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

The Korean Institute of Power Electronics (전력전자학회)
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Suppression of Circulating Current in Parallel Operation of Three-Level AC/DC Converters

병렬 3레벨 AC/DC 전력변환 시스템의 영상분 순환전류 억제

  • Son, Young-Kwang (Dept. of Electrical and Computer Eng., Seoul National Univ.) ;
  • Chee, Seung-Jun (Mechatronics R&D Center, Samsung Electronics Co., LTD.) ;
  • Lee, Younggii (Dept. of Electrical and Computer Eng., Seoul National Univ.) ;
  • Sul, Seung-Ki (Dept. of Electrical and Computer Eng., Seoul National University)
  • Received : 2016.04.18
  • Accepted : 2016.06.28
  • Published : 2016.08.20
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Abstract

Zero-sequence Circulating Current (ZSCC) flows inevitably in parallel converters that share common DC and AC sources. The ZSCC commonly flowing in all converters increases loss and decreases the overall capacity of parallel converters. This paper proposes a simple and effective ZSCC suppression method based on the Space Vector PWM (SVPWM) with the ZSCC controller. The zero-sequence voltage for the proposed SVPWM is calculated on the basis of the grid voltage and not on the phase voltage references. The limit of the linear modulation region of the converters with the proposed method is analyzed and compared with other methods, thereby proving that the limit of the region can be extended with the proposed method. The effectiveness of the proposed method has been verified through the experimental setup comprising four parallel three-level converters. The ZSCC is confirmed to be well suppressed, and the linear modulation region is extended simultaneously with the proposed method. Moreover, the proposed control method does not require any communication between the converters to suppress the ZSCC unlike other conventional methods.

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References

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