Fabrication of Insulation Coatings on Additively Manufactured CuCrZr Electrical Windings

Abstract

To lower the AC losses in electrical machines, additive manufacturing (AM) has been adopted to exploit the geometrical freedom in winding design. However, AM brings about new challenges such as surface roughness and porosity which can create difficulties for post processing of the windings such as applying insulation coatings. The paper investigates the influence of surface roughness (profile) of AM-processed CuCrZr as a potential candidate for electrical windings in terms of geometry, surface roughness, porosity, and oxidation on their insulation. The feasibility and characteristics of insulations applied via three processing techniques namely powder, spray and dip coating are compared. The entire process is quantified via techniques such as computed tomography, surface profilometry, optical microscopy, X-ray photon spectroscopy and breakdown voltage at different stages of the coating process. The study also includes coating on a commercial rectangular copper wire as a reference. The initial assessment of coatings concludes that surface roughness and the coating process are both vital determinants for the success of insulating AM components. Basic surface smoothening is needed to get rid of burs and spray coating technique was the best among others for its capability to produce conformal coating.