Electronic Thesis and Dissertation Repository


Master of Engineering Science


Electrical and Computer Engineering


Dr. Moschopoulos


Single-stage AC-DC converters integrate an AC-DC front-end converter with a DC-DC back-end converter. Compared with conventional two-stage AC-DC converters, single-stage AC-DC converters use less components and only one controller, which is used to regulate the output voltage. As a result, the cost, size and complexity of AC-DC converters can be reduced, but single-stage converters do not perform as well as two-stage converters, and most have drawbacks that are related to the fact that the DC bus voltage is not controlled an can become excessive.

A new single-phase single-stage AC-DC converter that uses stacked flyback converters is proposed in this thesis. The proposed converter consists of two low power flyback converters stacked on top of each other and an active clamp that helps the main switches operate with ZVS. The stacked structure helps reduce the voltage stresses typical fund in many single-stage converters. In the thesis, the operation of the converter is explained, the steady-state characteristics of the converter are determined and its design is discussed. The feasibility of the new converter is confirmed with experimental results obtained from a 100VAC~220VAC worldwide input, 48V output, 100kHz switching frequency and 200 W output power prototype converter.