一种减小反激PFC储能电容容量的控制方式

A Method to Reduce the Flyback PFC Storage Capacitor Control Mode

DCM Flyback PFC变换器主要应用于中小功率场合,具有开关管零电流开通、二极管无反向恢复、PF高等优点。在电力电子得到广泛应用的今天,限制设备功率密度提高的往往是无源器件。本文推导了DCM Flyback PFC变换器在开关周期内的导通时间及工频周期内的输入电流表达式,并提出一种变占空比的控制方法,可以在PF不小于0.9的情况下,满足相同输出电压纹波并使变换器的储能电容减小为原来的65.6%,大大提高了设备的功率密度。最后,用Saber搭建了一个200W仿真模型,验证了理论分析的正确性。

DCM Flyback PFC converter is mainly used in medium and low power applications, having 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 tess than 0.9. The simulation results from a 200W universal input prototype are given to verify the effectiveness of the analysis.