Performance evaluation of a 3-level ANPC photovoltaic grid-connected inverter with 650V SiC devices and optimized PWM

Photovoltaic energy conversion has been on the spotlight of scientific research for several years. Special attention was paid to the grid-connected inverters that do not feature an insulation transformer (transformerless topologies). In this framework, Neutral Point Clamped inverters have gained interest due to the low ground leakage current. Recently, the research has been focused on high-efficiency MOSFET-based topologies. In this paper an Active-NPC topology is equipped with 650V ROHM SiC devices. A new modulation strategy that allows to exploit the characteristics of Sic MOSFETs, is proposed. It permits to obtain very high efficiency due to the parallel operation of the devices during the freewheeling phases of the inverter output current. Simulation and experimental results show the benefits of this choice.