Defining proper initial geometry of an 8 MW liquid-cooled direct-drive permanent magnet synchronous generator for wind turbine applications based on minimizing mass

The minimum mass of the active materials needed to build an 8 MW liquid-cooled direct-drive permanent-magnet synchronous generator (LC DD-PMSG) is sought. Proper set of generator dimensions is defined based on a constrained steepest descent method with variable step size. The design variables have been defined in terms of two quantities: stator length and the ratio of induced voltage to rated voltage (EMF factor).