Control of High Performance DC-AC Inverters Using Frequency Domain Based Repetitive Control

This paper presents a digital plug-in frequency domain based repetitive control scheme for tracking output voltage of a single-phase DC-AC inverter used in uninterruptible power supply. The proposed controller consists of a deadbeat controller and an online updated repetitive controller based on Fourier series approximation. The learning algorithm in the repetitive control is designed in frequency domain instead of commonly used time domain. It gives the freedom of choosing different learning gains individually for each harmonic component. Moreover, the time delay introduced due to filters used can be easily compensated for each harmonic component to be eliminated. Therefore, this approach offers better convergence of the voltage tracking error as compared to conventional time domain based repetitive approach. Experimental results are presented to validate the advantage of the proposed frequency domain based repetitive control scheme