Cascaded multilevel inverter for vertical stabilization and radial control power supplies

This paper presents the analysis and topology selection for the power supplies of the two DTT equatorial in-vessel coils for plasma vertical stabilization and fast radial control. The physics requirements and assumptions are analyzed in order to identify the system specifications. Since the basic configuration with two independent power supply circuits is too vulnerable to fast plasma events as disruptions, a circuit configuration including both coils is introduced. Two successive solutions, with three or two power converters, are proposed to supply such a common circuit. The adopted topology, based on cascaded H-bridge converters with IGBTs, is simulated by means of a simplified circuital model, that also consider the plasma disruptions. The simulation results show that vertical stabilization and fast radial control functions can be simultaneously achieved with two identical power converters and a passive imbalance branch by using a specific current control scheme.