A Study on Scalability of Superconducting Rotating Machines with Passive Quench Protection Approach

This study explores the scalability of superconducting rotating machines that employ no-insulation (NI) REBCO field windings for high-torque, low-speed applications such as ship propulsions and wind-turbine generators. A survey of published quench data reveals that stored magnetic energy and peak field jointly influence quench survivability. A 36.5 MW, 120 rpm partially superconducting machine design is then introduced to assess feasibility at the multi-megawatt scale: the 20 K design attains a 6.55 T air-gap field, 638 Nm/L torque density, and a 22 min charging time constant through stainless-steel co-winding. Experimental efforts on quench behavior are also conducted: quench trials on 2×280 and 2×450-turn NI REBCO coils survived twelve repeated quenches at 180 A with peak temperatures of 80–90 K and no degradation. These test campaigns provide insights into quench behaviors of NI REBCO coils, guiding analysis and design approaches for the next large-scale coils. Ongoing work will extend testing to a 16-coil CRUISE rotor and a ship-scale coil, and will refine distributed quench models to map safe operating envelopes.