Design and Implementation of an Observer-based Robust Control of a Single DC Source Multilevel Inverter for UPS Applications

Abstract

This study introduces an innovative disturbance observer to tackle external disturbances and model uncertainties, along with a control strategy based on Lyapunov functions, ensuring global asymptotic stability for a single-phase multilevel inverter for UPS applications. The stability analysis of the proposed method is presented, based on two theorems. The first Theorem guarantees presents a disturbance observer, provides a bounded estimation error for the unknown disturbance, in the single-phase UPS inverter (UPSI). The bounded estimation is then used in designing an observer-based robust controller in the second Theorem, which ensures the convergence of tracking error to a small neighborhood of the origin. The numerical and practical results indicate that the developed control scheme ensures global stability and leads to the desired sinusoidal voltage with an almost low THD. Meanwhile, almost zero steady-state error in the output voltage (OV), and robust dynamic performance under uncertainties and disturbances are attained. © 2013 IEEE.