Advanced numerical Methods for accelerating Calculation of Eddy Current Loss in Roebel-Bars in Turbogenerator End-Regions

Determination of eddy current loss in conductors is of high relevance for the design of electrical machines. This article introduces, discusses, and benchmarks different approaches to accelerate the calculation process of eddy current loss in Roebel-bars influenced by magnetic air gap and stray fields in a turbogenerator's end-region. The seven different approaches presented range from comprehensive transient three-dimensional finite-element models to simplified semi-analytical two-dimensional approximations requiring only one magnetostatic computation. For the first time, this eddy current phenomenon in stator bars is simulated in a comprehensive finite-element model with time integration. Due to the high accuracy achieved, a classification of further novel and established approaches to calculate eddy current loss can be made in terms of correctness and computation time. All methods discussed can also be employed in other fields of application, especially to those eddy current problems which are subject to different geometrical scales.