Critical Design Problems and Possible Solutions to a Superconducting Squirrel-Cage Induction Machine: An Electrical Machines’ Expert Point-of-View

Induction machines, known for their robustness and low cost, remain underexplored with superconductors. One promising solution is using High-Temperature Superconducting (HTS) tapes or bars in the rotor cage, resulting in induction-synchronous machines. However, this solution still has limited magnetic flux density due to the iron core saturation and requires rotating cryostats. An alternative solution is using HTS stator windings and air-core designs, which enable a static cryostat and higher magnetic flux densities. We analyze the design of different topologies of induction machines with air-core and limited air-core and HTS only in the stator windings, enabling the use of a static cryostat in the stator. Using a 50 kW reference machine, the performance of air-core, limited air-core, and iron-core HTS topologies is evaluated. These are analyzed via finite-element calibrated models for the machine performance and estimation of AC HTS tape losses. Findings revealed that, besides the AC losses, reactive power also plays a crucial role. The best configuration achieved 635 kW, 95.3 % efficiency, and 823 kvar.