A Single-Phase Five-Level Grid-Connected Inverter for Photovoltaic Applications

With the increasing energy demands and environmental impacts from conventional energy sources, especially fossil fuels, renewable energy sources are increasingly popular. Among which, photovoltaic (PV) energy generation systems stands out due to their ease of installation, maintenance and low acquisition cost. Single-phase PV systems connected to the grid are commonly used in small and medium-sized residential and commercial installations. This paper proposes a single-phase five-level inverter for grid-connected PV systems. A PWM technique is applied to balance the voltages across the dc-link capacitors. Moreover, the technique has a suitable performance in terms of conducting and switching losses. The results shows the effectiveness of the technique for injecting suitable low distorted currents into the grid. Moreover, the system operates correctly to balance the voltages across the dc-link capacitors and under abrupt changes of the available power from the PV panels.