Virtual space vector modulation strategy for common‐mode voltage reduction in three‐phase three‐level flying‐capacitor split‐source inverters

Abstract

Transformerless systems play an important role in many applications, such as photovoltaic generation systems and motor drives, since they present reduced size and high efficiency. On the other hand, the flying-capacitor split-source inverter (FC-SSI) merges the boost and the inverter stage in a single power conversion system. It is important to point out that conventional modulation strategies applied to the FC-SSI can result in unacceptable common-mode voltage (CMV) which is one of the main causes of leakage currents. To overcome this problem, this paper proposes a virtual space vector modulation technique for FC-SSI. The proposed modulation strategy manipulates the switching vectors in order to result in constant CMV enabling the transformerless operation. Simulation and experimental results, as well as a comparative analysis with existing modulation techniques, are provided to show the good features of the proposed modulation strategy.