Design of New Power Management System in Wireless Sensor Network

A new power management circuit which includes energy conversion sub-system (photovoltaic battery),energy storage sub-system(lithium-ion battery+ultracapacitor energy conversion sub-system) and power management sub-system is designed. The power management circuit provides electricity to the wireless sensor node. The energy conversion sub-system adopts four solar photovoltaic batteries to capture energy from the environment. One of the solar photovoltaic batteries is installed above the packaged wireless sensor node, the others are installed on the three sides. Experimented under standard sunlight, it is tested that the V-T curve and I-T curve of lithiumion battery and wireless sensor node and the response curve of sunshine change and that of loaded power pulse of the energy management system . As can be seen clearly, in the energy management system where the lithium-ion battery-ultracapacitor hybrid energy storage technology is applied , the charge/discharge procedure of the lithium-ion battery gets remarkably optimization due to ultracapacitor´s filtering function, so as to slow its aging course. Besides, despite the change of voltage upon lithium-ion battery, the wireless sensor node can work steadily as realizing its continuous working. Thus, the rationality of power management system is proved.