{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/31746"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/31746","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Selection of Primary Side Devices for LLC Resonant Converters","abstract":"The demand for high power density, high efficiency bus converters has increased interest in resonant topologies, particularly the LLC resonant converter. LLC resonant converters offer several advantages in efficiency, power density, and hold up time extension capability. Among high voltage (>500V) MOSFETs, Super Junction MOSFETs, such as Infineon's CoolMOS parts, offer lower Rds on than conventional parts and are a natural choice for this application to improve efficiency. However, there is a history of converter failure due to reverse recovery problems with the primary switch's body diode. Before selecting CoolMOS devices for use in a LLC resonant converter, it is necessary to investigate its performance in this application. Field failures of PWM soft switching phase shift full bridge converters have been attributed to large reverse recovery charge in the primary side MOSFET body diode. Under low load conditions the device cannot fully recover, and the large reverse recovery current can cause the device to enter secondary break down, leading to failure. The unique structure of Super Junction MOSFETs, such as CoolMOS, avoid this failure mode by providing a different path for the reverse current; however, the reverse recovery charge of CoolMOS devices is large and can cause a loss of efficiency. For this reason, it is important to avoid conditions under which the reverse recovery characteristics of the body diode can be seen.","abstract_html":"The demand for high power density, high efficiency bus converters has increased interest in resonant topologies, particularly the LLC resonant converter. LLC resonant converters offer several advantages in efficiency, power density, and hold up time extension capability. Among high voltage (>500V) MOSFETs, Super Junction MOSFETs, such as Infineon's CoolMOS parts, offer lower Rds on than conventional parts and are a natural choice for this application to improve efficiency. However, there is a history of converter failure due to reverse recovery problems with the primary switch's body diode. Before selecting CoolMOS devices for use in a LLC resonant converter, it is necessary to investigate its performance in this application. Field failures of PWM soft switching phase shift full bridge converters have been attributed to large reverse recovery charge in the primary side MOSFET body diode. Under low load conditions the device cannot fully recover, and the large reverse recovery current can cause the device to enter secondary break down, leading to failure. The unique structure of Super Junction MOSFETs, such as CoolMOS, avoid this failure mode by providing a different path for the reverse current; however, the reverse recovery charge of CoolMOS devices is large and can cause a loss of efficiency. For this reason, it is important to avoid conditions under which the reverse recovery characteristics of the body diode can be seen.","abstract_has_math":false,"creators":["Person, Clark Edwin"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Electrical and Computer Engineering","degree_department":"Electrical and Computer Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Lee, Fred C."],"committee_members":["Wang, Fei Fred","Xu, Ming"],"year":2008,"date_issued":"2008-04-16","date_published":"2008-04-16","updated_at":"2026-07-22T22:19:33Z","subjects":["DC/DC","LLC Resonant Converter","Superjuction MOSFET"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-04172008-110626"],"render_values":[{"text":"etd-04172008-110626","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/31746","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Lee, Fred C."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Wang, Fei Fred","Xu, Ming"]},{"key":"dc:contributor.department","label":"Department","values":["Electrical and Computer Engineering"]},{"key":"dc:creator","label":"Author","values":["Person, Clark Edwin"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:33:47Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:33:47Z","2008-04-23"]},{"key":"dc:date.issued","label":"Date","values":["2008-04-16"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical and Computer Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["DC/DC","LLC Resonant Converter","Superjuction MOSFET"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-04172008-110626"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/31746"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The demand for high power density, high efficiency bus converters has increased interest in resonant topologies, particularly the LLC resonant converter. LLC resonant converters offer several advantages in efficiency, power density, and hold up time extension capability. Among high voltage (>500V) MOSFETs, Super Junction MOSFETs, such as Infineon's CoolMOS parts, offer lower Rds on than conventional parts and are a natural choice for this application to improve efficiency. However, there is a history of converter failure due to reverse recovery problems with the primary switch's body diode. Before selecting CoolMOS devices for use in a LLC resonant converter, it is necessary to investigate its performance in this application. Field failures of PWM soft switching phase shift full bridge converters have been attributed to large reverse recovery charge in the primary side MOSFET body diode. Under low load conditions the device cannot fully recover, and the large reverse recovery current can cause the device to enter secondary break down, leading to failure. The unique structure of Super Junction MOSFETs, such as CoolMOS, avoid this failure mode by providing a different path for the reverse current; however, the reverse recovery charge of CoolMOS devices is large and can cause a loss of efficiency. For this reason, it is important to avoid conditions under which the reverse recovery characteristics of the body diode can be seen."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:title","label":"Title","values":["Selection of Primary Side Devices for LLC Resonant Converters"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Lee, Fred C."],"dc:contributor.committeemember":["Wang, Fei Fred","Xu, Ming"],"dc:contributor.department":["Electrical and Computer Engineering"],"dc:creator":["Person, Clark Edwin"],"dc:date.accessioned":["2014-03-14T20:33:47Z"],"dc:date.available":["2014-03-14T20:33:47Z","2008-04-23"],"dc:date.issued":["2008-04-16"],"dc:description.abstract":["The demand for high power density, high efficiency bus converters has increased interest in resonant topologies, particularly the LLC resonant converter. LLC resonant converters offer several advantages in efficiency, power density, and hold up time extension capability. Among high voltage (>500V) MOSFETs, Super Junction MOSFETs, such as Infineon's CoolMOS parts, offer lower Rds on than conventional parts and are a natural choice for this application to improve efficiency. However, there is a history of converter failure due to reverse recovery problems with the primary switch's body diode. Before selecting CoolMOS devices for use in a LLC resonant converter, it is necessary to investigate its performance in this application. Field failures of PWM soft switching phase shift full bridge converters have been attributed to large reverse recovery charge in the primary side MOSFET body diode. Under low load conditions the device cannot fully recover, and the large reverse recovery current can cause the device to enter secondary break down, leading to failure. The unique structure of Super Junction MOSFETs, such as CoolMOS, avoid this failure mode by providing a different path for the reverse current; however, the reverse recovery charge of CoolMOS devices is large and can cause a loss of efficiency. For this reason, it is important to avoid conditions under which the reverse recovery characteristics of the body diode can be seen."],"dc:description.degree":["Master of Science"],"dc:identifier.other":["etd-04172008-110626"],"dc:identifier.uri":["http://hdl.handle.net/10919/31746"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["DC/DC","LLC Resonant Converter","Superjuction MOSFET"],"dc:title":["Selection of Primary Side Devices for LLC Resonant Converters"],"dc:type":["Thesis"],"thesis:degree_discipline":["Electrical and Computer Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:33Z"}