Design of Supercapacitor Bank and Filter to Mitigate Converter Interaction in a Tokamak Power Supply

The spread of the research for the exploitation of nuclear fusion as an energy source is fostering several projects in different fields. The introduction of relatively new technologies, such as supercapacitors and four-quadrant power electronic converters, is becoming attractive for coil power supplies to mitigate the problems related to the connection to the external AC grid. This paper is focused on the design and optimization of a bank of supercapacitors with an input filter, able to fully supply the power and the energy required by a superconducting coil of DTT, a large experimental facility under construction in Italy. Two different topologies are presented: a single-source configuration that exploits the advantages of an interleaved control strategy by paralleling several H-bridges; a different solution based on a higher number of smaller sources supplying only part of the load current. The control and modeling strategy and the interaction with the converters are described in order to identify the best filter solution and the most suitable approach for design and sizing. Finally, the topology with the smallest source is pinpointed.