Optimal Design of Series-Parallel Differential Power Processing Converters for Photovoltaic Array Energy Systems

A scheme is proposed for maximum power point tracking in series-parallel photovoltaic arrays using differential power processing, based on bidirectional Cuk converters and inverted buck converters for adjusting module current and voltage respectively. Converter transfer functions are derived using linearization and state space time averaging. These are used to develop design criteria for well-behaved transient response, and reduction of the effect of non-minimum phase. A representative design with about 10 ms settling is presented. It is shown that this can form the basis of a successful perturb-and-observe control system.