Electromechanical Dynamics Analysis of Pole-Piece Rotors in Pseudo Direct-Drive Wind Turbine Generators

This paper analyses the electromechanical dynamics of the pole-piece rotors in a pseudo direct-drive wind turbine generator. The investigated generator has a rated power of 10 MW and was designed in the INNWIND.EU project. One way coupled finite element analysis (FEA) was used to calculate the rotor dynamic defections caused by electromagnetic forces in the air gap. Results show that the deflection exceeds the air gap length which is not mechanically feasible. To solve the problem, three structural modifications are proposed and tested in FEA to reduce the pole piece deflection significantly. The results of the three solutions are compared to idenfity the most promising one. It shows that a ribbed rotor piece topology is the most suitable option because it achieves a reasonable tradeoff between the torque generation and mechanical deflection.