Evaluation of loss generated by edge- burrs in electrical steel

This thesis investigates the impact of edge burr faults on total power loss in electrical machine core laminations. Analytical techniques, experimental work and FEM modelling have been utilised to investigate the effect of the phenomenon from different aspects. Measurements of overall specific total loss and analytical techniques were used to separate the power loss components over wide magnetising frequency ranges. Two techniques were used in this project for edge burr simulation; these include (1) the short circuiting of two Epstein-size and three Epstein-size and large-size, non-oriented steel laminations by lead-free solder in the rolling and transverse directions and (2) the by clamping system method, which was designed for the application of edge burrs on toroid cores. Various sizes of artificial edge burrs were applied at set points and then in a random manner to confirm their effect and show the extent of their effect in different case scenarios and the tests were completely repeatable. 3-D FEM modelling for toroid cores was also used to study the impact of core geometry on the total core loss. This method provided a clear explanation for why smaller toroid cores have higher power loss than the larger ones. The research presented in this thesis can be utilised by electrical steel manufacturers and electrical machine designers to evaluate the impact of edge burr faults on the properties of magnetic cores. The evaluation is beneficial because it could reduce the risk of local overheating of laminated magnetic material, which can lead to destruction of such an electrical machine