A new topology of superconducting magnetic coupling
Résumé
Magnetic couplings and gears receive nowadays a particular attention since they are becoming competitive compared to their mechanical counterpart. Indeed, the use of rare earth permanent magnets may lead to high torque density magnetic transmissions with the benefit of reduced maintenance and improved reliability. Superconducting (SC) materials offer the possibility to produce high magnetic fields. An original topology of a magnetic coupling using HTS materials is then proposed here. It comprises two rotating parts: The input rotor (prime mover) is made from HTS solenoids and YBCO bulks. Fundamental to the operation of the SC rotor is the modulation (by the YBCO bulks operating as perfect screens) of the magnetic field produced by the two solenoids supplied by direct currents in contra-direction. Hence, the field is shaped in a suitable way so the radial flux density along a circle in the airgap is multipolar as in conventional ac machines. The flux density waveform contains a number of space harmonics which rotate at different speeds [1]. The load is connected to a p pole-pairs permanent magnet output rotor. The value of p is chosen to be equal to one of the harmonic numbers produced by the input rotor. The torque is then transmitted to the load at a different speed (gear operation) or at the same speed (coupling). The study will focus on evaluating the influence of the design parameters on the torque transmission capability of the superconducting magnetic coupling.