Multilevel technology is an attractive solution to increase the cost effectiveness and power density of dc solid state transformers. In this article, a novel five-level (5L) dual active bridge (DAB) converter topology is proposed. By stacking two neutral-point-clamped (NPC) converters at the primary side, the proposed topology could quadruple the input dc-bus voltage of a conventional two-level (2L) DAB converter. Besides, by analyzing the working principle of the 5L-DAB converter, a voltage balancing control method is carried out. With the aid of the voltage balancing method, voltages of the four series-connected dc-bus capacitors in the 5L-DAB converter can be actively balanced, guaranteeing safe operation voltage for all the semiconductor switches. After that, the operation range of the proposed voltage balancing method is derived by theoretical analysis. Finally, the performance of the proposed converter topology and voltage balancing method have been verified by experimental results.

中文翻译：

---

新型 5 电平双有源桥式变换器的电容器电压平衡控制


多级技术是提高直流固态变压器的成本效益和功率密度的有吸引力的解决方案。在本文中，提出了一种新型五电平 (5L) 双有源桥 (DAB) 转换器拓扑。通过在初级侧堆叠两个中性点钳位 (NPC) 转换器，所提出的拓扑可以使传统两电平 (2L) DAB 转换器的输入直流总线电压增加四倍。此外，通过分析5L-DAB变换器的工作原理，提出了一种电压平衡控制方法。借助电压平衡方法，可以主动平衡5L-DAB变换器中四个串联直流母线电容器的电压，保证所有半导体开关的安全工作电压。之后，通过理论分析得出了所提出的电压平衡方法的操作范围。最后，实验结果验证了所提出的变换器拓扑和电压平衡方法的性能。