{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/127446"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/127446","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Superconducting rotor with self-contained thermal management system","abstract":"Superconducting (SC) electric machines can reach incredibly high specific power and are especially desirable for weight-sensitive applications including aircraft electric propulsion. However, thermal management of the cryogenic environment has posed challenges to building practical aerospace SC machines. Traditional cryogenic refrigeration involves boiling liquid cryogen, such as liquid helium and nitrogen, in the rotor. Although rotary unions can transfer cryogen from the stationary reservoir at low rotation speeds, they are unreliable at the several thousand revolutions per minute (rpm) required by aircraft propulsors. Closed-loop cryocoolers with integrated compressors are new options for cryogenic refrigeration because of their independence from liquid transfer. Nevertheless, they deliver only a fraction of the cooling power liquid cryogen does. Therefore, a rotor structure with low thermal leakage is critical for cryogen-free refrigeration. Mechanical strength, thermal management, and electromagnetic circuits should be carefully balanced through multiphysics optimization. High-fidelity models must be developed and integrated. This dissertation describes efforts to design a cryogen-free SC rotor with high-temperature superconducting coils, a spoke-suspended torque coupler, and a rotor-embedded cryocooler. The machine’s thermal, electrical, and mechanical models are derived analytically to show the tradeoffs between machine-specific power and thermal leakage. Experimental setups and plans are also discussed in detail to validate the analytical derivation.","abstract_html":"Superconducting (SC) electric machines can reach incredibly high specific power and are especially desirable for weight-sensitive applications including aircraft electric propulsion. However, thermal management of the cryogenic environment has posed challenges to building practical aerospace SC machines. Traditional cryogenic refrigeration involves boiling liquid cryogen, such as liquid helium and nitrogen, in the rotor. Although rotary unions can transfer cryogen from the stationary reservoir at low rotation speeds, they are unreliable at the several thousand revolutions per minute (rpm) required by aircraft propulsors. Closed-loop cryocoolers with integrated compressors are new options for cryogenic refrigeration because of their independence from liquid transfer. Nevertheless, they deliver only a fraction of the cooling power liquid cryogen does. Therefore, a rotor structure with low thermal leakage is critical for cryogen-free refrigeration. Mechanical strength, thermal management, and electromagnetic circuits should be carefully balanced through multiphysics optimization. High-fidelity models must be developed and integrated. This dissertation describes efforts to design a cryogen-free SC rotor with high-temperature superconducting coils, a spoke-suspended torque coupler, and a rotor-embedded cryocooler. The machine’s thermal, electrical, and mechanical models are derived analytically to show the tradeoffs between machine-specific power and thermal leakage. Experimental setups and plans are also discussed in detail to validate the analytical derivation.","abstract_has_math":false,"creators":["Xiao, Jianqiao"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Haran, Kiruba S","Miljkovic, Nenad","Ansell, Phillip J","Stillwell, Andrew R"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-11-19","date_published":"2024-11-19","updated_at":"2026-07-22T22:25:04Z","subjects":["Superconducting","Electric Machine","Cryogenic","Torque Tube"],"languages":["eng","en"],"rights":["Copyright 2024 Jianqiao Xiao"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/127446","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Haran, Kiruba S","Miljkovic, Nenad","Ansell, Phillip J","Stillwell, Andrew R"]},{"key":"dc:creator","label":"Author","values":["Xiao, Jianqiao"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2024-11-19","2024-12"]},{"key":"dc:type","label":"Dc Type","values":["Thesis","text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical & Computer Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Superconducting","Electric Machine","Cryogenic","Torque Tube"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng","en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2024 Jianqiao Xiao"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/127446"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Superconducting (SC) electric machines can reach incredibly high specific power and are especially desirable for weight-sensitive applications including aircraft electric propulsion. However, thermal management of the cryogenic environment has posed challenges to building practical aerospace SC machines. Traditional cryogenic refrigeration involves boiling liquid cryogen, such as liquid helium and nitrogen, in the rotor. Although rotary unions can transfer cryogen from the stationary reservoir at low rotation speeds, they are unreliable at the several thousand revolutions per minute (rpm) required by aircraft propulsors. Closed-loop cryocoolers with integrated compressors are new options for cryogenic refrigeration because of their independence from liquid transfer. Nevertheless, they deliver only a fraction of the cooling power liquid cryogen does. Therefore, a rotor structure with low thermal leakage is critical for cryogen-free refrigeration. Mechanical strength, thermal management, and electromagnetic circuits should be carefully balanced through multiphysics optimization. High-fidelity models must be developed and integrated. This dissertation describes efforts to design a cryogen-free SC rotor with high-temperature superconducting coils, a spoke-suspended torque coupler, and a rotor-embedded cryocooler. The machine’s thermal, electrical, and mechanical models are derived analytically to show the tradeoffs between machine-specific power and thermal leakage. Experimental setups and plans are also discussed in detail to validate the analytical derivation.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-12-01","The student, Jianqiao Xiao, accepted the attached license on 2024-11-18 at 20:32.","The student, Jianqiao Xiao, submitted this Dissertation for approval on 2024-11-18 at 20:43.","This Dissertation was approved for publication on 2024-11-19 at 09:30.","DSpace SAF Submission Ingestion Package generated from Vireo submission #21255 on 2025-03-28 at 14:53:39"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Superconducting rotor with self-contained thermal management system"]}]}],"canonical_facts":{"dc:contributor":["Haran, Kiruba S","Miljkovic, Nenad","Ansell, Phillip J","Stillwell, Andrew R"],"dc:creator":["Xiao, Jianqiao"],"dc:date":["2024-11-19","2024-12"],"dc:description":["Superconducting (SC) electric machines can reach incredibly high specific power and are especially desirable for weight-sensitive applications including aircraft electric propulsion. However, thermal management of the cryogenic environment has posed challenges to building practical aerospace SC machines. Traditional cryogenic refrigeration involves boiling liquid cryogen, such as liquid helium and nitrogen, in the rotor. Although rotary unions can transfer cryogen from the stationary reservoir at low rotation speeds, they are unreliable at the several thousand revolutions per minute (rpm) required by aircraft propulsors. Closed-loop cryocoolers with integrated compressors are new options for cryogenic refrigeration because of their independence from liquid transfer. Nevertheless, they deliver only a fraction of the cooling power liquid cryogen does. Therefore, a rotor structure with low thermal leakage is critical for cryogen-free refrigeration. Mechanical strength, thermal management, and electromagnetic circuits should be carefully balanced through multiphysics optimization. High-fidelity models must be developed and integrated. This dissertation describes efforts to design a cryogen-free SC rotor with high-temperature superconducting coils, a spoke-suspended torque coupler, and a rotor-embedded cryocooler. The machine’s thermal, electrical, and mechanical models are derived analytically to show the tradeoffs between machine-specific power and thermal leakage. Experimental setups and plans are also discussed in detail to validate the analytical derivation.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-12-01","The student, Jianqiao Xiao, accepted the attached license on 2024-11-18 at 20:32.","The student, Jianqiao Xiao, submitted this Dissertation for approval on 2024-11-18 at 20:43.","This Dissertation was approved for publication on 2024-11-19 at 09:30.","DSpace SAF Submission Ingestion Package generated from Vireo submission #21255 on 2025-03-28 at 14:53:39"],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/127446"],"dc:language":["eng","en"],"dc:rights":["Copyright 2024 Jianqiao Xiao"],"dc:subject":["Superconducting","Electric Machine","Cryogenic","Torque Tube"],"dc:title":["Superconducting rotor with self-contained thermal management system"],"dc:type":["Thesis","text"],"thesis:degree_discipline":["Electrical & Computer Engr"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:04Z"}