Structure optimization of rotor supporting of permanent magnet direct drive synchronous generators for large wind turbine based on genetic algorithm and finite element method

As wind turbines increase their power rating, the size and mass grows as well. The higher reliability is demanded in order to minimize the maintenance. Permanent magnet direct drive (PMDD) synchronous generators are a good solution since they omit the gearbox. While the large generator mass has been also a key difficult problem limiting the practical use of PMDD generator, which makes them difficult to build, transport and install. In this paper, the rotor supporting structure of a 7MW PMDD generator is optimized by combining finite element method with genetic algorithm (GA) in order to improve the optimization efficiency. In this optimization function, it takes the minimum weight as the objective, the structure parameters of rotor supporting as the key design variables, and the deflection as the constraint condition. Comprehensive simulations and comparisons demonstrate that the method is very feasible and efficient, which could give good reference to the structural optimization in practice.