Date of Award

1-2012

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering (MSEE)

Department

Electrical Engineering

First Advisor

Dr.Abbas A. Fardoun

Second Advisor

Malik E Elbuluk

Third Advisor

Dr. Hassan Hejase

Abstract

High power factor AC-DC rectifiers have gained a lot of attention due to demanding international regulations. The international harmonics’ standards, i.e. IEC 61000-3-2 and EN 61000-3-2 require low harmonic content of the main line current, or in other words, high power factor. Also, new market initiatives such as the 80 PLUS initiative, require high efficiency of the power supply. These standards specify the AC line current harmonics’ limits depending on load and application.

In this research, a new converter, with high power factor and high efficiency, operating in discontinuous capacitor voltage mode (DCVM) – is investigated targeting personal computers (PC) and server applications. To the best of our knowledge, this is the first publish bridgeless topology operating in DCVM.

To ensure high efficiency, the bridgeless rectifier topology is modified by eliminating two diodes and replacing them with two unidirectional switches. On the other hand, the DCVM has the advantages of no need for high frequency input filter, soft turn-off switching, low switch current stress and high efficiency at low loads.

A comparison between full bridge DCVM buck power factor correction (PFC) converter and the proposed topology is presented. The present topology found to have higher efficiency than that of the full bridge DCVM buck PFC converter, and less THD. Hence, the power factor has been significantly improved. The comparison is summarized and tabulated in chapter five

Design procedure, simulation and measurements are in chapter five. Simulation results are presented to demonstrate the topology’s performance. Orcad PSpice software has been used to simulate the proposed topology. Measurements are presented to verify the theoretical analysis and the simulation findings. The harmonics at the input current are also compared with the IEC 61000-3-2 harmonic standard values. A step by step design procedure for the converter has been developed at any operating point over universal line input voltage (90-265Vrms). Small signal analysis and bode plots for the proposed topology were developed for the line-to-output and control-to-output transfer functions.

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