Analysis and Design of Smart PV Modules

摘要

This paper explores the design of smart photovoltaic (PV) modules-PV modules in which PV cells in close proximity are electrically grouped to form pixels and are connected to dc-dc converter blocks which reside embedded in the back pane of the modules. An auto-connected flyback converter topology processing less than full power is used to provide high gain and perform maximum power point tracking. These dc-dc converters interface with cascaded H-bridge inverter modules operating on feed-forward control for dc-link voltage ripple rejection. By means of feed-forward control, a significant reduction in dc link capacitance is achieved by enduring higher dc link ripple voltages. The dc link electrolytic capacitors are replaced with film capacitors, thus offering an improvement in the reliability of the smart PV module. The proposed configuration is capable of producing 120 V/240 V ac voltages. The PV module now becomes a smart ac module by virtue of embedded intelligence to selectively actuate the individual dc-dc converters and control the output ac voltages directly, thus becoming a true plug-and-power energy system. Such a concept is ideal for curved surfaces such as building-integrated PV system applications where gradients of insolation and temperature cause not only variations from PV module to PV module but also from group to group of cells within the module itself. A detailed analysis along with simulation and experimental results confirm the feasibility of the proposed concept.