Integration of electromagnetic finite element models in a multibody simulation to evaluate vibrations in direct-drive generators

This paper introduces a novel electromechanical model for calculating electromagnetic excited structural vibrations and structure borne acoustics for gearless wind turbines. Therefore, the wind turbine model structure is explained and a drivetrain model is derived to investigate the drivetrain decoupled from the aerodynamic excitations. The drivetrain model is fed with results from an electromagnetic finite element model of the generator considering air gap width changes and the wind turbine torque and speed characteristics. Furthermore, an exemplary ramp-up of the drivetrain is simulated. It can be seen, that generator structure oscillations are excited during certain rotational speeds, which may be relevant for the acoustic behavior of the turbine.