Advancements in Superconducting Electric Propulsion: Comparative Analysis and Progress Update of CHEETA and CRUISE Motors
Thanatheepan Balachandran, Noah Salk, Jianqiao Xiao, Samith Sirimanna, Uijong Bong, Yiming Zhao, Himalaya Rautela, Phoenix Bauer, Raatan Venkataraaman, Sangar Santhanam, Kiruba S. Haran
Abstract
This paper summarizes the efforts in developing the world's most power-dense and efficient electric aircraft propulsion motor through the synergistic CHEETA (Center for High-Efficiency Electrical Technologies for Aircraft) and CRUISE (CRyogen-free Ultra-hIgh field Superconducting Electric motor) projects. The partially superconducting (SC) motor being developed under the CRUISE program features an inrunner rotor with an embedded cryocooler and high-temperature superconducting (HTS) field windings, and a slotless stator armature composed of room-temperature conductors. The CHEETA machine has the same high-level features as CRUISE, however, the armature is also cryogenically cooled to achieve the highest possible efficiency and power density. To close the machine design, four key challenges were addressed: (1) integrate a compact and rotationally-compatible cryocooler into the shaft bore with enough heat lift to cool the HTS coils to sub-50 K; (2) design a rotor cryogenic thermal management system (TMS) that minimizes the heat load to the cryocooler's cold head while simultaneously transferring torque; (3) develop robust, conduction-cooled and quench tolerant HTS magnets; (4) construct an air-core armature that maximizes electrical loading and exhibits low ac losses. In the case of CRUISE, successfully overcoming these challenges resulted in a 10 MW design that achieves 40 kW/kg continuous specific power (127 Nm/kg specific torque) and 99.4% efficiency.