二次侧绕组串-并联自调整的交错并联正激变流器

Interleaved Forward Converter With Series-Parallel Auto Regulated Secondary Windings

针对宽输入电压范围的要求,提出一种新型的整流结构,并将其应用于交错并联的正激变流器中。此整流结构能够使变压器的二次绕组随着占空比的变化自动调整成串联或者并联结构。在输入电压比较低的情况下,两个变压器的二次绕组可以工作在串联状态,以提高输出电压的稳态增益。这种新型的整流结构扩展了交错并联正激变流器的占空比范围,使之能够大于0.5。通过交错并联,降低了一次电流应力;通过新型整流结构,减小了二次电压应力和输出纹波电流。研制的一台240W的样机,证明了理论和分析的正确性。

In this paper,a new rectifier topology is proposed. It is used in an interleaved active-clamp forward converter with series-parallel auto regulated secondary windings. With the proposed topology the secondary side of the two interleaving channels works in series when the input voltage is low and the steady state conversion gain of the converter can be improved. The maximum duty cycle can be extended to be larger than 0.5. The steady state of secondary side windings are determined by duty cycle of the converter. Accordingly,the current stress of primary side can be reduced by using interleaving structure. And the voltage stresses of secondary side are reduced by the proposed rectifier as well as the current ripple in the output filter inductor. A 240W prototype is built up to verify the theoretical analysis.