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Study of Matrix Converter as a Current-Controlled Power Supply in QUEST Tokamak

Xiaolong LIU, Kazuo NAKAMURA¹⁾, Yi JIANG, Tatsuya YOSHISUE, Osamu MITARAI²⁾, Makoto HASEGAWA¹⁾, Kazutoshi TOKUNAGA¹⁾, Hideki ZUSHI¹⁾, Kazuaki HANADA¹⁾, Akihide FUJISAWA¹⁾, Hiroshi IDEI¹⁾, Shoji KAWASAKI¹⁾, Hisatoshi NAKASHIMA¹⁾, Aki HIGASHIJIMA¹⁾ and Kuniaki ARAKI¹⁾

IGSES, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka, 816-8580, Japan

1)

RIAM, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka, 816-8580, Japan

2)

Tokai University, 9-1-1, Toroku, Kumamoto, 862-8652, Japan

(Received 6 December 2010 / Accepted 10 August 2011 / Published 21 October 2011)

Abstract

Because QUEST tokamak has a divertor configuration with a higher κ and a negative n-index, a precise power supply with a rapid response is needed to control the vertical position of the plasma. A matrix converter is a direct power conversion device that uses an array of controlled bidirectional switches as the main power elements for creating a variable-output current system. This paper presents a novel three-phase to two-phase topological matrix converter as a proposed power supply that stabilizes the plasma vertical position and achieves unity input power factor. An indirect control strategy in which the matrix converter is split into a virtual rectifier stage and a virtual inverter stage is adopted. In the virtual rectifier stage, the instantaneous active power and reactive power are decoupled on the basis of system equations derived from the DQ transformation; hence, unity power factor is achieved. Space vector pulse width modulation is adopted to determine the switching time of each switch in the virtual rectifier; the output voltage of the virtual rectifier is adjusted by the virtual inverter stage to obtain the desired load current. Theoretical analyses and simulation results are provided to verify its feasibility.

Copyright (c) 2011 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

matrix converter, unity power factor, vertical position instability, DQ transformation

DOI: 10.1585/pfr.6.2405137

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References

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This paper may be cited as follows:

Xiaolong LIU, Kazuo NAKAMURA, Yi JIANG, Tatsuya YOSHISUE, Osamu MITARAI, Makoto HASEGAWA, Kazutoshi TOKUNAGA, Hideki ZUSHI, Kazuaki HANADA, Akihide FUJISAWA, Hiroshi IDEI, Shoji KAWASAKI, Hisatoshi NAKASHIMA, Aki HIGASHIJIMA and Kuniaki ARAKI, Plasma Fusion Res. 6, 2405137 (2011).