Investigation on planetary gearbox fault mechanism under variable speed conditions based on rigid-flexible coupling dynamics model

Dynamic behaviors of wind turbine planetary gears are greatly affected by the transfer paths and variable conditions. However, previous studies have mainly considered single transfer path and stationary operating conditions. To overcome this problem, a rigid-flexible coupling dynamics model of wind turbine planetary gearbox under different transfer paths and variable conditions is established. By simulating the modal-based rigid-flexible coupling dynamics model, the gearbox output shaft speed as well as the box vibration response in the stationary condition are obtained well, which can be characterized by its frequency features. By conducting order envelope analysis on the simulated acceleration signals in the variable speed condition, the feature order in the sun gear fault state is obtained on the simulated acceleration signal. The planetary gearbox dynamics tests results are in good agreement with the simulation results. The experiment results verify the correctness of the established rigid-flexible coupling dynamics model. This modeling method provides a new idea for multi-path modeling of wind turbine gearboxes and the study of fault mechanism under variable speed conditions.