Research On Low-power Raido Frequency Energy Harvesting System

Environmental energy harvesting is a kind of energy harvesting method that can directly obtain energy from the environment and convert it into electrical energy.Compared with the traditional power supply technology,it has been widely recognized by the society because of its advantages of sustainability,green,no environmental pollution and the battery is no need for manual replacement.Among many environmental energy harvesting technologies,environmental radio frequency energy harvesting technology has been widely concerned because of the advantages of wide coverage and long transmission distance.The technology composes of antenna,matching circuit,doubled voltage rectifier circuit.With the help of the principle of the conversion between electromagnetic field and electric energy,the technology realizes the wireless collection and application of electric energy.Aiming at problems that low energy acquisition,low collection efficiency and low output voltage of RFEH system caused by the characteristics of high frequency and low power of environment RF energy,a high gain omnidirectional micro-strip antenna,a voltage doubled rectifier system design method and a matching circuit optimization method are proposed.Firstly,in order to solve the problem of low energy acquisition,an omnidirectional micro-strip antenna is designed by the meandering technology and the loading technology.In order to improve the antenna gain,a dual-G type metamaterial element is designed to adapt to 0.915GHz signal and load it into the micro-strip antenna.The antenna is used as the front-end of RFEH system to improve the system power from environmental sources.Secondly,in order to solve the low collection efficiency and low output voltage,this paper designs doubled voltage rectifier system and optimizes matching circuit respectively.Starting with the research and analysis of the traditional mathematical model of doubled voltage rectifier system,the diode mathematical model is established.Based on that,the exhaustive method is used to balance the boost effect and component loss of the doubled voltage rectifier circuit,and different types’diodes are used to build a low-power doubled voltage rectifier system that meets the output voltage requirements.In addition,based on the proposed mathematical model,the calculation model of matching circuit parameters is obtained and the best matching parameters are obtained by using quantum particle swarm optimization to improve system matching performance.Finally,simulation test and physical test are both used to analyze the designed RFEH system and verify the feasibility and effectiveness of designed antenna and proposed method.The experimental results show that the designed antenna meets the requirements of high gain and omnidirectional,and can improve the harvest power of the system.These also show that the proposed design and optimization method can significantly improve the output power and transmission efficiency of RFEH system.The experimental results show that the system can output 2.74 Vvoltage at-5dBm input power,and the circuit conversion efficiency can reach 39%.