Discontinuous PWM Operation of a Single-Phase PV Generator With Low-Voltage Energy Storage

Using energy storage (ES) in grid-connected photovoltaic (PV) generators is an efficient solution to deliver regulated power to the grid despite fluctuations in solar irradiance. The article analyses a single-phase grid-connected PV generators with ES, where the ES has a low voltage, namely without too many series-connected storing cells. The PV generator consists of three subsystems connected by a common dc-link capacitor: a PV unit, an ES unit, and an inverter. Furthermore, in the proposed solution, the inverter does not switch for a significant portion of the grid period, resulting in lower switching losses. The single-phase inverter discontinuous operation implies the need of an appropriate control strategy in the boost dc–dc converter of the ES unit. The proposed control employs an augmented state model that accounts for resonant variables. The proposed PV solution with low-voltage ES, including its control, is validated in a 350-VA experimental prototype to verify the novel approach.