An Input-Series-Output-Parallel Cascaded Converter System Applied to DC Microgrids

Direct current transformer (DCT) is a key piece of equipment in direct (DC) microgrids, and the mainstream topologies mainly include LLC resonant converter (LLC) dual active bridge (DAB). In this paper, novel bi-directional buck/boost + CLLLC cascade topology proposed for input-series-output-parallel system DC microgrid. To solve problem that frequency variation causes to deviate from optimal operating point, resulting low efficiency, inability achieve soft switching function. The operates near point as DCT, only providing electrical isolation voltage matching, while controls output sharing each module. Compared other cascaded systems, paper has high simplifies parameter design, suitable wide input conditions. adopts three-loop control strategy, establishes small-signal modeling system, its stability verified by theoretical analysis simulation. simulation experimental results verify correctness based on effectiveness strategy.