Numerical Modeling and Transient Analysis of a Linear Induction Motor With Close-Ended Coated Superconductor Coils as Secondary

We devised a linear induction motor (LIM) that uses the close-ended coated superconductor coils as the secondary to explore the potential solutions of enhancing the thrust performance at large clearance, which is generally required for the linear propulsion of transit systems. In this proposal, the coated superconductor coils are embedded into a ferromagnetic yoke whose function is to guide and concentrate the travelling fields generated by the three-phase conventional stator. To make a preliminary study before the laboratory demonstration, we built a numerical model of this proposal by resorting to the finite-element software of MagNet, a recognized professional tool to simulate the electrical machines in the scientific community. Through a treatment of the power law, the developed numerical model has included the nonlinear constitutive law of superconductor, which is currently thought to be difficult in the MagNet environment. This general treatment takes a step forward toward the use of the professional software to perform complex simulations of the superconducting machines. Based on the numerical model, we carried out a set of transient studies on the proposed LIM to observe the distributions of travelling flux, the starting characteristics, and the time evolutions of thrust and speed. The achieved results clearly display that the proposed LIM has advantages over the conventional type and could be thereby regarded as a candidate for developing high thrust LIM with large clearance.