SuperMachine, a modular superconducting electrical machine for energy & transport applications

High Temperature Superconducting (HTS) machines offer potential for mass reduction in high torque low speed generators for multi-MW direct drive wind turbines and aerospace propulsion. The SuperMachine concept is a fully air-cored HTS machine, containing no iron and permanent magnets, thus eliminating saturation effects. In order to provide flux focussing an array of air-cored rotor field HTS coils is used to produce a pole-pair module in either radial or axial configuration, with the stator consisting of air-cored copper coils. The Biot-Savart method is applied to the SuperMachine topology to give a fast design optimisation tool. Verification of the SuperMachine concept and design tool was achieved by testing a pole-pair HTS coil array module in the axial configuration at 77 K in liquid nitrogen. The Biot-Savart design and optimisation tool is applied to design a 22 MW generator for direct drive wind turbine, and a 2 MW, 6000 rpm aircraft propulsion motor. For the wind study the optimised SuperMachine design is estimated to be half the mass of the equivalent permanent magnet generator. The aerospace study demonstrates the flexibility of the Biot-Savart tool to optimise the power density for active mass (W/kg) for minimum mass or cost, 55 kW/kg and 33 kW/kg respectively.