Simple fuzzy control of a PWM inverter for a UPS system

A number of control strategies for regulation of PWM inverters in uninterruptible power supplies have been developed. In this paper, a new approach for combining a fuzzy logic controller with a regular sampled pulse-width modulator is presented. The proposed inverter system employs a closed-loop digital feedback with a sinusoidal reference and the pulsewidth is determined at every sampling instant. The fuzzy controller is used to reduce the harmonic distortion and to provide good fundamental regulation. The proposed control scheme is verified by simulations for sudden load changes and nonlinear load conditions. A high output voltage accuracy, very low output voltage distortion and a fast response are realized