Design, construction and performance of an EMS-based HTS maglev vehicle

A laboratory-scale EMS-based HTS maglev vehicle operating over a 1.5 m guideway has been successfully constructed. The fully integrated system consists of a vehicle chassis, four dependent magnetic circuits, four distance sensors, and control and power amplification circuits. As key component of the system, each magnetic circuit includes a U-shape iron core with one HTS coil forming each pole. Eight HTS coils made of Bi-2223 multi-filamentary tape were used to provide the magnetic motive force. Several questions relating to the unique characteristics of the HTS material in a controlled magnetic circuit are discussed. The most important consideration for such applications is that the anisotropic critical current of the Bi-2223/Ag tape depends strongly on the magnetic field. The commercially available FEA software ANSYS was used to simulate the field distribution along the magnetic circuit and HTS coil winding, and thereby identify how the magnetic circuit alters the field distribution in the coil winding and therefore also the critical current. A general optimization process is described for finding the best position in the U-shape iron core to hold the HTS coils. In this process the critical current of the HTS tape and the force-current characteristic of the magnetic circuit are considered synthetically. The results demonstrate the feasibility and stability of HTS material in a typical maglev system and other similar controllability applications.