Coordinated Balancing Charging Strategy for Cascaded H-Bridge Inverter With Supercapacitor and DC–DC Stage

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This article presents a coordinated balancing charging strategy for the cascaded H-bridge inverter (CHBI) with supercapacitor (SC) and dc–dc stage by adopting multistage adjustment of the SCs’ charging powers. The power distribution constraints among the submodules (SMs) are analyzed to prevent over-modulation of the H-bridges. The reactive power distribution is optimized to expand the stable operation range of the CHBI in case of significant disparity in the active power distribution among the SMs. The relationship among the charging powers of different SCs is also derived under the aforementioned constraints. Finally, the effectiveness of the presented strategy is verified through the experimental results on a 16-kW CHBI single-phase prototype with four SMs.