{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/139348"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/139348","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Miniaturizing High Step-Down, High Output Current Power Converters","abstract":"Power conversion systems providing high voltage step-down capability at high output current are required in many applications, such as data center servers, electric vehicle charging, and USB power delivery. Converter miniaturization is a critical but especially challenging design goal, and transformers present a key bottleneck in this effort. To address this challenge, a new paradigm for magnetic component design is proposed in which magnetic and electronic elements are viewed as a single ``coupled electronic and magnetic system'' (CEMS). The first proposed CEMS is the Variable Inverter/Rectifier Transformer (VIRT), which enables a transformer with fractional and reconfigurable effective turns ratios (e.g. 12:0.5, 12:2/3, 12:1, and 12:2). Its wide gain variation and high step-down capability are utilized in a 120-380V input, 5-20V, 5A/36W output dc/dc converter having a peak efficiency of 96% and greater than 93% efficiency across the wide range. The VIRT is also employed in a two-stage universal ac input, 5/9/12V, 5A/50W output portable charger having a component power density of 55W/in3 and a peak end-to-end efficiency of 95.7%. Challenges associated with leveraging highly interleaved high-layer-count planar windings - another means for handling high current - are elucidated and mitigation strategies are proposed. A novel winding termination strategy is demonstrated to reduce ac resistance by more than 40% in a highly interleaved design. A CEMS that is especially well suited for processing high output current is derived by combining the VIRT with popular multi-phase concepts. The resulting split-phase half-turn VIRT is employed in a 380V input, 12V/1kW output data center supply having a peak efficiency of 97.7% and a full-load efficiency of 97.1% with a transformer volume up to 36% smaller than best-in-class alternatives. Finally, a generalized modeling framework for developing new CEMS implementations is presented.","abstract_html":"Power conversion systems providing high voltage step-down capability at high output current are required in many applications, such as data center servers, electric vehicle charging, and USB power delivery. Converter miniaturization is a critical but especially challenging design goal, and transformers present a key bottleneck in this effort. To address this challenge, a new paradigm for magnetic component design is proposed in which magnetic and electronic elements are viewed as a single ``coupled electronic and magnetic system'' (CEMS). The first proposed CEMS is the Variable Inverter/Rectifier Transformer (VIRT), which enables a transformer with fractional and reconfigurable effective turns ratios (e.g. 12:0.5, 12:2/3, 12:1, and 12:2). Its wide gain variation and high step-down capability are utilized in a 120-380V input, 5-20V, 5A/36W output dc/dc converter having a peak efficiency of 96% and greater than 93% efficiency across the wide range. The VIRT is also employed in a two-stage universal ac input, 5/9/12V, 5A/50W output portable charger having a component power density of 55W/in3 and a peak end-to-end efficiency of 95.7%. Challenges associated with leveraging highly interleaved high-layer-count planar windings - another means for handling high current - are elucidated and mitigation strategies are proposed. A novel winding termination strategy is demonstrated to reduce ac resistance by more than 40% in a highly interleaved design. A CEMS that is especially well suited for processing high output current is derived by combining the VIRT with popular multi-phase concepts. The resulting split-phase half-turn VIRT is employed in a 380V input, 12V/1kW output data center supply having a peak efficiency of 97.7% and a full-load efficiency of 97.1% with a transformer volume up to 36% smaller than best-in-class alternatives. Finally, a generalized modeling framework for developing new CEMS implementations is presented.","abstract_has_math":false,"creators":["Ranjram, Mike Kavian"],"institution":"Massachusetts Institute of Technology","degree_name":"Doctoral","degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science","school":null,"contributors":[],"advisors":["Perreault, David J."],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021-06","date_published":"2021-06","updated_at":"2026-07-22T22:22:22Z","subjects":[],"languages":[],"rights":["In Copyright - Educational Use Permitted","Copyright MIT"],"rights_urls":["http://rightsstatements.org/page/InC-EDU/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/1721.1/139348","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Perreault, David J."]},{"key":"dc:contributor.department","label":"Department","values":["Massachusetts Institute of Technology. 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Converter miniaturization is a critical but especially challenging design goal, and transformers present a key bottleneck in this effort. To address this challenge, a new paradigm for magnetic component design is proposed in which magnetic and electronic elements are viewed as a single ``coupled electronic and magnetic system'' (CEMS). The first proposed CEMS is the Variable Inverter/Rectifier Transformer (VIRT), which enables a transformer with fractional and reconfigurable effective turns ratios (e.g. 12:0.5, 12:2/3, 12:1, and 12:2). Its wide gain variation and high step-down capability are utilized in a 120-380V input, 5-20V, 5A/36W output dc/dc converter having a peak efficiency of 96% and greater than 93% efficiency across the wide range. The VIRT is also employed in a two-stage universal ac input, 5/9/12V, 5A/50W output portable charger having a component power density of 55W/in3 and a peak end-to-end efficiency of 95.7%. Challenges associated with leveraging highly interleaved high-layer-count planar windings - another means for handling high current - are elucidated and mitigation strategies are proposed. A novel winding termination strategy is demonstrated to reduce ac resistance by more than 40% in a highly interleaved design. A CEMS that is especially well suited for processing high output current is derived by combining the VIRT with popular multi-phase concepts. The resulting split-phase half-turn VIRT is employed in a 380V input, 12V/1kW output data center supply having a peak efficiency of 97.7% and a full-load efficiency of 97.1% with a transformer volume up to 36% smaller than best-in-class alternatives. Finally, a generalized modeling framework for developing new CEMS implementations is presented."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph.D."]},{"key":"dc:title","label":"Title","values":["Miniaturizing High Step-Down, High Output Current Power Converters"]}]}],"canonical_facts":{"dc:contributor.advisor":["Perreault, David J."],"dc:contributor.department":["Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science"],"dc:creator":["Ranjram, Mike Kavian"],"dc:date.accessioned":["2022-01-14T15:05:38Z"],"dc:date.available":["2022-01-14T15:05:38Z"],"dc:date.issued":["2021-06"],"dc:description.abstract":["Power conversion systems providing high voltage step-down capability at high output current are required in many applications, such as data center servers, electric vehicle charging, and USB power delivery. Converter miniaturization is a critical but especially challenging design goal, and transformers present a key bottleneck in this effort. To address this challenge, a new paradigm for magnetic component design is proposed in which magnetic and electronic elements are viewed as a single ``coupled electronic and magnetic system'' (CEMS). The first proposed CEMS is the Variable Inverter/Rectifier Transformer (VIRT), which enables a transformer with fractional and reconfigurable effective turns ratios (e.g. 12:0.5, 12:2/3, 12:1, and 12:2). Its wide gain variation and high step-down capability are utilized in a 120-380V input, 5-20V, 5A/36W output dc/dc converter having a peak efficiency of 96% and greater than 93% efficiency across the wide range. The VIRT is also employed in a two-stage universal ac input, 5/9/12V, 5A/50W output portable charger having a component power density of 55W/in3 and a peak end-to-end efficiency of 95.7%. Challenges associated with leveraging highly interleaved high-layer-count planar windings - another means for handling high current - are elucidated and mitigation strategies are proposed. A novel winding termination strategy is demonstrated to reduce ac resistance by more than 40% in a highly interleaved design. A CEMS that is especially well suited for processing high output current is derived by combining the VIRT with popular multi-phase concepts. The resulting split-phase half-turn VIRT is employed in a 380V input, 12V/1kW output data center supply having a peak efficiency of 97.7% and a full-load efficiency of 97.1% with a transformer volume up to 36% smaller than best-in-class alternatives. Finally, a generalized modeling framework for developing new CEMS implementations is presented."],"dc:description.degree":["Ph.D."],"dc:identifier.uri":["https://hdl.handle.net/1721.1/139348"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["In Copyright - Educational Use Permitted","Copyright MIT"],"dc:rights.uri":["http://rightsstatements.org/page/InC-EDU/1.0/"],"dc:title":["Miniaturizing High Step-Down, High Output Current Power Converters"],"dc:type":["Thesis"],"thesis:degree_name":["Doctoral","Doctor of Philosophy"]},"updated_at":"2026-07-22T22:22:22Z"}