Design of Ultra-Local Model Control Based on Interval Type-2 Fuzzy Logic for Nine-Level Packed E-Cell

This article incorporates a novel ultralocal model (ULM) control based on single input interval type-2 (SIT2) fuzzy logic control (FLC) to ensure the stable operation of a nine-level packed E-cell (PEC9) inverter in a grid-connected mode. By adopting seven switching components and a single dc source, the number of circuit components has been reduced in the PEC9 topology. This inverter has the possibility to switch various multilevel voltages (nine-, seven-, or five-level) under faulty switching devices without the need for any modification in the inverter configuration. This article proposes a ULM for the regulation of PEC9; it utilizes the input/output data of the system without adopting any parameters of the inverter where it is devoid of issues brought on by model mismatch. In the proposed structure, an extended observer error (ESO) is utilized to estimate the unmodeled dynamics of the inverter and to eliminate their effects in the feedback. Since the observer can remove the uncertainties from an unknown system, the ULM controller does not need to accurate setting of the control coefficients, which makes it a good option to be easy implementation for practical applications. In addition, an SIT2-FLC can be adopted as the supplementary controller to improve the inverter's stability by eliminating the estimation error of ESO. The time-domain experimental examinations have been carried out by conducting practical scenarios on a laboratory prototype of PEC9 to appraise the superior feasibility of the proposed scheme.