Study Of Key Technique For Wireless Electrical Energy Transmission System

Wireless Power Transmission(WPT)is currently a hot topic.At present,the decives using electromagnetic coupling always have big volume and bring a certain level of electromagnetic radiation,which is a dispute in the biological safety.The carrier power also decays rapidly in high frequency.It is not applicable in certain occasions such as implantable devices.In contrast,Ultrasonic Wireless Power Transmission(UWPT)system has the advantages of non-electromagnetic radiation and good directivity which becomes an emerging field.The key technique for UWPT system is studied in the paper.The research work mainly includes the following three aspects:(1)Theoretical study and simulation are made for UWPT system.The ultrasonic propagation characteristics and the piezoelectric conversion characteristics of ultrasonic transducers are explored.The sound field distribution in the medium and the influence of parameters,frequency,transducers size,medium,distance,angle are analyzed.According to the sound field visualization simulation based on Matlab:The direction of the ultrasonic wave enhanced with the increase of frequency and the transducer size.Transducers get the highest efficiency under the condition of the Angle 0.(2)Based on the principles of statistical acoustics,an UWPT system is designed to monitor the influence of the factors.The power fading characteristic of ultrasonic channel is studied and modeled using statistical methods.The characteristics of the channel can be described and predicted by the established models which are verified by the experimental data and the simulation results.(3)An voltage conversion circuit is designed based on the chip MAX 1672.As the energy generated from transducers is not stable,a DC-DC circuit is designed and optimized.The unstable voltage is changed into 5.0V output voltage through the circuit.The output voltage can be adjusted from 1.25 V to 5.5V through the external resistors.The paper provides a new design method of WPT system.Under the condition of ultrasonic frequency 40 KHz,transducer size 38 mm,angle?0,distance 10 cm,the system outputs 4.91 V and transfers 10.5 mW power in the medium of pure water.The design ofultrasonic wireless power transmission system is realized.The system's performance is close to the literature.