Modular Smart Transformer Topology for the Interconnection of Multiple Isolated AC and DC Grids

The Smart Transformer enables the interconnection of multiple AC and DC grids with potentially different voltage levels. In most configurations, each grid needs to be isolated for preventing the propagation of faults. Actual literature mostly considers a single isolated interconnection, which is not opti-mized for the interconnection of multiple AC and DC grids. By utilizing the modularity of the Cascaded H-Bridge (CHB) converter and the corresponding connected Dual Active Bridge (DAB) to each H-bridge, this work proposes a system design for feeding multiple AC and DC grids. Requirements for the DC grid isolation and integration are discussed and the proposed topology is demonstrated to enable reduced losses compared to the commonly adopted configuration. The commonly adopted and the proposed configuration are compared and experimental results validate reduced losses for a large range of operation compared to the conventional solution.