Transformerless split-inductor neutral point clamped three-level PV grid-connected inverter

Abstract

The neutral point clamped three-level PV grid-connected inverter characterized with low leakage current and low voltage stress of switches, is suitable for transformerless PV grid-connected inverter with higher input voltage. Nevertheless, shoot-through problem of the power devices exists still in bridge leg. So its reliability has been degraded. In order to solve this problem, an improved three-level grid-connected inverter is proposed based on the neutral point clamped three-level inverter and the dual Buck half bridge inverter in this paper, which guarantees no high-frequency common-mode voltage and no shoot-through issue. And then, the freewheel diode of bridge legs of dual Buck half bridge inverter can be ignored considering unity power factor of PV grid-connected inverter, and a straightforward topology has been derived. The operation mode, running style, common-mode characteristic, and control strategy are analyzed. Finally, both of the simulation and the experimental results verify the feasibility of proposed three-level inverter.