用于PFC的Buck/Boost有源储能电容变换器研究

针对PFC变换器,推导输入功率因数为1时,储能电容容值与其电压及输出功率的关系,表明容值与直流母线电压及其纹波成反比,与功率成正比。鉴于电容纹波电压受制于直流母线电压平均值,提出采用Buck/Boost有源储能电容变换器取代直流母线电容,增大了其电压变化的自由度,使电容能量实现满充满放,保证输入功率因数为1,能将容值大幅减小,因而可以采用薄膜电容或瓷片电容作为储能电容。分析了该变换器的工作原理,提出了采用输入电压移相以实现所需占空比的SPWM控制方法和实现电路,制作了60 W的样机进行实验验证,实验结果表明所提方法是有效的。

Research on Buck/Boost active storage capacitor converter for PFC

In Power factor correction converter,the input power is pulsating while the output power is con-stant,and storage capacitor is needed to balance the power difference.Being widely used in PFC convert-er,electrolytic capacitor is large in size and its life-time is relatively short.For the improvement of the power density and the life time of PFC converter,it is necessary to use other kinds of capacitor instead of electrolytic capacitor.Relationship among the storage capacitance,its voltage and output power was ana-lyzed,supposing the input power factor is 1.The proposed method of Buck/Boost active storage capacitor converter largely reduces the capacitance while the input power factor is unity and thus film or ceramic capacitor can be used as storage capacitor.The mechanism and new control method as well as the imple-mentation circuit were analyzed.Experiments of a 60W prototype were done to verify the analysis.