Hybrid direct power/current control using feedback linearization of three-level four-leg voltage source shunt active power filter

This paper proposes a hybrid direct power/current control-three dimensional space vector modulation combined with feedback linearization control for three-phase three-level four-leg shunt active power filter (SAPF). The four-leg SAPF ensures full compensation of harmonic phase currents, harmonic neutral current, reactive power and unbalanced nonlinear load currents. It also regulates its self-sustaining DC bus voltage. The voltage-balancing control of two split DC capacitors of the three-level four-leg SAPF is achieved using three-level three dimensional space vector modulation with balancing strategy based on the effective use of the redundant switching states of the inverter voltage vectors. Complete simulation of the resultant active filtering system validates the efficiency of the proposed nonlinear control method. Compared to the traditional control, the use of feedback linearization control allows to exhibit excellent transient response during balanced and unbalanced load, and grid voltage.