抑制输出能量倒灌的二次侧自复位正激变换器的能量传输过程分析

A New Forward Converter with Self-Magnetically Reset on the Secondary Side

针对传统单管正激变换器磁复位方式存在的不足,提出一种应用于单管正激变换器的二次侧自磁复位方法。在基本正激拓扑基础上,通过引入储能电容、辅助电感和两个二极管构造励磁能量转移通路,将变压器的励磁能量传输至负载端,提高变压器利用率。深入分析变换器工作在"正激CCM(L_1)/DCM(L_2)+反激DCM"时的能量传输过程;对该模式下的基本关系式进行推导,得出输入输出关系以及临界电感的表达式;对关键元件的参数进行分析。不仅实现可靠磁复位,且变换器效率较电阻、电容、二极管型(RCD)复位方式提高了4.7%。实例及实验结果验证了所提出电路的可行性及理论分析的正确性。

In view of the shortcomings of the traditional magnetic reset methods,a self-magnetic reset method applied to the secondary side of the single switch forward converter was proposed.Based on the basic forward topology,the excitation energy transfer path was constructed by introducing energy storage capacitor,auxiliary inductor and two diodes,thus the excitation energy of the transformer was transmitted to the load end,and the utilization ratio of the transformer was also improved.The energy transmission process of the converter working in"forward CCM(L1)/DCM(L2)+flyback DCM"was analyzed in depth;the basic relationship under this mode was deduced,and the expression of inputoutput relationship and critical inductance was obtained;the parameters of key components were analyzed.Not only the reliable magnetic reset is realized,but also the converter efficiency is improved by 4.7%compared with the reset mode of resistor,capacitor and diode(RCD).Examples and experimental results show the feasibility of the proposed circuit and the correctness of theoretical analysis.