In this paper, a new topology of multilevel inverter (MLI) is designed with a fewer number of components and low total harmonic distortion (THD) for high-power photovoltaic (PV) systems. The key limitations of conventional MLI topologies are high total harmonic distortion (THD) and the use of a large number of switching components due to which the cost of the overall inverter is high. In conventional MLI, THD can be significantly reduced by the addition of a large value filter element at the input side; however, it will result in increased size and cost. Thus, achieving a pure sinusoidal AC at the output and to maintain a low THD level is a major issue in conventional MLIs. The proposed MLI has the advantage of decreasing the output THD by using a modified form of the cascaded H-Bridge structure and sine pulse width modulation technique. The proposed inverter consists of 6 unidirectional switches and 2 bidirectional switches, and there is no extra requirement for additional voltage balancing capacitors or clinching diodes. The individual switching states and SPWM operation for generating the gate pulses of the proposed MLI are discussed in detail. Relevant waveforms are plotted, equations are derived, and mathematical analysis is carried out. A steady-state analysis of the proposed MLI demonstrates an output voltage with 17 levels while using only four DC sources. Simulation results of the proposed MLI for single-phase and three-phase structures are obtained, and comparison is carried out with existing MLI topologies which shows that the proposed MLI has significantly low THD and better performance. From the results, it is clear that the proposed MLI has a THD of 3.52% in comparison with four conventional MLIs whose THDs are 6.1%, 6.63%, 7.3%, and 9.93%. Moreover, the proposed MLI generates 17 voltage levels by using only 08 switching devices, whereas the conventional MLIs use more than 10 switching devices for the generation of 15 voltage levels.

中文翻译：

---

一种具有低总谐波失真的 17 级多电平大功率应用逆变器

在本文中，为大功率光伏 (PV) 系统设计了一种新的多电平逆变器 (MLI) 拓扑结构，具有更少的组件和低总谐波失真 (THD)。传统 MLI 拓扑的主要限制是高总谐波失真 (THD) 和使用大量开关组件，因此整体逆变器的成本很高。在传统的MLI中，可以通过在输入端增加一个大值滤波器元件来显着降低THD；但是，这将导致尺寸和成本增加。因此，在输出端实现纯正弦交流电并保持低 THD 水平是传统 MLI 的主要问题。所提出的 MLI 具有通过使用改进形式的级联 H 桥结构和正弦脉宽调制技术来降低输出 THD 的优点。建议的逆变器由 6 个单向开关和 2 个双向开关组成，不需要额外的电压平衡电容器或钳位二极管。详细讨论了用于生成所提议的 MLI 的门脉冲的各个开关状态和 SPWM 操作。绘制相关波形，导出方程，并进行数学分析。所提议的 MLI 的稳态分析表明，当仅使用四个直流电源时，输出电压具有 17 个电平。获得了所提出的单相和三相结构的 MLI 的仿真结果，并与现有的 MLI 拓扑进行了比较，表明所提出的 MLI 具有显着低的 THD 和更好的性能。从结果中可以明显看出，建议的 MLI 的 THD 为 3。与 THD 为 6.1%、6.63%、7.3% 和 9.93% 的四个传统 MLI 相比，为 52%。此外，所提出的 MLI 仅使用 08 个开关器件即可生成 17 个电压电平，而传统 MLI 使用 10 个以上的开关器件来生成 15 个电压电平。