Digitally Controlled Flyback Converter with Online Adaptive Tuning and Estimation

This paper introduces design and implementation of a digital controller for an experimental low-power fly back converter in a solar-powered system with power management. Multiple operating modes are used to maintain high efficiency over wide ranges of input voltages and loads. A current, crossover frequency and phase margin estimation technique to perform load-dependent mode switching and control system stability is proposed and tested. An adaptive tuning digital PID regulator design example is described, with emphasis on practical limitations imposed by the LM3S1138 controller and the program of arithmetic due to sampling and processing. Experiment and simulation results of demonstrating system functionality are presented for a fly back converter.