Superconducting permanent magnet motor design and first tests

A permanent magnet motor with a superconducting armature has the high current densities of superconductors and the simplicity of a cooled rotating permanent magnet inductor to benefit from the better magnetic properties of rare earth magnets when the temperature decreases. A small-scale model has been developed to prove the experimental feasibility and to study its behavior. The layout of this eight-pole, 750-rpm, 15-kW machine is conventional with a horizontal axis and a rotating inductor. The three-phase winding was made with (6+1) cable of 0.25-mm-diameter strands comprising 597102 NbTi filaments. This model required a fiber glass composite helium cryostat. The helium enthalpy recovery from the helium vessel cools the NdFeB magnets. The cantilevered rotating part inside the armature facilitates the cooling. The machine has been assembled. The main cryogenic and first electrical tests are reported. The experimental demonstration of a superconducting permanent magnet motor has been proved with satisfactory operation.<>