C-HIL Implementation of Cascaded Multilevel Inverter for Vertical Stabilization and Radial Control Power Supplies of Divertor Tokamak Test

This paper deals with a Controller Hardware in the Loop (C-HIL) implementation of a cascaded multilevel inverter to supply the two Divertor Tokamak Test (DTT) equatorial in-vessel coils for plasma Vertical Stabilization (VS) and fast Radial Control (RC). The power converters suitable to drive the VS coils are medium-voltage inverters capable of delivering high-output currents. The adopted converter topology to power the VS coils is based on cascaded H-bridge IGBT converters implemented in a modular way. The number of 7 modules used in this paper is reduced compared to a previous solution with 8 modules. Every H-bridge converter employs Pulse-Width Modulation (PWM) on a switching leg and an unfolder technique in the other switching leg to attain the requested output current. The unfolder technique facilitates the minimization of the switching losses. The proposed schemes and the results showcased are tailored to the requirements of DTT. In this paper, the complete description of the hardware system, the current control, and C-HIL results are reported.