采用平均法的含输入滤波器电压型Buck变换器稳定性分析

输入滤波器与DC-DC变换器之间的相互作用是分布式电源系统中的一个常见问题。基于平均模型，研究含有2阶输入滤波器和电压型Buck变换器的级联系统稳定性问题。结果表明，输入滤波器对后级Buck变换器稳定性具有双重效果，即根据阻尼电阻Rf的不同，可以扩大或减小独立运行的Buck变换器稳定运行的参数范围。当PI控制器的参数选择在扩大了的稳定性参数范围内， 阻尼电阻Rf的极端增大或减小都会引起系统的低频振荡。这种情况下，现有的阻尼电阻设计标准将不再适用。电路实验验证了理论分析的结果。

Stability Analysis of Voltage-mode Buck Converter With Input Filter Based on Average Approach

Interaction between input filter and DC-DC converter is a common phenomenon in distributed power supply systems.Based on the averaged model, the stability of a cascaded system, which employs a voltage-mode controlled Buck converter and a second-order input filter, was investigated.It is found that the input filter has double effects on the stability of the stand-alone Buck converter.That is, it can either enlarge or decrease the stable region of the parameters depending upon the selection of the damping resistor Rf.If the gain and time constant of the PI controller are selected in the enlarged stable region, extremely increasing and decreasing the damping resistor Rf will lead to instability.In this case, the existing design criterion of the damping resistor will be inapplicable.Experimental results are presented for verifying the theoretical analysis.