Analysis of a Novel Stator Construction Employing Steel Wire in Place of Laminations

Abstract

This paper examines a novel method of constructing large diameter generators using many layers of steel wire in place of laminations. The stator coreback is formed by winding thin steel wire around the outside of the armature coils and then encapsulating the structure in epoxy. This technique simplifies the manufacturing process by removing the requirement to build a large support structure to carry the laminations. The electromagnetic behavior of a wire coreback is very different from traditional laminations, however, and produces abrupt changes in flux density across its thickness. The material is difficult to model using conventional FEA techniques due to the large number of elements required to mesh the small diameter wire. This paper examines two alternative modeling approaches. Method 1 uses two-dimensional (2-D) FEA to model the steel wire as a lamination oriented in the “wrong” direction. Method 2 uses a quasi-analytic approach based on detailed 3-D FE analysis of a small section of the generator to capture the flux density profile in the airgap. The two models are benchmarked against a prototype generator tested in the laboratory, and it is shown that the quasi-analytical technique gives the most accurate prediction of performance.