Research on SVPWM Method for Leakage Current Suppression and Switching Loss Reduction in Nonisolated Three-Level Inverters

The high-power nonisolated three-level inverters face challenges related to switching loss, leakage current suppression, and controlling the neutral point (NP) potential. This article aims to address these issues by analyzing the mechanism of leakage current generation, developing a loss reduction strategy, and identifying factors that influence the NP potential. Given that the existing modulation algorithms fail to account for all three control objectives simultaneously, this article proposes a new modulation strategy called loss reduction-improved large-medium-small vector method (LR-ILMSVM). To achieve this, the modulation sector is redivided, and an appropriate switching sequence is selected. The LR-ILMSVM strategy takes into account the suppression of leakage current, the reduction of switching loss, and the control of NP potential. By limiting the operation times of the maximum current phase switch, a compromise is made between NP potential control and switching loss reduction to fulfill the three control objectives. The effectiveness of this proposed modulation strategy is validated through simulation and experimentation.