峰值电流控制FAC变换器小信号建模与分析

Small Signal Modeling and Experimental Analysis of Peak Current Mode Controlled Boost Type FAC

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。

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 open-loop 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,ac-cording to the theoretical analysis above,a 12 V/50 W circuit prototype is built,and the theoretical analysis is verified by the experimental results.