具有柔性调控、灵活组网能力的多端口电力电子变压器是构建交直流配电网，实现交流、直流互联的基础。这种面向交直流配电网的电力电子变压器包含多级电能变换环节和大量的元器件，制约了其效率、功率密度和可靠性的提升。因此，电力电子变压器综合性能全面提升以满足配电网应用需求的关键在于电路拓扑的简洁化设计，减少电能变换环节数量，降低元器件需求。基于电路拓扑简洁化设计的研究思路，本项目拟包含如下研究内容：①研究电力电子变压器电路拓扑简洁化设计理论；②剖析子模块电容电压波动特性的影响机理，探究低开关频率下的电容电压均衡控制策略；③研究电力电子变压器软开关特性，探求低开关损耗的软开关设计方法；④研究电力电子变压器故障耦合特性及传播机理，探求端口电路故障隔离设计方法。研究成果能促进控制理论、电力电子、新能源并网技术等学科的交叉融合，有望为交直流混合配电网应用提供理论支撑。

The multi-port power electronic transformer with flexible control and networking capability is the basis of constructing AC/DC hybrid distribution grid to realize AC and DC interconnection.However，this kind of power electronic transformer for AC/DC power distribution grid includes a plurality of power conversion links and a large number of components, which limits its efficiency, power density and reliability improvement.Therefore, the key to improve the comprehensive proformance of power electronic transformer to meet the application requirements of distribution grid is to simplify the design of the circuit topology, reduce the number of energy conversion links and the components. Considering the idea of simple design of circuit topology, this project contains the following:①research the simplified topology design theory of power electronic transformer circuit; ② analyze the influence mechanism of the capacitor voltage fluctuation characteristics of the sub modules, and seek the capacitor voltage balance control strategy under low switching frequency; ③study on the soft switching characteristics of power electronic transformers and discuss the design method with low switching loss; ④research the fault coupling characteristics and propagation mechanism of power electronic transformer, and explore the fault isolation method of port circuits.The results can promote the integration of control theory, power electronics, grid connected technology. It is expected to provide theoretical support for the application of AC/DC hybrid power distribution grid.