A Novel Dual‐Switch Capacitor Series DC Transformer Topology With Faults and Inrush Current Suppression

ABSTRACT The DC transformer serves as a crucial interface between multiterminal flexible DC distribution networks, DC loads, and DC microgrids. This paper introduces a topology for a dual switched capacitor series DC transformer designed specifically for multiterminal flexible DC distribution networks. The proposed structure effectively locks the series module during medium‐voltage DC side short circuit faults, blocking capacitor discharge and swiftly isolating the fault to restore normal operation. Additionally, this topology addresses the issue of step‐like power flow fluctuations caused by instantaneous communication faults, which typically result in power flow diverting to the transformer with the lowest impedance and triggering protective shutdowns. By employing the dual switch capacitor series module to block external surges, the system's reliability is significantly enhanced. Compared with the conventional full‐bridge + DAB topology, our approach eliminates two switching tubes, thus offering benefits like suppressed fault and inrush currents, improved efficiency, and reduced economic costs. The effectiveness and practicality of the proposed method are substantiated through simulations and extensive engineering tests, underscoring its significant engineering value.