping， comprehensive meshing error， eccentricity， gravity， bendingtorsional coupling and support bearing. The model provides some theoretical reference for the characteristic analysis and vibration control of similar wind turbine gearbox system.

Key words: wind turbine, gearbox, gear system, coupling vibration, dynamical model