Multi-port modular multilevel converters for the supply of the future circular collider two-stage klystrons

The new generation of high-efficiency klystrons for future particle colliders requires two high-voltage, series-connected power supplies. As an alternative to conventional klystron power converters, the use of Multi-port Modular Multilevel Converters with three DC output terminals is proposed. However, due to the high asymmetry of the converter, the balancing of the arm energies is challenging. Therefore, this paper analyses the conditions that guarantee energy balance and proposes a design and control strategy that allows stable converter operation.