Design and control of an advanced PV inverter

In this paper the design and the control of an advanced PV (Photovoltaic) inverter is discussed. The input power stage consists of a dc-dc converter based on coupled-inductors boost topology. This circuital configuration guarantees the high voltage amplification needed in grid-connected PV applications. The second power stage is a three-phase inverter operated in order to exploit the functionality of a two legs configuration. The operation principle of the proposed circuit is analyzed and a proper PV panel model is used. The adopted control strategy is based upon sliding control technique in order to exploit its well-known properties of robustness. Furthermore, a Maximum Power Point Tracking (MPPT) approach based on the extremum seeking scheme has been employed for fast tracking the irradiation changes by performing an adaptive sliding surface. Moreover, a great attention has been devoted to the control of the inverter in order to obtain power factor correction, effective reduction of both unbalances and waveforms distortion. Finally, the numerical results reported in the paper permit to confirm the feasibility of the proposed design and control strategy.