| Magnetic coupled resonant wireless power transfer(MCR-WPT)technology is an important direction in the field of wireless power transfer(WPT)research,which can achieve efficient transmission of electrical energy at medium distances.It shows wider application prospects in real life and has become a research hotspot in this field.However,in the current research,the transmission distance and transmission efficiency of MCR-WPT still cannot meet the needs of some applications,and the optimal operating frequency of the multi-load system is not stable as the number of loads changes.Therefore,this paper has carried out basic theoretical analysis and simulation research on the transmission distance,transmission efficiency and optimal operating frequency of MCR-WPT.The research content of this paper is mainly divided into the following aspects.This article first introduces and analyzes the key features of the MCR-WPT system.Based on the single resonator model,the coupling mode theory and the mutual inductance theory are analyzed,and the system topology,the different structure types of the resonator in space and composition are studied in detail.The transmission characteristics of the system and high-frequency energy conversion technology are introduced.Secondly,after reasonable design of the main parameters of the system,a more detailed theoretical analysis of the traditional double-resonant coil structure is carried out.Under the premise of optimal transmission of the system,the change of transmission efficiency with the transmission distance is studied.The above content has laid a theoretical foundation for further research in this article.Then,in view of the short transmission distance of the MCR-WPT dual resonant coil system,a three-coil system structure with relay coils was used for improvement.A series of work such as system modeling and circuit equivalence are carried out to obtain the optimal frequency configuration of the system and the mathematical model of the system transmission efficiency changing with distance.In the simulation experiment,compared with the dual-coil system,the transmission distance between the three-coil system is increased while the transmission efficiency is unchanged,and the output power is improved.So the superiority of the three-coil system is verified.At the same time,for the problem that the optimal operating frequency changes with the number of loads in a single relay-multi-load MCR-WPT system,a spatial arrangement method of receiving coils is proposed.When the arrangement radius changes within a certain effective area,the optimal operating frequency of the system can be kept constant.Finally,class E power amplifier is added as the high-frequency power supply of the system to improve the transmission efficiency and output power of the system.In addition,in view of the shortcomings of the large voltage and current values of the switch tube in the traditional class E power amplifier,a new class E power amplifier was designed and applied to the three-coil MCR-WPT system with relay coil.According to its working principle,the parameters of each component in the system are designed,and the complete MCR-WPT system model is established using Matlab/Simulink for simulation.The results show that compared with the traditional class E power amplifier,the current and voltage values of the switch tube in the new class E power amplifier are reduced under the same system parameters and the transmission characteristics remain unchanged,so that the safety and reliability of the system have been improved to a certain extent. |
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