Use of computerized magnetic field solutions in design optimization of turbogenerators

This paper details the use of computerized magnetic field solutions, based on magnetic vector potential, to optimize rotor slot asymmetries for minimum eddy current losses in strands of stator conductors of turbogenerators due to radial flux. This optimization results in minimum peaks of air gap flux densities and minimum densities in critically saturated parts of the rotor and stator. Loss and saturation reductions as high as 34% and 13%, respectively, were achieved. A 4-pole 659 MVA asymmetrical rotor turbogenerator and a 2-pole 733 MVA standard rotor turbogenerator were used to demonstrate the procedure and results of rotor optimizations. Useful rotor design optimization guide lines, computerized flux plots for the optimum asymmetrical rotors and experimental test results are given.