Self-Programmable PID Compensator for Digitally Controlled SMPS

Abstract

This paper shows an auto-tuning system for digitally controlled switch-mode power supplies (SMPS) that automatically adjusts parameters of PID compensator based on pre-specified bandwidth requirements. The PID compensator parameters are determined from intentionally introduced limit cycle oscillations (LCOs) through two consecutive auto-tuning procedures. First, the placement of poles and zeros is defined from LCOs at the corner frequency of the power stage. Then, the gain of the PID compensator is found from the oscillations occurring at the desired crossover frequency of the system. The proposed auto-tuning procedure is verified through Matlab/Simulink simulations that show fast load transient response and short settling time