Research On Load Characteristics Of Small-sized Maglev Wind Turbine

Development of wind power is the need of China’s energy strategy. As a flexible and convenient power generation method, the small-sized wind turbine can find vaster development space in rural fields and urban tall buildings. Magnetic bearings have the characteristics of no contact, no friction and no wear. Replacing the traditional mechanical bearings in small-sized wind turbine with magnetic bearings can decrease the start-up resistance moment, reduce the start-up wind speed and improve the efficiency of power generation. However, the spindle bearings in wind turbines need to bear complex load changes, not only the static loads, such as the weight of the impeller and the spindle, but also the dynamic loads caused by rotation of the spindle and wind loads. While wind turbines are working, the direction and speed of wind change a lot, the dynamic and static loads are large, and the dynamic loads change frequently. Therefore, the load characteristics of the wind turbine need to be researched.Taking a small-sized horizontal axis wind turbine as the research object, this paper researched the load characteristics of wind turbine and its effect on the spindle bearing structure. The bearing part and whole structure were optimized and designed as well. The main research works of the paper are showing as follows:(1)Based on the blade element and momentum theory, the theoretical calculation method for the aerodynamic loads of the impeller in wind turbine was derived, including axial thrust and rotary moment. Moreover, the calculation steps of the aerodynamic loads were summarized.(2)The aerodynamic performance of wind turbine was simulated using Computational Fluid Dynamics(CFD) method. The aerodynamic loads of the impeller under different conditions, such as normal operation, yaw and shutdown, were calculated as well. Then, the aerodynamic loads were equivalently acted on the spindle of wind turbine. Furthermore, the bearing capacity of the spindle bearings was calculated according to the balance relationship of forces.(3)The effect of the load characteristics in wind turbine on the spindle bearing structure was researched. According to the results of loads calculation, the spindle magnetic bearing was optimized and designed from the aspects of structure form, technical parameters and so on. What’s more, the whole structure of the small-sized maglev wind turbine was designed.(4)A set of tooling structure was designed for the assembling of radial permanent magnetic bearing. On this basis, an experimental prototype of the small-sized maglev wind turbine was manufactured. In addition, the scheme of load measurement for the small-sized maglev wind turbine was established.The research work in the paper can provide evidence for the bearing capacity calculation of the magnetic bearing in wind turbine. Moreover, it can also lay some foundation for the application and extension of magnetic bearing in wind turbine.