Reducing charge redistribution loss for supercapacitor-operated energy harvesting wireless sensor nodes

With increasing demand of long term applications, supercapacitors have been widely chosen as energy storage devices for energy harvesting aware wireless sensor networks( WSNs) due to their long charging-discharging life cycles. However, few studies have focused on charge redistribution effect of supercapacitors in WSNs. In this paper, we investigate charge redistribution of supercapacitor and explore how it affects long term energy neutral operation (ENO). The Variable Leakage Resistance (VLR) model is used to analyze the charge redistribution effect. Our results indicate that charge redistribution may cause considerable amount of extra energy loss in long term ENO. A practical algorithm to minimize charge redistribution loss during energy neutral operation is proposed. The algorithm is computationally lightweight and can be incorporated into the state-of-the-art duty cycling power management strategies in WSNs. The proposed algorithm is proved to be effective in keeping the main branch and the delayed branch balanced and thus lowering energy dissipation from charge redistribution.