| Magnetically Coupled Resonant Wireless Power Transfer(MCR-WPT)technology has received more and more attention and is widely used at home and abroad due to the advantages of high transmission efficiency,high output power and medium and long distance transmission.However,there are still some problems in practical application,such as the change of load and the relative position of charging equipment during the charging process will affect the system transmission efficiency and output power,resulting in the degradation of the system transmission performance.Therefore,how to realize the stable output of the system when the coupling coefficient and load change becomes a critical problem to be solved in the current MCR-WPT system.To address the above problems,the two-coil system with series-series structure is selected as the research object in this paper,and the research is carried out in two aspects of improving the system transmission efficiency and output power.The main research work of this article is as follows:1、MCR-WPT system performance analysis:In order to improve the system transmission performance,firstly,the system equivalent circuit model is established according to the circuit theory,and the expressions of the system transmission efficiency and output power are derived as well as the corresponding load value when working in the optimal transmission state,and it is concluded that the system transmission performance is related to the load,and the optimal load is related to the coupling coefficient,so when the coupling coefficient or load changes will lead to the system Therefore,when the coupling coefficient or load changes,the transmission performance of the system will change.Then the influence of system parameters on the system transmission performance is analyzed,focusing on two parameters of coupling coefficient and load.Finally,the impedance matching technique is studied,and the impedance-matching based system performance enhancement method is proposed.2、Maximum efficiency tracking based on fuzzy control:For the problem that the system transmission efficiency decreases due to the change of coupling coefficient or load during the system operation,the maximum efficiency tracking based on fuzzy control is proposed,and the maximum efficiency transmission of the system is achieved by dynamically adjusting the duty cycle of the DC/DC converter to convert the equivalent load of the system to the optimal load corresponding to the maximum efficiency point.It is also compared with the maximum efficiency tracking based on perturbation observation,and the superiority of the proposed method is verified.Also,since the system causes the system output voltage to change during the maximum efficiency tracking,the output voltage is stabilized by phase shift control.3、Impedance matching based system power control:Firstly,the maximum power transmission of the system when the coupling coefficient or load changes is achieved by maximum power tracking,then the maximum power output of the power supply is achieved by impedance matching technology,and the impedance matching algorithm and the design of the matching network are studied,and the method of double-end matching of the system is proposed so as to further improve the output power of the system.Finally,an experimental platform is built to verify the proposed scheme,which lays a theoretical foundation for improving the transmission performance of the system. |
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