Quasi-Z-Source inverter with energy storage for Photovoltaic power generation systems

In this paper the Quasi-Z-Source Inverter (QZSI) with Energy Storage for Photovoltaic Power Generation Systems is presented. The energy storage device was integrated to QZSI topology with no need for an extra charging circuit. This upgraded topology acquires the operating characteristics from the traditional QZSI, plus the capability of operating under very low PV power conditions. Its main operating points are classified into two modes, the low PV power mode, where the battery is discharged and the high power mode, where the battery is charge up. An extended input power operating range is achieved since the lack of Photovoltaic power can be compensated by the battery. Quasi-Z-Source inverters are very suitable for Photovoltaic power generation systems and this upgrade makes them even more suitable for this type of applications. To obtain the experimental data, a prototype was built and used to demonstrate that the Quasi-Z-Source inverter is capable of managing the State of Charge of a battery and the AC output voltage in each operating mode.