Control Strategy for Reducing Ripple Current in DC-Link Capacitor of Single-Phase UPS

Abstract

This letter proposes a control strategy for reducing a ripple current in DC-link capacitor of single-phase uninterruptible power supplies (UPS). The proposed method aims to reduce the capacitor current by reducing the difference between the input and output instantaneous power. The input current waveform should satisfy harmonic current regulation and be as close as possible to the load current. Therefore, an auxiliary buck chopper was added to compensate to the ripple current in DC-link capacitor. Experimental result confirm that the proposed method reduces the RMS value of the DC-link ripple current by 27.9%.