Robust control of decoupled 4-leg voltage inverters

This article proposed the robust control method for the decoupled four-leg voltage-source inverters in order to overcome the uncertainties of the system. Four-leg inverters are capable to deal with unbalanced load in a standalone photovoltaic power supply system and adopted in many applications such as UPS systems and satellite Erath stations. Most of the studies in four-leg inverters control neglected the coupling in the power stage of the system. However, in this study, the coupling is considered. And the goal is to design a robust controller based on the decouple model of the four-leg inverters. In order to regulate the transient response of the system in uncertain cases, a robust H-infinity controller is designed and applied to a four-leg inverter. The robust performance, robust stability and disturbance attenuation on process input are investigated. The proposed strategy is evaluated by simulation. Simulation results illustrate the effect of the H-infinity method in improving the time-domain performance of the four-leg inverter systems.