Analyzing the impact of press plate structure on the flux and loss distributions in the end region of large generators by transient 3-dimensional finite-element method with an improved core loss model

The strong leakage magnetic flux in the end region of large synchronous generators results in significant eddy currents in the end components which can possibly lead to overheating thus threatening the safe operation of large generators and is an essential issue at the design stage. The press plate is a major end component of large generators that fastens the stator end-core packets and shields the stator core back-iron from the intensive leakage flux. This paper describes a transient 3-dimensional (3D) finite-element analysis (FEA) based approach to calculate the magnetic field and loss distributions in the end region of large generators, and incorporates an enhanced laminated core model combining the impacts of anisotropic and nonlinear material properties, hysteresis effects, and the reaction of induced in-plane eddy currents on the magnetic field and loss distributions in the stator core. The method is validated by the agreement between the temperatures predicted by a 3D thermal FEA and the measured results. Then, the influences of different material properties and dimensions of the press plate on the magnetic flux and loss distributions in the end region are evaluated by the proposed 3D FEA.