Micro-energy storage system using permanent magnet and high-temperature superconductor

This paper presents the design and experiment with a micro-energy storage system using an axial-flux permanent magnet and a high-temperature superconductor (HTS). This system consists of a three-phase planar stator, flywheel, and HTS. The three-phase planar stator is fabricated with five lines, width of 100 μm, and height of 50 μm for low eddy current loss and high current density. The flywheel with a diameter of 50 mm is integrated by eight motor/generator magnets on the upper side and a single bearing magnet on the bottom side. The HTS is made of melt-textured yttrium-barium-copper-oxide (YBCO) and is used as the non-contact bearing by a levitation force. The maximum rotational speed of the flywheel is 51,000 rpm at 12 V and 0.68 A. At this speed, the flywheel stores a rotational kinetic energy of 337 J and the no-load three-phase electric output is 802 mVrms. By using a three-phase full-wave rectifier, an electric output power of 50 mW is measured.