PV-BESS CHB Operating in the Overmodulation Region

In this paper a photovoltaic (PV) battery energy storage system (BESS) cascaded H-Bridge (CHB) inverter able to operate in the overmodulation region is proposed. The overmodulation issue is addressed by means of a hardware solution consisting of an additional power cell in the cascade fed by a battery instead of a PV Generator (PVG). The effect of the additional BESS cell is an improved MPPT efficiency obtained thanks to a more quickly reduction of the modulation index when a predefined upper limit is exceeded. Numerical simulations carried out in PLECS environment evidence the effectiveness of the proposed hardware solution along with the control and modulation approach in terms of extended operating range and MPPT efficiency.