Fast Calculation of the Magnetic Field and Loss Distributions in the Stator Core End Packets and Finger Plates of Large Synchronous Generators

The significant eddy current losses in the stator core end packets and finger plates of large synchronous generators due to the end leakage fluxes may lead to partial overheating and predicting the relevant loss distributions is crucial for their design. Compared to the accurate but extremely time-consuming three-dimensional (3D) finite-element analysis (FEA), quasi-3D simulations can provide acceptable solutions of the magnetic field in the generator end region within a short period of time and is thus a proper tool at the initial design stage. This paper proposes a method to estimate the eddy current distributions in the stator end core and finger plates based on a novel quasi-3D finite-difference (FD) scheme. To compensate the errors caused by the inherent assumption of classical quasi-3D formulation that the geometries of end components are peripherally consistent, regional conformal mappings based on Schwarz-Christoffel transformation are adopted to incorporate the impacts of the cross flux caused by the local armature windings and slot/tooth geometry. The corresponding 3D FEAs, which are verified by the agreement between their results and the measured temperatures, are used as the benchmark for this study. The proposed method is validated by the agreement between the results generated by the proposed fast method and 3D FEAs.