Direct current (Dc) networks have proven advantages in high voltage direct current (HVDC) transmission systems, and now they are expanding to medium- and low-voltage distribution networks. One of the major challenges is to develop reliable dc–dc voltage transformation achieving high efficiency and performance, especially at high voltage and high step ratio. New resonant modular multilevel topologies have arisen as an alternative, mainly because of advantages such as optional use of transformers, natural voltage balance, simple control, and soft-switching capability. However, this type of operation generates a high peak current, does not allow control of power flow in all power range, and has a limited range of voltage variation. This article proposes an asymmetrical triangular current mode applied to high step ratio modular multilevel dc–dc converters. The proposed modulation increases the efficiency and achieves bidirectional control of the power, soft-switching, and a natural balance of the voltage in the cell capacitors. The experimental results show the bidirectional operation and the capacitor voltage balance of the converter under different operating conditions with higher efficiency (97.72%) and lower peak current compared to previous reports of this topology using resonant operation.

中文翻译：

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用于双向高步比模块化多电平 DC-DC 转换器的非对称三角电流模式 (ATCM)

直流 (Dc) 网络在高压直流 (HVDC) 传输系统中已被证明具有优势，现在它们正在扩展到中低压配电网络。主要挑战之一是开发可靠的 dc-dc 电压变换，以实现高效率和高性能，尤其是在高电压和高步长比下。新的谐振模块化多电平拓扑结构已经出现作为替代方案，主要是因为变压器的可选使用、自然电压平衡、简单控制和软开关能力等优点。然而，这种类型的操作会产生高峰值电流，不允许在所有功率范围内控制功率流，并且电压变化范围有限。本文提出了一种应用于高步长比模块化多电平 DC-DC 转换器的非对称三角电流模式。所提出的调制提高了效率并实现了功率的双向控制、软开关和电池电容器中电压的自然平衡。实验结果表明，与之前使用谐振操作的这种拓扑结构相比，转换器在不同操作条件下的双向操作和电容器电压平衡具有更高的效率 (97.72%) 和更低的峰值电流。