This thesis investigates the influence of different lamination materials along with rotor pole geometry on the performance of a Wound Field Synchronous Machine. Both Non-Oriented (NO) and Grain-Oriented (GO) laminations are analyzed with the original and modified rotor structure to recognize how generator operation is affected. In the first part of this work, the state-of-the-art of NO and GO steel sheets is examined and nine materials from different manufacturers are selected on the basis of their permeability and power loss figure. Due to an incomplete characterization of the selected materials, i.e., low field measurements of magnetization curves, several methods for extrapolation to high field values are evaluated.