反激开关电源中基于PC817A与TL431配合的环路动态补偿设计

Dynamic Compensating Design Based on PC817A and TL431 in Single Flyback SMP

开关电源市场中占很大份额的单端反激开关电源通常采用PC817A与TL431配合来组成控制环路。然而,目前设计这个环路的动态补偿参数,基本上采用试验方法。文中利用开关电源的小信号传递函数,对此环路的动态补偿进行了定性分析和定量计算,通过设计合适的相位裕量来保证开关电源的稳定性。其过程经实验证明具有较好的通用性,在实际应用中取得了很好的效果。

PC817A incooperation with TL431 is the general configuration to form the feedback loop of single flyback switching mode power supply （SMP）. This kind of power supply occupies a great share in the SMP market . However , the present main method of dynamic compensating design of this loop is trial and error. This article, basing on the theories of automatic control, tries to obtain the control-to-output transfer function by the qualitative analysis and quantitative calculation of the parameters designed for this feedback loop. Experiment shows that the designed procedure with an appropriate phase margin can guarantee the stabi - lity of the SMP and is a universal procedure and an effective one.