Transformerless inverters are prone to irregular voltage profiles, high harmonics and isolation problems while operating with photovoltaic systems and varying load conditions under stand-alone mode. The aim of the paper is to identify the drawbacks of transformerless inverters operating in stand-alone mode and to propose a new topology with improved performance and control. Further, an intelligent controller is designed to operate the proposed topology with various loads and varying load conditions. The developed controller achieves voltage regulation and low total harmonic distortion for the proposed topology when simulated under MATLAB/Simulink environment. Further, a laboratory prototype of the proposed inverter operating under stand-alone photovoltaic application is developed and operated with the developed control method. The proposed topology along with the developed controller achieves output voltage regulation and reduced THD under varying load conditions. The THD of the proposed system while operating with constant load is observed to be 1.8%, and for varying load condition, it is around 2.12%. Further, the efficiency and power loss of the system are calculated, and it is observed the system exhibits 98.5% efficiency. The achieved results are better when compared with existing work.

中文翻译：

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用于光伏应用的新型无变压器逆变器拓扑的智能控制

无变压器逆变器在光伏系统和独立模式下变化的负载条件下运行时，容易出现不规则的电压曲线、高谐波和隔离问题。本文的目的是确定在独立模式下运行的无变压器逆变器的缺点，并提出一种具有改进性能和控制的新拓扑。此外，智能控制器设计用于在各种负载和变化的负载条件下运行所提出的拓扑。在 MATLAB/Simulink 环境下仿真时，所开发的控制器实现了所提出拓扑的电压调节和低总谐波失真。此外，还开发了在独立光伏应用下运行的拟议逆变器的实验室原型，并使用开发的控制方法进行操作。所提出的拓扑结构与开发的控制器一起在变化的负载条件下实现了输出电压调节和降低的 THD。建议系统在恒定负载下运行时的 THD 为 1.8%，对于变化的负载条件，它约为 2.12%。此外，计算了系统的效率和功率损耗，观察到系统表现出 98.5% 的效率。与现有工作相比，取得的成果更好。