Dynamic characteristics of a wind turbine gearbox with amplitude modulation and gravity effect: Theoretical and experimental investigation

Amplitude modulation (AM) in planetary gears, arising from rotation of carrier, is a predominant phenomenon that yields unique yet complicated dynamic behavior. However, the effect of gravity of planetary gear components contributes additional frequency components in the modulation sidebands. In this paper, an extensive experimental investigation is performed to obtain the frequency components of the test rig having the configuration of a modern wind turbine gearbox. The experimental results present some new insight into the combined effect of AM and gravity. A dynamic model of a wind turbine gearbox (WTG) having a two-stage planetary gear set is developed to predict the dynamic response as observed in the experiment. The AM effect due to carrier rotation and the effect of gravity is implemented in the dynamic model. Frequency response and order analysis are carried out for the simulated and experimental signals. It is observed from the comparison of simulation and experimental results that the developed model is capable of correctly describing the dynamic characteristics of the WTG. These results help to understand the complex vibration response of multi-stage planetary gears in a WTG.