Flywheel energy storage system with a horizontal axle mounted on high Tc superconductor bearings Original Research Article

We studied on parameters affecting the nucleation and growth of a Y123 single-domained crystal in top-seeded melt processing. We developed a new processing, two-step undercooling technique. The keys of this technique are the controlled nucleation of Y123 at the primary undercooling state and the accelerated growth at the secondary undercooling temperature. Optimization of the processing parameters in the two-step undercooling technique considerably reduced the processing time required for the growth of the Y123 single crystal without degradation of the levitation property. We developed a new type of flywheel energy storage system that has a horizontal axle with high Tc superconductor bearings using the Y123 single-domained crystals. The dynamic properties, stiffness and damping, of the high Tc superconductor radial bearings applied in the flywheel energy storage system were experimentally estimated using the imbalance excitation method. The imbalance excitation method applied to this rotor-bearing system identified the direct stiffness and damping of the high temperature superconductor (HTS) bearings to be 2.8–3.3×105 N/m and 175–204 Ns/m, respectively.