Title page for ETD etd-02172003-211948

Type of Document Dissertation
Author Zhao, Qun
URN etd-02172003-211948
Title Performance Improvement of Power Conversion by Utilizing Coupled Inductors
Degree PhD
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Lee, Fred C. Committee Chair
Boroyevich, Dushan Committee Member
Chen, Dan Y. Committee Member
Huang, Alex Q. Committee Member
Nelson, Douglas J. Committee Member
  • coupled inductors
  • reverse recovery
  • DC-DC
  • power factor correction
  • high step-up
Date of Defense 2003-02-03
Availability unrestricted
This dissertation presents the derivation, analysis and application issues of advanced topologies with coupled inductors. The proposed innovative solutions can achieve significant performance improvement compared to the state-of-the-art technology.

New applications call for high-efficiency high step-up DC-DC converters. The basic topologies suffer from extreme duty ratios and severe rectifier reverse recovery. Utilizing coupled inductor is a simple solution to avoid extreme duty ratios, but the leakage inductance associated with the coupled inductor induces severe voltage stress and loss. An innovative solution is proposed featuring with efficient leakage energy recovery and alleviated rectifier reverse recovery. Impressive efficiency improvement is achieved with a simple topology structure. The coupled inductor switching cell is identified. Topology variations and evaluations are also addressed.

The concept that utilizes coupled inductors to alleviate rectifier reverse recovery is then extended, and new topologies suitable for other applications are generated. The proposed concept is demonstrated to solve the severe rectifier reverse recovery that occurs in continuous current mode (CCM) boost converters. Significant profile reduction and power density improvement can be achieved in front-end CCM power factor correction (PFC) boost converters, which are the overwhelmingly choice for use in telecommunications and server applications.

This dissertation also proposes topologies to realize the single-stage parallel PFC by utilizing coupled inductors. Compared to the state-of-the-art single-stage PFC converters, the proposed topologies introduce a new power flow pattern that minimizes the bulk-capacitor voltage stress and the switch current stress.

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