Predictive instantaneous value controlled PWM inverter for UPS

Abstract

A microprocessor-based pulse-width modulation (PWM) inverter (UPS) that obtains high-quality sinusoidal output voltage even under a rectifier load is proposed for uninterruptible power supplies. The proposed PWM inverter system uses a closed-loop digital feedback with a sinusoidal reference, and the PWM pattern is determined at every sampling instant. A modification that increases the maximum pulse width, which is limited by the computation time in conventional digital approaches, to provide larger output voltage and a repetitive control technique are applied to the proposed control system. A larger maximum pulse width, stable operation, high output voltage accuracy, very low output voltage distortion, and very fast response are realized.<>