The Transactions of the Korean Institute of Power Electronics (전력전자학회논문지)

The Korean Institute of Power Electronics (전력전자학회)
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A Control Scheme for Quality Improvement of Input-Output Current of Small DC-Link Capacitor Based Three-Level NPC Inverters

소용량 직류단 커패시터를 가지는 3-레벨 NPC 인버터의 입-출력 전류 품질 향상을 위한 제어 기법

  • In, Hyo-Chul (Dept. of Electrical and Computer Eng., Ajou University) ;
  • Kim, Seok-Min (Dept. of Electrical and Computer Eng., Ajou University) ;
  • Park, Seong-Soo (Dept. of Space Survey Information Tech., Ajou University) ;
  • Lee, Kyo-Beum (Dept. of Electrical and Computer Eng., Ajou University)
  • Received : 2017.04.15
  • Accepted : 2017.05.16
  • Published : 2017.08.20
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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.

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References

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