基于光伏发电系统的超级电容器充电效率的研究

针对光伏发电系统中超级电容器在恒压、恒流和恒功率充电模式下的充电特性,提出提高充电效率的计算方法。分析了对超级电容器充电时不同充电模式下的最高充电效率,获得了超级电容器分段充电效率曲线,表明恒功率充电方式在最大功率点跟踪控制下更适合对超级电容器充电。提出了在光伏发电系统中使用双级Buck-Boost变换器对超级电容器进行最大功率点跟踪/恒功率混合控制的充电策略,仿真结果表明该策略可以有效保证系统的充电效率。

Research on supercapacitor charging efficiency in photovoltaic system

The model of supercapacitor and its charging performance with constant voltage charging mode,constant current charging mode and constant power charging mode were studied.A numerical method to calculate the efficiency of these charging modes was inducted.To analyze the storage performance of supercapacitor in PV system,using this method,the maximum charging efficiencies of supercapacitor when its terminal voltage raise from zero to the rated voltage with different charging modes were presented.The multi-stage charging efficiency curves were retrieved,which indicated that the constant power charging mode is more suitable when supercapacitor are charged in PV system.A MPPT plus constant power control charging strategy using two-stage Buck-Boost converter to charge supercapacitor in PV system was proposed.The simulation results showed that this strategy effectively ensure the charging efficiency of the system.