PID-Fuzzy logic hybrid controller for a digitally controlled DC-DC converter

Abstract

This paper presents PID-Fuzzy logic hybrid controller to improve the dynamic response of Digitally Controlled DC-DC Converter. Classical linear techniques have stability limitations around the operating points. Fuzzy-PID hybrid controller has been available as a control methodology to control power systems. The aim is to improve the dynamic response of a digitally controlled DC-DC Converter under load variations. The fuzzy controller is implemented as gain scheduler that computes Proportional constant (K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> ), Integral constant (K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> ), and Derivative constant (K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ) values for PID controller. The design procedures of linear PID controller, non-linear Fuzzy logic controller (FLC), series combination of PID and FLC are introduced. The buck regulator topology is selected to illustrate the effect of each controller type on the converter performance. Comparison between Fuzzy-PID hybrid controller, classical PID controller and ordinary Fuzzy logic controller are presented. The comparison of results obtained separately from PID controller, Fuzzy logic Controller and Fuzzy-PID hybrid controller for a DC-DC converter shows the advantage of the proposed algorithm in terms of transient response under load variation conditions. Simulations were carried out using MATLAB/Simulink.