Paper Title
A Control Strategy to Stabilize PWM DC-DC Buck Converter With Input Filter Using Fuzzy-Pi and its Comparison Using Pi and Fuzzy Controllers

An Input filter is often employed for EMI noise reduction between a dc-dc converter and its power source. LC filters at the input of dc-dc converter can lead to instabilities due to filter interactions with the converter control. However, its presence in turn often results in degradation of dynamic performance and instability of the system even if the filter attenuation is brilliantly designed. Conventional methods to remedy this issue usually employ external resistors to damp filter oscillations. However such dissipative damping of input filter degrades the converter efficiency. This paper addresses the instability problem in dc-dc converters under strong influence of input filter interaction and proposes an alternate solution to this problem using a full state-feedback controller combined with a fuzzy PI control. This control algorithm assures stability of the system without using any passive components in the filter circuit and thus avoiding any undesirable losses. Simulation studies are carried out to confirm the effectiveness of the suggested control strategy under large perturbation. Keywords- Input filters interaction, state-feedback, dc-dc converters, control-loop stability, PI controller, fuzzy logic.