DESIGN OF NONLINEAR CONTROLLER FOR MULTI PORT POWER ELECTRONICS INTERFACE IN HYBRID ENERGY SYSTEMS

Abstract

The purpose of multi-input multi-output (MIMO) DC-DC Buck converter is to step down the input voltage to desired output voltage level. But it be comes more challenging in case of hybrid energy system (HES) due to input power fluctuations and load variations. Two renewable sources, photovoltaic (PV) and wind energy system have been used. As both have nonlinear power characteristic curves which vary with the variation in solar irradiance, tem perature, and wind speed. The output voltage and maximum power point do not remain constant because of varying environmental conditions, so non linear controller is more suitable to track them. In this thesis, the integral backstepping nonlinear controller has been proposed to regulate the output voltage, to control the charging of a battery and for maximum power point tracking by using a single MIMO converter. This converter has a single in ductor and can integrate several renewable energy sources and loads with less components. The extra power that is obtained from either PV or wind energy system is used to charge the battery. For simulation, MATLAB/Simulink has been used to check the performance of nonlinear controller under vary ing wind speed, solar irradiance, temperature and load conditions. To check further its performance, it has been compared with linear controller that is PID and nonlinear Fuzzy Logic Based (FLB) and backstepping controllers for different operating conditions.