中文摘要：

对实际的PWM芯片控制的Buck变换器中的非线性现象展开研究,建立了实际PWM控制芯片的非线性模型,得到UC3842控制下电感电流的分叉图和Lyapunov指数,进一步得到PWM芯片控制下Buck变换器周期态和混沌态下的频率响应特性.

英文摘要：

The paper discussed the nonlinear phenomenon of Buck converter based on PWM control chip. The nonlinear model of PWM control chip is established. The bifurcation chart of inductance current and Lyapunov index of precision model are gained. Frequency responses of Buck converter at period state and chaos state respectively under control of UC3842 are gotten.