Pulsed-Field Magnetization of Superconducting Tape Stacks for Motor Applications

The potential of (RE)BCO superconducting bulks in rotating machine designs has been explored through numerous experimental prototypes, with the bulks being magnetized to act as held poles. However, stacks of superconducting tapes have emerged as a promising alternative for trapped held magnets partly because of their suitability for the pulsed-field method of magnetization, which is considered the most practical method of trapping flux. The benefits of using a stack of tapes as rotor held poles suitable for motors are reported. The ability to have a long rectangular stack allows for motor designs with more efficient held poles in terms of the flux produced per unit area of the pole and easy scalability. Such a rectangular stack was experimentally magnetized for the first time using a race-track-shaped pulsed-held coil giving a highly uniform and well-defined trapped held. The unique self-supporting 120 mm by 12 mm stack was produced by compressing a high-temperature-superconducting tape coated with a thin layer of solder. Shorter rectangular stacks were pulse magnetized over a temperature range of 10-77 K using a fully automated pulsed magnetization system.