一種減小反激PFC儲能電容容量的控制方式

摘要：DCM Flyback PFC變換器主要應用于中小功率場合，具有開關管零電流開通、二極管無反向恢復、PF高等優點。在電力電子得到廣泛應用的今天，限制設備功率密度提高的往往是無源器件。本文推導了DCM Flyback PFC變換器在開關周期內的導通時間及工頻周期內的輸入電流表達式，并提出一種變占空比的控制方法，可以在PF不小于0.9的情況下，滿足相同輸出電壓紋波并使變換器的儲能電容減小為原來的65.6%，大大提高了設備的功率密度。最后,用Saber搭建了一個200W仿真模型，驗證了理論分析的正確性。 敘詞：功率因數校正 儲能電容 變占空比 功率密度 Abstract：DCM Flyback PFC converter is mainly used in medium and low power applicationshaving such advantages as zero-current turning on of switch, no reverse recovery of diode and high PF. At the time power electronics widely used today, passive components volume limits the improvement of power density. This paper derives the expressions of the switching turn-on time and the input current of DCM Flyback PFC converter, and based on which, a variable duty control is proposed so as to make the energy storage capacitor reduce to the original 65.6% at the same voltage ripple level while PF is not less than 0.9. The simulation results from a 200W universal input prototype are given to verify the effectiveness of the analysis.　 Keyword：Power factor correction, Energy storage capacitor, Variable duty control, Power density