Charging strategy for super capacitor of photovoltaic generation system

The improved RC model of super capacitor is applied in the analysis of its charging efficiency for different charging methods. A super capacitor charging system based on Bo CBB(Boost Cascaded Buck converter) is proposed for photovoltaic power generation system and a complete control strategy is designed for it. The Boost converter is connected to photovoltaic system and an improved perturb-observe method is adopted to track the maximum power point. A multi-step charging strategy is adopted to charge the super capacitor by the Buck converter. The concept of equivalent current source is applied in the modeling of Bo CBB front and back stages,based on which,the main circuits of charging system are modeled and the controller of current loop is designed. The charging efficiency of photovoltaic cell to super capacitor is simulated for different illumination intensities. A test platform is built and the comparative experiment shows the proposed charging strategy improves the charging efficiency effectively.