A fast high current switched resistor used for asymmetric 4-quadrant power supply in HL-2 M tokamak

• Published in: Fusion engineering and design Vol. 174; p. 112973
• Main Authors: Xue, Zheng, Li, Wei-bin, Xuan, Wei-min, Chen, Jun-hong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.2022; Elsevier Science Ltd
• Subjects: Asymmetry; Coils; Configurations; Converter; Converters; Electric potential; High current; High fast current switched resistor; Low currents; Parameters; Plasma; Plasma configuration; Plasma control; Plasma currents; Power supply; Quadrants; Resistors; Segments; Thyristors; Tokamak devices; Voltage; Converter; Plasma configuration; High fast current switched resistor
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2021.112973

•Multi-IGBT and multi-resistor connect in parallel could offer high current switching ability.•The designed topology could switch dynamically between high voltage and high current.•Load time-constant could be regulated dynamically.•Simulations and prototype experiments verified the temperature performance. In order to meet the requirement of diversified plasma configuration and plasma current fast ascending and breakdown segment, the PF7 coil power supply in HL-2 M tokamak has to offer low positive current and high negative voltage at the same time in that segment. The PF7 coil power supply is asymmetric and 4-quadrant, which is consisted of positive group and negative group thyristor converter. However, according to the latest plasma parameter and voltage-current evolution curve, high enough inversion voltage has to been offered by PF7 coil power supply in positive operation. Although it could meet the new requirement if the transformers have been upgraded, it will make deep control of PF7 power supply in most plasma configuration cases. In addition, the ripple will be high which will have a negative effect on plasma control. So, a fast high current switched resistor has been proposed to offer part of negative voltage for the special segment. The fast high current switched resistor is connected with thyristor positive group in series, which is consisted of several IGBTs and resistors. The resistors are connected in parallel so that the total resistance could be changed under different current range for constant voltage. The larger voltage the more resistors working under low current operation. Benefit from the fast high current switched resistor, the parameters of the two converter groups could be relatively low, the difficulty of control could be reduced, and the cost could be cut. The prototype has been made to verify the performance of the fast high current switched resistor. Depending on the experiment, the function is satisfied with the requirement and the theory. The fast high current switched resistor could offer large voltage for the power supply under low current, while the temperature rise of the resistor is low due to 600 s operation interval.