电流型单端初级电感变换器的不稳定性与分岔控制

基于电路平均和平均开关建模法,建立了连续模式下电流型单端初级电感变换器(SEPIC)的大信号模型.采用几何方法分析了稳态占空比对电流内环的影响,讨论了电路参数对系统稳定性的影响,并对不稳定区域中的非线性现象进行了仿真研究.理论及数值结果表明,当稳态占空比大于0.5时电流内环会变得不稳定,系统将呈现出分岔及混沌现象.基于斜坡补偿思想抑制了系统分岔的发生,扩大了系统的稳定区域.该方法不仅有助于系统参数的设计,同时也给系统稳定域边界的预测提供了一种有效的途径.

Instabilities and Bifurcation Control of Current-Programmed Single Ended Primary Inductor Converters

A large-signal averaged model for current-programmed single ended primary inductor converter(SEPIC) operating in continuous mode is derived by circuit averaging method and averaged switch modeling,the effects of the steady state duty cycle on inner-current loop stabilities are discussed geometrically,the stability criterion of the system is simulated,and the bifurcating behaviors and chaos associated with the system are analyzed.The theoretical and numerical results show that the inner-current loop tends to unstable when the steady state duty cycle exceeds 0.5 and complex dynamical phenomena arise in the system.Furthermore,a variable ramp compensation scheme is proposed to dynamically adjust the slope magnitude to avoid the occurrence of the bifurcation,which effectively enlarges the stability range of the system.