{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/108173"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/108173","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Efficient operation of variable-pole induction machines and drives","abstract":"Transportation electrification is a necessary step for a sustainable and clean energy future. As land vehicles and trucks are responsible for 82% of transportation emissions, electric vehicles (EVs) must become more affordable to replace conventional cars and reduce emissions. High power density, high efficiency, inexpensive drivetrains operating over a wide torque/speed range are critical for EVs. Most modern EVs use permanent magnet (PM) motors which rely on rare-earth material to achieve high energy efficiency. However, rare-earth magnets are expensive, have low recycling rates, and have high risk of price volatility. An induction machine (IM) is a magnet-free motor which offers a cost-effective, rugged and reliable alternative to permanent magnet motors. IMs have been widely established in EVs and are still used in modern designs. The magnetic pole count of an IM can be electronically varied by controlling a high number of stator currents as the cage-rotor naturally follows the stator. Variable-pole operation extends the speed range of an IM, a feature which is attractive in EV applications. Conventionally, pole count has been linked only to the machine operating speed, with a high pole at low speed and low pole at high speed. In this thesis, we show that pole count is a degree of freedom that can be used to improve drivetrain efficiency. Pole count must be selected based on both the required torque and operating speeds if the goal is to minimize losses or stator current. Low pole counts are more efficient than high pole counts at producing low and intermediate torque levels. By exploiting this property, experimental average power loss reduction and torque-per-ampere improvements of 1/3 and 2X were achieved at partial loading condition, where an EV operates for a predominant period of the time. We also show that power electronics converters for variable-pole IMs are more efficient than 3-phase fixed-pole converters.","abstract_html":"Transportation electrification is a necessary step for a sustainable and clean energy future. As land vehicles and trucks are responsible for 82% of transportation emissions, electric vehicles (EVs) must become more affordable to replace conventional cars and reduce emissions. High power density, high efficiency, inexpensive drivetrains operating over a wide torque/speed range are critical for EVs. Most modern EVs use permanent magnet (PM) motors which rely on rare-earth material to achieve high energy efficiency. However, rare-earth magnets are expensive, have low recycling rates, and have high risk of price volatility. An induction machine (IM) is a magnet-free motor which offers a cost-effective, rugged and reliable alternative to permanent magnet motors. IMs have been widely established in EVs and are still used in modern designs. The magnetic pole count of an IM can be electronically varied by controlling a high number of stator currents as the cage-rotor naturally follows the stator. Variable-pole operation extends the speed range of an IM, a feature which is attractive in EV applications. Conventionally, pole count has been linked only to the machine operating speed, with a high pole at low speed and low pole at high speed. In this thesis, we show that pole count is a degree of freedom that can be used to improve drivetrain efficiency. Pole count must be selected based on both the required torque and operating speeds if the goal is to minimize losses or stator current. Low pole counts are more efficient than high pole counts at producing low and intermediate torque levels. By exploiting this property, experimental average power loss reduction and torque-per-ampere improvements of 1/3 and 2X were achieved at partial loading condition, where an EV operates for a predominant period of the time. We also show that power electronics converters for variable-pole IMs are more efficient than 3-phase fixed-pole converters.","abstract_has_math":false,"creators":["Libbos, Elie"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Banerjee, Arijit"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-08-26T23:58:44Z","date_published":"2020-08-26T23:58:44Z","updated_at":"2026-07-22T22:24:47Z","subjects":["Induction machine","multiphase drives","power electronics","electric machines","electric drives","pole-changing","loss minimization","electric vehicles","traction","transportation"],"languages":["en"],"rights":["Copyright 2020 Elie Libbos"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/108173","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Banerjee, Arijit"]},{"key":"dc:creator","label":"Author","values":["Libbos, Elie"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2020-08-26T23:58:44Z","2022-08-26T23:58:55Z","2020-05-11","2020-05"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical & Computer Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"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":["Induction machine","multiphase drives","power electronics","electric machines","electric drives","pole-changing","loss minimization","electric vehicles","traction","transportation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2020 Elie Libbos"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/108173"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Transportation electrification is a necessary step for a sustainable and clean energy future. As land vehicles and trucks are responsible for 82% of transportation emissions, electric vehicles (EVs) must become more affordable to replace conventional cars and reduce emissions. High power density, high efficiency, inexpensive drivetrains operating over a wide torque/speed range are critical for EVs. Most modern EVs use permanent magnet (PM) motors which rely on rare-earth material to achieve high energy efficiency. However, rare-earth magnets are expensive, have low recycling rates, and have high risk of price volatility. An induction machine (IM) is a magnet-free motor which offers a cost-effective, rugged and reliable alternative to permanent magnet motors. IMs have been widely established in EVs and are still used in modern designs. The magnetic pole count of an IM can be electronically varied by controlling a high number of stator currents as the cage-rotor naturally follows the stator. Variable-pole operation extends the speed range of an IM, a feature which is attractive in EV applications. Conventionally, pole count has been linked only to the machine operating speed, with a high pole at low speed and low pole at high speed. In this thesis, we show that pole count is a degree of freedom that can be used to improve drivetrain efficiency. Pole count must be selected based on both the required torque and operating speeds if the goal is to minimize losses or stator current. Low pole counts are more efficient than high pole counts at producing low and intermediate torque levels. By exploiting this property, experimental average power loss reduction and torque-per-ampere improvements of 1/3 and 2X were achieved at partial loading condition, where an EV operates for a predominant period of the time. We also show that power electronics converters for variable-pole IMs are more efficient than 3-phase fixed-pole converters.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2022-05-01","The student, Elie Libbos, accepted the attached license on 2020-05-07 at 19:46.","The student, Elie Libbos, submitted this Thesis for approval on 2020-05-07 at 21:18.","This Thesis was approved for publication on 2020-05-11 at 10:13.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15286 on 2020-08-25 at 17:30:41","Made available in DSpace on 2020-08-26T23:58:44Z (GMT). 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As land vehicles and trucks are responsible for 82% of transportation emissions, electric vehicles (EVs) must become more affordable to replace conventional cars and reduce emissions. High power density, high efficiency, inexpensive drivetrains operating over a wide torque/speed range are critical for EVs. Most modern EVs use permanent magnet (PM) motors which rely on rare-earth material to achieve high energy efficiency. However, rare-earth magnets are expensive, have low recycling rates, and have high risk of price volatility. An induction machine (IM) is a magnet-free motor which offers a cost-effective, rugged and reliable alternative to permanent magnet motors. IMs have been widely established in EVs and are still used in modern designs. The magnetic pole count of an IM can be electronically varied by controlling a high number of stator currents as the cage-rotor naturally follows the stator. Variable-pole operation extends the speed range of an IM, a feature which is attractive in EV applications. Conventionally, pole count has been linked only to the machine operating speed, with a high pole at low speed and low pole at high speed. In this thesis, we show that pole count is a degree of freedom that can be used to improve drivetrain efficiency. Pole count must be selected based on both the required torque and operating speeds if the goal is to minimize losses or stator current. Low pole counts are more efficient than high pole counts at producing low and intermediate torque levels. By exploiting this property, experimental average power loss reduction and torque-per-ampere improvements of 1/3 and 2X were achieved at partial loading condition, where an EV operates for a predominant period of the time. We also show that power electronics converters for variable-pole IMs are more efficient than 3-phase fixed-pole converters.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2022-05-01","The student, Elie Libbos, accepted the attached license on 2020-05-07 at 19:46.","The student, Elie Libbos, submitted this Thesis for approval on 2020-05-07 at 21:18.","This Thesis was approved for publication on 2020-05-11 at 10:13.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15286 on 2020-08-25 at 17:30:41","Made available in DSpace on 2020-08-26T23:58:44Z (GMT). No. of bitstreams: 2 LIBBOS-THESIS-2020.pdf: 14991968 bytes, checksum: 805d620cfd2777e61750cc4499484441 (MD5) LICENSE.txt: 4208 bytes, checksum: 1e41b0916698c1846aec9a29c18502c2 (MD5) Previous issue date: 2020-05-11","Embargo set by: Seth Robbins for item 115786 Lift date: 2022-08-26T23:58:55Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/108173"],"dc:language":["en"],"dc:rights":["Copyright 2020 Elie Libbos"],"dc:subject":["Induction machine","multiphase drives","power electronics","electric machines","electric drives","pole-changing","loss minimization","electric vehicles","traction","transportation"],"dc:title":["Efficient operation of variable-pole induction machines and drives"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Electrical & Computer Engr"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:47Z"}