Research On Energy Self-supply Technology Of WSNs

Wireless Sensor Networks (WSNs) refer to many disciplines, and presently it hasbeen the research focus in IT field. In all of the factors affecting the life-span ofWireless Sensor Network (WSNs), the most important one is the power of WSNsnode. Therefore, researching the WSNs node power supply is very important.This paper described the common disciplines of node design. Layer DivisionMultiplexing was adopted in order to realize two kinds of nodes which have differentcommunication distance. The node has two power supply routes, one of which can beturned off to save energy. To match power supply system, the charge and dischargeprotection and estimating the rest remaining capacity of Li-ion battery is realized.Based on the research on the characteristics of super capacity and Li-ion battery, thenode power supply system of environment energy was designed. The system usessolar cell as energy scavenging device, and super capacity and Li-ion batteryconstitute multilevel energy storage structure. The energy store device consists of twosuper capacities in series which both have the rating voltage of 2.7V and capacitanceof 25F. The energy storage and support device consists of Li-ion battery. The systemcooperates with the node to scavenge energy from environment and supply it for thenode.The system software has been designed based on the embedded operation system,μCOS-Ⅱ. The software is divided into several tasks with different priorities to meetthe demand that the system could monitor the energy status of the energy store device,implement the energy information data sending, and switching among energy storedevices.The characteristics of the system were tested and the results were analyzed. Withthe duty cycle of 1%, two energy store devices can supply node for 24.6 hours. Theperformance of the system has achieved the design target approximately.