| Nowadays,radio power transmission is developing rapidly and has many advantages over wired power transmission.Among them,the magnetic coupling resonant wireless energy transmission mode has a broad application prospect because of its longer transmission distance,higher transmission power,better stability,stronger environmental adaptability and other characteristics.However,the transmission performance of this technology is also restricted by many factors.In practical application,the transmission efficiency will be unstable due to the change of system parameters,which needs to be solved.In this paper,the main factors affecting the transmission performance of the system are studied by analyzing the characteristics of the two topologies.The double closedloop PI control is used to realize the constant voltage control of the system,and the two topologies are respectively applicable occasions.This paper first introduces the common radio energy transmission technology,and briefly describes its structure,principle,advantages and disadvantages.Secondly,the transmission principle of the magnetically coupled resonant radio energy transmission system is analyzed.S-S traditional compensation topology and LCC-S high-order compensation topology are selected for detailed analysis.The mathematical model is built by using mutual inductance theory and AC impedance theory,and the influencing factors of the transmission characteristics are analyzed.Finally,MATLAB software is used to simulate the frequency characteristics,load characteristics and mutual inductance characteristics.By comparing different control strategies,a simulation model of S-S type radio energy transmission system based on BUCK circuit secondary side control was built.Double closed-loop PI control was selected to study its load output characteristics,and compared with single closed-loop control and open loop system.The input voltage,mutual inductance,load resistance and working frequency of the system are changed by using control variable method,and the output voltage and current waveform of the system under different control are analyzed.It is concluded that the waveform effect,robustness and stability of the system are better under double closed-loop control.Through the analysis of S-S magnetically coupled resonant radio energy transmission system,it is found that the transmission power of the system is low when the load is small.To solve this problem,this paper introduces LCC-S type high order compensation topology,and builds its simulation model in Simulink,analyzes its voltage and current output characteristics,and concludes that LCC-S type radio energy transmission system without any control means,can achieve constant voltage output,compared with S-S type topology analysis.The system transmits higher power when the load is small,and the S-S compensation topology is more suitable for the system with a large load.The main circuit of the system is given,and the finite element simulation of the coil in different distances and shapes is carried out by ANSYS/Maxwell software to select the appropriate transmission distance and coil shape.The experimental platform of radio energy transmission system was built,and the output voltage constant characteristics of S-S and LCC-S compensation topologies were verified experimentally.Experimental results show that S-S type compensation topology can realize power transmission and ensure its constant voltage output under double closedloop control,and LCC-S type compensation topology can realize constant voltage output under open loop state. |
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