Output voltage quality evaluation of stand-Alone four-leg inverters using linear & non-linear controllers

Abstract

This paper presents the design and experimental voltage quality evaluation of controllers for the output voltages of 3-phase four-leg voltage source inverters. These inverters are needed in stand-Alone power systems to supply linear and non-linear, balanced or unbalanced loads with constant RMS value voltages at fixed frequency. Comparisons include closed loop outer voltage controllers based on predictive, sliding mode and decoupled proportional-integral controllers in dqo synchronous space, fitted with an inner hysteretic current loop vector controller in abg space. The 3-phase four-leg VSI output voltages waveform quality is analysed under unbalanced and non-linear loads.