University of Western Ontario - Electronic Thesis and Dissertation Repository

Location of Thesis Examination

Room 2009B Spencer Engineering Building

Degree

Master of Engineering Science

Program

Electrical and Computer Engineering

Supervisor

Dr. Moschopoulos

Abstract

Pulse-width modulated (PWM) full-bridge boost converters are used in applications where the output voltage is considerably higher than the input voltage. Zero-voltage-switching (ZVS) is typically implemented in these converters. The objective of this thesis is to propose, analyze, design, implement, and experimentally confirm the operation of a new Zero-Voltage-Switching PWM DC-DC full-bridge boost converter that does not have any of the drawbacks that other converters of this type have, such as a complicated auxiliary circuit, increased current stresses in the main power switches and load dependent ZVS operation. In this thesis, the general operating principles of the converter are reviewed, and the converter’s operation is discussed in detail and analyzed mathematically. As a result of the mathematical analysis, key voltage and current equations that describe the operation of the auxiliary circuit and other converter devices have been derived. The steady state equations of each mode of operation are used as the basis of a MATLAB program that is used to generate steady-state characteristic curves that shows the effect that individual circuit parameters have on the operation of the auxiliary circuit and the boost converter.

Observations as to their steady-state characteristics are made and the curves are used as part of a design procedure to select the components of the converter, especially those of the auxiliary circuit. An experimental full-bridge DC-DC boost converter prototype is built based on the converter design and typically waveforms are presented to confirm the feasibility of the converter, as well as computer simulation results. The efficiency of the proposed converter operating with the auxiliary circuit is compared to that of a hard-switched PWM DC-DC full-bridge boost converter and the increased efficiency of the proposed converter is confirmed.

Keywords: Power conversion, DC-DC converter, Full-bridge converter, Boost Converter, Zero-voltage-switching, Soft-switching.

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