Topology Selection Algorithm for Interleaved H-Bridge Converters in Particle Accelerator and Nuclear Fusion Applications

Abstract

The parallel connection of interleaved H-bridges (HBs) is widely used in high-current low-ripple applications, such as particle accelerators and nuclear fusion systems, to handle the high-energy requirements and the four-quadrant functioning of the power converters. This parallel HB approach leverages low-power-rated semiconductors, while the interleaving technique offers output current ripple cancellation. The connection of a generic number of parallel HBs sharing a common dc bus is indicated as the common dc-bus configuration (CDC), whereas the configuration with galvanically isolated dc buses is referred to as the split dc-bus configuration (SDC). This article investigates both CDC and SDC topologies and compares the HB currents, the RMS of the HB currents, the RMS of the nonzero frequency component of the HB current, and the associated losses of the power converter. Specifically, the RMS of the nonzero frequency component of the current in CDC, which differs from that in SDC due to the presence of circulating current, is validated experimentally over specific sets of parallel HBs and gain ratios. The normalization of the RMS current in CDC is discussed to decouple the effect of the circulating current from the output current. Highlighting the advantages and disadvantages of CDC and SDC, an algorithm is proposed to automatically select the most appropriate topology for the power converter. The functionality of the proposed algorithm is demonstrated through illustrative design cases and validated numerically under varying system parameters and algorithm inputs, highlighting its robustness and adaptability.