Brushless doubly fed generator (BDFG) has a broad application prospect in variable speed constant frequency offshore wind power generation system, in recent years, MW-class generators for offshore wind turbine has been becoming the hot-spot of research. Due to the large volume of MW-class generators, if the solid rotor is used, there will be some difficulties in the process of transportation and installation. In order to reduce the rotor weight, in this paper, three rotors used for BDFG, which are consist of rotor spider, magnetic separation layer and magnetic barrier part, are designed, and the web number of three rotor spiders are 3, 4 and 5 respectively. The idle state and rated operation condition of the three rotors are simulated by FEA, according to analyzing the simulation results, it can be known that at the idle state and rated operation condition, the maximum stress is mainly distributed on the junction between support ribs and shaft, and its value is far less than the allowable stress value of materials, the maximum deformation is distributed on the outer edge, and can meet the operation requirement of the generator. Comparing the maximum deformation, it can be seen that the maximum deformation of the rotor with four webs is smaller than that of the rotor with three webs by 20.62%, and the maximum deformation of the rotor with five webs is smaller than that of the rotor with four webs by 15.62%, through comprehensive consideration, the rotor with four webs is selected. Finally, the super-synchronous and sub-synchronous operation conditions of the selected rotor are simulated, the maximum stress and deformation are all within the range of the allowable values, the reliability of the designed rotor is further verified.
The work is supported by Key Project of National Natural Science Foundation of China (51537007).