加底推挽变换器的输出电容结构优化

Optimizing output capacitor structure of add-on push-pull converter

传统加底推挽变换器(APPC)采用三电容结构,输入端口通过加底支路与输出电容直接连接,会对系统的闭环输入阻抗以及闭环音频衰减率产生不良的影响.为了消除该影响,将三电容结构优化为单电容结构,考虑杂散参数,建立基于单电容和三电容两种结构的APPC变换器的小信号模型,分析比较两种电容结构下的环路增益、闭环输出阻抗、闭环输入阻抗以及闭环音频衰减率.理论与实验结果证明,单电容结构更适用于APPC变换器.

Traditionnal add-on push-pull converter（APPC）was proposed with three-capacitor structure.The closed-loop input impedance and audio susceptibility worsen by the direct connection between input port and output capacitor.Three-capacitor structure was optimized as single-capacitor structure in order to eliminate the influence.An accurate model was developed to analyze the loop gain,output impedance,input impedance and audio susceptibility under two capacitor structures considering the parasitic parameters.The calculated and experimental results demonstrate that single-capacitor structure is more suitable for APPC.