PUBLICATIONS

This thesis proposes an improved five-level space vector modulation (SVM) of twoparallel three-level inverters to reduce leakage current. Two-parallel three-level inverters for higher power capacity are used in several applications, such as photovoltaic, wind power generation, and motor drive systems. The synchronized operation of parallel inverters makes the current distortion on the load side greater. Therefore, several asynchronous operation methods of parallel three-level inverters, such as interleaved modulation or five-level SVM, have been used to improve the current quality. These asynchronous operation methods are accompanied by several problems such as leakage current or zero-sequence circulating current (ZSCC). The five-level reduced common-mode voltage (RCMV) SVM has reduced ZSCC and reduced CMV compared to the interleaved modulation. The five-level RCMV SVM has a high-frequency CMV, and thus, it generates leakage current and problems such as electromagnetic interference and insulation breakdown. In this paper, the five-level reduced leakage current (RLC) SVM suppresses the leakage current by designing the switching sequence that lowers the CMV frequency of the five-level RCMV SVM. The effectiveness and validity of the proposed modulation are verified by simulations and experiments.