Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title A Control Scheme for Quality Improvement of Input-Output Current of Small DC-Link Capacitor Based Three-Level NPC Inverters
Authors Hyo-Chul In ; Seok-Min Kim ; Seong-Soo Park ; Kyo-Beum Lee
Page pp.369-372
ISSN 1229-2214
Keywords Electrolytic capacitor-less ; Neutral-point clamped inverter ; Neutral-point voltage control
Abstract This paper presents a control scheme for three-level NPC inverters using small DC-link capacitors. To reduce the inverter system volume, the film capacitor with small capacitance is a promising candidate for the DC-link. When small capacitors are applied in a three level inverter, however, the AC ripple component increases in the DC-link NPV (neutral point voltage). In addition, the three-phase input grid currents are distorted when the DC-link capacitors are fed by diode rectifier. In this paper, the additional circuit is applied to compensate for small capacitor systems defect, and the offset voltage injection method is presented for the stabilization in NPV. These two proposed processes evidently ensure the quality improvement of the input grid currents and output load currents. The feasibility of the proposed method is verified by experimental results.