| With the continuous improvement of science and technology in human society,the energy for social production is expanding rapidly.Electric energy is very representative among plenty kinds of energy.Nowadays,the vast majority of electric energy is transmitted through the transmission line.But it is not suitable for some specific application scenarios.Wireless power transfer technology gets rid of the shackles of wire and greatly improves the convenience.This paper is based on the magnetic coupling resonant technology,studies the traditional single coil model and omnidirectional model.The details are as follows:Based on the coupled mode theory and equivalent circuit model theory,the theoretical model of single coil MCR-WPT system is built,and the expressions of energy transmission and efficiency formula are derived.According to the equivalent circuit,the theoretical model of omnidirectional MCR-WPT system is built,and the transmission efficiency formula is derived.Through the electromagnetic simulation software Maxwell and Simplorer,the transient distribution of magnetic field and the function of resonant compensation are analyzed.According to the parameters in the efficiency formula,the system is analyzed mainly including coil parameters,system working frequency,coil mutual inductance,distance and offset angle between transmitting and receiving coils.Meanwhile,this paper presents a method for measuring the offset angle of receiving coil in single coil MCR-WPT system based on reflected impedance.The correctness of the proposed theoretical formula is proved by simulation and experiment.Furthermore,the theoretical formula is extended to omnidirectional system,and the maximum efficiency offset angle of omnidirectional MCR-WPT system is calculated by MATLAB simulation.The resonance frequency drift in single coil MCR-WPT system is analyzed.By using MATLAB simulation,the change trend of transmission efficiency when the system is in the state of over coupling,critical coupling and under coupling is obtained,and the position of critical point is deduced.The above theory is extended to omnidirectional system,and the optimal transmission distance of omnidirectional system is obtained by simulation.The driving circuit and inverter circuit of MCR-WPT transmitting module,the rectifier and filter circuit of receiving module and some peripheral circuits are designed.The overall circuit design scheme is given and the experimental device of omnidirectional wireless power transmission system is built.Several groups of control experiments are carried out.The experimental results show that the transmission efficiency of omni-directional MCR-WPT system can reach 45.7%when the system is in resonant state and the receiving coil is at the maximum power point,which is 9.5%higher than other cases on average. |
PDF Full Text Request