Research On Self-powered Wireless Sensor Network Nodes Based On Thermoelectric Energy Harvesting

In practice,wireless sensor network(WSN)gets rid of the shortcomings of high cost,poor maintenance and poor flexibility of traditional wired systems,and has been widely used in military,industrial,agricultural,anti-terrorism,disaster relief,environment,medical and other fields.At present,most WSNs are powered by batteries.The energy of the batteries limits the continuous long-term operation of the WSNs.Frequent battery replacements greatly increase the system maintenance workload.Therefore,it is necessary to collect wind,solar,thermal and vibration energy in the surrounding environment.Supply power to WSNs nodes,so as to achieve the purpose of permanent or semi-permanent self-powering.Considering the large number of heat sources in various industrial environments,this paper focuses on thermoelectric energy harvesting techniques.The self-powered system of WSNs nodes based on thermoelectric energy harvesting technology needs to design a DC-DC boost conversion circuit with appropriate parameters to increase the output voltage;select appropriate energy storage devices to store energy;apply effective maximum power tracking(Maximum Power Point Tracking,MPPT)algorithm to achieve the maximum power output of the thermoelectric generator(Thermoelectric Generator,TEG);design a step-down voltage regulator circuit,supply a stable voltage to the node,and at the same time play the role of protecting the node.Based on these contents,the main work of this paper is as follows:1.The model of the WSNs node self-powered system is established in Matlab/Simulink,including the TEG model,the DC-DC boost circuit model and the load model.The MPPT algorithm proposed in this paper is used in the simulation to achieve the maximum output power of the TEG.and boost the output voltage to 5.696 V.2.Design the hardware and software of the self-powered system of WSNs nodes.In terms of hardware,a suitable DC-DC boost circuit is designed,super capacitors are selected as energy storage devices,and a step-down voltage regulator circuit based on LTC1877 is designed;in terms of software,an overall program is written on the WSNs node,including initialization procedures,PWM Wave control program and MPPT algorithm program.3.Build an experimental platform to verify the boosting effect of the DC-DC circuit;verify the experimental effect of the buck regulator circuit;verify the performance of the MPPT algorithm at five different temperatures.The thermoelectric energy harvesting device,DC-DC boost conversion circuit,energy storage device,step-down voltage regulator circuit and nodes are connected to conduct WSNs node self-powered experiments.When the temperature of the heating table in the thermoelectric energy harvesting device is set to 150 °C,WSNs nodes work about 3.2s longer with the MPPT algorithm than without the MPPT algorithm,and the service life is extended by about 9%.