Research On SENSOR Node Design And Charge And Discharge Strategy In WRSNS

Wireless power transfer,based on magnetic coupling resonance(MCR-WPT),provides a new method for the energy supplement of wireless sensor networks.Suppling energy to network nodes by the MCR-WPT,and constructing wireless rechargeable sensor networks(WRSNs)have become one of research focuses of wireless sensor networks.In the WRSNs,design and the charging-discharging strategy of Sensor nodes directly affect efficiency of harvesting energy and determine the robustness of networks.Considering functional requirements of network nodes,design of dual power is used to ensure the stability of Sensor nodes.In the charging-discharging process of Sensor nodes,frequency,instance and load having influence on receiving power and transmission efficiency are analyzed,in order to find the optimal charging-discharging strategy,and provide the basis for energy distribution.The main work is as follows.Sensor nodes are designed and the WRSNs are built.According to functional characteristics of WRSNs' nodes,designing requirements and indicators are proposed.The structure,hardware and software designs are carried out.In hardware design,the power module is based on MCR-WPT,and is charged wirelessly.The dual power ensures Sensor nodes work stably and continuously.Functional characteristics of MCR-WPT are studied.In the charging-discharging process of Sensor nodes,the influence of frequency,distance and load on receiving power and transmission efficiency are analyzed.According to results,MCR-WPT transfers wireless energy with higher energy efficiency and higher power under the optimal working conditions.The charging-discharging strategy of Sensor nodes is studied.In the wireless charging-discharging process of Sensor nodes,according to charging and discharging conditions of rechargeable battery,which is divided into four types:no-charging and no-discharging,charging and no-discharging,discharging and no-charging,and charging and discharging at the same time.According to results,in the transmission distance range of 0?130mm,the charging and no-discharging conditions of lithium battery,suppling energy with higher efficiency and greater power,is the optiomal charging-discharging strategy.Based on the WRSNs' experimental platform,experimental results show that the designed chargeable nodes meet requirements,the resonant frequency is 83KHz,the transmission distance is 0-200mm,the horizontal offset is-80?+ 80mm and the deflection angle is-50?+50 degree,combined with the charging-discharging strategy of lithium battery,Sensor nodes achieve the optimal energy supply,and prolong the lifetime.