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This thesis focuses on the analysis and design of the LLC resonant half-bridge converter with natural interleaving power factor correction circuit. At first, the characteristics of the natural interleaving power factor correction will be analyzed. Since the natural interleaving PFC can raise the power levels and minimize the size of energy storage inductor, it is suitable for the front stage of the LCD TVs power supply. Then, the impact of Q and λ parameters on the LLC resonant half-bridge transfer function is analyzed. And the influence of Q and λ parameters on the curve of transfer function are analyzed by MATLAB software. We also consider the different requirements for the Q parameter in light load and heavy load, and select the appropriate Q parameter value, with which the LLC resonant half-bridge converter can have better efficiency at both light and full load. Finally, a prototype 150W AC-DC power converter with PFC is implemented. The efficiency of the front stage natural interleaved power factor correction circuit can reach 95%, and the maximum efficiency of the rear stage LLC resonant half-bridge converter is 93%. The maximum whole system efficiency is above 88%, meets current industry specification of 85%.
Date of Conference: 5-8 Dec. 2011