Distributed MPP-Tracking: Cross-Coupling Effects in Series and Parallel Connected DC/DC Converters
Juha Huusari, Teuvo Suntio · EU PVSEC · 2012
In practical photovoltaic installations, difficulties with partial shading and module have been observed to greatly reduce the energy yield. These difficulties are typically encountered in built environment, where the system is frequently shaded e.g. by nearby buildings. A widely recognized solution to overcome these difficulties is to utilize module-wise dc/dc converters, enabling module-level maximum power point (MPP) tracking and interfacing the module into a common dc link, i.e. the input terminal of a grid-connected inverter. This kind of distributed MPPtracking can be implemented either with output-series or output-parallel connected dc/dc converters. Of these two, the series configuration has been observed to contain operational anomalies which degrade the energy yield. So far, the origin for these anomalies has not been presented. This paper fills the gap by presenting small-signal models for both system configurations and with them explains the observed phenomenon.