Seven-level packed U-cell (PUC7) is known as a cost-effective low-component multilevel inverter. However, PUC7 challenge is the capacitor voltage balancing; so, it conventionally needs an additional voltage control integrated into the current control loop. Because of extra variables, the control problem is further complicated for the grid-connected PUC7. This article proposes an optimized sliding-mode control (OSMC) based on the current dynamical model to track the load current reference and to self-balance the capacitor voltage in both grid-connected and stand-alone operations. By optimizing the OSMC control factor using a visual-based optimization method, PUC7 switching operation is controlled to self-balance the capacitor voltage while any extra voltage controller is needed. An adaptive control law has been also proposed for self-tuning of the PUC7 current reference to track the load and dc source variations. Experimental and simulation results of PUC7 prove the excellent performance of the proposed OSMC in achieving capacitor self-voltage balancing operation.

中文翻译：

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基于开关的优化滑模控制七电平PUC逆变器电容自压平衡运行

七电平封装 U 型电池 (PUC7) 被称为具有成本效益的低元件多电平逆变器。但是，PUC7 的挑战是电容电压平衡；因此，它通常需要一个额外的电压控制集成到电流控制回路中。由于额外的变量，并网 PUC7 的控制问题更加复杂。本文提出了一种基于电流动态模型的优化滑模控制 (OSMC)，以跟踪负载电流参考并在并网和独立运行中自平衡电容器电压。通过使用基于视觉的优化方法优化 OSMC 控制因子，PUC7 开关操作被控制以自平衡电容器电压，同时需要任何额外的电压控制器。还提出了一种自适应控制律，用于自调整 PUC7 电流参考以跟踪负载和直流电源变化。PUC7 的实验和仿真结果证明了所提出的 OSMC 在实现电容器自电压平衡操作方面的优异性能。