Solid State Transformer for Low-Voltage Distribution System with DC/DC Stage-Controlled Split-Capacitor

In the future hybrid DC+AC grids, the solid state transformer (SST) would be required to provide both LVAC and LVDC terminals. As the LVDC terminal prefers a bipolar configuration, the LVDC terminal of SST should also be bipolar. In the absence of topology proposal and discussion on SST with bipolar LVDC terminal, this paper presents a preliminary study on it. Several SST topologies with bipolar LVDC are proposed; the control strategy for one of the proposed SST topology is also presented. The effectiveness of the proposed SST topologies and the control strategy are verified by simulation results.