Design And Test Of The Racetrack Rebco Excitation Magnet For Superconducting Linear Motor

As the technical advantages of independent of adhesive force and great grade ability for linear traction motor, its attractive perspectives for development of the novel rail transit system have opened up for us. Given the advantage of zero resistance and high current density for superconductor, the high temperature superconducting linear motors which are the good candidate for rail traction have property of large thrust under the condition of large air gap on the account of the high magnetic field of the superconducting magnet which can overcome the affect caused by leakage flux in traditional linear motor. The high temperature superconducting magnet technology is still in research stage. And especially there is lack of the electromagnetic simulation of the coated superconductor and its joining process.This paper firstly presents the three dimensional structure design of the high temperature synchronous motor which is consist of three phases copper armature coils as the stator and coated superconductor excitation magnet as the mover. To avoid causing degradation of the superconductivity of coated conductor, the route of tapes has been carefully designed, considering the allowable minimum bending radius. Based on H-formulation of Maxwell’s equations, the homogenization technique is used to model the stacks and coils of coated superconductors which have anomalous geometry size (the width-thickness ratio is up to millions). For the reason of the non-linear properties of superconductor, the distribution of electromagnetic field in electrified superconducting coil is distinct from copper coil. It is also found that the loss is produced mainly in the stage of ramping and there is greater loss with increasing ramping speed. For reducing the risk of quenching, it should to set a proper ramping procedure.Secondly, the influence of temperature, pressure and heating time on the characteristic of the joint were investigated while several joints were made under different soldering conditions and tested in liquid nitrogen bath. The results show that because the coated conductor tape is very thin (about 0.1 mm), easy to damage caused by deformation in some region of the tape, the surface of the joint making table should be smooth enough. Then a simple and effective joint of coated superconductor tapes making device and process were developed. Meanwhile, the results indicate that increasing the length of the lapped region and decreasing the thickness of the solder contribute to reduce the resistance of the joints. The joints microstructure was observed and displays that the solder spreads fully in the gap between the two tapes and the thickness of solder increases from center to the end in samples because of the inherent wrapping characteristic along with the traverse direction of the tape.Furthermore, the dry coil winding process and wet coil winding method were presented and compared with each other, a set of superconducting coils were fabricated utilizing the epoxy impregnation wet coil winding process, then cooled down and tested, while the critical current of single coil is above 150 A. Then the coils was assembled on the back plate and connected in series to form the excitation magnet. Lastly, the test system of the high temperature superconducting linear motor was built with high precision pull-pressure sensors and data acquisition system. Based on the test system, the dynamic operation of the linear motor was achieved. In addition, the field test of the superconducting magnet and thrust test of the linear motor were completed and good performance was obtained, while the critical current of superconducting magnet is above 130 A.