Design of a hybrid type-2 fuzzy logic/proportional- integral controller for single-phase three-wire inverter system

Abstract

This paper presents the design of a hybrid type-2 fuzzy logic (T2FL) / proportional-integral (PI) controller proposed to solve harmonic and balancing problems in the output voltage of a single-phase three-wire inverter system. The inverter system consists of a converter circuit with three legs and an auxiliary LC filter, and a voltage-based feedback control algorithm including a differential-mode and common-mode controllers. In this algorithm, a T2FL controller and a PI controller whose gain coefficients are optimized by particle swarm optimization (PSO) algorithm are used as the differential-mode controller and common-mode controller, respectively. To evaluate the effects on system performance of the proposed hybrid controller, the inverter is also controlled using traditional PI/PI controller and hybrid type-1 fuzzy logic (T1FL) / PI controller. Simulation results show that the hybrid T2FL/PI controlled inverter has faster dynamic response in the case of step load changes, and gives a better sinusoidal alternating current(AC) output voltage and a lower neutral line voltage under unbalanced linear and non-linear load conditions than the both conventional PI/PI and hybrid T1FL/PI controlled inverters. Key words: Proportional-integral controller, type-1 fuzzy logic controller, type-2 fuzzy logic controller, hybrid controller, particle swarm optimization algorithm, single phase three-wire inverter.