Hybrid Wind Turbine Gearbox Design And Dynamic Response Analysi

The semi-direct-drive wind power turbine with low gear-ratio gearbox has advantages of small volume,high efficiency and low transportation and installation cost,so it has now become the third mainstream wind turbine.The traditional mechanical gearbox requires complex oil filling lubrication and cooling systems resulting in high failure rate and maintenance cost.Therefore,our research team proposed a hybrid two-stage speed-up wind power gearbox which is composed of a mechanical planetary gear and a coaxial magnetic gear(CMG)for semi-direct-drive wind turbines.This hybrid wind power gearbox combines the advantages of the mechanical planetary gear with high transmission torque,strong transmission stiffness and the CMG with non-contact,low-friction transmission.It can reduce the complexity of the gearbox oil filling lubrication and cooling system,while providing automatic overload protection for the generator,so as to reduce energy consumption of the gearbox,as well as the operation and maintenance costs,and improve the operation reliability of the system.The main work of this paper is to design a hybrid two-stage wind power gearbox and conduct dynamic analysis and research on its dynamic analysis as follows:First,the design requirements and performance indexes of the hybrid two-stage wind power gearbox for semi-direct-drive wind turbines are determined.The selection design of the mechanical planetary gear is completed according to the empirical formula and calculation examples.Second,the dynamic response of the designed planetary gear is analyzed using the lumped parameter method.At first,all components of planetary gear are regarded as composed of concentrated mass blocks and springs,and then Newton’s second law and Lagrange’s equation are used to establish the translation-torsional coupling dynamics model of the planetary gear.At last,the wind speed in nature is simulated using a two-parameter Weibull wind speed model.The fourth order Runge-Kutta method is used to obtain the numerical solution of the dynamic response of the planetary components under time-varying wind speed to verify the feasibility and rationality of the selection design.Third,the operating principle of CMG is deduced and analyzed.At first,the field domain inside CMG is divided,and the Maxwell equation representing its electromagnetic characteristics is written.By transforming it into Laplace equation and Poisson equation,the radial and tangential magnetic density distributions in the inner and outer air gaps are obtained with the help of boundary conditions,and then the magnetic torque of the coaxial magnetic gear is obtained by using Maxwell tensor formula.Fourth,the high-speed CMG in the wind power gearbox is optimized.At first,The one-dimensional magnetic circuit model is used to calculate the initial size of CMG.In order to improve the utilization efficiency of the material,the Halbach array is used,and the output torque performance of three kinds of CMG with the same size and different Halbach array magnetization is compared,accordingly,the optimal magnetization mode is selected.According to this optimal mode,the parametric scanning test is carried out through Ansys Maxwell,and the sensitivity analysis of the structural parameters of the CMG is implemented,then the pre-optimization variables are determined.BP neural network and genetic algorithm are combined to optimize the pre-optimization variables,and finally the size of each component of the CMG with the best performance is obtained.The torque output performance of the CMG before and after optimization is compared by finite element method to verify the effectiveness of the optimization design strategy.Finally,based on the optimized size of each component of the CMG,the dynamics model of the CMG is derived by using the lumped parameter method.The magnetic coupling stiffness of the inner rotor-modulator subsystem and the outer rotor-modulator subsystem in the CMG is obtained by using Ansys Maxwell.Runge-Kutta method is used to solve the numerical solutions of the dynamic responses of the components of CMG when the generator is in the steady state and three-phase short-circuit operation respectively to verify the feasibility and rationality of the transmission scheme.