基于微生物燃料电池供能的无线温度传感系统设计

Design of wireless temperature sensing system powered by mcrobial fuel cell

微生物燃料电池(microbial full cell,MFC)是利用微生物作为生物催化剂将碳水化合物转化为电能的装置。针对MFC输出电压低、功率小、内阻大的特点,该文研制了一种具有最大功率点跟踪(maximum power point tracking,MPPT)功能的能量收集电路和两级升压电路;基于MSP430和CC2500芯片设计了环境温度传感系统。测试结果表明,MFC的输出电压维持在316~390 mV范围内,实现了最大输出功率的跟踪,MPPT电路和升压电路分别输出1.1和3.5 V电压;无线温度传感器以每13 ms的周期将环境温度无线传输到远程终端,验证了环境温度传感系统在最大功率点处对无线传感器网络节点供电工作的可行性,可为实现MFC主动式能量收集提供参考。

With the modernization of agriculture and social informatization,the internet of things(IoT)and the wireless sensor network(WSN)are widely used in the agricultural application.The sensor nodes play important roles in IoT and WSN system,which have strict requirements on the battery.In the traditional scheme,WSN is powered by the lithium battery or solar panel.It is very hard to recharge the lithium battery in the wild,while the solar panel is greatly limited by the environment.It brings great challenge to the power supply of sensor nodes.The microbial full cell(MFC)is one of the most promising renewable energy,which can be used for the self-power supply of the sensors in real application.MFC uses microbes as biocatalysts,which can transform carbohydrates into electrical energy.In order to improve the efficiency of MFC,lots research has been done.The maximum power output of MFC has been gradually improved.However,the output open-circuit voltage of MFC is low,about 0.7 V,and the internal resistance is large,so it is impossible to ensure the MFC working at the maximum power point.Based on the polarization curve and output power density of the MFC reactor,a power management module is designed to improve the efficiency of MFC in this paper.The output power management module consists of an energy harvesting circuit and a secondary booster circuit.The energy harvesting circuit consists of a DC-DC converter,hysteresis compactors(ADCMP609 and 74HC32)and a large capacitor,which has a function of the maximum power point tracking(MPPT).The circuit can boost the output voltage of MFC at the maximum power point,which improves the system energy conversion efficiency.The secondary booster circuit consists of an Ener Chip energy processor(CBC915),a charge pump(IC S882Z24),an Ener Chip solid state battery module(CBC51100).The secondary booster circuit can improve the voltage on the large capacitor connected with the output of the energy collection circuit and the working voltage of the wireless temperature sensor,and provide a stable power supply for the next stage circuit.The wireless temperature monitor system is powered by the proposed power management module.MSP430 and CC2500 chips are used in the temperature monitor system to collect the environmental temperature and send the real-time temperature data to the remote terminal.The measured results show that the output voltage of MFC in the system is maintained in the range from 316 to 390 mV,and the function of maximum power point tracking is realized.The output voltage of the energy harvesting circuit and the secondary booster circuit are 1.1 and 3.5 V,respectively.By using MFC as the power supply,the wireless temperature sensors deliver the environment temperature data to the remote terminal at a period of 13 ms.The proposed energy harvesting circuit for MFC with MPPT function provides an innovative solution to solve the problem of the power supply for sensor nodes,and has great potential in agricultural environmental monitoring system.