low cost PID controller implementation of SEPIC Converter using 8-bits Microcontroller Target for Photovoltaic Applications

Abstract

Power converters are widely used in renewable energy conversion systems such as photovoltaics. Their main role is to adapt the output voltage to a desired voltage shape. SEPIC is a DC/DC converter that has several advantages over other conventional structures in the same family. It is classified as a conversion structure with complex fourth-order topologies. A multi-physics model under MATLAB/Simulink is used to analyze the time behavior and design the appropriate controller. After system dimensioning, a linear control technique is adopted to generate the control law. The selected controller is PID. After sizing, modeling and simulation of the converter/regulator system, disturbances such as input voltage and load variations will be applied to verify the complete system robustness. Then, the digital PID control algorithm will be implemented on an embedded platform around an 8-bit microcontroller, the PIC18F4550. The controller parameters will be identified experimentally in the overall closed loop system. The results show the reliability of our system in terms of dynamics, stability, and accuracy. The main contribution to this work is the optimization of the PID controller for an 8-bit microcontroller architecture and the application of a SEPIC converter. In addition, we have proposed an online identification method using three potentiometers