Electronic Thesis and Dissertation Repository

Thesis Format



Master of Science


Electrical and Computer Engineering


Dr. Gerry Moschopoulos


A two-stage power converter with an AC-DC boost converter and a soft-switched DC-DC full-bridge converter is proposed in this thesis. The first stage has two interleaved modules that perform power factor correction; the second stage converts the output of the first stage to the desired output. An auxiliary circuit with a switch, a small transformer, and passive components is used to turn off the AC-DC converter switches with soft-switching; the auxiliary switch can also be turned on and off softly. The secondary of the auxiliary transformer is connected to the output of the overall converter so that some power can be transferred from the front-end converter to the output. This power is processed only once, thus reducing conversion losses. The thesis explains the operation of the converter and presents steady-state analysis and a design procedure. Results obtained from an experimental prototype are presented to confirm the converter’s feasibility.

Summary for Lay Audience

AC-DC power converters are used in many commercial and industrial applications to convert AC voltage into DC voltage to feed loads. This power conversion is typically done with two converter stages, an AC-DC stage followed by a DC-DC stage. The AC-DC stage shapes the input current so that it is sinusoidal and in phase with the input voltage to maximize power factor. The DC-DC stage takes the output of the AC-DC converter and converts to the required output voltage. Power fed from the input to the load is processed by two converter stages with this type of converter. Each stage generates power losses when converting power, which decreases converter efficiency. This thesis proposes a novel two-stage converter that processes some of the power fed to the load using only one converter stage. This direct power transfer reduces losses that would have been generated by the second-stage converter. In this thesis, the operation of the proposed converter is explained, its steady-state operation is analyzed, and a procedure for the design of key components and parameters is developed and demonstrated with an example. The feasibility of the converter is confirmed with results obtained from an experimental prototype.