Influence of material electromagnetic properties on HTS Linear Induction Motor used in rail transit

Secondary Eddy loss accounts for over 80% of the total loss of High-Temperature Superconducting (HTS) Linear Induction Motor (LIM) used in rail transit system, it is therefore of great significance to investigate the influence of the material electromagnetic properties on HTS LIM. In the paper, a newly proposed copper-iron (Cu-Fe) alloy is utilized to develop the secondary of HTS LIM. The four schemes of material electromagnetic properties are set up to comparatively analyze the electromagnetic distribution and performances of HTS LIM. The four schemes are aluminum reaction sheet-iron back iron, aluminum reaction sheet-steel No. 45 back iron, 16% Cu-Fe alloy (16% copper in weight) secondary, and 20% Cu-Fe alloy (20% copper in weight) secondary, respectively. Firstly, the electrical and magnetic properties of the main materials used in HTS LIM are investigated by experiments, respectively. And then three-dimensional transient (3-D) time-stepping finite element model of HTS LIM is established and the boundary conditions are given. The experimental results, carried out on the developed 3.5kW HTS LIM prototype, are shown to validate the accuracy of the established 3-D finite element model. The electromagnetic field and eddy current field distributions are studied by the established 3-D finite element model. The flux density around the HTS coils is also studied. On the basis of the field analysis, performances such as RMS phase current, thrust, power factor, etc. of the machine with the four secondary material schemes under different slips are investigated.