Effect of MPP-tracking dc/dc converter on VSI-based photovoltaic inverter dynamics

The utility-grid connection of a photovoltaic (PV) generator can be implemented by using a single or double-stage inverter. The single-stage inverter is connected directly to the PV generator, which is observed to significantly change the control dynamics of the inverter depending on the operating point. In the double-stage scheme, a dc/dc converter - operating either at open loop or under input-voltage-feedback control - is connected between the PV generator and the inverter. This paper investigates the effect of the dc/dc converter on the interfacing effects of the PV generator. The investigations show that the input-voltage-feedback control has clearly a stabilizing effect on the DC-link-voltage feedback control but the open-loop converter does not change the situation.