Electromagnetic design optimization of single-sided linear induction motor for improved drive performance based on linear metro application

Single-sided linear induction motors (SLIMs) have been increasingly developed in industries in the past ten years, especially in transportation systems. This is basically due to their merits of direct thrust, high acceleration and deceleration, less mechanical loss, etc. However, for the SLIMs special physical structure, including the cut-open magnetic circuit, different width between primary and secondary (along the axial direction), they suffer from longitudinal end-effect and transversal edge-effect, which would make their mutual inductance and secondary equivalent resistance change unregularly, and hence increase the complexity of their equivalent circuit model (ECM). Meanwhile, for the influence by skin effect resulted from the secondary eddy current, the resistance of secondary back-iron, etc., the SLIMs are inherited by seriously partial electromagnetic saturation or nonlinear effect particularly in large current excitation condition, and their accurate ECM are difficult to get, which might bring great difficulty to their electromagnetic design and performance analysis. In this paper, first, one improved ECM that fully considers longitudinal end-effect, transversal edge-effect, skin effect and electromagnetic saturation of secondary sheet back-iron, is presented. Second, the influence of different structure parameters on SLIM key drive indexes, e.g. thrust, efficiency and power factor, is analyzed. Third, a multi-objective optimization function is established based on genetic algorithm (GA), which aims to increase the efficiency, power factor and thrust as well as to reduce primary weight simultaneously.