峰值电流控制FAC变换器小信号建模与分析

摘要

Active clamp forward(FAC) converter is widely used in small and medium sized power DC/DC module converters. Especially,the Boost type FAC is simpler,safer and easier to be realized,because the auxiliary switch dose not need an isolated gate drive signal. A small signal model of Boost type FAC converter is built by state-space averaging approach,and an AC small-signal state equation and an equivalent circuit are obtained.Therefore, the openloop transfer functions of the entire circuit are presented. Then the amplitude-frequency curve and phase-frequency curve are plotted by a Matlab simulation,based on which the feedback loop compensation design is given. At last,according to the theoretical analysis above, a 12 V/50 W circuit prototype is built, and the theoretical analysis is verified by the experimental results.%有源箝位正激(FAC)拓扑在中小功率DC/DC模块电源中具有广泛的应用,其中的Boost型FAC由于辅助开关管驱动无需隔离,因此更为简单可靠,易于实现.根据状态空间平均法对峰值电流控制的Boost型FAC变换器建立了交流小信号模型,得到电路的交流小信号状态方程及等效电路图,并由此推导出电路的开环传递函数.通过将电流内环等效变换,得到全系统的开环传递函数.使用Matlab绘制了全系统开环传递函数的幅频和相频特性曲线,由此给出了补偿网络的设计方法和具体参数.最后根据理论分析制作了一台12 V/50 W的实验样机,实验结果证明了理论分析的正确性.