Prescribed-Performance Generalized Super-Twisting Control of NPC Converters

This article investigates the high-performance control problem of three-level neutral-point-clamped (NPC) converters, focusing on prescribed-performance voltage regulation, enhanced disturbance rejection, and current harmonic suppression. In the voltage regulation loop, a prescribed-performance generalized super-twisting control (GSTC) algorithm is proposed based on error transformation functions. This method features a simple structure, guarantees that the dc-link voltage strictly satisfies the predefined performance constraints, and enables accurate tracking of both continuous and discontinuous voltage reference signals. In addition, a filtered generalized proportional-integral (PI) observer with improved noise tolerance capability is developed to enhance the robustness of voltage regulation. In the current tracking loop, a periodic iterative learning GSTC method is presented to achieve fast and precise current control with low harmonic distortion. The convergence of both the proposed generalized super-twisting controllers and the observer is rigorously analyzed. Finally, experimental results validate the superiority of the proposed control scheme.