Current Sharing Control Strategy for parallel-connected H-Bridges DC-DC Converter: Modelling, Analysis and HIL test

Power Electronics Converters employed in nuclear fusion applications have been recently assuming a crucial role for reactors’ coils power supply systems as they are particularly challenging not only due to the very high current amplitude, but also to guarantee a proper plasma acceleration and its magnetic confinement for tens of years. To face such demanding requirements, with focus on the Poloidal Field Power Supplies of the Divertor Tokamak Test (DTT) facility, this paper analyzes a parallel-connected H-Bridges (HBs) DCDC converter characterized by relatively low voltages and very high current ratings (tens of kA), quite unusual in industry applications. A specific mathematical model, including the high frequency disturbances identification, has been pointed out for the first time in literature. A current control strategy, which aims at maximizing the current sharing among all HBs legs, is proposed as well. The simulation results have confirmed the validity of the presented control by keeping the load current error below 0.015% and by correctly balancing each HB leg current. These results have been furtherly validated through a Hardware-in-the-loop test facility.