Electrical, Thermal, and EMI Designs of High-Density, Low-Profile Power Supplies

This work presents the analyses and designs of high-density, low-profile power supplies, including the electrical, thermal, and EMI aspects. Emphasis is placed on forward and flyback converters. The efficiency improvements of employing synchronous rectification are theoretically derived and experimentally verified in forward and flyback converters. The performances of synchronous rectifiers in forward converters are analyzed with regards to transformer reset and SR driven method. The effectiveness of synchronous rectification in flyback converters is evaluated in various operation modes and control schemes. The paralleling techniques utilized to realize high-density, low-profile power conversion are presented. Current sharing in transformer paralleling is addressed and evaluated in forward topology. The performance and the operation principles of one-choke and two-choke interleaved forward converters are analyzed. The thermal management of high-density power supplies in sealed enclosures is optimized using computational fluid dynamics simulations. The theoretical limit of power density due to thermal constraint is determined. In addition, the thermal-design optimization guidelines are given and verified experimentally. A systematic methodology is developed to facilitate the analysis and design of conducted EMI problems in high-density power supplies. Partial element equivalent circuit method is employed for parasitic parameter extraction. Layout and packaging are optimized to minimize conducted EMI noises. Noise predictions by Saber simulations are confirmed by experimental measurements.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Department dc:contributor.department

Electrical and Computer Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1998

Author dc:creator

• Zhang, Michael Tao

Chairs dc:contributor.committeechair

• Jovanovic, Milan M.
• Lee, Fred C.

Committee members dc:contributor.committeemember

• Nelson, Douglas J.
• Chen, Dan Y.
• Chang, Lay Nam
• Boroyevich, Dushan

• none

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-173510281975580

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/30316