3-D Finite Element Method Analysis of Additional Load Losses in the End Region of Permanent-Magnet Generators

Machine design typically concentrates on the main magnetic and electric circuits while various additional losses are evaluated only by simple empirical equations. The objective of this paper is to examine the importance of the additional losses in the stator end region and in the housing of a 3.1 MW permanent-magnet wind generator. Stator stack clamping ring and finger plate losses are investigated using a 3-D finite element method. 2-D FEM analysis of the stator supporting housing losses is also performed. Two common mechanical component materials are analyzed in the 3-D studies; construction steel and stainless steel. The results show that failure to consider stator end areas and stator supporting constructions at the design stage can result in unwanted additional losses and affect machine efficiency. Indirect verification of the results is provided by efficiency measurements of different versions of the real 3.1 MW machine.