Dynamic analysis of planetary gears with gear crack of semi-direct drive wind turbine

With the increasingly severe of the energy and environmental problems, wind energy as a kind of clean and renewable energy has become more and more important. Semi-direct drive wind turbines have a good application potential due to their superior properties for wind power generation. As the key components, the planetary gearbox is commonly used in the wind generator, which sustains low speed, heavy load and transient conditions. The gearbox is easy to damage and difficult to maintenance because of the frequent disturbance under the random wind. Therefore, it is necessary to study the dynamic characteristics and failure mechanism of the gear transmission system under the condition of varying wind load. The dynamical model of the planetary gears with time-varying stiffness, tooth root crack and transmission error is established by using lumped mass method. The actual wind speed is simulated by Least squares support vector machine model, and the input torque load is also obtained. Considering the varying wind load and parameter excitations of system, the dynamic response of the PGT is calculated by numerical method. The dynamic responses of the transmission system such as vibration displacement of each gear, as well as dynamic meshing force of each pair of gear are investigated. Furthermore, the influence of tooth crack on dynamic response is carried out to find out the mapping relation between the gear failure and system vibration. The research results lay a foundation for vibration control and fault diagnosis of planetary gear transmission system of wind generator.