Superconducting Synchronous Motor Development for Airplane Applications - Mechanical and Electrical Design of a Prototype 100 kW Motor

Abstract

A 100 kW, 4500 RPM synchronous superconducting motor is being built at the Paihau-Robinson Research Institute, Victoria University of Wellington, New Zealand. The motor has superconducting excitation field coils on the rotor and a conventional stator winding. To minimize mass the motor is an air-core type, meaning no ferromagnetic materials are employed inside the motor. Some of the salient features of this motor include: 1) field winding coils employing REBCO CORC conductor; 2) field coils powered with a contactless superconducting dynamo exciter; 3) an EM shield on the rotor for protecting the field coils from high frequency magnetic fields due to stator harmonics and the switching of the drive electronics; 4) a unique single-layer winding design for the stator winding, where the stator coils are made with copper Litz wire and are liquid-cooled. This paper describes the electrical design and 3D simulation of the motor including the superconducting dynamo, and highlights stator and rotor coil developments that will be validated in the prototype. Sensitivity to critical design parameters has been assessed in simulation and initial sub-system prototypes manufactured for testing. Preliminary design is projecting this motor diameter and axial length as 360 mm and 550 mm respectively, with an efficiency of 96.4 % at the rated load. These numbers may be comparable with permanent magnet motors of similar rating, but this motor is being built to serve as a test-bed for evaluating different technologies for rotor and stator components. The ultimate goal for this program is a 3.0 MW machine with superconducting armature and field windings. In comparison with the permanent magnet motor in 2.5 - 3.0 MW range, the superconducting motors are expected to be 4 to 5 times smaller in size and mass with efficiency exceeding 99 %.