基于高开关频率精确模型的峰值电流型BUCK电源的补偿设计

针对工作在高开关频率的连续导电模式的峰值电流型BUCK电压源,建立了包含功率管导通电阻和寄生参数的精确小信号模型,设计一个新颖的电压环路的补偿模块,优化了瞬态响应。补偿模块仅增加一个极点,消除输出电容寄生电阻引入的零点。在此补偿模块基础上,分析了输出电压Vo对参考电压Vref的传递函数的频率响应,和补偿模块直流增益之间的关系,得出了补偿模块的最佳增益,使得输出电压对参考电压Vref的瞬态响应既快速又没有过冲和振荡,并且在Spice电路仿真中得到验证。

A Novel Compensation Design based on the Accurate Model of Peak Current Mode Converter in High Frequency

An accurate small signal model of peak current mode(PCM)Buck converter in high frequency under continuous conduction mode is built by using the averaged switch network method.The switch conduction loss and other main parasitic parameters are considered in the presented model.Based on the accurate model,a novel compensation network for the voltage loop is proposed,which just eliminates the zero point of the voltage loop.The relationship between the gain of the proposed compensation network and the transient response of the output voltage relative to the reference voltage(Vref)at the input node of error amplifier is investigated.In this way,an optimal gain for the transient output voltage is obtained and the validity of the optimal transient response without overshoot and oscillation relative to Vref is proved by the Spice circuit simulator.