In this article, three cascaded transformer multilevel inverters (CTMIs) are proposed. One of the topologies employs cascaded transformers coupled to three-level (3L) neutral-point clamped (NPC) legs, of which one is shared between the transformers. The other two are based on cascaded transformers associated to 3L NPC and two-level (2L) legs, where one 2L leg is shared between the transformers. The proposed topologies use transformers with asymmetrical turns ratios, which allows for synthesizing the maximum number of output voltage levels, significantly reducing the total harmonic distortion. Compared to other conventional CTMIs, the proposed configurations can produce a greater number of levels using the same number of transformers, so that it is possible to have a higher levels-per-switch ratio. In addition, the proposed systems have a natural balancing that self-regulates the dc-link capacitor voltages. Simulations and experimental results confirm the feasibility of the proposed configurations.

中文翻译：

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基于NPC的不对称匝数比级联变压器多电平逆变器


在本文中，提出了三种级联变压器多电平逆变器（CTMI）。其中一种拓扑采用级联变压器，耦合到三级 (3L) 中性点钳位 (NPC) 支路，其中一个支路在变压器之间共享。另外两个基于与 3L NPC 和两级 (2L) 支路关联的级联变压器，其中一个 2L 支路在变压器之间共享。所提出的拓扑使用具有不对称匝数比的变压器，这允许合成最大数量的输出电压电平，从而显着降低总谐波失真。与其他传统的 CTMI 相比，所提出的配置可以使用相同数量的变压器产生更多的电平，从而可以具有更高的每次切换电平比。此外，所提出的系统具有自然平衡功能，可以自动调节直流母线电容器电压。仿真和实验结果证实了所提出的配置的可行性。