Lightweight design of rotor supporting structure of large PM wind generator based on response surface model

As wind turbines increase their power rating, their size and mass increase as well. Therefore, the higher reliability is needed in order to minimize maintenance. Direct-drive PM (DDPM) generators are a good solution to this problem because they omit the gearbox. The large generator mass has been also a difficult problem limiting the practical use of DDPM generators, which makes them difficult to build, transport and install. In this paper, a rotor supporting a 7MW DDPM generators is optimized by a response surface model (RSM). The dimensions that greatly influence the stiffness are taken as optimized design variables. Minimizing the mass is taken as the optimized objective, and the stiffness demands are taken as constraint conditions. The simulations show that the required level of stiffness can be met while reducing the mass by 11000 kg (34%) and the optimization results show the validity of the optimization method for the lightweight design of structures.