Analytical assessment and overview of copper-coated secondary elements in linear induction motors as a rare-earth free motor option for transportation systems

Background In the context of the global transition to renewable energy sources, the development of technologies that remain sustainable throughout their entire life cycle and do not depend on critical materials has become particularly significant. In this regard, linear induction motors (LIM) are considered an alternative to permanent-magnet drives, which require rare-earth elements. Copper-coated solid secondary elements may improve LIM electromagnetic performance while maintaining a rare-earth-free design. Methods This study analyzes the feasibility of using copper-coated solid secondary elements to enhance LIM electromagnetic performance. A review of existing research on copper coating deposition, its properties and application to solid secondary elements is provided, with attention to cold gas dynamic spray deposition of copper onto iron. LIM parameters for a high-speed transportation system were calculated analytically using a corrected Γ-shaped equivalent circuit and the complex magnetic resistance approach. The characteristics of the conventional design were compared with those of versions employing copper-coated solid secondary elements. The copper-layer thickness varied from 0 to 0.002 m. Results The analysis demonstrates that the use of copper-coated solid secondary elements is a promising approach to improving the performance of LIMs without relying on rare-earth materials. Compared with the uncoated secondary element, thrust force decreased at a copper thickness of 0.0001 m and then increased with coating thickness. Favorable changes in operating slip, vehicle velocity, power factor and efficiency were also observed with increasing copper-layer thickness. Conclusions Copper-coated solid secondary elements show potential for improving the electromagnetic characteristics of LIMs without significant structural modifications. Further studies are needed to optimize the copper-layer thickness, evaluate thermal, mechanical and edge effects, and validate the results through experimental testing and FEM analysis. The proposed approach may support the development of reliable and environmentally sustainable rare-earth-free drive systems for transportation and industrial applications.