Flying-capacitor (FC)-based multicell inverters have recently drawn more attentions due to their outstanding performances. In this article, a new approach to actively control the FC voltages in seven-level full-bridge FC multicell (FCM) inverters is presented. In the proposed method, first, the output current's direction and voltage of the FCs are measured and are interpreted into logic variables. Next, these logic variables are fed into a set of equations, named as logic equations, to achieve two goals: 1) to adjust the voltage of the FCs at their reference values; 2) to generate the required voltage level at the output which is determined by pulsewidth modulation unit. Since the proposed method does need neither the optimization of cost functions nor the utilization of proportional-integral controllers, it is straightforward and simple to be implemented, specifically for the FC-based industrial inverters. To verify the performance and feasibility of the proposed logic equations-based active voltage balancing method, the simulation and experimental results obtained from a seven-level full-bridge FCM inverter are provided. The proposed method is validated under the transient conditions such as variations of modulation index and the dynamic changes of dc-link voltage to demonstrate its robustness and performance.

中文翻译：

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没有成本函数优化的简单有源电容器电压平衡方法，适用于七级全桥飞跨电容器多单元逆变器

基于飞电容（FC）的多单元逆变器由于其出色的性能，最近引起了更多关注。在本文中，提出了一种主动控制七级全桥FC多单元（FCM）逆变器中FC电压的新方法。在提出的方法中，首先，测量FC的输出电流方向和电压，并将其解释为逻辑变量。接下来，将这些逻辑变量馈入一组称为逻辑方程的方程组，以实现两个目标：1）将FC的电压调整为其参考值；2）在输出上生成所需的电压电平，该电压电平由脉宽调制单元确定。由于所提出的方法既不需要优化成本函数，也不需要利用比例积分控制器，它非常容易实现，特别是对于基于FC的工业逆变器而言。为了验证所提出的基于逻辑方程的有源电压平衡方法的性能和可行性，提供了从七电平全桥FCM逆变器获得的仿真和实验结果。该方法在瞬态条件下得到了验证，该方法在诸如调制指数变化和直流母线电压动态变化等瞬态条件下均能证明其鲁棒性和性能。