An HTS Machine Concept with a Passive Rotor

Electrical motors or generators normally incorporate copper windings on either the rotor or stator or both components. Copper windings, as well known, have significant resistive. On the other hand, superconductors, with their near zero resistance, have negligible losses under large current flows. Researchers have voiced concern that the main challenge associated with superconducting machines is the necessary cryogenic cooling system and the need to couple them to the rotating rotor structure. This paper describes a novel architecture for superconducting motors or generators. This paper approaches the problem from a new perspective that eliminates the need for rotating the cryocoolers by keeping the field windings stationary and yet generating an emf which is more effective than a comparable conventional copper machine. MgB
₂
or 2
^nd
generation superconductors are proposed for both the DC excitation and AC armature coils. Thus the proposed machine becomes fully superconducting. The main benefit of the proposed fully superconducting machine will have high torque at a compact size which is expected to be useful at offshore wind power generators where weight and size is the biggest concern due to transportation and installation limits. The challenges associated with this particular topology are also discussed and possible solutions proposed. A comparison of the torque with a comparable copper machine provides encouraging results which warrant further pursuit of this topology.