Electromagnetic Shielding Technique for No-Insulation Superconducting Rotor Windings in Electrical Aircraft Propulsion

No-insulation (NI) high-temperature superconductor (HTS) machine is a kind of synchronous semisuperconducting machine with the high power density and enhanced thermal stability, which has great potential for electric aircraft propulsion systems. However, NI HTS rotor windings in this machine always suffer the problem of eddy currents and losses induced by ripple magnetic fields in the synchronous machine environment, which can significantly reduce the efficiency and safety of the HTS machine. In this article, an electromagnetic (EM) shielding technique is developed to minimize this induced eddy current and loss in NI HTS rotor windings. A numerical model is developed to analyze the effectiveness of this shielding technique, and experiments are performed to validate the model. Then, the effect of this EM shielding on the induced eddy current and loss of NI coil is studied using this model. Results show that EM shielding technique based on copper discs can effectively reduce the eddy current and loss on NI HTS coil at the operating temperature range of HTS machines, 20 K-30 K; thus, it is promising to solve the problem of eddy current and loss of NI HTS machine design in electric aircraft propulsion.