Energy Acquisition Self-powered System And Energy Balance Model

Wireless sensor network is widely used in security monitoring,smart power grid,smart home system and other fields.Previous wireless sensor nodes are battery powered,and the system life is limited by the battery capacity,and the battery capacity is limited due to the device size and weight.Energy harvesting receives energy from the surrounding environment（such as solar,piezoelectric,thermal,and radio frequency）to keep the device operating.The background of this paper comes from the national key research and development program of "Science and Technology Winter Olympics" key project: the key technology project of design,construction,operation and maintenance of snow venues for the Winter Olympics under complex mountain conditions.The combination of energy acquisition technology and wireless sensor network is expected to eventually realize the self-sustaining wireless sensor network node with infinite life,collect environmental data,carry out safety monitoring,establish system simulation model,and study the energy relationship of the energy balance system.Firstly,a simulation model is established in the Simulink simulation module,and several key parameters are set to conduct system-level simulation.The integrated simulation model can be used to observe the energy of the system,and observe the energy change of the system by modifying the parameters,guide the device selection of the actual hardware equipment and conduct simulation verification before establishing a new set of equipment.It mainly includes energy generation model,ultracapacitor energy consumption model,power management model and sensor node energy consumption model.In the model,maximum power tracking technology（MPPT）is used to make photovoltaic cells work at the maximum power point,and the control accuracy reaches 93.93%～95.63%.Adjustable parameter Settings include:sensor node working mode time,ambient temperature difference,illumination intensity,RF chip transmitting power,MCU main frequency,etc.Secondly,based on the established simulation model,hardware design verification is carried out to design and produce stable self-powered wireless sensing equipment,which is used for safety and environment monitoring and venue security of the Winter Olympics.Each self-powered wireless sensing device is composed of three modules: energy generation module,energy storage module and sensor node module.The system converts ambient energy into electricity and uses an energy management chip to increase the output voltage of the TEG,which is stored in the ultracapacitor.The power management circuit is used to control its output,and the output voltage of 3.3V is stable,so that the sensor node can operate continuously.The power consumption of the sensor nodes in the sleep mode is 57.6μA.After low-power processing of the program logic,the cycle running time of the system is reduced by65.7%,and the average power consumption of the sensor nodes is reduced by 85%.The simulation results of the simulation model（the simulated voltage of the ultracapacitor）are compared with the measured data of the hardware equipment（the voltage value）,and the error is very small.In the charging section of the system operation,the error fluctuates within 5%;After the sensor node starts to work,due to the instantaneous power change,the error increases,the average value is 7%,and the peak value remains within 15%.