Derivation of Families of Nonisolated DC Transformers Based on Integration of Switched-Capacitor and Resonant Converters

Systematic approaches are proposed for the derivation of non-isolated DC transformer (NDCX) topologies based on integration of switched-capacitor converters (SCC) and resonant converters (RC). The first method for NDCX topology construction is to replace the capacitor branch in a SCC with a resonant branch, which is composed of resonant capacitor, a resonant inductor and a high frequency transformer associated with the secondary-side rectifier circuit, in the RC, thereby families of NDCX topologies are derived. Based on the circuit derived from the first method, by further integrating of switches or windings, new families of NDCX topologies with reduced number of switches or improved conversion ratio have been derived. With these methods, various NDCX topologies suitable for high-current output applications can be further obtained. Comparisons and extensions of derived NDCX topologies are conducted to reflect the trade-off between efficiency and power density. One of the proposed NDCX topology is analyzed in detail and verified with experimental results to show the feasibility and effectiveness of derived NDCX topologies.