Abstract

DC-DC converters are a fundamental piece in the power conditioner required to interface the PV module or array to the loads or the grid. This since the PV source is characterized by having a soft response, i.e. its voltage has a large variation between open circuit and maximum power point, and by having low magnitude. Moreover, power generated varies with solar irradiance and due to shadows. Thus, the DC-DC converter in the power conditioner has to provide a large voltage gain and must be able of following the maximum power point of the source as the irradiance varies. Also, it is highly desirable that the current drawn from the source should be continuous, and with as little ripple as possible to optimize energy harvesting. Over the years, several DC-DC topologies that can comply with these requirements have been proposed and tested. Among these, two appear as good candidates due to their performance in terms of voltage gain and input current regulation, the quasi-Y source, and the quasi-Z source converters. In this paper analysis and comparison of these two topologies is performed and it is shown that the latter offers better operation characteristics in terms of performance and power density.