Electronic Thesis and Dissertation Repository


Master of Engineering Science


Electrical and Computer Engineering


Moschopoulos, Gerry


AC-DC converters with input power factor correction (PFC) that consist of two or more interleaved boost converter modules are popular in industry. PFC is a must in today’s AC-DC converters as their input current must meet harmonic standards set by regulatory agencies. With interleaving, the input current of each module can make to be discontinuous and the size of their input inductors since interleaving can reduce the high ripple in each module and produce a net input current with a ripple that is comparable to that achieved with a single boost converter module with a large input inductor.

In high- frequency converters, so as to achieve low harmonic, fast dynamic response, low size, and high-power density the frequency should be increased. The drawback of increasing the switching frequency is increasing the switching losses. This is reason that why soft-switching methods should be used. The focus of the thesis is on zero current switching (ZCS) methods for IGBT converters. The auxiliary switch in the proposed converter is activated whenever a main converter switch is about to be turned off, gradually diverting current away from the switch so that it can turn off with ZCS and eliminate the switching losses. In addition, the auxiliary circuit is designed in a way that it can be activated only when the converter is operating with heavier loads and not used when the converter is operating with light load to maximize the overall efficiency.

The operation of the novel converter will then be explained and the mathematical analysis in steady-state will be derived. Based on the results of the analysis, general design guidelines will be provided. Finally, the design procedure will be confirmed by experimental results obtained from the proof of concept prototype.