| In the past decade,it has become the consensus of governments and people around the world to reduce emissions of carbon dioxide and other greenhouse gases and prevent global average temperature from rising.As a responsible country in the world,China has shouldered great responsibilities and obligations in this major battle of energy conservation and emission reduction.It is under the current background that China has continuously intensified energy conservation and emission reduction efforts in recent years to accelerate the development of new and renewable energy.Wind power industry in China started late,although through digesting and absorbing foreign technology introduction,have been able to independently design and manufacture for mw wind turbines,but 10 mw level of large scale wind power generating set is still in development,also need to be assiduous research,further enhance the independent innovation ability,solve the large sea wind power generator set research and development challenges.In response to the national manufacturing strategy of "made in China 2025",this paper makes an in-depth study and summary of the modeling and calculation methods of large permanent magnet direct drive wheel hubs,which can effectively guide the design.Thus,it avoids the blind spot caused by the limitation of conventional design methods and ensures the reliability and stability of products.The accurate simulation of the running state of the wheel hub of the permanent magnet direct drive wind generator is faced with three major problems: 1)the contact nonlinearity of the ball roller of the variable propeller bearing is strong;2)accurate transmission path simulation of blade load;3)the three fan blades contain a lot of load conditions.In order to accurately simulate the working state of the bearing ball roller and gear,this paper studies its simplification and modeling method in detail.As for the bearing ball roller,the contact nonlinearity of the bearing ball roller is simulated by using the three-dimensional rod element which is only subjected to tension but not compression,equivalent to the stiffness of the ball roller.In this paper,according to the real deformation and force characteristics of gear meshing in the variable rotor motor,it is equivalent to a radial force and tangential force,which can accurately show the real situation of gear meshing in the variable rotor motor.In order to accurately simulate the actual load of the blade subjected to the hub,this paper took into account all the load conditions in the actual service period of the three blades through statistical analysis of the distribution law of the load,keeping the height consistent with the actual operation state of the hub.On the basis of successfully solving the three difficulties mentioned above,the stiffness and fatigue life of large permanent magnet direct drive wheel hub were further analyzed numerically,the hub strength was checked and the fatigue strength of the wheel hub was evaluated.The finite element calculation model of the wheel hub is checked to ensure that the load and constraint conditions are reliable,the mesh density is sufficient,and the calculation results are accurate and reliable.The model has been mass produced more than 1000,since the installation and operation of the unit,the wheel hub has not occurred any fault,proving the rationality of the finite element calculation method of the wheel hub in this paper and the reliability of the results. |
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