Structural comparison of permanent magnet direct drive generator topologies for 5MW wind turbines

Direct drive electrical generators offer a reliable alternative to conventional induction machines since they omit the gearbox from the drivetrain. Their large structural mass though makes them difficult to manufacture, transfer and assembly. Topologies other than the conventional iron-cored have been suggested in literature to minimise this attribute. This paper will investigate the structural stiffness of three different permanent magnet direct drive generator topologies against static forces that apply to such wind turbine generators. Finite element analysis (FEA) models of all tested generators were developed. Results from the structural analysis will be used to draw valuable conclusions.