A multiport ac–dc converter topology is proposed that offers bidirectional power transfer capability between the two dc ports and the ac port. The decoupling of power flows can be exploited as a pole voltage balancing mechanism to accommodate unbalanced dc side loads in bipolar dc distribution systems. The proposed topology gains bipolar operation by using two three-phase two-level voltage-sourced converters connected in a differential fashion with a center-tapped transformer. The analysis shows that no penalties are incurred in terms of increased power ratings for either the grid interface transformer or the semiconductors; only access to the center point of the converter side winding is required. A control scheme for the topology is proposed with the ability to independently control power flows between the different ports. Both the topology and control scheme are validated by extensive simulations and experiments.

中文翻译：

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用于双极直流配电的具有独立控制交流和直流功率流的多端口转换器

提出了一种多端口 ac-dc 转换器拓扑，可在两个 dc 端口和 ac 端口之间提供双向功率传输能力。功率流的去耦可用作极电压平衡机制，以适应双极直流配电系统中不平衡的直流侧负载。所提出的拓扑通过使用两个三相两电平电压源转换器以差分方式与中心抽头变压器连接来获得双极操作。分析表明，无论是电网接口变压器还是半导体，都不会因提高额定功率而受到惩罚；只需要访问转换器侧绕组的中心点。提出了一种拓扑控制方案，能够独立控制不同端口之间的功率流。